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The patch is generated using this command: tools/clang/tools/extra/clang-tidy/tool/run-clang-tidy.py -fix \ -checks=-*,llvm-namespace-comment -header-filter='llvm/.*|clang/.*' \ llvm/lib/ Thanks to Eugene Kosov for the original patch! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240137 91177308-0d34-0410-b5e6-96231b3b80d8
4489 lines
173 KiB
C++
4489 lines
173 KiB
C++
//===- SROA.cpp - Scalar Replacement Of Aggregates ------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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/// \file
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/// This transformation implements the well known scalar replacement of
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/// aggregates transformation. It tries to identify promotable elements of an
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/// aggregate alloca, and promote them to registers. It will also try to
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/// convert uses of an element (or set of elements) of an alloca into a vector
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/// or bitfield-style integer scalar if appropriate.
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///
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/// It works to do this with minimal slicing of the alloca so that regions
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/// which are merely transferred in and out of external memory remain unchanged
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/// and are not decomposed to scalar code.
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///
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/// Because this also performs alloca promotion, it can be thought of as also
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/// serving the purpose of SSA formation. The algorithm iterates on the
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/// function until all opportunities for promotion have been realized.
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///
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/SetVector.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Analysis/AssumptionCache.h"
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#include "llvm/Analysis/Loads.h"
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#include "llvm/Analysis/PtrUseVisitor.h"
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#include "llvm/Analysis/ValueTracking.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/DIBuilder.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/DebugInfo.h"
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#include "llvm/IR/DerivedTypes.h"
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#include "llvm/IR/Dominators.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/IRBuilder.h"
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#include "llvm/IR/InstVisitor.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/IntrinsicInst.h"
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#include "llvm/IR/LLVMContext.h"
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#include "llvm/IR/Operator.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/MathExtras.h"
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#include "llvm/Support/TimeValue.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/Transforms/Utils/PromoteMemToReg.h"
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#include "llvm/Transforms/Utils/SSAUpdater.h"
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#if __cplusplus >= 201103L && !defined(NDEBUG)
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// We only use this for a debug check in C++11
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#include <random>
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#endif
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using namespace llvm;
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#define DEBUG_TYPE "sroa"
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STATISTIC(NumAllocasAnalyzed, "Number of allocas analyzed for replacement");
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STATISTIC(NumAllocaPartitions, "Number of alloca partitions formed");
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STATISTIC(MaxPartitionsPerAlloca, "Maximum number of partitions per alloca");
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STATISTIC(NumAllocaPartitionUses, "Number of alloca partition uses rewritten");
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STATISTIC(MaxUsesPerAllocaPartition, "Maximum number of uses of a partition");
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STATISTIC(NumNewAllocas, "Number of new, smaller allocas introduced");
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STATISTIC(NumPromoted, "Number of allocas promoted to SSA values");
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STATISTIC(NumLoadsSpeculated, "Number of loads speculated to allow promotion");
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STATISTIC(NumDeleted, "Number of instructions deleted");
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STATISTIC(NumVectorized, "Number of vectorized aggregates");
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/// Hidden option to force the pass to not use DomTree and mem2reg, instead
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/// forming SSA values through the SSAUpdater infrastructure.
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static cl::opt<bool> ForceSSAUpdater("force-ssa-updater", cl::init(false),
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cl::Hidden);
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/// Hidden option to enable randomly shuffling the slices to help uncover
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/// instability in their order.
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static cl::opt<bool> SROARandomShuffleSlices("sroa-random-shuffle-slices",
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cl::init(false), cl::Hidden);
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/// Hidden option to experiment with completely strict handling of inbounds
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/// GEPs.
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static cl::opt<bool> SROAStrictInbounds("sroa-strict-inbounds", cl::init(false),
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cl::Hidden);
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namespace {
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/// \brief A custom IRBuilder inserter which prefixes all names if they are
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/// preserved.
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template <bool preserveNames = true>
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class IRBuilderPrefixedInserter
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: public IRBuilderDefaultInserter<preserveNames> {
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std::string Prefix;
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public:
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void SetNamePrefix(const Twine &P) { Prefix = P.str(); }
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protected:
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void InsertHelper(Instruction *I, const Twine &Name, BasicBlock *BB,
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BasicBlock::iterator InsertPt) const {
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IRBuilderDefaultInserter<preserveNames>::InsertHelper(
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I, Name.isTriviallyEmpty() ? Name : Prefix + Name, BB, InsertPt);
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}
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};
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// Specialization for not preserving the name is trivial.
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template <>
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class IRBuilderPrefixedInserter<false>
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: public IRBuilderDefaultInserter<false> {
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public:
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void SetNamePrefix(const Twine &P) {}
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};
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/// \brief Provide a typedef for IRBuilder that drops names in release builds.
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#ifndef NDEBUG
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typedef llvm::IRBuilder<true, ConstantFolder, IRBuilderPrefixedInserter<true>>
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IRBuilderTy;
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#else
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typedef llvm::IRBuilder<false, ConstantFolder, IRBuilderPrefixedInserter<false>>
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IRBuilderTy;
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#endif
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} // namespace
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namespace {
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/// \brief A used slice of an alloca.
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///
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/// This structure represents a slice of an alloca used by some instruction. It
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/// stores both the begin and end offsets of this use, a pointer to the use
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/// itself, and a flag indicating whether we can classify the use as splittable
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/// or not when forming partitions of the alloca.
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class Slice {
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/// \brief The beginning offset of the range.
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uint64_t BeginOffset;
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/// \brief The ending offset, not included in the range.
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uint64_t EndOffset;
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/// \brief Storage for both the use of this slice and whether it can be
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/// split.
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PointerIntPair<Use *, 1, bool> UseAndIsSplittable;
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public:
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Slice() : BeginOffset(), EndOffset() {}
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Slice(uint64_t BeginOffset, uint64_t EndOffset, Use *U, bool IsSplittable)
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: BeginOffset(BeginOffset), EndOffset(EndOffset),
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UseAndIsSplittable(U, IsSplittable) {}
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uint64_t beginOffset() const { return BeginOffset; }
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uint64_t endOffset() const { return EndOffset; }
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bool isSplittable() const { return UseAndIsSplittable.getInt(); }
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void makeUnsplittable() { UseAndIsSplittable.setInt(false); }
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Use *getUse() const { return UseAndIsSplittable.getPointer(); }
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bool isDead() const { return getUse() == nullptr; }
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void kill() { UseAndIsSplittable.setPointer(nullptr); }
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/// \brief Support for ordering ranges.
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///
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/// This provides an ordering over ranges such that start offsets are
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/// always increasing, and within equal start offsets, the end offsets are
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/// decreasing. Thus the spanning range comes first in a cluster with the
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/// same start position.
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bool operator<(const Slice &RHS) const {
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if (beginOffset() < RHS.beginOffset())
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return true;
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if (beginOffset() > RHS.beginOffset())
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return false;
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if (isSplittable() != RHS.isSplittable())
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return !isSplittable();
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if (endOffset() > RHS.endOffset())
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return true;
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return false;
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}
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/// \brief Support comparison with a single offset to allow binary searches.
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friend LLVM_ATTRIBUTE_UNUSED bool operator<(const Slice &LHS,
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uint64_t RHSOffset) {
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return LHS.beginOffset() < RHSOffset;
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}
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friend LLVM_ATTRIBUTE_UNUSED bool operator<(uint64_t LHSOffset,
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const Slice &RHS) {
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return LHSOffset < RHS.beginOffset();
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}
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bool operator==(const Slice &RHS) const {
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return isSplittable() == RHS.isSplittable() &&
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beginOffset() == RHS.beginOffset() && endOffset() == RHS.endOffset();
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}
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bool operator!=(const Slice &RHS) const { return !operator==(RHS); }
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};
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} // end anonymous namespace
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namespace llvm {
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template <typename T> struct isPodLike;
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template <> struct isPodLike<Slice> { static const bool value = true; };
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}
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namespace {
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/// \brief Representation of the alloca slices.
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///
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/// This class represents the slices of an alloca which are formed by its
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/// various uses. If a pointer escapes, we can't fully build a representation
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/// for the slices used and we reflect that in this structure. The uses are
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/// stored, sorted by increasing beginning offset and with unsplittable slices
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/// starting at a particular offset before splittable slices.
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class AllocaSlices {
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public:
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/// \brief Construct the slices of a particular alloca.
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AllocaSlices(const DataLayout &DL, AllocaInst &AI);
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/// \brief Test whether a pointer to the allocation escapes our analysis.
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///
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/// If this is true, the slices are never fully built and should be
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/// ignored.
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bool isEscaped() const { return PointerEscapingInstr; }
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/// \brief Support for iterating over the slices.
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/// @{
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typedef SmallVectorImpl<Slice>::iterator iterator;
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typedef iterator_range<iterator> range;
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iterator begin() { return Slices.begin(); }
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iterator end() { return Slices.end(); }
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typedef SmallVectorImpl<Slice>::const_iterator const_iterator;
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typedef iterator_range<const_iterator> const_range;
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const_iterator begin() const { return Slices.begin(); }
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const_iterator end() const { return Slices.end(); }
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/// @}
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/// \brief Erase a range of slices.
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void erase(iterator Start, iterator Stop) { Slices.erase(Start, Stop); }
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/// \brief Insert new slices for this alloca.
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///
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/// This moves the slices into the alloca's slices collection, and re-sorts
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/// everything so that the usual ordering properties of the alloca's slices
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/// hold.
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void insert(ArrayRef<Slice> NewSlices) {
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int OldSize = Slices.size();
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Slices.append(NewSlices.begin(), NewSlices.end());
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auto SliceI = Slices.begin() + OldSize;
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std::sort(SliceI, Slices.end());
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std::inplace_merge(Slices.begin(), SliceI, Slices.end());
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}
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// Forward declare an iterator to befriend it.
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class partition_iterator;
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/// \brief A partition of the slices.
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///
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/// An ephemeral representation for a range of slices which can be viewed as
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/// a partition of the alloca. This range represents a span of the alloca's
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/// memory which cannot be split, and provides access to all of the slices
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/// overlapping some part of the partition.
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///
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/// Objects of this type are produced by traversing the alloca's slices, but
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/// are only ephemeral and not persistent.
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class Partition {
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private:
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friend class AllocaSlices;
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friend class AllocaSlices::partition_iterator;
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/// \brief The begining and ending offsets of the alloca for this partition.
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uint64_t BeginOffset, EndOffset;
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/// \brief The start end end iterators of this partition.
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iterator SI, SJ;
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/// \brief A collection of split slice tails overlapping the partition.
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SmallVector<Slice *, 4> SplitTails;
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/// \brief Raw constructor builds an empty partition starting and ending at
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/// the given iterator.
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Partition(iterator SI) : SI(SI), SJ(SI) {}
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public:
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/// \brief The start offset of this partition.
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///
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/// All of the contained slices start at or after this offset.
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uint64_t beginOffset() const { return BeginOffset; }
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/// \brief The end offset of this partition.
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///
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/// All of the contained slices end at or before this offset.
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uint64_t endOffset() const { return EndOffset; }
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/// \brief The size of the partition.
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///
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/// Note that this can never be zero.
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uint64_t size() const {
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assert(BeginOffset < EndOffset && "Partitions must span some bytes!");
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return EndOffset - BeginOffset;
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}
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/// \brief Test whether this partition contains no slices, and merely spans
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/// a region occupied by split slices.
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bool empty() const { return SI == SJ; }
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/// \name Iterate slices that start within the partition.
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/// These may be splittable or unsplittable. They have a begin offset >= the
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/// partition begin offset.
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/// @{
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// FIXME: We should probably define a "concat_iterator" helper and use that
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// to stitch together pointee_iterators over the split tails and the
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// contiguous iterators of the partition. That would give a much nicer
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// interface here. We could then additionally expose filtered iterators for
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// split, unsplit, and unsplittable splices based on the usage patterns.
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iterator begin() const { return SI; }
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iterator end() const { return SJ; }
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/// @}
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/// \brief Get the sequence of split slice tails.
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///
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/// These tails are of slices which start before this partition but are
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/// split and overlap into the partition. We accumulate these while forming
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/// partitions.
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ArrayRef<Slice *> splitSliceTails() const { return SplitTails; }
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};
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/// \brief An iterator over partitions of the alloca's slices.
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///
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/// This iterator implements the core algorithm for partitioning the alloca's
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/// slices. It is a forward iterator as we don't support backtracking for
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/// efficiency reasons, and re-use a single storage area to maintain the
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/// current set of split slices.
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///
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/// It is templated on the slice iterator type to use so that it can operate
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/// with either const or non-const slice iterators.
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class partition_iterator
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: public iterator_facade_base<partition_iterator,
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std::forward_iterator_tag, Partition> {
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friend class AllocaSlices;
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/// \brief Most of the state for walking the partitions is held in a class
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/// with a nice interface for examining them.
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Partition P;
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/// \brief We need to keep the end of the slices to know when to stop.
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AllocaSlices::iterator SE;
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/// \brief We also need to keep track of the maximum split end offset seen.
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/// FIXME: Do we really?
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uint64_t MaxSplitSliceEndOffset;
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/// \brief Sets the partition to be empty at given iterator, and sets the
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/// end iterator.
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partition_iterator(AllocaSlices::iterator SI, AllocaSlices::iterator SE)
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: P(SI), SE(SE), MaxSplitSliceEndOffset(0) {
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// If not already at the end, advance our state to form the initial
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// partition.
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if (SI != SE)
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advance();
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}
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/// \brief Advance the iterator to the next partition.
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///
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/// Requires that the iterator not be at the end of the slices.
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void advance() {
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assert((P.SI != SE || !P.SplitTails.empty()) &&
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"Cannot advance past the end of the slices!");
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// Clear out any split uses which have ended.
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if (!P.SplitTails.empty()) {
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if (P.EndOffset >= MaxSplitSliceEndOffset) {
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// If we've finished all splits, this is easy.
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P.SplitTails.clear();
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MaxSplitSliceEndOffset = 0;
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} else {
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// Remove the uses which have ended in the prior partition. This
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// cannot change the max split slice end because we just checked that
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// the prior partition ended prior to that max.
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P.SplitTails.erase(
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std::remove_if(
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P.SplitTails.begin(), P.SplitTails.end(),
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[&](Slice *S) { return S->endOffset() <= P.EndOffset; }),
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P.SplitTails.end());
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assert(std::any_of(P.SplitTails.begin(), P.SplitTails.end(),
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[&](Slice *S) {
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return S->endOffset() == MaxSplitSliceEndOffset;
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}) &&
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"Could not find the current max split slice offset!");
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assert(std::all_of(P.SplitTails.begin(), P.SplitTails.end(),
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[&](Slice *S) {
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return S->endOffset() <= MaxSplitSliceEndOffset;
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}) &&
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"Max split slice end offset is not actually the max!");
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}
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}
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// If P.SI is already at the end, then we've cleared the split tail and
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// now have an end iterator.
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if (P.SI == SE) {
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assert(P.SplitTails.empty() && "Failed to clear the split slices!");
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return;
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}
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// If we had a non-empty partition previously, set up the state for
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// subsequent partitions.
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if (P.SI != P.SJ) {
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// Accumulate all the splittable slices which started in the old
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// partition into the split list.
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for (Slice &S : P)
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if (S.isSplittable() && S.endOffset() > P.EndOffset) {
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P.SplitTails.push_back(&S);
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MaxSplitSliceEndOffset =
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std::max(S.endOffset(), MaxSplitSliceEndOffset);
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}
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// Start from the end of the previous partition.
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P.SI = P.SJ;
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// If P.SI is now at the end, we at most have a tail of split slices.
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if (P.SI == SE) {
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P.BeginOffset = P.EndOffset;
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P.EndOffset = MaxSplitSliceEndOffset;
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return;
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}
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// If the we have split slices and the next slice is after a gap and is
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// not splittable immediately form an empty partition for the split
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// slices up until the next slice begins.
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if (!P.SplitTails.empty() && P.SI->beginOffset() != P.EndOffset &&
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!P.SI->isSplittable()) {
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P.BeginOffset = P.EndOffset;
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P.EndOffset = P.SI->beginOffset();
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return;
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}
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}
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// OK, we need to consume new slices. Set the end offset based on the
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// current slice, and step SJ past it. The beginning offset of the
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// parttion is the beginning offset of the next slice unless we have
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// pre-existing split slices that are continuing, in which case we begin
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// at the prior end offset.
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P.BeginOffset = P.SplitTails.empty() ? P.SI->beginOffset() : P.EndOffset;
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P.EndOffset = P.SI->endOffset();
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++P.SJ;
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// There are two strategies to form a partition based on whether the
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// partition starts with an unsplittable slice or a splittable slice.
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if (!P.SI->isSplittable()) {
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// When we're forming an unsplittable region, it must always start at
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// the first slice and will extend through its end.
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assert(P.BeginOffset == P.SI->beginOffset());
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// Form a partition including all of the overlapping slices with this
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// unsplittable slice.
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while (P.SJ != SE && P.SJ->beginOffset() < P.EndOffset) {
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if (!P.SJ->isSplittable())
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P.EndOffset = std::max(P.EndOffset, P.SJ->endOffset());
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++P.SJ;
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}
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// We have a partition across a set of overlapping unsplittable
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// partitions.
|
|
return;
|
|
}
|
|
|
|
// If we're starting with a splittable slice, then we need to form
|
|
// a synthetic partition spanning it and any other overlapping splittable
|
|
// splices.
|
|
assert(P.SI->isSplittable() && "Forming a splittable partition!");
|
|
|
|
// Collect all of the overlapping splittable slices.
|
|
while (P.SJ != SE && P.SJ->beginOffset() < P.EndOffset &&
|
|
P.SJ->isSplittable()) {
|
|
P.EndOffset = std::max(P.EndOffset, P.SJ->endOffset());
|
|
++P.SJ;
|
|
}
|
|
|
|
// Back upiP.EndOffset if we ended the span early when encountering an
|
|
// unsplittable slice. This synthesizes the early end offset of
|
|
// a partition spanning only splittable slices.
|
|
if (P.SJ != SE && P.SJ->beginOffset() < P.EndOffset) {
|
|
assert(!P.SJ->isSplittable());
|
|
P.EndOffset = P.SJ->beginOffset();
|
|
}
|
|
}
|
|
|
|
public:
|
|
bool operator==(const partition_iterator &RHS) const {
|
|
assert(SE == RHS.SE &&
|
|
"End iterators don't match between compared partition iterators!");
|
|
|
|
// The observed positions of partitions is marked by the P.SI iterator and
|
|
// the emptyness of the split slices. The latter is only relevant when
|
|
// P.SI == SE, as the end iterator will additionally have an empty split
|
|
// slices list, but the prior may have the same P.SI and a tail of split
|
|
// slices.
|
|
if (P.SI == RHS.P.SI &&
|
|
P.SplitTails.empty() == RHS.P.SplitTails.empty()) {
|
|
assert(P.SJ == RHS.P.SJ &&
|
|
"Same set of slices formed two different sized partitions!");
|
|
assert(P.SplitTails.size() == RHS.P.SplitTails.size() &&
|
|
"Same slice position with differently sized non-empty split "
|
|
"slice tails!");
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
partition_iterator &operator++() {
|
|
advance();
|
|
return *this;
|
|
}
|
|
|
|
Partition &operator*() { return P; }
|
|
};
|
|
|
|
/// \brief A forward range over the partitions of the alloca's slices.
|
|
///
|
|
/// This accesses an iterator range over the partitions of the alloca's
|
|
/// slices. It computes these partitions on the fly based on the overlapping
|
|
/// offsets of the slices and the ability to split them. It will visit "empty"
|
|
/// partitions to cover regions of the alloca only accessed via split
|
|
/// slices.
|
|
iterator_range<partition_iterator> partitions() {
|
|
return make_range(partition_iterator(begin(), end()),
|
|
partition_iterator(end(), end()));
|
|
}
|
|
|
|
/// \brief Access the dead users for this alloca.
|
|
ArrayRef<Instruction *> getDeadUsers() const { return DeadUsers; }
|
|
|
|
/// \brief Access the dead operands referring to this alloca.
|
|
///
|
|
/// These are operands which have cannot actually be used to refer to the
|
|
/// alloca as they are outside its range and the user doesn't correct for
|
|
/// that. These mostly consist of PHI node inputs and the like which we just
|
|
/// need to replace with undef.
|
|
ArrayRef<Use *> getDeadOperands() const { return DeadOperands; }
|
|
|
|
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
|
|
void print(raw_ostream &OS, const_iterator I, StringRef Indent = " ") const;
|
|
void printSlice(raw_ostream &OS, const_iterator I,
|
|
StringRef Indent = " ") const;
|
|
void printUse(raw_ostream &OS, const_iterator I,
|
|
StringRef Indent = " ") const;
|
|
void print(raw_ostream &OS) const;
|
|
void dump(const_iterator I) const;
|
|
void dump() const;
|
|
#endif
|
|
|
|
private:
|
|
template <typename DerivedT, typename RetT = void> class BuilderBase;
|
|
class SliceBuilder;
|
|
friend class AllocaSlices::SliceBuilder;
|
|
|
|
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
|
|
/// \brief Handle to alloca instruction to simplify method interfaces.
|
|
AllocaInst &AI;
|
|
#endif
|
|
|
|
/// \brief The instruction responsible for this alloca not having a known set
|
|
/// of slices.
|
|
///
|
|
/// When an instruction (potentially) escapes the pointer to the alloca, we
|
|
/// store a pointer to that here and abort trying to form slices of the
|
|
/// alloca. This will be null if the alloca slices are analyzed successfully.
|
|
Instruction *PointerEscapingInstr;
|
|
|
|
/// \brief The slices of the alloca.
|
|
///
|
|
/// We store a vector of the slices formed by uses of the alloca here. This
|
|
/// vector is sorted by increasing begin offset, and then the unsplittable
|
|
/// slices before the splittable ones. See the Slice inner class for more
|
|
/// details.
|
|
SmallVector<Slice, 8> Slices;
|
|
|
|
/// \brief Instructions which will become dead if we rewrite the alloca.
|
|
///
|
|
/// Note that these are not separated by slice. This is because we expect an
|
|
/// alloca to be completely rewritten or not rewritten at all. If rewritten,
|
|
/// all these instructions can simply be removed and replaced with undef as
|
|
/// they come from outside of the allocated space.
|
|
SmallVector<Instruction *, 8> DeadUsers;
|
|
|
|
/// \brief Operands which will become dead if we rewrite the alloca.
|
|
///
|
|
/// These are operands that in their particular use can be replaced with
|
|
/// undef when we rewrite the alloca. These show up in out-of-bounds inputs
|
|
/// to PHI nodes and the like. They aren't entirely dead (there might be
|
|
/// a GEP back into the bounds using it elsewhere) and nor is the PHI, but we
|
|
/// want to swap this particular input for undef to simplify the use lists of
|
|
/// the alloca.
|
|
SmallVector<Use *, 8> DeadOperands;
|
|
};
|
|
} // namespace
|
|
|
|
static Value *foldSelectInst(SelectInst &SI) {
|
|
// If the condition being selected on is a constant or the same value is
|
|
// being selected between, fold the select. Yes this does (rarely) happen
|
|
// early on.
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(SI.getCondition()))
|
|
return SI.getOperand(1 + CI->isZero());
|
|
if (SI.getOperand(1) == SI.getOperand(2))
|
|
return SI.getOperand(1);
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
/// \brief A helper that folds a PHI node or a select.
|
|
static Value *foldPHINodeOrSelectInst(Instruction &I) {
|
|
if (PHINode *PN = dyn_cast<PHINode>(&I)) {
|
|
// If PN merges together the same value, return that value.
|
|
return PN->hasConstantValue();
|
|
}
|
|
return foldSelectInst(cast<SelectInst>(I));
|
|
}
|
|
|
|
/// \brief Builder for the alloca slices.
|
|
///
|
|
/// This class builds a set of alloca slices by recursively visiting the uses
|
|
/// of an alloca and making a slice for each load and store at each offset.
|
|
class AllocaSlices::SliceBuilder : public PtrUseVisitor<SliceBuilder> {
|
|
friend class PtrUseVisitor<SliceBuilder>;
|
|
friend class InstVisitor<SliceBuilder>;
|
|
typedef PtrUseVisitor<SliceBuilder> Base;
|
|
|
|
const uint64_t AllocSize;
|
|
AllocaSlices &AS;
|
|
|
|
SmallDenseMap<Instruction *, unsigned> MemTransferSliceMap;
|
|
SmallDenseMap<Instruction *, uint64_t> PHIOrSelectSizes;
|
|
|
|
/// \brief Set to de-duplicate dead instructions found in the use walk.
|
|
SmallPtrSet<Instruction *, 4> VisitedDeadInsts;
|
|
|
|
public:
|
|
SliceBuilder(const DataLayout &DL, AllocaInst &AI, AllocaSlices &AS)
|
|
: PtrUseVisitor<SliceBuilder>(DL),
|
|
AllocSize(DL.getTypeAllocSize(AI.getAllocatedType())), AS(AS) {}
|
|
|
|
private:
|
|
void markAsDead(Instruction &I) {
|
|
if (VisitedDeadInsts.insert(&I).second)
|
|
AS.DeadUsers.push_back(&I);
|
|
}
|
|
|
|
void insertUse(Instruction &I, const APInt &Offset, uint64_t Size,
|
|
bool IsSplittable = false) {
|
|
// Completely skip uses which have a zero size or start either before or
|
|
// past the end of the allocation.
|
|
if (Size == 0 || Offset.uge(AllocSize)) {
|
|
DEBUG(dbgs() << "WARNING: Ignoring " << Size << " byte use @" << Offset
|
|
<< " which has zero size or starts outside of the "
|
|
<< AllocSize << " byte alloca:\n"
|
|
<< " alloca: " << AS.AI << "\n"
|
|
<< " use: " << I << "\n");
|
|
return markAsDead(I);
|
|
}
|
|
|
|
uint64_t BeginOffset = Offset.getZExtValue();
|
|
uint64_t EndOffset = BeginOffset + Size;
|
|
|
|
// Clamp the end offset to the end of the allocation. Note that this is
|
|
// formulated to handle even the case where "BeginOffset + Size" overflows.
|
|
// This may appear superficially to be something we could ignore entirely,
|
|
// but that is not so! There may be widened loads or PHI-node uses where
|
|
// some instructions are dead but not others. We can't completely ignore
|
|
// them, and so have to record at least the information here.
|
|
assert(AllocSize >= BeginOffset); // Established above.
|
|
if (Size > AllocSize - BeginOffset) {
|
|
DEBUG(dbgs() << "WARNING: Clamping a " << Size << " byte use @" << Offset
|
|
<< " to remain within the " << AllocSize << " byte alloca:\n"
|
|
<< " alloca: " << AS.AI << "\n"
|
|
<< " use: " << I << "\n");
|
|
EndOffset = AllocSize;
|
|
}
|
|
|
|
AS.Slices.push_back(Slice(BeginOffset, EndOffset, U, IsSplittable));
|
|
}
|
|
|
|
void visitBitCastInst(BitCastInst &BC) {
|
|
if (BC.use_empty())
|
|
return markAsDead(BC);
|
|
|
|
return Base::visitBitCastInst(BC);
|
|
}
|
|
|
|
void visitGetElementPtrInst(GetElementPtrInst &GEPI) {
|
|
if (GEPI.use_empty())
|
|
return markAsDead(GEPI);
|
|
|
|
if (SROAStrictInbounds && GEPI.isInBounds()) {
|
|
// FIXME: This is a manually un-factored variant of the basic code inside
|
|
// of GEPs with checking of the inbounds invariant specified in the
|
|
// langref in a very strict sense. If we ever want to enable
|
|
// SROAStrictInbounds, this code should be factored cleanly into
|
|
// PtrUseVisitor, but it is easier to experiment with SROAStrictInbounds
|
|
// by writing out the code here where we have tho underlying allocation
|
|
// size readily available.
|
|
APInt GEPOffset = Offset;
|
|
const DataLayout &DL = GEPI.getModule()->getDataLayout();
|
|
for (gep_type_iterator GTI = gep_type_begin(GEPI),
|
|
GTE = gep_type_end(GEPI);
|
|
GTI != GTE; ++GTI) {
|
|
ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand());
|
|
if (!OpC)
|
|
break;
|
|
|
|
// Handle a struct index, which adds its field offset to the pointer.
|
|
if (StructType *STy = dyn_cast<StructType>(*GTI)) {
|
|
unsigned ElementIdx = OpC->getZExtValue();
|
|
const StructLayout *SL = DL.getStructLayout(STy);
|
|
GEPOffset +=
|
|
APInt(Offset.getBitWidth(), SL->getElementOffset(ElementIdx));
|
|
} else {
|
|
// For array or vector indices, scale the index by the size of the
|
|
// type.
|
|
APInt Index = OpC->getValue().sextOrTrunc(Offset.getBitWidth());
|
|
GEPOffset += Index * APInt(Offset.getBitWidth(),
|
|
DL.getTypeAllocSize(GTI.getIndexedType()));
|
|
}
|
|
|
|
// If this index has computed an intermediate pointer which is not
|
|
// inbounds, then the result of the GEP is a poison value and we can
|
|
// delete it and all uses.
|
|
if (GEPOffset.ugt(AllocSize))
|
|
return markAsDead(GEPI);
|
|
}
|
|
}
|
|
|
|
return Base::visitGetElementPtrInst(GEPI);
|
|
}
|
|
|
|
void handleLoadOrStore(Type *Ty, Instruction &I, const APInt &Offset,
|
|
uint64_t Size, bool IsVolatile) {
|
|
// We allow splitting of non-volatile loads and stores where the type is an
|
|
// integer type. These may be used to implement 'memcpy' or other "transfer
|
|
// of bits" patterns.
|
|
bool IsSplittable = Ty->isIntegerTy() && !IsVolatile;
|
|
|
|
insertUse(I, Offset, Size, IsSplittable);
|
|
}
|
|
|
|
void visitLoadInst(LoadInst &LI) {
|
|
assert((!LI.isSimple() || LI.getType()->isSingleValueType()) &&
|
|
"All simple FCA loads should have been pre-split");
|
|
|
|
if (!IsOffsetKnown)
|
|
return PI.setAborted(&LI);
|
|
|
|
const DataLayout &DL = LI.getModule()->getDataLayout();
|
|
uint64_t Size = DL.getTypeStoreSize(LI.getType());
|
|
return handleLoadOrStore(LI.getType(), LI, Offset, Size, LI.isVolatile());
|
|
}
|
|
|
|
void visitStoreInst(StoreInst &SI) {
|
|
Value *ValOp = SI.getValueOperand();
|
|
if (ValOp == *U)
|
|
return PI.setEscapedAndAborted(&SI);
|
|
if (!IsOffsetKnown)
|
|
return PI.setAborted(&SI);
|
|
|
|
const DataLayout &DL = SI.getModule()->getDataLayout();
|
|
uint64_t Size = DL.getTypeStoreSize(ValOp->getType());
|
|
|
|
// If this memory access can be shown to *statically* extend outside the
|
|
// bounds of of the allocation, it's behavior is undefined, so simply
|
|
// ignore it. Note that this is more strict than the generic clamping
|
|
// behavior of insertUse. We also try to handle cases which might run the
|
|
// risk of overflow.
|
|
// FIXME: We should instead consider the pointer to have escaped if this
|
|
// function is being instrumented for addressing bugs or race conditions.
|
|
if (Size > AllocSize || Offset.ugt(AllocSize - Size)) {
|
|
DEBUG(dbgs() << "WARNING: Ignoring " << Size << " byte store @" << Offset
|
|
<< " which extends past the end of the " << AllocSize
|
|
<< " byte alloca:\n"
|
|
<< " alloca: " << AS.AI << "\n"
|
|
<< " use: " << SI << "\n");
|
|
return markAsDead(SI);
|
|
}
|
|
|
|
assert((!SI.isSimple() || ValOp->getType()->isSingleValueType()) &&
|
|
"All simple FCA stores should have been pre-split");
|
|
handleLoadOrStore(ValOp->getType(), SI, Offset, Size, SI.isVolatile());
|
|
}
|
|
|
|
void visitMemSetInst(MemSetInst &II) {
|
|
assert(II.getRawDest() == *U && "Pointer use is not the destination?");
|
|
ConstantInt *Length = dyn_cast<ConstantInt>(II.getLength());
|
|
if ((Length && Length->getValue() == 0) ||
|
|
(IsOffsetKnown && Offset.uge(AllocSize)))
|
|
// Zero-length mem transfer intrinsics can be ignored entirely.
|
|
return markAsDead(II);
|
|
|
|
if (!IsOffsetKnown)
|
|
return PI.setAborted(&II);
|
|
|
|
insertUse(II, Offset, Length ? Length->getLimitedValue()
|
|
: AllocSize - Offset.getLimitedValue(),
|
|
(bool)Length);
|
|
}
|
|
|
|
void visitMemTransferInst(MemTransferInst &II) {
|
|
ConstantInt *Length = dyn_cast<ConstantInt>(II.getLength());
|
|
if (Length && Length->getValue() == 0)
|
|
// Zero-length mem transfer intrinsics can be ignored entirely.
|
|
return markAsDead(II);
|
|
|
|
// Because we can visit these intrinsics twice, also check to see if the
|
|
// first time marked this instruction as dead. If so, skip it.
|
|
if (VisitedDeadInsts.count(&II))
|
|
return;
|
|
|
|
if (!IsOffsetKnown)
|
|
return PI.setAborted(&II);
|
|
|
|
// This side of the transfer is completely out-of-bounds, and so we can
|
|
// nuke the entire transfer. However, we also need to nuke the other side
|
|
// if already added to our partitions.
|
|
// FIXME: Yet another place we really should bypass this when
|
|
// instrumenting for ASan.
|
|
if (Offset.uge(AllocSize)) {
|
|
SmallDenseMap<Instruction *, unsigned>::iterator MTPI =
|
|
MemTransferSliceMap.find(&II);
|
|
if (MTPI != MemTransferSliceMap.end())
|
|
AS.Slices[MTPI->second].kill();
|
|
return markAsDead(II);
|
|
}
|
|
|
|
uint64_t RawOffset = Offset.getLimitedValue();
|
|
uint64_t Size = Length ? Length->getLimitedValue() : AllocSize - RawOffset;
|
|
|
|
// Check for the special case where the same exact value is used for both
|
|
// source and dest.
|
|
if (*U == II.getRawDest() && *U == II.getRawSource()) {
|
|
// For non-volatile transfers this is a no-op.
|
|
if (!II.isVolatile())
|
|
return markAsDead(II);
|
|
|
|
return insertUse(II, Offset, Size, /*IsSplittable=*/false);
|
|
}
|
|
|
|
// If we have seen both source and destination for a mem transfer, then
|
|
// they both point to the same alloca.
|
|
bool Inserted;
|
|
SmallDenseMap<Instruction *, unsigned>::iterator MTPI;
|
|
std::tie(MTPI, Inserted) =
|
|
MemTransferSliceMap.insert(std::make_pair(&II, AS.Slices.size()));
|
|
unsigned PrevIdx = MTPI->second;
|
|
if (!Inserted) {
|
|
Slice &PrevP = AS.Slices[PrevIdx];
|
|
|
|
// Check if the begin offsets match and this is a non-volatile transfer.
|
|
// In that case, we can completely elide the transfer.
|
|
if (!II.isVolatile() && PrevP.beginOffset() == RawOffset) {
|
|
PrevP.kill();
|
|
return markAsDead(II);
|
|
}
|
|
|
|
// Otherwise we have an offset transfer within the same alloca. We can't
|
|
// split those.
|
|
PrevP.makeUnsplittable();
|
|
}
|
|
|
|
// Insert the use now that we've fixed up the splittable nature.
|
|
insertUse(II, Offset, Size, /*IsSplittable=*/Inserted && Length);
|
|
|
|
// Check that we ended up with a valid index in the map.
|
|
assert(AS.Slices[PrevIdx].getUse()->getUser() == &II &&
|
|
"Map index doesn't point back to a slice with this user.");
|
|
}
|
|
|
|
// Disable SRoA for any intrinsics except for lifetime invariants.
|
|
// FIXME: What about debug intrinsics? This matches old behavior, but
|
|
// doesn't make sense.
|
|
void visitIntrinsicInst(IntrinsicInst &II) {
|
|
if (!IsOffsetKnown)
|
|
return PI.setAborted(&II);
|
|
|
|
if (II.getIntrinsicID() == Intrinsic::lifetime_start ||
|
|
II.getIntrinsicID() == Intrinsic::lifetime_end) {
|
|
ConstantInt *Length = cast<ConstantInt>(II.getArgOperand(0));
|
|
uint64_t Size = std::min(AllocSize - Offset.getLimitedValue(),
|
|
Length->getLimitedValue());
|
|
insertUse(II, Offset, Size, true);
|
|
return;
|
|
}
|
|
|
|
Base::visitIntrinsicInst(II);
|
|
}
|
|
|
|
Instruction *hasUnsafePHIOrSelectUse(Instruction *Root, uint64_t &Size) {
|
|
// We consider any PHI or select that results in a direct load or store of
|
|
// the same offset to be a viable use for slicing purposes. These uses
|
|
// are considered unsplittable and the size is the maximum loaded or stored
|
|
// size.
|
|
SmallPtrSet<Instruction *, 4> Visited;
|
|
SmallVector<std::pair<Instruction *, Instruction *>, 4> Uses;
|
|
Visited.insert(Root);
|
|
Uses.push_back(std::make_pair(cast<Instruction>(*U), Root));
|
|
const DataLayout &DL = Root->getModule()->getDataLayout();
|
|
// If there are no loads or stores, the access is dead. We mark that as
|
|
// a size zero access.
|
|
Size = 0;
|
|
do {
|
|
Instruction *I, *UsedI;
|
|
std::tie(UsedI, I) = Uses.pop_back_val();
|
|
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
|
|
Size = std::max(Size, DL.getTypeStoreSize(LI->getType()));
|
|
continue;
|
|
}
|
|
if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
|
|
Value *Op = SI->getOperand(0);
|
|
if (Op == UsedI)
|
|
return SI;
|
|
Size = std::max(Size, DL.getTypeStoreSize(Op->getType()));
|
|
continue;
|
|
}
|
|
|
|
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I)) {
|
|
if (!GEP->hasAllZeroIndices())
|
|
return GEP;
|
|
} else if (!isa<BitCastInst>(I) && !isa<PHINode>(I) &&
|
|
!isa<SelectInst>(I)) {
|
|
return I;
|
|
}
|
|
|
|
for (User *U : I->users())
|
|
if (Visited.insert(cast<Instruction>(U)).second)
|
|
Uses.push_back(std::make_pair(I, cast<Instruction>(U)));
|
|
} while (!Uses.empty());
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
void visitPHINodeOrSelectInst(Instruction &I) {
|
|
assert(isa<PHINode>(I) || isa<SelectInst>(I));
|
|
if (I.use_empty())
|
|
return markAsDead(I);
|
|
|
|
// TODO: We could use SimplifyInstruction here to fold PHINodes and
|
|
// SelectInsts. However, doing so requires to change the current
|
|
// dead-operand-tracking mechanism. For instance, suppose neither loading
|
|
// from %U nor %other traps. Then "load (select undef, %U, %other)" does not
|
|
// trap either. However, if we simply replace %U with undef using the
|
|
// current dead-operand-tracking mechanism, "load (select undef, undef,
|
|
// %other)" may trap because the select may return the first operand
|
|
// "undef".
|
|
if (Value *Result = foldPHINodeOrSelectInst(I)) {
|
|
if (Result == *U)
|
|
// If the result of the constant fold will be the pointer, recurse
|
|
// through the PHI/select as if we had RAUW'ed it.
|
|
enqueueUsers(I);
|
|
else
|
|
// Otherwise the operand to the PHI/select is dead, and we can replace
|
|
// it with undef.
|
|
AS.DeadOperands.push_back(U);
|
|
|
|
return;
|
|
}
|
|
|
|
if (!IsOffsetKnown)
|
|
return PI.setAborted(&I);
|
|
|
|
// See if we already have computed info on this node.
|
|
uint64_t &Size = PHIOrSelectSizes[&I];
|
|
if (!Size) {
|
|
// This is a new PHI/Select, check for an unsafe use of it.
|
|
if (Instruction *UnsafeI = hasUnsafePHIOrSelectUse(&I, Size))
|
|
return PI.setAborted(UnsafeI);
|
|
}
|
|
|
|
// For PHI and select operands outside the alloca, we can't nuke the entire
|
|
// phi or select -- the other side might still be relevant, so we special
|
|
// case them here and use a separate structure to track the operands
|
|
// themselves which should be replaced with undef.
|
|
// FIXME: This should instead be escaped in the event we're instrumenting
|
|
// for address sanitization.
|
|
if (Offset.uge(AllocSize)) {
|
|
AS.DeadOperands.push_back(U);
|
|
return;
|
|
}
|
|
|
|
insertUse(I, Offset, Size);
|
|
}
|
|
|
|
void visitPHINode(PHINode &PN) { visitPHINodeOrSelectInst(PN); }
|
|
|
|
void visitSelectInst(SelectInst &SI) { visitPHINodeOrSelectInst(SI); }
|
|
|
|
/// \brief Disable SROA entirely if there are unhandled users of the alloca.
|
|
void visitInstruction(Instruction &I) { PI.setAborted(&I); }
|
|
};
|
|
|
|
AllocaSlices::AllocaSlices(const DataLayout &DL, AllocaInst &AI)
|
|
:
|
|
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
|
|
AI(AI),
|
|
#endif
|
|
PointerEscapingInstr(nullptr) {
|
|
SliceBuilder PB(DL, AI, *this);
|
|
SliceBuilder::PtrInfo PtrI = PB.visitPtr(AI);
|
|
if (PtrI.isEscaped() || PtrI.isAborted()) {
|
|
// FIXME: We should sink the escape vs. abort info into the caller nicely,
|
|
// possibly by just storing the PtrInfo in the AllocaSlices.
|
|
PointerEscapingInstr = PtrI.getEscapingInst() ? PtrI.getEscapingInst()
|
|
: PtrI.getAbortingInst();
|
|
assert(PointerEscapingInstr && "Did not track a bad instruction");
|
|
return;
|
|
}
|
|
|
|
Slices.erase(std::remove_if(Slices.begin(), Slices.end(),
|
|
[](const Slice &S) {
|
|
return S.isDead();
|
|
}),
|
|
Slices.end());
|
|
|
|
#if __cplusplus >= 201103L && !defined(NDEBUG)
|
|
if (SROARandomShuffleSlices) {
|
|
std::mt19937 MT(static_cast<unsigned>(sys::TimeValue::now().msec()));
|
|
std::shuffle(Slices.begin(), Slices.end(), MT);
|
|
}
|
|
#endif
|
|
|
|
// Sort the uses. This arranges for the offsets to be in ascending order,
|
|
// and the sizes to be in descending order.
|
|
std::sort(Slices.begin(), Slices.end());
|
|
}
|
|
|
|
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
|
|
|
|
void AllocaSlices::print(raw_ostream &OS, const_iterator I,
|
|
StringRef Indent) const {
|
|
printSlice(OS, I, Indent);
|
|
OS << "\n";
|
|
printUse(OS, I, Indent);
|
|
}
|
|
|
|
void AllocaSlices::printSlice(raw_ostream &OS, const_iterator I,
|
|
StringRef Indent) const {
|
|
OS << Indent << "[" << I->beginOffset() << "," << I->endOffset() << ")"
|
|
<< " slice #" << (I - begin())
|
|
<< (I->isSplittable() ? " (splittable)" : "");
|
|
}
|
|
|
|
void AllocaSlices::printUse(raw_ostream &OS, const_iterator I,
|
|
StringRef Indent) const {
|
|
OS << Indent << " used by: " << *I->getUse()->getUser() << "\n";
|
|
}
|
|
|
|
void AllocaSlices::print(raw_ostream &OS) const {
|
|
if (PointerEscapingInstr) {
|
|
OS << "Can't analyze slices for alloca: " << AI << "\n"
|
|
<< " A pointer to this alloca escaped by:\n"
|
|
<< " " << *PointerEscapingInstr << "\n";
|
|
return;
|
|
}
|
|
|
|
OS << "Slices of alloca: " << AI << "\n";
|
|
for (const_iterator I = begin(), E = end(); I != E; ++I)
|
|
print(OS, I);
|
|
}
|
|
|
|
LLVM_DUMP_METHOD void AllocaSlices::dump(const_iterator I) const {
|
|
print(dbgs(), I);
|
|
}
|
|
LLVM_DUMP_METHOD void AllocaSlices::dump() const { print(dbgs()); }
|
|
|
|
#endif // !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
|
|
|
|
namespace {
|
|
/// \brief Implementation of LoadAndStorePromoter for promoting allocas.
|
|
///
|
|
/// This subclass of LoadAndStorePromoter adds overrides to handle promoting
|
|
/// the loads and stores of an alloca instruction, as well as updating its
|
|
/// debug information. This is used when a domtree is unavailable and thus
|
|
/// mem2reg in its full form can't be used to handle promotion of allocas to
|
|
/// scalar values.
|
|
class AllocaPromoter : public LoadAndStorePromoter {
|
|
AllocaInst &AI;
|
|
DIBuilder &DIB;
|
|
|
|
SmallVector<DbgDeclareInst *, 4> DDIs;
|
|
SmallVector<DbgValueInst *, 4> DVIs;
|
|
|
|
public:
|
|
AllocaPromoter(ArrayRef<const Instruction *> Insts,
|
|
SSAUpdater &S,
|
|
AllocaInst &AI, DIBuilder &DIB)
|
|
: LoadAndStorePromoter(Insts, S), AI(AI), DIB(DIB) {}
|
|
|
|
void run(const SmallVectorImpl<Instruction *> &Insts) {
|
|
// Retain the debug information attached to the alloca for use when
|
|
// rewriting loads and stores.
|
|
if (auto *L = LocalAsMetadata::getIfExists(&AI)) {
|
|
if (auto *DINode = MetadataAsValue::getIfExists(AI.getContext(), L)) {
|
|
for (User *U : DINode->users())
|
|
if (DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(U))
|
|
DDIs.push_back(DDI);
|
|
else if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(U))
|
|
DVIs.push_back(DVI);
|
|
}
|
|
}
|
|
|
|
LoadAndStorePromoter::run(Insts);
|
|
|
|
// While we have the debug information, clear it off of the alloca. The
|
|
// caller takes care of deleting the alloca.
|
|
while (!DDIs.empty())
|
|
DDIs.pop_back_val()->eraseFromParent();
|
|
while (!DVIs.empty())
|
|
DVIs.pop_back_val()->eraseFromParent();
|
|
}
|
|
|
|
bool
|
|
isInstInList(Instruction *I,
|
|
const SmallVectorImpl<Instruction *> &Insts) const override {
|
|
Value *Ptr;
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(I))
|
|
Ptr = LI->getOperand(0);
|
|
else
|
|
Ptr = cast<StoreInst>(I)->getPointerOperand();
|
|
|
|
// Only used to detect cycles, which will be rare and quickly found as
|
|
// we're walking up a chain of defs rather than down through uses.
|
|
SmallPtrSet<Value *, 4> Visited;
|
|
|
|
do {
|
|
if (Ptr == &AI)
|
|
return true;
|
|
|
|
if (BitCastInst *BCI = dyn_cast<BitCastInst>(Ptr))
|
|
Ptr = BCI->getOperand(0);
|
|
else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Ptr))
|
|
Ptr = GEPI->getPointerOperand();
|
|
else
|
|
return false;
|
|
|
|
} while (Visited.insert(Ptr).second);
|
|
|
|
return false;
|
|
}
|
|
|
|
void updateDebugInfo(Instruction *Inst) const override {
|
|
for (DbgDeclareInst *DDI : DDIs)
|
|
if (StoreInst *SI = dyn_cast<StoreInst>(Inst))
|
|
ConvertDebugDeclareToDebugValue(DDI, SI, DIB);
|
|
else if (LoadInst *LI = dyn_cast<LoadInst>(Inst))
|
|
ConvertDebugDeclareToDebugValue(DDI, LI, DIB);
|
|
for (DbgValueInst *DVI : DVIs) {
|
|
Value *Arg = nullptr;
|
|
if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
|
|
// If an argument is zero extended then use argument directly. The ZExt
|
|
// may be zapped by an optimization pass in future.
|
|
if (ZExtInst *ZExt = dyn_cast<ZExtInst>(SI->getOperand(0)))
|
|
Arg = dyn_cast<Argument>(ZExt->getOperand(0));
|
|
else if (SExtInst *SExt = dyn_cast<SExtInst>(SI->getOperand(0)))
|
|
Arg = dyn_cast<Argument>(SExt->getOperand(0));
|
|
if (!Arg)
|
|
Arg = SI->getValueOperand();
|
|
} else if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
|
|
Arg = LI->getPointerOperand();
|
|
} else {
|
|
continue;
|
|
}
|
|
DIB.insertDbgValueIntrinsic(Arg, 0, DVI->getVariable(),
|
|
DVI->getExpression(), DVI->getDebugLoc(),
|
|
Inst);
|
|
}
|
|
}
|
|
};
|
|
} // namespace
|
|
|
|
namespace {
|
|
/// \brief An optimization pass providing Scalar Replacement of Aggregates.
|
|
///
|
|
/// This pass takes allocations which can be completely analyzed (that is, they
|
|
/// don't escape) and tries to turn them into scalar SSA values. There are
|
|
/// a few steps to this process.
|
|
///
|
|
/// 1) It takes allocations of aggregates and analyzes the ways in which they
|
|
/// are used to try to split them into smaller allocations, ideally of
|
|
/// a single scalar data type. It will split up memcpy and memset accesses
|
|
/// as necessary and try to isolate individual scalar accesses.
|
|
/// 2) It will transform accesses into forms which are suitable for SSA value
|
|
/// promotion. This can be replacing a memset with a scalar store of an
|
|
/// integer value, or it can involve speculating operations on a PHI or
|
|
/// select to be a PHI or select of the results.
|
|
/// 3) Finally, this will try to detect a pattern of accesses which map cleanly
|
|
/// onto insert and extract operations on a vector value, and convert them to
|
|
/// this form. By doing so, it will enable promotion of vector aggregates to
|
|
/// SSA vector values.
|
|
class SROA : public FunctionPass {
|
|
const bool RequiresDomTree;
|
|
|
|
LLVMContext *C;
|
|
DominatorTree *DT;
|
|
AssumptionCache *AC;
|
|
|
|
/// \brief Worklist of alloca instructions to simplify.
|
|
///
|
|
/// Each alloca in the function is added to this. Each new alloca formed gets
|
|
/// added to it as well to recursively simplify unless that alloca can be
|
|
/// directly promoted. Finally, each time we rewrite a use of an alloca other
|
|
/// the one being actively rewritten, we add it back onto the list if not
|
|
/// already present to ensure it is re-visited.
|
|
SetVector<AllocaInst *, SmallVector<AllocaInst *, 16>> Worklist;
|
|
|
|
/// \brief A collection of instructions to delete.
|
|
/// We try to batch deletions to simplify code and make things a bit more
|
|
/// efficient.
|
|
SetVector<Instruction *, SmallVector<Instruction *, 8>> DeadInsts;
|
|
|
|
/// \brief Post-promotion worklist.
|
|
///
|
|
/// Sometimes we discover an alloca which has a high probability of becoming
|
|
/// viable for SROA after a round of promotion takes place. In those cases,
|
|
/// the alloca is enqueued here for re-processing.
|
|
///
|
|
/// Note that we have to be very careful to clear allocas out of this list in
|
|
/// the event they are deleted.
|
|
SetVector<AllocaInst *, SmallVector<AllocaInst *, 16>> PostPromotionWorklist;
|
|
|
|
/// \brief A collection of alloca instructions we can directly promote.
|
|
std::vector<AllocaInst *> PromotableAllocas;
|
|
|
|
/// \brief A worklist of PHIs to speculate prior to promoting allocas.
|
|
///
|
|
/// All of these PHIs have been checked for the safety of speculation and by
|
|
/// being speculated will allow promoting allocas currently in the promotable
|
|
/// queue.
|
|
SetVector<PHINode *, SmallVector<PHINode *, 2>> SpeculatablePHIs;
|
|
|
|
/// \brief A worklist of select instructions to speculate prior to promoting
|
|
/// allocas.
|
|
///
|
|
/// All of these select instructions have been checked for the safety of
|
|
/// speculation and by being speculated will allow promoting allocas
|
|
/// currently in the promotable queue.
|
|
SetVector<SelectInst *, SmallVector<SelectInst *, 2>> SpeculatableSelects;
|
|
|
|
public:
|
|
SROA(bool RequiresDomTree = true)
|
|
: FunctionPass(ID), RequiresDomTree(RequiresDomTree), C(nullptr),
|
|
DT(nullptr) {
|
|
initializeSROAPass(*PassRegistry::getPassRegistry());
|
|
}
|
|
bool runOnFunction(Function &F) override;
|
|
void getAnalysisUsage(AnalysisUsage &AU) const override;
|
|
|
|
const char *getPassName() const override { return "SROA"; }
|
|
static char ID;
|
|
|
|
private:
|
|
friend class PHIOrSelectSpeculator;
|
|
friend class AllocaSliceRewriter;
|
|
|
|
bool presplitLoadsAndStores(AllocaInst &AI, AllocaSlices &AS);
|
|
AllocaInst *rewritePartition(AllocaInst &AI, AllocaSlices &AS,
|
|
AllocaSlices::Partition &P);
|
|
bool splitAlloca(AllocaInst &AI, AllocaSlices &AS);
|
|
bool runOnAlloca(AllocaInst &AI);
|
|
void clobberUse(Use &U);
|
|
void deleteDeadInstructions(SmallPtrSetImpl<AllocaInst *> &DeletedAllocas);
|
|
bool promoteAllocas(Function &F);
|
|
};
|
|
} // namespace
|
|
|
|
char SROA::ID = 0;
|
|
|
|
FunctionPass *llvm::createSROAPass(bool RequiresDomTree) {
|
|
return new SROA(RequiresDomTree);
|
|
}
|
|
|
|
INITIALIZE_PASS_BEGIN(SROA, "sroa", "Scalar Replacement Of Aggregates", false,
|
|
false)
|
|
INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
|
|
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
|
|
INITIALIZE_PASS_END(SROA, "sroa", "Scalar Replacement Of Aggregates", false,
|
|
false)
|
|
|
|
/// Walk the range of a partitioning looking for a common type to cover this
|
|
/// sequence of slices.
|
|
static Type *findCommonType(AllocaSlices::const_iterator B,
|
|
AllocaSlices::const_iterator E,
|
|
uint64_t EndOffset) {
|
|
Type *Ty = nullptr;
|
|
bool TyIsCommon = true;
|
|
IntegerType *ITy = nullptr;
|
|
|
|
// Note that we need to look at *every* alloca slice's Use to ensure we
|
|
// always get consistent results regardless of the order of slices.
|
|
for (AllocaSlices::const_iterator I = B; I != E; ++I) {
|
|
Use *U = I->getUse();
|
|
if (isa<IntrinsicInst>(*U->getUser()))
|
|
continue;
|
|
if (I->beginOffset() != B->beginOffset() || I->endOffset() != EndOffset)
|
|
continue;
|
|
|
|
Type *UserTy = nullptr;
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(U->getUser())) {
|
|
UserTy = LI->getType();
|
|
} else if (StoreInst *SI = dyn_cast<StoreInst>(U->getUser())) {
|
|
UserTy = SI->getValueOperand()->getType();
|
|
}
|
|
|
|
if (IntegerType *UserITy = dyn_cast_or_null<IntegerType>(UserTy)) {
|
|
// If the type is larger than the partition, skip it. We only encounter
|
|
// this for split integer operations where we want to use the type of the
|
|
// entity causing the split. Also skip if the type is not a byte width
|
|
// multiple.
|
|
if (UserITy->getBitWidth() % 8 != 0 ||
|
|
UserITy->getBitWidth() / 8 > (EndOffset - B->beginOffset()))
|
|
continue;
|
|
|
|
// Track the largest bitwidth integer type used in this way in case there
|
|
// is no common type.
|
|
if (!ITy || ITy->getBitWidth() < UserITy->getBitWidth())
|
|
ITy = UserITy;
|
|
}
|
|
|
|
// To avoid depending on the order of slices, Ty and TyIsCommon must not
|
|
// depend on types skipped above.
|
|
if (!UserTy || (Ty && Ty != UserTy))
|
|
TyIsCommon = false; // Give up on anything but an iN type.
|
|
else
|
|
Ty = UserTy;
|
|
}
|
|
|
|
return TyIsCommon ? Ty : ITy;
|
|
}
|
|
|
|
/// PHI instructions that use an alloca and are subsequently loaded can be
|
|
/// rewritten to load both input pointers in the pred blocks and then PHI the
|
|
/// results, allowing the load of the alloca to be promoted.
|
|
/// From this:
|
|
/// %P2 = phi [i32* %Alloca, i32* %Other]
|
|
/// %V = load i32* %P2
|
|
/// to:
|
|
/// %V1 = load i32* %Alloca -> will be mem2reg'd
|
|
/// ...
|
|
/// %V2 = load i32* %Other
|
|
/// ...
|
|
/// %V = phi [i32 %V1, i32 %V2]
|
|
///
|
|
/// We can do this to a select if its only uses are loads and if the operands
|
|
/// to the select can be loaded unconditionally.
|
|
///
|
|
/// FIXME: This should be hoisted into a generic utility, likely in
|
|
/// Transforms/Util/Local.h
|
|
static bool isSafePHIToSpeculate(PHINode &PN) {
|
|
// For now, we can only do this promotion if the load is in the same block
|
|
// as the PHI, and if there are no stores between the phi and load.
|
|
// TODO: Allow recursive phi users.
|
|
// TODO: Allow stores.
|
|
BasicBlock *BB = PN.getParent();
|
|
unsigned MaxAlign = 0;
|
|
bool HaveLoad = false;
|
|
for (User *U : PN.users()) {
|
|
LoadInst *LI = dyn_cast<LoadInst>(U);
|
|
if (!LI || !LI->isSimple())
|
|
return false;
|
|
|
|
// For now we only allow loads in the same block as the PHI. This is
|
|
// a common case that happens when instcombine merges two loads through
|
|
// a PHI.
|
|
if (LI->getParent() != BB)
|
|
return false;
|
|
|
|
// Ensure that there are no instructions between the PHI and the load that
|
|
// could store.
|
|
for (BasicBlock::iterator BBI = &PN; &*BBI != LI; ++BBI)
|
|
if (BBI->mayWriteToMemory())
|
|
return false;
|
|
|
|
MaxAlign = std::max(MaxAlign, LI->getAlignment());
|
|
HaveLoad = true;
|
|
}
|
|
|
|
if (!HaveLoad)
|
|
return false;
|
|
|
|
const DataLayout &DL = PN.getModule()->getDataLayout();
|
|
|
|
// We can only transform this if it is safe to push the loads into the
|
|
// predecessor blocks. The only thing to watch out for is that we can't put
|
|
// a possibly trapping load in the predecessor if it is a critical edge.
|
|
for (unsigned Idx = 0, Num = PN.getNumIncomingValues(); Idx != Num; ++Idx) {
|
|
TerminatorInst *TI = PN.getIncomingBlock(Idx)->getTerminator();
|
|
Value *InVal = PN.getIncomingValue(Idx);
|
|
|
|
// If the value is produced by the terminator of the predecessor (an
|
|
// invoke) or it has side-effects, there is no valid place to put a load
|
|
// in the predecessor.
|
|
if (TI == InVal || TI->mayHaveSideEffects())
|
|
return false;
|
|
|
|
// If the predecessor has a single successor, then the edge isn't
|
|
// critical.
|
|
if (TI->getNumSuccessors() == 1)
|
|
continue;
|
|
|
|
// If this pointer is always safe to load, or if we can prove that there
|
|
// is already a load in the block, then we can move the load to the pred
|
|
// block.
|
|
if (isDereferenceablePointer(InVal, DL) ||
|
|
isSafeToLoadUnconditionally(InVal, TI, MaxAlign))
|
|
continue;
|
|
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
static void speculatePHINodeLoads(PHINode &PN) {
|
|
DEBUG(dbgs() << " original: " << PN << "\n");
|
|
|
|
Type *LoadTy = cast<PointerType>(PN.getType())->getElementType();
|
|
IRBuilderTy PHIBuilder(&PN);
|
|
PHINode *NewPN = PHIBuilder.CreatePHI(LoadTy, PN.getNumIncomingValues(),
|
|
PN.getName() + ".sroa.speculated");
|
|
|
|
// Get the AA tags and alignment to use from one of the loads. It doesn't
|
|
// matter which one we get and if any differ.
|
|
LoadInst *SomeLoad = cast<LoadInst>(PN.user_back());
|
|
|
|
AAMDNodes AATags;
|
|
SomeLoad->getAAMetadata(AATags);
|
|
unsigned Align = SomeLoad->getAlignment();
|
|
|
|
// Rewrite all loads of the PN to use the new PHI.
|
|
while (!PN.use_empty()) {
|
|
LoadInst *LI = cast<LoadInst>(PN.user_back());
|
|
LI->replaceAllUsesWith(NewPN);
|
|
LI->eraseFromParent();
|
|
}
|
|
|
|
// Inject loads into all of the pred blocks.
|
|
for (unsigned Idx = 0, Num = PN.getNumIncomingValues(); Idx != Num; ++Idx) {
|
|
BasicBlock *Pred = PN.getIncomingBlock(Idx);
|
|
TerminatorInst *TI = Pred->getTerminator();
|
|
Value *InVal = PN.getIncomingValue(Idx);
|
|
IRBuilderTy PredBuilder(TI);
|
|
|
|
LoadInst *Load = PredBuilder.CreateLoad(
|
|
InVal, (PN.getName() + ".sroa.speculate.load." + Pred->getName()));
|
|
++NumLoadsSpeculated;
|
|
Load->setAlignment(Align);
|
|
if (AATags)
|
|
Load->setAAMetadata(AATags);
|
|
NewPN->addIncoming(Load, Pred);
|
|
}
|
|
|
|
DEBUG(dbgs() << " speculated to: " << *NewPN << "\n");
|
|
PN.eraseFromParent();
|
|
}
|
|
|
|
/// Select instructions that use an alloca and are subsequently loaded can be
|
|
/// rewritten to load both input pointers and then select between the result,
|
|
/// allowing the load of the alloca to be promoted.
|
|
/// From this:
|
|
/// %P2 = select i1 %cond, i32* %Alloca, i32* %Other
|
|
/// %V = load i32* %P2
|
|
/// to:
|
|
/// %V1 = load i32* %Alloca -> will be mem2reg'd
|
|
/// %V2 = load i32* %Other
|
|
/// %V = select i1 %cond, i32 %V1, i32 %V2
|
|
///
|
|
/// We can do this to a select if its only uses are loads and if the operand
|
|
/// to the select can be loaded unconditionally.
|
|
static bool isSafeSelectToSpeculate(SelectInst &SI) {
|
|
Value *TValue = SI.getTrueValue();
|
|
Value *FValue = SI.getFalseValue();
|
|
const DataLayout &DL = SI.getModule()->getDataLayout();
|
|
bool TDerefable = isDereferenceablePointer(TValue, DL);
|
|
bool FDerefable = isDereferenceablePointer(FValue, DL);
|
|
|
|
for (User *U : SI.users()) {
|
|
LoadInst *LI = dyn_cast<LoadInst>(U);
|
|
if (!LI || !LI->isSimple())
|
|
return false;
|
|
|
|
// Both operands to the select need to be dereferencable, either
|
|
// absolutely (e.g. allocas) or at this point because we can see other
|
|
// accesses to it.
|
|
if (!TDerefable &&
|
|
!isSafeToLoadUnconditionally(TValue, LI, LI->getAlignment()))
|
|
return false;
|
|
if (!FDerefable &&
|
|
!isSafeToLoadUnconditionally(FValue, LI, LI->getAlignment()))
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
static void speculateSelectInstLoads(SelectInst &SI) {
|
|
DEBUG(dbgs() << " original: " << SI << "\n");
|
|
|
|
IRBuilderTy IRB(&SI);
|
|
Value *TV = SI.getTrueValue();
|
|
Value *FV = SI.getFalseValue();
|
|
// Replace the loads of the select with a select of two loads.
|
|
while (!SI.use_empty()) {
|
|
LoadInst *LI = cast<LoadInst>(SI.user_back());
|
|
assert(LI->isSimple() && "We only speculate simple loads");
|
|
|
|
IRB.SetInsertPoint(LI);
|
|
LoadInst *TL =
|
|
IRB.CreateLoad(TV, LI->getName() + ".sroa.speculate.load.true");
|
|
LoadInst *FL =
|
|
IRB.CreateLoad(FV, LI->getName() + ".sroa.speculate.load.false");
|
|
NumLoadsSpeculated += 2;
|
|
|
|
// Transfer alignment and AA info if present.
|
|
TL->setAlignment(LI->getAlignment());
|
|
FL->setAlignment(LI->getAlignment());
|
|
|
|
AAMDNodes Tags;
|
|
LI->getAAMetadata(Tags);
|
|
if (Tags) {
|
|
TL->setAAMetadata(Tags);
|
|
FL->setAAMetadata(Tags);
|
|
}
|
|
|
|
Value *V = IRB.CreateSelect(SI.getCondition(), TL, FL,
|
|
LI->getName() + ".sroa.speculated");
|
|
|
|
DEBUG(dbgs() << " speculated to: " << *V << "\n");
|
|
LI->replaceAllUsesWith(V);
|
|
LI->eraseFromParent();
|
|
}
|
|
SI.eraseFromParent();
|
|
}
|
|
|
|
/// \brief Build a GEP out of a base pointer and indices.
|
|
///
|
|
/// This will return the BasePtr if that is valid, or build a new GEP
|
|
/// instruction using the IRBuilder if GEP-ing is needed.
|
|
static Value *buildGEP(IRBuilderTy &IRB, Value *BasePtr,
|
|
SmallVectorImpl<Value *> &Indices, Twine NamePrefix) {
|
|
if (Indices.empty())
|
|
return BasePtr;
|
|
|
|
// A single zero index is a no-op, so check for this and avoid building a GEP
|
|
// in that case.
|
|
if (Indices.size() == 1 && cast<ConstantInt>(Indices.back())->isZero())
|
|
return BasePtr;
|
|
|
|
return IRB.CreateInBoundsGEP(nullptr, BasePtr, Indices,
|
|
NamePrefix + "sroa_idx");
|
|
}
|
|
|
|
/// \brief Get a natural GEP off of the BasePtr walking through Ty toward
|
|
/// TargetTy without changing the offset of the pointer.
|
|
///
|
|
/// This routine assumes we've already established a properly offset GEP with
|
|
/// Indices, and arrived at the Ty type. The goal is to continue to GEP with
|
|
/// zero-indices down through type layers until we find one the same as
|
|
/// TargetTy. If we can't find one with the same type, we at least try to use
|
|
/// one with the same size. If none of that works, we just produce the GEP as
|
|
/// indicated by Indices to have the correct offset.
|
|
static Value *getNaturalGEPWithType(IRBuilderTy &IRB, const DataLayout &DL,
|
|
Value *BasePtr, Type *Ty, Type *TargetTy,
|
|
SmallVectorImpl<Value *> &Indices,
|
|
Twine NamePrefix) {
|
|
if (Ty == TargetTy)
|
|
return buildGEP(IRB, BasePtr, Indices, NamePrefix);
|
|
|
|
// Pointer size to use for the indices.
|
|
unsigned PtrSize = DL.getPointerTypeSizeInBits(BasePtr->getType());
|
|
|
|
// See if we can descend into a struct and locate a field with the correct
|
|
// type.
|
|
unsigned NumLayers = 0;
|
|
Type *ElementTy = Ty;
|
|
do {
|
|
if (ElementTy->isPointerTy())
|
|
break;
|
|
|
|
if (ArrayType *ArrayTy = dyn_cast<ArrayType>(ElementTy)) {
|
|
ElementTy = ArrayTy->getElementType();
|
|
Indices.push_back(IRB.getIntN(PtrSize, 0));
|
|
} else if (VectorType *VectorTy = dyn_cast<VectorType>(ElementTy)) {
|
|
ElementTy = VectorTy->getElementType();
|
|
Indices.push_back(IRB.getInt32(0));
|
|
} else if (StructType *STy = dyn_cast<StructType>(ElementTy)) {
|
|
if (STy->element_begin() == STy->element_end())
|
|
break; // Nothing left to descend into.
|
|
ElementTy = *STy->element_begin();
|
|
Indices.push_back(IRB.getInt32(0));
|
|
} else {
|
|
break;
|
|
}
|
|
++NumLayers;
|
|
} while (ElementTy != TargetTy);
|
|
if (ElementTy != TargetTy)
|
|
Indices.erase(Indices.end() - NumLayers, Indices.end());
|
|
|
|
return buildGEP(IRB, BasePtr, Indices, NamePrefix);
|
|
}
|
|
|
|
/// \brief Recursively compute indices for a natural GEP.
|
|
///
|
|
/// This is the recursive step for getNaturalGEPWithOffset that walks down the
|
|
/// element types adding appropriate indices for the GEP.
|
|
static Value *getNaturalGEPRecursively(IRBuilderTy &IRB, const DataLayout &DL,
|
|
Value *Ptr, Type *Ty, APInt &Offset,
|
|
Type *TargetTy,
|
|
SmallVectorImpl<Value *> &Indices,
|
|
Twine NamePrefix) {
|
|
if (Offset == 0)
|
|
return getNaturalGEPWithType(IRB, DL, Ptr, Ty, TargetTy, Indices,
|
|
NamePrefix);
|
|
|
|
// We can't recurse through pointer types.
|
|
if (Ty->isPointerTy())
|
|
return nullptr;
|
|
|
|
// We try to analyze GEPs over vectors here, but note that these GEPs are
|
|
// extremely poorly defined currently. The long-term goal is to remove GEPing
|
|
// over a vector from the IR completely.
|
|
if (VectorType *VecTy = dyn_cast<VectorType>(Ty)) {
|
|
unsigned ElementSizeInBits = DL.getTypeSizeInBits(VecTy->getScalarType());
|
|
if (ElementSizeInBits % 8 != 0) {
|
|
// GEPs over non-multiple of 8 size vector elements are invalid.
|
|
return nullptr;
|
|
}
|
|
APInt ElementSize(Offset.getBitWidth(), ElementSizeInBits / 8);
|
|
APInt NumSkippedElements = Offset.sdiv(ElementSize);
|
|
if (NumSkippedElements.ugt(VecTy->getNumElements()))
|
|
return nullptr;
|
|
Offset -= NumSkippedElements * ElementSize;
|
|
Indices.push_back(IRB.getInt(NumSkippedElements));
|
|
return getNaturalGEPRecursively(IRB, DL, Ptr, VecTy->getElementType(),
|
|
Offset, TargetTy, Indices, NamePrefix);
|
|
}
|
|
|
|
if (ArrayType *ArrTy = dyn_cast<ArrayType>(Ty)) {
|
|
Type *ElementTy = ArrTy->getElementType();
|
|
APInt ElementSize(Offset.getBitWidth(), DL.getTypeAllocSize(ElementTy));
|
|
APInt NumSkippedElements = Offset.sdiv(ElementSize);
|
|
if (NumSkippedElements.ugt(ArrTy->getNumElements()))
|
|
return nullptr;
|
|
|
|
Offset -= NumSkippedElements * ElementSize;
|
|
Indices.push_back(IRB.getInt(NumSkippedElements));
|
|
return getNaturalGEPRecursively(IRB, DL, Ptr, ElementTy, Offset, TargetTy,
|
|
Indices, NamePrefix);
|
|
}
|
|
|
|
StructType *STy = dyn_cast<StructType>(Ty);
|
|
if (!STy)
|
|
return nullptr;
|
|
|
|
const StructLayout *SL = DL.getStructLayout(STy);
|
|
uint64_t StructOffset = Offset.getZExtValue();
|
|
if (StructOffset >= SL->getSizeInBytes())
|
|
return nullptr;
|
|
unsigned Index = SL->getElementContainingOffset(StructOffset);
|
|
Offset -= APInt(Offset.getBitWidth(), SL->getElementOffset(Index));
|
|
Type *ElementTy = STy->getElementType(Index);
|
|
if (Offset.uge(DL.getTypeAllocSize(ElementTy)))
|
|
return nullptr; // The offset points into alignment padding.
|
|
|
|
Indices.push_back(IRB.getInt32(Index));
|
|
return getNaturalGEPRecursively(IRB, DL, Ptr, ElementTy, Offset, TargetTy,
|
|
Indices, NamePrefix);
|
|
}
|
|
|
|
/// \brief Get a natural GEP from a base pointer to a particular offset and
|
|
/// resulting in a particular type.
|
|
///
|
|
/// The goal is to produce a "natural" looking GEP that works with the existing
|
|
/// composite types to arrive at the appropriate offset and element type for
|
|
/// a pointer. TargetTy is the element type the returned GEP should point-to if
|
|
/// possible. We recurse by decreasing Offset, adding the appropriate index to
|
|
/// Indices, and setting Ty to the result subtype.
|
|
///
|
|
/// If no natural GEP can be constructed, this function returns null.
|
|
static Value *getNaturalGEPWithOffset(IRBuilderTy &IRB, const DataLayout &DL,
|
|
Value *Ptr, APInt Offset, Type *TargetTy,
|
|
SmallVectorImpl<Value *> &Indices,
|
|
Twine NamePrefix) {
|
|
PointerType *Ty = cast<PointerType>(Ptr->getType());
|
|
|
|
// Don't consider any GEPs through an i8* as natural unless the TargetTy is
|
|
// an i8.
|
|
if (Ty == IRB.getInt8PtrTy(Ty->getAddressSpace()) && TargetTy->isIntegerTy(8))
|
|
return nullptr;
|
|
|
|
Type *ElementTy = Ty->getElementType();
|
|
if (!ElementTy->isSized())
|
|
return nullptr; // We can't GEP through an unsized element.
|
|
APInt ElementSize(Offset.getBitWidth(), DL.getTypeAllocSize(ElementTy));
|
|
if (ElementSize == 0)
|
|
return nullptr; // Zero-length arrays can't help us build a natural GEP.
|
|
APInt NumSkippedElements = Offset.sdiv(ElementSize);
|
|
|
|
Offset -= NumSkippedElements * ElementSize;
|
|
Indices.push_back(IRB.getInt(NumSkippedElements));
|
|
return getNaturalGEPRecursively(IRB, DL, Ptr, ElementTy, Offset, TargetTy,
|
|
Indices, NamePrefix);
|
|
}
|
|
|
|
/// \brief Compute an adjusted pointer from Ptr by Offset bytes where the
|
|
/// resulting pointer has PointerTy.
|
|
///
|
|
/// This tries very hard to compute a "natural" GEP which arrives at the offset
|
|
/// and produces the pointer type desired. Where it cannot, it will try to use
|
|
/// the natural GEP to arrive at the offset and bitcast to the type. Where that
|
|
/// fails, it will try to use an existing i8* and GEP to the byte offset and
|
|
/// bitcast to the type.
|
|
///
|
|
/// The strategy for finding the more natural GEPs is to peel off layers of the
|
|
/// pointer, walking back through bit casts and GEPs, searching for a base
|
|
/// pointer from which we can compute a natural GEP with the desired
|
|
/// properties. The algorithm tries to fold as many constant indices into
|
|
/// a single GEP as possible, thus making each GEP more independent of the
|
|
/// surrounding code.
|
|
static Value *getAdjustedPtr(IRBuilderTy &IRB, const DataLayout &DL, Value *Ptr,
|
|
APInt Offset, Type *PointerTy, Twine NamePrefix) {
|
|
// Even though we don't look through PHI nodes, we could be called on an
|
|
// instruction in an unreachable block, which may be on a cycle.
|
|
SmallPtrSet<Value *, 4> Visited;
|
|
Visited.insert(Ptr);
|
|
SmallVector<Value *, 4> Indices;
|
|
|
|
// We may end up computing an offset pointer that has the wrong type. If we
|
|
// never are able to compute one directly that has the correct type, we'll
|
|
// fall back to it, so keep it and the base it was computed from around here.
|
|
Value *OffsetPtr = nullptr;
|
|
Value *OffsetBasePtr;
|
|
|
|
// Remember any i8 pointer we come across to re-use if we need to do a raw
|
|
// byte offset.
|
|
Value *Int8Ptr = nullptr;
|
|
APInt Int8PtrOffset(Offset.getBitWidth(), 0);
|
|
|
|
Type *TargetTy = PointerTy->getPointerElementType();
|
|
|
|
do {
|
|
// First fold any existing GEPs into the offset.
|
|
while (GEPOperator *GEP = dyn_cast<GEPOperator>(Ptr)) {
|
|
APInt GEPOffset(Offset.getBitWidth(), 0);
|
|
if (!GEP->accumulateConstantOffset(DL, GEPOffset))
|
|
break;
|
|
Offset += GEPOffset;
|
|
Ptr = GEP->getPointerOperand();
|
|
if (!Visited.insert(Ptr).second)
|
|
break;
|
|
}
|
|
|
|
// See if we can perform a natural GEP here.
|
|
Indices.clear();
|
|
if (Value *P = getNaturalGEPWithOffset(IRB, DL, Ptr, Offset, TargetTy,
|
|
Indices, NamePrefix)) {
|
|
// If we have a new natural pointer at the offset, clear out any old
|
|
// offset pointer we computed. Unless it is the base pointer or
|
|
// a non-instruction, we built a GEP we don't need. Zap it.
|
|
if (OffsetPtr && OffsetPtr != OffsetBasePtr)
|
|
if (Instruction *I = dyn_cast<Instruction>(OffsetPtr)) {
|
|
assert(I->use_empty() && "Built a GEP with uses some how!");
|
|
I->eraseFromParent();
|
|
}
|
|
OffsetPtr = P;
|
|
OffsetBasePtr = Ptr;
|
|
// If we also found a pointer of the right type, we're done.
|
|
if (P->getType() == PointerTy)
|
|
return P;
|
|
}
|
|
|
|
// Stash this pointer if we've found an i8*.
|
|
if (Ptr->getType()->isIntegerTy(8)) {
|
|
Int8Ptr = Ptr;
|
|
Int8PtrOffset = Offset;
|
|
}
|
|
|
|
// Peel off a layer of the pointer and update the offset appropriately.
|
|
if (Operator::getOpcode(Ptr) == Instruction::BitCast) {
|
|
Ptr = cast<Operator>(Ptr)->getOperand(0);
|
|
} else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(Ptr)) {
|
|
if (GA->mayBeOverridden())
|
|
break;
|
|
Ptr = GA->getAliasee();
|
|
} else {
|
|
break;
|
|
}
|
|
assert(Ptr->getType()->isPointerTy() && "Unexpected operand type!");
|
|
} while (Visited.insert(Ptr).second);
|
|
|
|
if (!OffsetPtr) {
|
|
if (!Int8Ptr) {
|
|
Int8Ptr = IRB.CreateBitCast(
|
|
Ptr, IRB.getInt8PtrTy(PointerTy->getPointerAddressSpace()),
|
|
NamePrefix + "sroa_raw_cast");
|
|
Int8PtrOffset = Offset;
|
|
}
|
|
|
|
OffsetPtr = Int8PtrOffset == 0
|
|
? Int8Ptr
|
|
: IRB.CreateInBoundsGEP(IRB.getInt8Ty(), Int8Ptr,
|
|
IRB.getInt(Int8PtrOffset),
|
|
NamePrefix + "sroa_raw_idx");
|
|
}
|
|
Ptr = OffsetPtr;
|
|
|
|
// On the off chance we were targeting i8*, guard the bitcast here.
|
|
if (Ptr->getType() != PointerTy)
|
|
Ptr = IRB.CreateBitCast(Ptr, PointerTy, NamePrefix + "sroa_cast");
|
|
|
|
return Ptr;
|
|
}
|
|
|
|
/// \brief Compute the adjusted alignment for a load or store from an offset.
|
|
static unsigned getAdjustedAlignment(Instruction *I, uint64_t Offset,
|
|
const DataLayout &DL) {
|
|
unsigned Alignment;
|
|
Type *Ty;
|
|
if (auto *LI = dyn_cast<LoadInst>(I)) {
|
|
Alignment = LI->getAlignment();
|
|
Ty = LI->getType();
|
|
} else if (auto *SI = dyn_cast<StoreInst>(I)) {
|
|
Alignment = SI->getAlignment();
|
|
Ty = SI->getValueOperand()->getType();
|
|
} else {
|
|
llvm_unreachable("Only loads and stores are allowed!");
|
|
}
|
|
|
|
if (!Alignment)
|
|
Alignment = DL.getABITypeAlignment(Ty);
|
|
|
|
return MinAlign(Alignment, Offset);
|
|
}
|
|
|
|
/// \brief Test whether we can convert a value from the old to the new type.
|
|
///
|
|
/// This predicate should be used to guard calls to convertValue in order to
|
|
/// ensure that we only try to convert viable values. The strategy is that we
|
|
/// will peel off single element struct and array wrappings to get to an
|
|
/// underlying value, and convert that value.
|
|
static bool canConvertValue(const DataLayout &DL, Type *OldTy, Type *NewTy) {
|
|
if (OldTy == NewTy)
|
|
return true;
|
|
if (IntegerType *OldITy = dyn_cast<IntegerType>(OldTy))
|
|
if (IntegerType *NewITy = dyn_cast<IntegerType>(NewTy))
|
|
if (NewITy->getBitWidth() >= OldITy->getBitWidth())
|
|
return true;
|
|
if (DL.getTypeSizeInBits(NewTy) != DL.getTypeSizeInBits(OldTy))
|
|
return false;
|
|
if (!NewTy->isSingleValueType() || !OldTy->isSingleValueType())
|
|
return false;
|
|
|
|
// We can convert pointers to integers and vice-versa. Same for vectors
|
|
// of pointers and integers.
|
|
OldTy = OldTy->getScalarType();
|
|
NewTy = NewTy->getScalarType();
|
|
if (NewTy->isPointerTy() || OldTy->isPointerTy()) {
|
|
if (NewTy->isPointerTy() && OldTy->isPointerTy())
|
|
return true;
|
|
if (NewTy->isIntegerTy() || OldTy->isIntegerTy())
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/// \brief Generic routine to convert an SSA value to a value of a different
|
|
/// type.
|
|
///
|
|
/// This will try various different casting techniques, such as bitcasts,
|
|
/// inttoptr, and ptrtoint casts. Use the \c canConvertValue predicate to test
|
|
/// two types for viability with this routine.
|
|
static Value *convertValue(const DataLayout &DL, IRBuilderTy &IRB, Value *V,
|
|
Type *NewTy) {
|
|
Type *OldTy = V->getType();
|
|
assert(canConvertValue(DL, OldTy, NewTy) && "Value not convertable to type");
|
|
|
|
if (OldTy == NewTy)
|
|
return V;
|
|
|
|
if (IntegerType *OldITy = dyn_cast<IntegerType>(OldTy))
|
|
if (IntegerType *NewITy = dyn_cast<IntegerType>(NewTy))
|
|
if (NewITy->getBitWidth() > OldITy->getBitWidth())
|
|
return IRB.CreateZExt(V, NewITy);
|
|
|
|
// See if we need inttoptr for this type pair. A cast involving both scalars
|
|
// and vectors requires and additional bitcast.
|
|
if (OldTy->getScalarType()->isIntegerTy() &&
|
|
NewTy->getScalarType()->isPointerTy()) {
|
|
// Expand <2 x i32> to i8* --> <2 x i32> to i64 to i8*
|
|
if (OldTy->isVectorTy() && !NewTy->isVectorTy())
|
|
return IRB.CreateIntToPtr(IRB.CreateBitCast(V, DL.getIntPtrType(NewTy)),
|
|
NewTy);
|
|
|
|
// Expand i128 to <2 x i8*> --> i128 to <2 x i64> to <2 x i8*>
|
|
if (!OldTy->isVectorTy() && NewTy->isVectorTy())
|
|
return IRB.CreateIntToPtr(IRB.CreateBitCast(V, DL.getIntPtrType(NewTy)),
|
|
NewTy);
|
|
|
|
return IRB.CreateIntToPtr(V, NewTy);
|
|
}
|
|
|
|
// See if we need ptrtoint for this type pair. A cast involving both scalars
|
|
// and vectors requires and additional bitcast.
|
|
if (OldTy->getScalarType()->isPointerTy() &&
|
|
NewTy->getScalarType()->isIntegerTy()) {
|
|
// Expand <2 x i8*> to i128 --> <2 x i8*> to <2 x i64> to i128
|
|
if (OldTy->isVectorTy() && !NewTy->isVectorTy())
|
|
return IRB.CreateBitCast(IRB.CreatePtrToInt(V, DL.getIntPtrType(OldTy)),
|
|
NewTy);
|
|
|
|
// Expand i8* to <2 x i32> --> i8* to i64 to <2 x i32>
|
|
if (!OldTy->isVectorTy() && NewTy->isVectorTy())
|
|
return IRB.CreateBitCast(IRB.CreatePtrToInt(V, DL.getIntPtrType(OldTy)),
|
|
NewTy);
|
|
|
|
return IRB.CreatePtrToInt(V, NewTy);
|
|
}
|
|
|
|
return IRB.CreateBitCast(V, NewTy);
|
|
}
|
|
|
|
/// \brief Test whether the given slice use can be promoted to a vector.
|
|
///
|
|
/// This function is called to test each entry in a partioning which is slated
|
|
/// for a single slice.
|
|
static bool isVectorPromotionViableForSlice(AllocaSlices::Partition &P,
|
|
const Slice &S, VectorType *Ty,
|
|
uint64_t ElementSize,
|
|
const DataLayout &DL) {
|
|
// First validate the slice offsets.
|
|
uint64_t BeginOffset =
|
|
std::max(S.beginOffset(), P.beginOffset()) - P.beginOffset();
|
|
uint64_t BeginIndex = BeginOffset / ElementSize;
|
|
if (BeginIndex * ElementSize != BeginOffset ||
|
|
BeginIndex >= Ty->getNumElements())
|
|
return false;
|
|
uint64_t EndOffset =
|
|
std::min(S.endOffset(), P.endOffset()) - P.beginOffset();
|
|
uint64_t EndIndex = EndOffset / ElementSize;
|
|
if (EndIndex * ElementSize != EndOffset || EndIndex > Ty->getNumElements())
|
|
return false;
|
|
|
|
assert(EndIndex > BeginIndex && "Empty vector!");
|
|
uint64_t NumElements = EndIndex - BeginIndex;
|
|
Type *SliceTy = (NumElements == 1)
|
|
? Ty->getElementType()
|
|
: VectorType::get(Ty->getElementType(), NumElements);
|
|
|
|
Type *SplitIntTy =
|
|
Type::getIntNTy(Ty->getContext(), NumElements * ElementSize * 8);
|
|
|
|
Use *U = S.getUse();
|
|
|
|
if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(U->getUser())) {
|
|
if (MI->isVolatile())
|
|
return false;
|
|
if (!S.isSplittable())
|
|
return false; // Skip any unsplittable intrinsics.
|
|
} else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(U->getUser())) {
|
|
if (II->getIntrinsicID() != Intrinsic::lifetime_start &&
|
|
II->getIntrinsicID() != Intrinsic::lifetime_end)
|
|
return false;
|
|
} else if (U->get()->getType()->getPointerElementType()->isStructTy()) {
|
|
// Disable vector promotion when there are loads or stores of an FCA.
|
|
return false;
|
|
} else if (LoadInst *LI = dyn_cast<LoadInst>(U->getUser())) {
|
|
if (LI->isVolatile())
|
|
return false;
|
|
Type *LTy = LI->getType();
|
|
if (P.beginOffset() > S.beginOffset() || P.endOffset() < S.endOffset()) {
|
|
assert(LTy->isIntegerTy());
|
|
LTy = SplitIntTy;
|
|
}
|
|
if (!canConvertValue(DL, SliceTy, LTy))
|
|
return false;
|
|
} else if (StoreInst *SI = dyn_cast<StoreInst>(U->getUser())) {
|
|
if (SI->isVolatile())
|
|
return false;
|
|
Type *STy = SI->getValueOperand()->getType();
|
|
if (P.beginOffset() > S.beginOffset() || P.endOffset() < S.endOffset()) {
|
|
assert(STy->isIntegerTy());
|
|
STy = SplitIntTy;
|
|
}
|
|
if (!canConvertValue(DL, STy, SliceTy))
|
|
return false;
|
|
} else {
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/// \brief Test whether the given alloca partitioning and range of slices can be
|
|
/// promoted to a vector.
|
|
///
|
|
/// This is a quick test to check whether we can rewrite a particular alloca
|
|
/// partition (and its newly formed alloca) into a vector alloca with only
|
|
/// whole-vector loads and stores such that it could be promoted to a vector
|
|
/// SSA value. We only can ensure this for a limited set of operations, and we
|
|
/// don't want to do the rewrites unless we are confident that the result will
|
|
/// be promotable, so we have an early test here.
|
|
static VectorType *isVectorPromotionViable(AllocaSlices::Partition &P,
|
|
const DataLayout &DL) {
|
|
// Collect the candidate types for vector-based promotion. Also track whether
|
|
// we have different element types.
|
|
SmallVector<VectorType *, 4> CandidateTys;
|
|
Type *CommonEltTy = nullptr;
|
|
bool HaveCommonEltTy = true;
|
|
auto CheckCandidateType = [&](Type *Ty) {
|
|
if (auto *VTy = dyn_cast<VectorType>(Ty)) {
|
|
CandidateTys.push_back(VTy);
|
|
if (!CommonEltTy)
|
|
CommonEltTy = VTy->getElementType();
|
|
else if (CommonEltTy != VTy->getElementType())
|
|
HaveCommonEltTy = false;
|
|
}
|
|
};
|
|
// Consider any loads or stores that are the exact size of the slice.
|
|
for (const Slice &S : P)
|
|
if (S.beginOffset() == P.beginOffset() &&
|
|
S.endOffset() == P.endOffset()) {
|
|
if (auto *LI = dyn_cast<LoadInst>(S.getUse()->getUser()))
|
|
CheckCandidateType(LI->getType());
|
|
else if (auto *SI = dyn_cast<StoreInst>(S.getUse()->getUser()))
|
|
CheckCandidateType(SI->getValueOperand()->getType());
|
|
}
|
|
|
|
// If we didn't find a vector type, nothing to do here.
|
|
if (CandidateTys.empty())
|
|
return nullptr;
|
|
|
|
// Remove non-integer vector types if we had multiple common element types.
|
|
// FIXME: It'd be nice to replace them with integer vector types, but we can't
|
|
// do that until all the backends are known to produce good code for all
|
|
// integer vector types.
|
|
if (!HaveCommonEltTy) {
|
|
CandidateTys.erase(std::remove_if(CandidateTys.begin(), CandidateTys.end(),
|
|
[](VectorType *VTy) {
|
|
return !VTy->getElementType()->isIntegerTy();
|
|
}),
|
|
CandidateTys.end());
|
|
|
|
// If there were no integer vector types, give up.
|
|
if (CandidateTys.empty())
|
|
return nullptr;
|
|
|
|
// Rank the remaining candidate vector types. This is easy because we know
|
|
// they're all integer vectors. We sort by ascending number of elements.
|
|
auto RankVectorTypes = [&DL](VectorType *RHSTy, VectorType *LHSTy) {
|
|
assert(DL.getTypeSizeInBits(RHSTy) == DL.getTypeSizeInBits(LHSTy) &&
|
|
"Cannot have vector types of different sizes!");
|
|
assert(RHSTy->getElementType()->isIntegerTy() &&
|
|
"All non-integer types eliminated!");
|
|
assert(LHSTy->getElementType()->isIntegerTy() &&
|
|
"All non-integer types eliminated!");
|
|
return RHSTy->getNumElements() < LHSTy->getNumElements();
|
|
};
|
|
std::sort(CandidateTys.begin(), CandidateTys.end(), RankVectorTypes);
|
|
CandidateTys.erase(
|
|
std::unique(CandidateTys.begin(), CandidateTys.end(), RankVectorTypes),
|
|
CandidateTys.end());
|
|
} else {
|
|
// The only way to have the same element type in every vector type is to
|
|
// have the same vector type. Check that and remove all but one.
|
|
#ifndef NDEBUG
|
|
for (VectorType *VTy : CandidateTys) {
|
|
assert(VTy->getElementType() == CommonEltTy &&
|
|
"Unaccounted for element type!");
|
|
assert(VTy == CandidateTys[0] &&
|
|
"Different vector types with the same element type!");
|
|
}
|
|
#endif
|
|
CandidateTys.resize(1);
|
|
}
|
|
|
|
// Try each vector type, and return the one which works.
|
|
auto CheckVectorTypeForPromotion = [&](VectorType *VTy) {
|
|
uint64_t ElementSize = DL.getTypeSizeInBits(VTy->getElementType());
|
|
|
|
// While the definition of LLVM vectors is bitpacked, we don't support sizes
|
|
// that aren't byte sized.
|
|
if (ElementSize % 8)
|
|
return false;
|
|
assert((DL.getTypeSizeInBits(VTy) % 8) == 0 &&
|
|
"vector size not a multiple of element size?");
|
|
ElementSize /= 8;
|
|
|
|
for (const Slice &S : P)
|
|
if (!isVectorPromotionViableForSlice(P, S, VTy, ElementSize, DL))
|
|
return false;
|
|
|
|
for (const Slice *S : P.splitSliceTails())
|
|
if (!isVectorPromotionViableForSlice(P, *S, VTy, ElementSize, DL))
|
|
return false;
|
|
|
|
return true;
|
|
};
|
|
for (VectorType *VTy : CandidateTys)
|
|
if (CheckVectorTypeForPromotion(VTy))
|
|
return VTy;
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
/// \brief Test whether a slice of an alloca is valid for integer widening.
|
|
///
|
|
/// This implements the necessary checking for the \c isIntegerWideningViable
|
|
/// test below on a single slice of the alloca.
|
|
static bool isIntegerWideningViableForSlice(const Slice &S,
|
|
uint64_t AllocBeginOffset,
|
|
Type *AllocaTy,
|
|
const DataLayout &DL,
|
|
bool &WholeAllocaOp) {
|
|
uint64_t Size = DL.getTypeStoreSize(AllocaTy);
|
|
|
|
uint64_t RelBegin = S.beginOffset() - AllocBeginOffset;
|
|
uint64_t RelEnd = S.endOffset() - AllocBeginOffset;
|
|
|
|
// We can't reasonably handle cases where the load or store extends past
|
|
// the end of the aloca's type and into its padding.
|
|
if (RelEnd > Size)
|
|
return false;
|
|
|
|
Use *U = S.getUse();
|
|
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(U->getUser())) {
|
|
if (LI->isVolatile())
|
|
return false;
|
|
// Note that we don't count vector loads or stores as whole-alloca
|
|
// operations which enable integer widening because we would prefer to use
|
|
// vector widening instead.
|
|
if (!isa<VectorType>(LI->getType()) && RelBegin == 0 && RelEnd == Size)
|
|
WholeAllocaOp = true;
|
|
if (IntegerType *ITy = dyn_cast<IntegerType>(LI->getType())) {
|
|
if (ITy->getBitWidth() < DL.getTypeStoreSizeInBits(ITy))
|
|
return false;
|
|
} else if (RelBegin != 0 || RelEnd != Size ||
|
|
!canConvertValue(DL, AllocaTy, LI->getType())) {
|
|
// Non-integer loads need to be convertible from the alloca type so that
|
|
// they are promotable.
|
|
return false;
|
|
}
|
|
} else if (StoreInst *SI = dyn_cast<StoreInst>(U->getUser())) {
|
|
Type *ValueTy = SI->getValueOperand()->getType();
|
|
if (SI->isVolatile())
|
|
return false;
|
|
// Note that we don't count vector loads or stores as whole-alloca
|
|
// operations which enable integer widening because we would prefer to use
|
|
// vector widening instead.
|
|
if (!isa<VectorType>(ValueTy) && RelBegin == 0 && RelEnd == Size)
|
|
WholeAllocaOp = true;
|
|
if (IntegerType *ITy = dyn_cast<IntegerType>(ValueTy)) {
|
|
if (ITy->getBitWidth() < DL.getTypeStoreSizeInBits(ITy))
|
|
return false;
|
|
} else if (RelBegin != 0 || RelEnd != Size ||
|
|
!canConvertValue(DL, ValueTy, AllocaTy)) {
|
|
// Non-integer stores need to be convertible to the alloca type so that
|
|
// they are promotable.
|
|
return false;
|
|
}
|
|
} else if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(U->getUser())) {
|
|
if (MI->isVolatile() || !isa<Constant>(MI->getLength()))
|
|
return false;
|
|
if (!S.isSplittable())
|
|
return false; // Skip any unsplittable intrinsics.
|
|
} else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(U->getUser())) {
|
|
if (II->getIntrinsicID() != Intrinsic::lifetime_start &&
|
|
II->getIntrinsicID() != Intrinsic::lifetime_end)
|
|
return false;
|
|
} else {
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/// \brief Test whether the given alloca partition's integer operations can be
|
|
/// widened to promotable ones.
|
|
///
|
|
/// This is a quick test to check whether we can rewrite the integer loads and
|
|
/// stores to a particular alloca into wider loads and stores and be able to
|
|
/// promote the resulting alloca.
|
|
static bool isIntegerWideningViable(AllocaSlices::Partition &P, Type *AllocaTy,
|
|
const DataLayout &DL) {
|
|
uint64_t SizeInBits = DL.getTypeSizeInBits(AllocaTy);
|
|
// Don't create integer types larger than the maximum bitwidth.
|
|
if (SizeInBits > IntegerType::MAX_INT_BITS)
|
|
return false;
|
|
|
|
// Don't try to handle allocas with bit-padding.
|
|
if (SizeInBits != DL.getTypeStoreSizeInBits(AllocaTy))
|
|
return false;
|
|
|
|
// We need to ensure that an integer type with the appropriate bitwidth can
|
|
// be converted to the alloca type, whatever that is. We don't want to force
|
|
// the alloca itself to have an integer type if there is a more suitable one.
|
|
Type *IntTy = Type::getIntNTy(AllocaTy->getContext(), SizeInBits);
|
|
if (!canConvertValue(DL, AllocaTy, IntTy) ||
|
|
!canConvertValue(DL, IntTy, AllocaTy))
|
|
return false;
|
|
|
|
// While examining uses, we ensure that the alloca has a covering load or
|
|
// store. We don't want to widen the integer operations only to fail to
|
|
// promote due to some other unsplittable entry (which we may make splittable
|
|
// later). However, if there are only splittable uses, go ahead and assume
|
|
// that we cover the alloca.
|
|
// FIXME: We shouldn't consider split slices that happen to start in the
|
|
// partition here...
|
|
bool WholeAllocaOp =
|
|
P.begin() != P.end() ? false : DL.isLegalInteger(SizeInBits);
|
|
|
|
for (const Slice &S : P)
|
|
if (!isIntegerWideningViableForSlice(S, P.beginOffset(), AllocaTy, DL,
|
|
WholeAllocaOp))
|
|
return false;
|
|
|
|
for (const Slice *S : P.splitSliceTails())
|
|
if (!isIntegerWideningViableForSlice(*S, P.beginOffset(), AllocaTy, DL,
|
|
WholeAllocaOp))
|
|
return false;
|
|
|
|
return WholeAllocaOp;
|
|
}
|
|
|
|
static Value *extractInteger(const DataLayout &DL, IRBuilderTy &IRB, Value *V,
|
|
IntegerType *Ty, uint64_t Offset,
|
|
const Twine &Name) {
|
|
DEBUG(dbgs() << " start: " << *V << "\n");
|
|
IntegerType *IntTy = cast<IntegerType>(V->getType());
|
|
assert(DL.getTypeStoreSize(Ty) + Offset <= DL.getTypeStoreSize(IntTy) &&
|
|
"Element extends past full value");
|
|
uint64_t ShAmt = 8 * Offset;
|
|
if (DL.isBigEndian())
|
|
ShAmt = 8 * (DL.getTypeStoreSize(IntTy) - DL.getTypeStoreSize(Ty) - Offset);
|
|
if (ShAmt) {
|
|
V = IRB.CreateLShr(V, ShAmt, Name + ".shift");
|
|
DEBUG(dbgs() << " shifted: " << *V << "\n");
|
|
}
|
|
assert(Ty->getBitWidth() <= IntTy->getBitWidth() &&
|
|
"Cannot extract to a larger integer!");
|
|
if (Ty != IntTy) {
|
|
V = IRB.CreateTrunc(V, Ty, Name + ".trunc");
|
|
DEBUG(dbgs() << " trunced: " << *V << "\n");
|
|
}
|
|
return V;
|
|
}
|
|
|
|
static Value *insertInteger(const DataLayout &DL, IRBuilderTy &IRB, Value *Old,
|
|
Value *V, uint64_t Offset, const Twine &Name) {
|
|
IntegerType *IntTy = cast<IntegerType>(Old->getType());
|
|
IntegerType *Ty = cast<IntegerType>(V->getType());
|
|
assert(Ty->getBitWidth() <= IntTy->getBitWidth() &&
|
|
"Cannot insert a larger integer!");
|
|
DEBUG(dbgs() << " start: " << *V << "\n");
|
|
if (Ty != IntTy) {
|
|
V = IRB.CreateZExt(V, IntTy, Name + ".ext");
|
|
DEBUG(dbgs() << " extended: " << *V << "\n");
|
|
}
|
|
assert(DL.getTypeStoreSize(Ty) + Offset <= DL.getTypeStoreSize(IntTy) &&
|
|
"Element store outside of alloca store");
|
|
uint64_t ShAmt = 8 * Offset;
|
|
if (DL.isBigEndian())
|
|
ShAmt = 8 * (DL.getTypeStoreSize(IntTy) - DL.getTypeStoreSize(Ty) - Offset);
|
|
if (ShAmt) {
|
|
V = IRB.CreateShl(V, ShAmt, Name + ".shift");
|
|
DEBUG(dbgs() << " shifted: " << *V << "\n");
|
|
}
|
|
|
|
if (ShAmt || Ty->getBitWidth() < IntTy->getBitWidth()) {
|
|
APInt Mask = ~Ty->getMask().zext(IntTy->getBitWidth()).shl(ShAmt);
|
|
Old = IRB.CreateAnd(Old, Mask, Name + ".mask");
|
|
DEBUG(dbgs() << " masked: " << *Old << "\n");
|
|
V = IRB.CreateOr(Old, V, Name + ".insert");
|
|
DEBUG(dbgs() << " inserted: " << *V << "\n");
|
|
}
|
|
return V;
|
|
}
|
|
|
|
static Value *extractVector(IRBuilderTy &IRB, Value *V, unsigned BeginIndex,
|
|
unsigned EndIndex, const Twine &Name) {
|
|
VectorType *VecTy = cast<VectorType>(V->getType());
|
|
unsigned NumElements = EndIndex - BeginIndex;
|
|
assert(NumElements <= VecTy->getNumElements() && "Too many elements!");
|
|
|
|
if (NumElements == VecTy->getNumElements())
|
|
return V;
|
|
|
|
if (NumElements == 1) {
|
|
V = IRB.CreateExtractElement(V, IRB.getInt32(BeginIndex),
|
|
Name + ".extract");
|
|
DEBUG(dbgs() << " extract: " << *V << "\n");
|
|
return V;
|
|
}
|
|
|
|
SmallVector<Constant *, 8> Mask;
|
|
Mask.reserve(NumElements);
|
|
for (unsigned i = BeginIndex; i != EndIndex; ++i)
|
|
Mask.push_back(IRB.getInt32(i));
|
|
V = IRB.CreateShuffleVector(V, UndefValue::get(V->getType()),
|
|
ConstantVector::get(Mask), Name + ".extract");
|
|
DEBUG(dbgs() << " shuffle: " << *V << "\n");
|
|
return V;
|
|
}
|
|
|
|
static Value *insertVector(IRBuilderTy &IRB, Value *Old, Value *V,
|
|
unsigned BeginIndex, const Twine &Name) {
|
|
VectorType *VecTy = cast<VectorType>(Old->getType());
|
|
assert(VecTy && "Can only insert a vector into a vector");
|
|
|
|
VectorType *Ty = dyn_cast<VectorType>(V->getType());
|
|
if (!Ty) {
|
|
// Single element to insert.
|
|
V = IRB.CreateInsertElement(Old, V, IRB.getInt32(BeginIndex),
|
|
Name + ".insert");
|
|
DEBUG(dbgs() << " insert: " << *V << "\n");
|
|
return V;
|
|
}
|
|
|
|
assert(Ty->getNumElements() <= VecTy->getNumElements() &&
|
|
"Too many elements!");
|
|
if (Ty->getNumElements() == VecTy->getNumElements()) {
|
|
assert(V->getType() == VecTy && "Vector type mismatch");
|
|
return V;
|
|
}
|
|
unsigned EndIndex = BeginIndex + Ty->getNumElements();
|
|
|
|
// When inserting a smaller vector into the larger to store, we first
|
|
// use a shuffle vector to widen it with undef elements, and then
|
|
// a second shuffle vector to select between the loaded vector and the
|
|
// incoming vector.
|
|
SmallVector<Constant *, 8> Mask;
|
|
Mask.reserve(VecTy->getNumElements());
|
|
for (unsigned i = 0; i != VecTy->getNumElements(); ++i)
|
|
if (i >= BeginIndex && i < EndIndex)
|
|
Mask.push_back(IRB.getInt32(i - BeginIndex));
|
|
else
|
|
Mask.push_back(UndefValue::get(IRB.getInt32Ty()));
|
|
V = IRB.CreateShuffleVector(V, UndefValue::get(V->getType()),
|
|
ConstantVector::get(Mask), Name + ".expand");
|
|
DEBUG(dbgs() << " shuffle: " << *V << "\n");
|
|
|
|
Mask.clear();
|
|
for (unsigned i = 0; i != VecTy->getNumElements(); ++i)
|
|
Mask.push_back(IRB.getInt1(i >= BeginIndex && i < EndIndex));
|
|
|
|
V = IRB.CreateSelect(ConstantVector::get(Mask), V, Old, Name + "blend");
|
|
|
|
DEBUG(dbgs() << " blend: " << *V << "\n");
|
|
return V;
|
|
}
|
|
|
|
namespace {
|
|
/// \brief Visitor to rewrite instructions using p particular slice of an alloca
|
|
/// to use a new alloca.
|
|
///
|
|
/// Also implements the rewriting to vector-based accesses when the partition
|
|
/// passes the isVectorPromotionViable predicate. Most of the rewriting logic
|
|
/// lives here.
|
|
class AllocaSliceRewriter : public InstVisitor<AllocaSliceRewriter, bool> {
|
|
// Befriend the base class so it can delegate to private visit methods.
|
|
friend class llvm::InstVisitor<AllocaSliceRewriter, bool>;
|
|
typedef llvm::InstVisitor<AllocaSliceRewriter, bool> Base;
|
|
|
|
const DataLayout &DL;
|
|
AllocaSlices &AS;
|
|
SROA &Pass;
|
|
AllocaInst &OldAI, &NewAI;
|
|
const uint64_t NewAllocaBeginOffset, NewAllocaEndOffset;
|
|
Type *NewAllocaTy;
|
|
|
|
// This is a convenience and flag variable that will be null unless the new
|
|
// alloca's integer operations should be widened to this integer type due to
|
|
// passing isIntegerWideningViable above. If it is non-null, the desired
|
|
// integer type will be stored here for easy access during rewriting.
|
|
IntegerType *IntTy;
|
|
|
|
// If we are rewriting an alloca partition which can be written as pure
|
|
// vector operations, we stash extra information here. When VecTy is
|
|
// non-null, we have some strict guarantees about the rewritten alloca:
|
|
// - The new alloca is exactly the size of the vector type here.
|
|
// - The accesses all either map to the entire vector or to a single
|
|
// element.
|
|
// - The set of accessing instructions is only one of those handled above
|
|
// in isVectorPromotionViable. Generally these are the same access kinds
|
|
// which are promotable via mem2reg.
|
|
VectorType *VecTy;
|
|
Type *ElementTy;
|
|
uint64_t ElementSize;
|
|
|
|
// The original offset of the slice currently being rewritten relative to
|
|
// the original alloca.
|
|
uint64_t BeginOffset, EndOffset;
|
|
// The new offsets of the slice currently being rewritten relative to the
|
|
// original alloca.
|
|
uint64_t NewBeginOffset, NewEndOffset;
|
|
|
|
uint64_t SliceSize;
|
|
bool IsSplittable;
|
|
bool IsSplit;
|
|
Use *OldUse;
|
|
Instruction *OldPtr;
|
|
|
|
// Track post-rewrite users which are PHI nodes and Selects.
|
|
SmallPtrSetImpl<PHINode *> &PHIUsers;
|
|
SmallPtrSetImpl<SelectInst *> &SelectUsers;
|
|
|
|
// Utility IR builder, whose name prefix is setup for each visited use, and
|
|
// the insertion point is set to point to the user.
|
|
IRBuilderTy IRB;
|
|
|
|
public:
|
|
AllocaSliceRewriter(const DataLayout &DL, AllocaSlices &AS, SROA &Pass,
|
|
AllocaInst &OldAI, AllocaInst &NewAI,
|
|
uint64_t NewAllocaBeginOffset,
|
|
uint64_t NewAllocaEndOffset, bool IsIntegerPromotable,
|
|
VectorType *PromotableVecTy,
|
|
SmallPtrSetImpl<PHINode *> &PHIUsers,
|
|
SmallPtrSetImpl<SelectInst *> &SelectUsers)
|
|
: DL(DL), AS(AS), Pass(Pass), OldAI(OldAI), NewAI(NewAI),
|
|
NewAllocaBeginOffset(NewAllocaBeginOffset),
|
|
NewAllocaEndOffset(NewAllocaEndOffset),
|
|
NewAllocaTy(NewAI.getAllocatedType()),
|
|
IntTy(IsIntegerPromotable
|
|
? Type::getIntNTy(
|
|
NewAI.getContext(),
|
|
DL.getTypeSizeInBits(NewAI.getAllocatedType()))
|
|
: nullptr),
|
|
VecTy(PromotableVecTy),
|
|
ElementTy(VecTy ? VecTy->getElementType() : nullptr),
|
|
ElementSize(VecTy ? DL.getTypeSizeInBits(ElementTy) / 8 : 0),
|
|
BeginOffset(), EndOffset(), IsSplittable(), IsSplit(), OldUse(),
|
|
OldPtr(), PHIUsers(PHIUsers), SelectUsers(SelectUsers),
|
|
IRB(NewAI.getContext(), ConstantFolder()) {
|
|
if (VecTy) {
|
|
assert((DL.getTypeSizeInBits(ElementTy) % 8) == 0 &&
|
|
"Only multiple-of-8 sized vector elements are viable");
|
|
++NumVectorized;
|
|
}
|
|
assert((!IntTy && !VecTy) || (IntTy && !VecTy) || (!IntTy && VecTy));
|
|
}
|
|
|
|
bool visit(AllocaSlices::const_iterator I) {
|
|
bool CanSROA = true;
|
|
BeginOffset = I->beginOffset();
|
|
EndOffset = I->endOffset();
|
|
IsSplittable = I->isSplittable();
|
|
IsSplit =
|
|
BeginOffset < NewAllocaBeginOffset || EndOffset > NewAllocaEndOffset;
|
|
DEBUG(dbgs() << " rewriting " << (IsSplit ? "split " : ""));
|
|
DEBUG(AS.printSlice(dbgs(), I, ""));
|
|
DEBUG(dbgs() << "\n");
|
|
|
|
// Compute the intersecting offset range.
|
|
assert(BeginOffset < NewAllocaEndOffset);
|
|
assert(EndOffset > NewAllocaBeginOffset);
|
|
NewBeginOffset = std::max(BeginOffset, NewAllocaBeginOffset);
|
|
NewEndOffset = std::min(EndOffset, NewAllocaEndOffset);
|
|
|
|
SliceSize = NewEndOffset - NewBeginOffset;
|
|
|
|
OldUse = I->getUse();
|
|
OldPtr = cast<Instruction>(OldUse->get());
|
|
|
|
Instruction *OldUserI = cast<Instruction>(OldUse->getUser());
|
|
IRB.SetInsertPoint(OldUserI);
|
|
IRB.SetCurrentDebugLocation(OldUserI->getDebugLoc());
|
|
IRB.SetNamePrefix(Twine(NewAI.getName()) + "." + Twine(BeginOffset) + ".");
|
|
|
|
CanSROA &= visit(cast<Instruction>(OldUse->getUser()));
|
|
if (VecTy || IntTy)
|
|
assert(CanSROA);
|
|
return CanSROA;
|
|
}
|
|
|
|
private:
|
|
// Make sure the other visit overloads are visible.
|
|
using Base::visit;
|
|
|
|
// Every instruction which can end up as a user must have a rewrite rule.
|
|
bool visitInstruction(Instruction &I) {
|
|
DEBUG(dbgs() << " !!!! Cannot rewrite: " << I << "\n");
|
|
llvm_unreachable("No rewrite rule for this instruction!");
|
|
}
|
|
|
|
Value *getNewAllocaSlicePtr(IRBuilderTy &IRB, Type *PointerTy) {
|
|
// Note that the offset computation can use BeginOffset or NewBeginOffset
|
|
// interchangeably for unsplit slices.
|
|
assert(IsSplit || BeginOffset == NewBeginOffset);
|
|
uint64_t Offset = NewBeginOffset - NewAllocaBeginOffset;
|
|
|
|
#ifndef NDEBUG
|
|
StringRef OldName = OldPtr->getName();
|
|
// Skip through the last '.sroa.' component of the name.
|
|
size_t LastSROAPrefix = OldName.rfind(".sroa.");
|
|
if (LastSROAPrefix != StringRef::npos) {
|
|
OldName = OldName.substr(LastSROAPrefix + strlen(".sroa."));
|
|
// Look for an SROA slice index.
|
|
size_t IndexEnd = OldName.find_first_not_of("0123456789");
|
|
if (IndexEnd != StringRef::npos && OldName[IndexEnd] == '.') {
|
|
// Strip the index and look for the offset.
|
|
OldName = OldName.substr(IndexEnd + 1);
|
|
size_t OffsetEnd = OldName.find_first_not_of("0123456789");
|
|
if (OffsetEnd != StringRef::npos && OldName[OffsetEnd] == '.')
|
|
// Strip the offset.
|
|
OldName = OldName.substr(OffsetEnd + 1);
|
|
}
|
|
}
|
|
// Strip any SROA suffixes as well.
|
|
OldName = OldName.substr(0, OldName.find(".sroa_"));
|
|
#endif
|
|
|
|
return getAdjustedPtr(IRB, DL, &NewAI,
|
|
APInt(DL.getPointerSizeInBits(), Offset), PointerTy,
|
|
#ifndef NDEBUG
|
|
Twine(OldName) + "."
|
|
#else
|
|
Twine()
|
|
#endif
|
|
);
|
|
}
|
|
|
|
/// \brief Compute suitable alignment to access this slice of the *new*
|
|
/// alloca.
|
|
///
|
|
/// You can optionally pass a type to this routine and if that type's ABI
|
|
/// alignment is itself suitable, this will return zero.
|
|
unsigned getSliceAlign(Type *Ty = nullptr) {
|
|
unsigned NewAIAlign = NewAI.getAlignment();
|
|
if (!NewAIAlign)
|
|
NewAIAlign = DL.getABITypeAlignment(NewAI.getAllocatedType());
|
|
unsigned Align =
|
|
MinAlign(NewAIAlign, NewBeginOffset - NewAllocaBeginOffset);
|
|
return (Ty && Align == DL.getABITypeAlignment(Ty)) ? 0 : Align;
|
|
}
|
|
|
|
unsigned getIndex(uint64_t Offset) {
|
|
assert(VecTy && "Can only call getIndex when rewriting a vector");
|
|
uint64_t RelOffset = Offset - NewAllocaBeginOffset;
|
|
assert(RelOffset / ElementSize < UINT32_MAX && "Index out of bounds");
|
|
uint32_t Index = RelOffset / ElementSize;
|
|
assert(Index * ElementSize == RelOffset);
|
|
return Index;
|
|
}
|
|
|
|
void deleteIfTriviallyDead(Value *V) {
|
|
Instruction *I = cast<Instruction>(V);
|
|
if (isInstructionTriviallyDead(I))
|
|
Pass.DeadInsts.insert(I);
|
|
}
|
|
|
|
Value *rewriteVectorizedLoadInst() {
|
|
unsigned BeginIndex = getIndex(NewBeginOffset);
|
|
unsigned EndIndex = getIndex(NewEndOffset);
|
|
assert(EndIndex > BeginIndex && "Empty vector!");
|
|
|
|
Value *V = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "load");
|
|
return extractVector(IRB, V, BeginIndex, EndIndex, "vec");
|
|
}
|
|
|
|
Value *rewriteIntegerLoad(LoadInst &LI) {
|
|
assert(IntTy && "We cannot insert an integer to the alloca");
|
|
assert(!LI.isVolatile());
|
|
Value *V = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "load");
|
|
V = convertValue(DL, IRB, V, IntTy);
|
|
assert(NewBeginOffset >= NewAllocaBeginOffset && "Out of bounds offset");
|
|
uint64_t Offset = NewBeginOffset - NewAllocaBeginOffset;
|
|
if (Offset > 0 || NewEndOffset < NewAllocaEndOffset)
|
|
V = extractInteger(DL, IRB, V, cast<IntegerType>(LI.getType()), Offset,
|
|
"extract");
|
|
return V;
|
|
}
|
|
|
|
bool visitLoadInst(LoadInst &LI) {
|
|
DEBUG(dbgs() << " original: " << LI << "\n");
|
|
Value *OldOp = LI.getOperand(0);
|
|
assert(OldOp == OldPtr);
|
|
|
|
Type *TargetTy = IsSplit ? Type::getIntNTy(LI.getContext(), SliceSize * 8)
|
|
: LI.getType();
|
|
bool IsPtrAdjusted = false;
|
|
Value *V;
|
|
if (VecTy) {
|
|
V = rewriteVectorizedLoadInst();
|
|
} else if (IntTy && LI.getType()->isIntegerTy()) {
|
|
V = rewriteIntegerLoad(LI);
|
|
} else if (NewBeginOffset == NewAllocaBeginOffset &&
|
|
canConvertValue(DL, NewAllocaTy, LI.getType())) {
|
|
V = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), LI.isVolatile(),
|
|
LI.getName());
|
|
} else {
|
|
Type *LTy = TargetTy->getPointerTo();
|
|
V = IRB.CreateAlignedLoad(getNewAllocaSlicePtr(IRB, LTy),
|
|
getSliceAlign(TargetTy), LI.isVolatile(),
|
|
LI.getName());
|
|
IsPtrAdjusted = true;
|
|
}
|
|
V = convertValue(DL, IRB, V, TargetTy);
|
|
|
|
if (IsSplit) {
|
|
assert(!LI.isVolatile());
|
|
assert(LI.getType()->isIntegerTy() &&
|
|
"Only integer type loads and stores are split");
|
|
assert(SliceSize < DL.getTypeStoreSize(LI.getType()) &&
|
|
"Split load isn't smaller than original load");
|
|
assert(LI.getType()->getIntegerBitWidth() ==
|
|
DL.getTypeStoreSizeInBits(LI.getType()) &&
|
|
"Non-byte-multiple bit width");
|
|
// Move the insertion point just past the load so that we can refer to it.
|
|
IRB.SetInsertPoint(std::next(BasicBlock::iterator(&LI)));
|
|
// Create a placeholder value with the same type as LI to use as the
|
|
// basis for the new value. This allows us to replace the uses of LI with
|
|
// the computed value, and then replace the placeholder with LI, leaving
|
|
// LI only used for this computation.
|
|
Value *Placeholder =
|
|
new LoadInst(UndefValue::get(LI.getType()->getPointerTo()));
|
|
V = insertInteger(DL, IRB, Placeholder, V, NewBeginOffset - BeginOffset,
|
|
"insert");
|
|
LI.replaceAllUsesWith(V);
|
|
Placeholder->replaceAllUsesWith(&LI);
|
|
delete Placeholder;
|
|
} else {
|
|
LI.replaceAllUsesWith(V);
|
|
}
|
|
|
|
Pass.DeadInsts.insert(&LI);
|
|
deleteIfTriviallyDead(OldOp);
|
|
DEBUG(dbgs() << " to: " << *V << "\n");
|
|
return !LI.isVolatile() && !IsPtrAdjusted;
|
|
}
|
|
|
|
bool rewriteVectorizedStoreInst(Value *V, StoreInst &SI, Value *OldOp) {
|
|
if (V->getType() != VecTy) {
|
|
unsigned BeginIndex = getIndex(NewBeginOffset);
|
|
unsigned EndIndex = getIndex(NewEndOffset);
|
|
assert(EndIndex > BeginIndex && "Empty vector!");
|
|
unsigned NumElements = EndIndex - BeginIndex;
|
|
assert(NumElements <= VecTy->getNumElements() && "Too many elements!");
|
|
Type *SliceTy = (NumElements == 1)
|
|
? ElementTy
|
|
: VectorType::get(ElementTy, NumElements);
|
|
if (V->getType() != SliceTy)
|
|
V = convertValue(DL, IRB, V, SliceTy);
|
|
|
|
// Mix in the existing elements.
|
|
Value *Old = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "load");
|
|
V = insertVector(IRB, Old, V, BeginIndex, "vec");
|
|
}
|
|
StoreInst *Store = IRB.CreateAlignedStore(V, &NewAI, NewAI.getAlignment());
|
|
Pass.DeadInsts.insert(&SI);
|
|
|
|
(void)Store;
|
|
DEBUG(dbgs() << " to: " << *Store << "\n");
|
|
return true;
|
|
}
|
|
|
|
bool rewriteIntegerStore(Value *V, StoreInst &SI) {
|
|
assert(IntTy && "We cannot extract an integer from the alloca");
|
|
assert(!SI.isVolatile());
|
|
if (DL.getTypeSizeInBits(V->getType()) != IntTy->getBitWidth()) {
|
|
Value *Old =
|
|
IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "oldload");
|
|
Old = convertValue(DL, IRB, Old, IntTy);
|
|
assert(BeginOffset >= NewAllocaBeginOffset && "Out of bounds offset");
|
|
uint64_t Offset = BeginOffset - NewAllocaBeginOffset;
|
|
V = insertInteger(DL, IRB, Old, SI.getValueOperand(), Offset, "insert");
|
|
}
|
|
V = convertValue(DL, IRB, V, NewAllocaTy);
|
|
StoreInst *Store = IRB.CreateAlignedStore(V, &NewAI, NewAI.getAlignment());
|
|
Pass.DeadInsts.insert(&SI);
|
|
(void)Store;
|
|
DEBUG(dbgs() << " to: " << *Store << "\n");
|
|
return true;
|
|
}
|
|
|
|
bool visitStoreInst(StoreInst &SI) {
|
|
DEBUG(dbgs() << " original: " << SI << "\n");
|
|
Value *OldOp = SI.getOperand(1);
|
|
assert(OldOp == OldPtr);
|
|
|
|
Value *V = SI.getValueOperand();
|
|
|
|
// Strip all inbounds GEPs and pointer casts to try to dig out any root
|
|
// alloca that should be re-examined after promoting this alloca.
|
|
if (V->getType()->isPointerTy())
|
|
if (AllocaInst *AI = dyn_cast<AllocaInst>(V->stripInBoundsOffsets()))
|
|
Pass.PostPromotionWorklist.insert(AI);
|
|
|
|
if (SliceSize < DL.getTypeStoreSize(V->getType())) {
|
|
assert(!SI.isVolatile());
|
|
assert(V->getType()->isIntegerTy() &&
|
|
"Only integer type loads and stores are split");
|
|
assert(V->getType()->getIntegerBitWidth() ==
|
|
DL.getTypeStoreSizeInBits(V->getType()) &&
|
|
"Non-byte-multiple bit width");
|
|
IntegerType *NarrowTy = Type::getIntNTy(SI.getContext(), SliceSize * 8);
|
|
V = extractInteger(DL, IRB, V, NarrowTy, NewBeginOffset - BeginOffset,
|
|
"extract");
|
|
}
|
|
|
|
if (VecTy)
|
|
return rewriteVectorizedStoreInst(V, SI, OldOp);
|
|
if (IntTy && V->getType()->isIntegerTy())
|
|
return rewriteIntegerStore(V, SI);
|
|
|
|
StoreInst *NewSI;
|
|
if (NewBeginOffset == NewAllocaBeginOffset &&
|
|
NewEndOffset == NewAllocaEndOffset &&
|
|
canConvertValue(DL, V->getType(), NewAllocaTy)) {
|
|
V = convertValue(DL, IRB, V, NewAllocaTy);
|
|
NewSI = IRB.CreateAlignedStore(V, &NewAI, NewAI.getAlignment(),
|
|
SI.isVolatile());
|
|
} else {
|
|
Value *NewPtr = getNewAllocaSlicePtr(IRB, V->getType()->getPointerTo());
|
|
NewSI = IRB.CreateAlignedStore(V, NewPtr, getSliceAlign(V->getType()),
|
|
SI.isVolatile());
|
|
}
|
|
(void)NewSI;
|
|
Pass.DeadInsts.insert(&SI);
|
|
deleteIfTriviallyDead(OldOp);
|
|
|
|
DEBUG(dbgs() << " to: " << *NewSI << "\n");
|
|
return NewSI->getPointerOperand() == &NewAI && !SI.isVolatile();
|
|
}
|
|
|
|
/// \brief Compute an integer value from splatting an i8 across the given
|
|
/// number of bytes.
|
|
///
|
|
/// Note that this routine assumes an i8 is a byte. If that isn't true, don't
|
|
/// call this routine.
|
|
/// FIXME: Heed the advice above.
|
|
///
|
|
/// \param V The i8 value to splat.
|
|
/// \param Size The number of bytes in the output (assuming i8 is one byte)
|
|
Value *getIntegerSplat(Value *V, unsigned Size) {
|
|
assert(Size > 0 && "Expected a positive number of bytes.");
|
|
IntegerType *VTy = cast<IntegerType>(V->getType());
|
|
assert(VTy->getBitWidth() == 8 && "Expected an i8 value for the byte");
|
|
if (Size == 1)
|
|
return V;
|
|
|
|
Type *SplatIntTy = Type::getIntNTy(VTy->getContext(), Size * 8);
|
|
V = IRB.CreateMul(
|
|
IRB.CreateZExt(V, SplatIntTy, "zext"),
|
|
ConstantExpr::getUDiv(
|
|
Constant::getAllOnesValue(SplatIntTy),
|
|
ConstantExpr::getZExt(Constant::getAllOnesValue(V->getType()),
|
|
SplatIntTy)),
|
|
"isplat");
|
|
return V;
|
|
}
|
|
|
|
/// \brief Compute a vector splat for a given element value.
|
|
Value *getVectorSplat(Value *V, unsigned NumElements) {
|
|
V = IRB.CreateVectorSplat(NumElements, V, "vsplat");
|
|
DEBUG(dbgs() << " splat: " << *V << "\n");
|
|
return V;
|
|
}
|
|
|
|
bool visitMemSetInst(MemSetInst &II) {
|
|
DEBUG(dbgs() << " original: " << II << "\n");
|
|
assert(II.getRawDest() == OldPtr);
|
|
|
|
// If the memset has a variable size, it cannot be split, just adjust the
|
|
// pointer to the new alloca.
|
|
if (!isa<Constant>(II.getLength())) {
|
|
assert(!IsSplit);
|
|
assert(NewBeginOffset == BeginOffset);
|
|
II.setDest(getNewAllocaSlicePtr(IRB, OldPtr->getType()));
|
|
Type *CstTy = II.getAlignmentCst()->getType();
|
|
II.setAlignment(ConstantInt::get(CstTy, getSliceAlign()));
|
|
|
|
deleteIfTriviallyDead(OldPtr);
|
|
return false;
|
|
}
|
|
|
|
// Record this instruction for deletion.
|
|
Pass.DeadInsts.insert(&II);
|
|
|
|
Type *AllocaTy = NewAI.getAllocatedType();
|
|
Type *ScalarTy = AllocaTy->getScalarType();
|
|
|
|
// If this doesn't map cleanly onto the alloca type, and that type isn't
|
|
// a single value type, just emit a memset.
|
|
if (!VecTy && !IntTy &&
|
|
(BeginOffset > NewAllocaBeginOffset || EndOffset < NewAllocaEndOffset ||
|
|
SliceSize != DL.getTypeStoreSize(AllocaTy) ||
|
|
!AllocaTy->isSingleValueType() ||
|
|
!DL.isLegalInteger(DL.getTypeSizeInBits(ScalarTy)) ||
|
|
DL.getTypeSizeInBits(ScalarTy) % 8 != 0)) {
|
|
Type *SizeTy = II.getLength()->getType();
|
|
Constant *Size = ConstantInt::get(SizeTy, NewEndOffset - NewBeginOffset);
|
|
CallInst *New = IRB.CreateMemSet(
|
|
getNewAllocaSlicePtr(IRB, OldPtr->getType()), II.getValue(), Size,
|
|
getSliceAlign(), II.isVolatile());
|
|
(void)New;
|
|
DEBUG(dbgs() << " to: " << *New << "\n");
|
|
return false;
|
|
}
|
|
|
|
// If we can represent this as a simple value, we have to build the actual
|
|
// value to store, which requires expanding the byte present in memset to
|
|
// a sensible representation for the alloca type. This is essentially
|
|
// splatting the byte to a sufficiently wide integer, splatting it across
|
|
// any desired vector width, and bitcasting to the final type.
|
|
Value *V;
|
|
|
|
if (VecTy) {
|
|
// If this is a memset of a vectorized alloca, insert it.
|
|
assert(ElementTy == ScalarTy);
|
|
|
|
unsigned BeginIndex = getIndex(NewBeginOffset);
|
|
unsigned EndIndex = getIndex(NewEndOffset);
|
|
assert(EndIndex > BeginIndex && "Empty vector!");
|
|
unsigned NumElements = EndIndex - BeginIndex;
|
|
assert(NumElements <= VecTy->getNumElements() && "Too many elements!");
|
|
|
|
Value *Splat =
|
|
getIntegerSplat(II.getValue(), DL.getTypeSizeInBits(ElementTy) / 8);
|
|
Splat = convertValue(DL, IRB, Splat, ElementTy);
|
|
if (NumElements > 1)
|
|
Splat = getVectorSplat(Splat, NumElements);
|
|
|
|
Value *Old =
|
|
IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "oldload");
|
|
V = insertVector(IRB, Old, Splat, BeginIndex, "vec");
|
|
} else if (IntTy) {
|
|
// If this is a memset on an alloca where we can widen stores, insert the
|
|
// set integer.
|
|
assert(!II.isVolatile());
|
|
|
|
uint64_t Size = NewEndOffset - NewBeginOffset;
|
|
V = getIntegerSplat(II.getValue(), Size);
|
|
|
|
if (IntTy && (BeginOffset != NewAllocaBeginOffset ||
|
|
EndOffset != NewAllocaBeginOffset)) {
|
|
Value *Old =
|
|
IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "oldload");
|
|
Old = convertValue(DL, IRB, Old, IntTy);
|
|
uint64_t Offset = NewBeginOffset - NewAllocaBeginOffset;
|
|
V = insertInteger(DL, IRB, Old, V, Offset, "insert");
|
|
} else {
|
|
assert(V->getType() == IntTy &&
|
|
"Wrong type for an alloca wide integer!");
|
|
}
|
|
V = convertValue(DL, IRB, V, AllocaTy);
|
|
} else {
|
|
// Established these invariants above.
|
|
assert(NewBeginOffset == NewAllocaBeginOffset);
|
|
assert(NewEndOffset == NewAllocaEndOffset);
|
|
|
|
V = getIntegerSplat(II.getValue(), DL.getTypeSizeInBits(ScalarTy) / 8);
|
|
if (VectorType *AllocaVecTy = dyn_cast<VectorType>(AllocaTy))
|
|
V = getVectorSplat(V, AllocaVecTy->getNumElements());
|
|
|
|
V = convertValue(DL, IRB, V, AllocaTy);
|
|
}
|
|
|
|
Value *New = IRB.CreateAlignedStore(V, &NewAI, NewAI.getAlignment(),
|
|
II.isVolatile());
|
|
(void)New;
|
|
DEBUG(dbgs() << " to: " << *New << "\n");
|
|
return !II.isVolatile();
|
|
}
|
|
|
|
bool visitMemTransferInst(MemTransferInst &II) {
|
|
// Rewriting of memory transfer instructions can be a bit tricky. We break
|
|
// them into two categories: split intrinsics and unsplit intrinsics.
|
|
|
|
DEBUG(dbgs() << " original: " << II << "\n");
|
|
|
|
bool IsDest = &II.getRawDestUse() == OldUse;
|
|
assert((IsDest && II.getRawDest() == OldPtr) ||
|
|
(!IsDest && II.getRawSource() == OldPtr));
|
|
|
|
unsigned SliceAlign = getSliceAlign();
|
|
|
|
// For unsplit intrinsics, we simply modify the source and destination
|
|
// pointers in place. This isn't just an optimization, it is a matter of
|
|
// correctness. With unsplit intrinsics we may be dealing with transfers
|
|
// within a single alloca before SROA ran, or with transfers that have
|
|
// a variable length. We may also be dealing with memmove instead of
|
|
// memcpy, and so simply updating the pointers is the necessary for us to
|
|
// update both source and dest of a single call.
|
|
if (!IsSplittable) {
|
|
Value *AdjustedPtr = getNewAllocaSlicePtr(IRB, OldPtr->getType());
|
|
if (IsDest)
|
|
II.setDest(AdjustedPtr);
|
|
else
|
|
II.setSource(AdjustedPtr);
|
|
|
|
if (II.getAlignment() > SliceAlign) {
|
|
Type *CstTy = II.getAlignmentCst()->getType();
|
|
II.setAlignment(
|
|
ConstantInt::get(CstTy, MinAlign(II.getAlignment(), SliceAlign)));
|
|
}
|
|
|
|
DEBUG(dbgs() << " to: " << II << "\n");
|
|
deleteIfTriviallyDead(OldPtr);
|
|
return false;
|
|
}
|
|
// For split transfer intrinsics we have an incredibly useful assurance:
|
|
// the source and destination do not reside within the same alloca, and at
|
|
// least one of them does not escape. This means that we can replace
|
|
// memmove with memcpy, and we don't need to worry about all manner of
|
|
// downsides to splitting and transforming the operations.
|
|
|
|
// If this doesn't map cleanly onto the alloca type, and that type isn't
|
|
// a single value type, just emit a memcpy.
|
|
bool EmitMemCpy =
|
|
!VecTy && !IntTy &&
|
|
(BeginOffset > NewAllocaBeginOffset || EndOffset < NewAllocaEndOffset ||
|
|
SliceSize != DL.getTypeStoreSize(NewAI.getAllocatedType()) ||
|
|
!NewAI.getAllocatedType()->isSingleValueType());
|
|
|
|
// If we're just going to emit a memcpy, the alloca hasn't changed, and the
|
|
// size hasn't been shrunk based on analysis of the viable range, this is
|
|
// a no-op.
|
|
if (EmitMemCpy && &OldAI == &NewAI) {
|
|
// Ensure the start lines up.
|
|
assert(NewBeginOffset == BeginOffset);
|
|
|
|
// Rewrite the size as needed.
|
|
if (NewEndOffset != EndOffset)
|
|
II.setLength(ConstantInt::get(II.getLength()->getType(),
|
|
NewEndOffset - NewBeginOffset));
|
|
return false;
|
|
}
|
|
// Record this instruction for deletion.
|
|
Pass.DeadInsts.insert(&II);
|
|
|
|
// Strip all inbounds GEPs and pointer casts to try to dig out any root
|
|
// alloca that should be re-examined after rewriting this instruction.
|
|
Value *OtherPtr = IsDest ? II.getRawSource() : II.getRawDest();
|
|
if (AllocaInst *AI =
|
|
dyn_cast<AllocaInst>(OtherPtr->stripInBoundsOffsets())) {
|
|
assert(AI != &OldAI && AI != &NewAI &&
|
|
"Splittable transfers cannot reach the same alloca on both ends.");
|
|
Pass.Worklist.insert(AI);
|
|
}
|
|
|
|
Type *OtherPtrTy = OtherPtr->getType();
|
|
unsigned OtherAS = OtherPtrTy->getPointerAddressSpace();
|
|
|
|
// Compute the relative offset for the other pointer within the transfer.
|
|
unsigned IntPtrWidth = DL.getPointerSizeInBits(OtherAS);
|
|
APInt OtherOffset(IntPtrWidth, NewBeginOffset - BeginOffset);
|
|
unsigned OtherAlign = MinAlign(II.getAlignment() ? II.getAlignment() : 1,
|
|
OtherOffset.zextOrTrunc(64).getZExtValue());
|
|
|
|
if (EmitMemCpy) {
|
|
// Compute the other pointer, folding as much as possible to produce
|
|
// a single, simple GEP in most cases.
|
|
OtherPtr = getAdjustedPtr(IRB, DL, OtherPtr, OtherOffset, OtherPtrTy,
|
|
OtherPtr->getName() + ".");
|
|
|
|
Value *OurPtr = getNewAllocaSlicePtr(IRB, OldPtr->getType());
|
|
Type *SizeTy = II.getLength()->getType();
|
|
Constant *Size = ConstantInt::get(SizeTy, NewEndOffset - NewBeginOffset);
|
|
|
|
CallInst *New = IRB.CreateMemCpy(
|
|
IsDest ? OurPtr : OtherPtr, IsDest ? OtherPtr : OurPtr, Size,
|
|
MinAlign(SliceAlign, OtherAlign), II.isVolatile());
|
|
(void)New;
|
|
DEBUG(dbgs() << " to: " << *New << "\n");
|
|
return false;
|
|
}
|
|
|
|
bool IsWholeAlloca = NewBeginOffset == NewAllocaBeginOffset &&
|
|
NewEndOffset == NewAllocaEndOffset;
|
|
uint64_t Size = NewEndOffset - NewBeginOffset;
|
|
unsigned BeginIndex = VecTy ? getIndex(NewBeginOffset) : 0;
|
|
unsigned EndIndex = VecTy ? getIndex(NewEndOffset) : 0;
|
|
unsigned NumElements = EndIndex - BeginIndex;
|
|
IntegerType *SubIntTy =
|
|
IntTy ? Type::getIntNTy(IntTy->getContext(), Size * 8) : nullptr;
|
|
|
|
// Reset the other pointer type to match the register type we're going to
|
|
// use, but using the address space of the original other pointer.
|
|
if (VecTy && !IsWholeAlloca) {
|
|
if (NumElements == 1)
|
|
OtherPtrTy = VecTy->getElementType();
|
|
else
|
|
OtherPtrTy = VectorType::get(VecTy->getElementType(), NumElements);
|
|
|
|
OtherPtrTy = OtherPtrTy->getPointerTo(OtherAS);
|
|
} else if (IntTy && !IsWholeAlloca) {
|
|
OtherPtrTy = SubIntTy->getPointerTo(OtherAS);
|
|
} else {
|
|
OtherPtrTy = NewAllocaTy->getPointerTo(OtherAS);
|
|
}
|
|
|
|
Value *SrcPtr = getAdjustedPtr(IRB, DL, OtherPtr, OtherOffset, OtherPtrTy,
|
|
OtherPtr->getName() + ".");
|
|
unsigned SrcAlign = OtherAlign;
|
|
Value *DstPtr = &NewAI;
|
|
unsigned DstAlign = SliceAlign;
|
|
if (!IsDest) {
|
|
std::swap(SrcPtr, DstPtr);
|
|
std::swap(SrcAlign, DstAlign);
|
|
}
|
|
|
|
Value *Src;
|
|
if (VecTy && !IsWholeAlloca && !IsDest) {
|
|
Src = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "load");
|
|
Src = extractVector(IRB, Src, BeginIndex, EndIndex, "vec");
|
|
} else if (IntTy && !IsWholeAlloca && !IsDest) {
|
|
Src = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "load");
|
|
Src = convertValue(DL, IRB, Src, IntTy);
|
|
uint64_t Offset = NewBeginOffset - NewAllocaBeginOffset;
|
|
Src = extractInteger(DL, IRB, Src, SubIntTy, Offset, "extract");
|
|
} else {
|
|
Src =
|
|
IRB.CreateAlignedLoad(SrcPtr, SrcAlign, II.isVolatile(), "copyload");
|
|
}
|
|
|
|
if (VecTy && !IsWholeAlloca && IsDest) {
|
|
Value *Old =
|
|
IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "oldload");
|
|
Src = insertVector(IRB, Old, Src, BeginIndex, "vec");
|
|
} else if (IntTy && !IsWholeAlloca && IsDest) {
|
|
Value *Old =
|
|
IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "oldload");
|
|
Old = convertValue(DL, IRB, Old, IntTy);
|
|
uint64_t Offset = NewBeginOffset - NewAllocaBeginOffset;
|
|
Src = insertInteger(DL, IRB, Old, Src, Offset, "insert");
|
|
Src = convertValue(DL, IRB, Src, NewAllocaTy);
|
|
}
|
|
|
|
StoreInst *Store = cast<StoreInst>(
|
|
IRB.CreateAlignedStore(Src, DstPtr, DstAlign, II.isVolatile()));
|
|
(void)Store;
|
|
DEBUG(dbgs() << " to: " << *Store << "\n");
|
|
return !II.isVolatile();
|
|
}
|
|
|
|
bool visitIntrinsicInst(IntrinsicInst &II) {
|
|
assert(II.getIntrinsicID() == Intrinsic::lifetime_start ||
|
|
II.getIntrinsicID() == Intrinsic::lifetime_end);
|
|
DEBUG(dbgs() << " original: " << II << "\n");
|
|
assert(II.getArgOperand(1) == OldPtr);
|
|
|
|
// Record this instruction for deletion.
|
|
Pass.DeadInsts.insert(&II);
|
|
|
|
ConstantInt *Size =
|
|
ConstantInt::get(cast<IntegerType>(II.getArgOperand(0)->getType()),
|
|
NewEndOffset - NewBeginOffset);
|
|
Value *Ptr = getNewAllocaSlicePtr(IRB, OldPtr->getType());
|
|
Value *New;
|
|
if (II.getIntrinsicID() == Intrinsic::lifetime_start)
|
|
New = IRB.CreateLifetimeStart(Ptr, Size);
|
|
else
|
|
New = IRB.CreateLifetimeEnd(Ptr, Size);
|
|
|
|
(void)New;
|
|
DEBUG(dbgs() << " to: " << *New << "\n");
|
|
return true;
|
|
}
|
|
|
|
bool visitPHINode(PHINode &PN) {
|
|
DEBUG(dbgs() << " original: " << PN << "\n");
|
|
assert(BeginOffset >= NewAllocaBeginOffset && "PHIs are unsplittable");
|
|
assert(EndOffset <= NewAllocaEndOffset && "PHIs are unsplittable");
|
|
|
|
// We would like to compute a new pointer in only one place, but have it be
|
|
// as local as possible to the PHI. To do that, we re-use the location of
|
|
// the old pointer, which necessarily must be in the right position to
|
|
// dominate the PHI.
|
|
IRBuilderTy PtrBuilder(IRB);
|
|
if (isa<PHINode>(OldPtr))
|
|
PtrBuilder.SetInsertPoint(OldPtr->getParent()->getFirstInsertionPt());
|
|
else
|
|
PtrBuilder.SetInsertPoint(OldPtr);
|
|
PtrBuilder.SetCurrentDebugLocation(OldPtr->getDebugLoc());
|
|
|
|
Value *NewPtr = getNewAllocaSlicePtr(PtrBuilder, OldPtr->getType());
|
|
// Replace the operands which were using the old pointer.
|
|
std::replace(PN.op_begin(), PN.op_end(), cast<Value>(OldPtr), NewPtr);
|
|
|
|
DEBUG(dbgs() << " to: " << PN << "\n");
|
|
deleteIfTriviallyDead(OldPtr);
|
|
|
|
// PHIs can't be promoted on their own, but often can be speculated. We
|
|
// check the speculation outside of the rewriter so that we see the
|
|
// fully-rewritten alloca.
|
|
PHIUsers.insert(&PN);
|
|
return true;
|
|
}
|
|
|
|
bool visitSelectInst(SelectInst &SI) {
|
|
DEBUG(dbgs() << " original: " << SI << "\n");
|
|
assert((SI.getTrueValue() == OldPtr || SI.getFalseValue() == OldPtr) &&
|
|
"Pointer isn't an operand!");
|
|
assert(BeginOffset >= NewAllocaBeginOffset && "Selects are unsplittable");
|
|
assert(EndOffset <= NewAllocaEndOffset && "Selects are unsplittable");
|
|
|
|
Value *NewPtr = getNewAllocaSlicePtr(IRB, OldPtr->getType());
|
|
// Replace the operands which were using the old pointer.
|
|
if (SI.getOperand(1) == OldPtr)
|
|
SI.setOperand(1, NewPtr);
|
|
if (SI.getOperand(2) == OldPtr)
|
|
SI.setOperand(2, NewPtr);
|
|
|
|
DEBUG(dbgs() << " to: " << SI << "\n");
|
|
deleteIfTriviallyDead(OldPtr);
|
|
|
|
// Selects can't be promoted on their own, but often can be speculated. We
|
|
// check the speculation outside of the rewriter so that we see the
|
|
// fully-rewritten alloca.
|
|
SelectUsers.insert(&SI);
|
|
return true;
|
|
}
|
|
};
|
|
} // namespace
|
|
|
|
namespace {
|
|
/// \brief Visitor to rewrite aggregate loads and stores as scalar.
|
|
///
|
|
/// This pass aggressively rewrites all aggregate loads and stores on
|
|
/// a particular pointer (or any pointer derived from it which we can identify)
|
|
/// with scalar loads and stores.
|
|
class AggLoadStoreRewriter : public InstVisitor<AggLoadStoreRewriter, bool> {
|
|
// Befriend the base class so it can delegate to private visit methods.
|
|
friend class llvm::InstVisitor<AggLoadStoreRewriter, bool>;
|
|
|
|
const DataLayout &DL;
|
|
|
|
/// Queue of pointer uses to analyze and potentially rewrite.
|
|
SmallVector<Use *, 8> Queue;
|
|
|
|
/// Set to prevent us from cycling with phi nodes and loops.
|
|
SmallPtrSet<User *, 8> Visited;
|
|
|
|
/// The current pointer use being rewritten. This is used to dig up the used
|
|
/// value (as opposed to the user).
|
|
Use *U;
|
|
|
|
public:
|
|
AggLoadStoreRewriter(const DataLayout &DL) : DL(DL) {}
|
|
|
|
/// Rewrite loads and stores through a pointer and all pointers derived from
|
|
/// it.
|
|
bool rewrite(Instruction &I) {
|
|
DEBUG(dbgs() << " Rewriting FCA loads and stores...\n");
|
|
enqueueUsers(I);
|
|
bool Changed = false;
|
|
while (!Queue.empty()) {
|
|
U = Queue.pop_back_val();
|
|
Changed |= visit(cast<Instruction>(U->getUser()));
|
|
}
|
|
return Changed;
|
|
}
|
|
|
|
private:
|
|
/// Enqueue all the users of the given instruction for further processing.
|
|
/// This uses a set to de-duplicate users.
|
|
void enqueueUsers(Instruction &I) {
|
|
for (Use &U : I.uses())
|
|
if (Visited.insert(U.getUser()).second)
|
|
Queue.push_back(&U);
|
|
}
|
|
|
|
// Conservative default is to not rewrite anything.
|
|
bool visitInstruction(Instruction &I) { return false; }
|
|
|
|
/// \brief Generic recursive split emission class.
|
|
template <typename Derived> class OpSplitter {
|
|
protected:
|
|
/// The builder used to form new instructions.
|
|
IRBuilderTy IRB;
|
|
/// The indices which to be used with insert- or extractvalue to select the
|
|
/// appropriate value within the aggregate.
|
|
SmallVector<unsigned, 4> Indices;
|
|
/// The indices to a GEP instruction which will move Ptr to the correct slot
|
|
/// within the aggregate.
|
|
SmallVector<Value *, 4> GEPIndices;
|
|
/// The base pointer of the original op, used as a base for GEPing the
|
|
/// split operations.
|
|
Value *Ptr;
|
|
|
|
/// Initialize the splitter with an insertion point, Ptr and start with a
|
|
/// single zero GEP index.
|
|
OpSplitter(Instruction *InsertionPoint, Value *Ptr)
|
|
: IRB(InsertionPoint), GEPIndices(1, IRB.getInt32(0)), Ptr(Ptr) {}
|
|
|
|
public:
|
|
/// \brief Generic recursive split emission routine.
|
|
///
|
|
/// This method recursively splits an aggregate op (load or store) into
|
|
/// scalar or vector ops. It splits recursively until it hits a single value
|
|
/// and emits that single value operation via the template argument.
|
|
///
|
|
/// The logic of this routine relies on GEPs and insertvalue and
|
|
/// extractvalue all operating with the same fundamental index list, merely
|
|
/// formatted differently (GEPs need actual values).
|
|
///
|
|
/// \param Ty The type being split recursively into smaller ops.
|
|
/// \param Agg The aggregate value being built up or stored, depending on
|
|
/// whether this is splitting a load or a store respectively.
|
|
void emitSplitOps(Type *Ty, Value *&Agg, const Twine &Name) {
|
|
if (Ty->isSingleValueType())
|
|
return static_cast<Derived *>(this)->emitFunc(Ty, Agg, Name);
|
|
|
|
if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
|
|
unsigned OldSize = Indices.size();
|
|
(void)OldSize;
|
|
for (unsigned Idx = 0, Size = ATy->getNumElements(); Idx != Size;
|
|
++Idx) {
|
|
assert(Indices.size() == OldSize && "Did not return to the old size");
|
|
Indices.push_back(Idx);
|
|
GEPIndices.push_back(IRB.getInt32(Idx));
|
|
emitSplitOps(ATy->getElementType(), Agg, Name + "." + Twine(Idx));
|
|
GEPIndices.pop_back();
|
|
Indices.pop_back();
|
|
}
|
|
return;
|
|
}
|
|
|
|
if (StructType *STy = dyn_cast<StructType>(Ty)) {
|
|
unsigned OldSize = Indices.size();
|
|
(void)OldSize;
|
|
for (unsigned Idx = 0, Size = STy->getNumElements(); Idx != Size;
|
|
++Idx) {
|
|
assert(Indices.size() == OldSize && "Did not return to the old size");
|
|
Indices.push_back(Idx);
|
|
GEPIndices.push_back(IRB.getInt32(Idx));
|
|
emitSplitOps(STy->getElementType(Idx), Agg, Name + "." + Twine(Idx));
|
|
GEPIndices.pop_back();
|
|
Indices.pop_back();
|
|
}
|
|
return;
|
|
}
|
|
|
|
llvm_unreachable("Only arrays and structs are aggregate loadable types");
|
|
}
|
|
};
|
|
|
|
struct LoadOpSplitter : public OpSplitter<LoadOpSplitter> {
|
|
LoadOpSplitter(Instruction *InsertionPoint, Value *Ptr)
|
|
: OpSplitter<LoadOpSplitter>(InsertionPoint, Ptr) {}
|
|
|
|
/// Emit a leaf load of a single value. This is called at the leaves of the
|
|
/// recursive emission to actually load values.
|
|
void emitFunc(Type *Ty, Value *&Agg, const Twine &Name) {
|
|
assert(Ty->isSingleValueType());
|
|
// Load the single value and insert it using the indices.
|
|
Value *GEP =
|
|
IRB.CreateInBoundsGEP(nullptr, Ptr, GEPIndices, Name + ".gep");
|
|
Value *Load = IRB.CreateLoad(GEP, Name + ".load");
|
|
Agg = IRB.CreateInsertValue(Agg, Load, Indices, Name + ".insert");
|
|
DEBUG(dbgs() << " to: " << *Load << "\n");
|
|
}
|
|
};
|
|
|
|
bool visitLoadInst(LoadInst &LI) {
|
|
assert(LI.getPointerOperand() == *U);
|
|
if (!LI.isSimple() || LI.getType()->isSingleValueType())
|
|
return false;
|
|
|
|
// We have an aggregate being loaded, split it apart.
|
|
DEBUG(dbgs() << " original: " << LI << "\n");
|
|
LoadOpSplitter Splitter(&LI, *U);
|
|
Value *V = UndefValue::get(LI.getType());
|
|
Splitter.emitSplitOps(LI.getType(), V, LI.getName() + ".fca");
|
|
LI.replaceAllUsesWith(V);
|
|
LI.eraseFromParent();
|
|
return true;
|
|
}
|
|
|
|
struct StoreOpSplitter : public OpSplitter<StoreOpSplitter> {
|
|
StoreOpSplitter(Instruction *InsertionPoint, Value *Ptr)
|
|
: OpSplitter<StoreOpSplitter>(InsertionPoint, Ptr) {}
|
|
|
|
/// Emit a leaf store of a single value. This is called at the leaves of the
|
|
/// recursive emission to actually produce stores.
|
|
void emitFunc(Type *Ty, Value *&Agg, const Twine &Name) {
|
|
assert(Ty->isSingleValueType());
|
|
// Extract the single value and store it using the indices.
|
|
Value *Store = IRB.CreateStore(
|
|
IRB.CreateExtractValue(Agg, Indices, Name + ".extract"),
|
|
IRB.CreateInBoundsGEP(nullptr, Ptr, GEPIndices, Name + ".gep"));
|
|
(void)Store;
|
|
DEBUG(dbgs() << " to: " << *Store << "\n");
|
|
}
|
|
};
|
|
|
|
bool visitStoreInst(StoreInst &SI) {
|
|
if (!SI.isSimple() || SI.getPointerOperand() != *U)
|
|
return false;
|
|
Value *V = SI.getValueOperand();
|
|
if (V->getType()->isSingleValueType())
|
|
return false;
|
|
|
|
// We have an aggregate being stored, split it apart.
|
|
DEBUG(dbgs() << " original: " << SI << "\n");
|
|
StoreOpSplitter Splitter(&SI, *U);
|
|
Splitter.emitSplitOps(V->getType(), V, V->getName() + ".fca");
|
|
SI.eraseFromParent();
|
|
return true;
|
|
}
|
|
|
|
bool visitBitCastInst(BitCastInst &BC) {
|
|
enqueueUsers(BC);
|
|
return false;
|
|
}
|
|
|
|
bool visitGetElementPtrInst(GetElementPtrInst &GEPI) {
|
|
enqueueUsers(GEPI);
|
|
return false;
|
|
}
|
|
|
|
bool visitPHINode(PHINode &PN) {
|
|
enqueueUsers(PN);
|
|
return false;
|
|
}
|
|
|
|
bool visitSelectInst(SelectInst &SI) {
|
|
enqueueUsers(SI);
|
|
return false;
|
|
}
|
|
};
|
|
} // namespace
|
|
|
|
/// \brief Strip aggregate type wrapping.
|
|
///
|
|
/// This removes no-op aggregate types wrapping an underlying type. It will
|
|
/// strip as many layers of types as it can without changing either the type
|
|
/// size or the allocated size.
|
|
static Type *stripAggregateTypeWrapping(const DataLayout &DL, Type *Ty) {
|
|
if (Ty->isSingleValueType())
|
|
return Ty;
|
|
|
|
uint64_t AllocSize = DL.getTypeAllocSize(Ty);
|
|
uint64_t TypeSize = DL.getTypeSizeInBits(Ty);
|
|
|
|
Type *InnerTy;
|
|
if (ArrayType *ArrTy = dyn_cast<ArrayType>(Ty)) {
|
|
InnerTy = ArrTy->getElementType();
|
|
} else if (StructType *STy = dyn_cast<StructType>(Ty)) {
|
|
const StructLayout *SL = DL.getStructLayout(STy);
|
|
unsigned Index = SL->getElementContainingOffset(0);
|
|
InnerTy = STy->getElementType(Index);
|
|
} else {
|
|
return Ty;
|
|
}
|
|
|
|
if (AllocSize > DL.getTypeAllocSize(InnerTy) ||
|
|
TypeSize > DL.getTypeSizeInBits(InnerTy))
|
|
return Ty;
|
|
|
|
return stripAggregateTypeWrapping(DL, InnerTy);
|
|
}
|
|
|
|
/// \brief Try to find a partition of the aggregate type passed in for a given
|
|
/// offset and size.
|
|
///
|
|
/// This recurses through the aggregate type and tries to compute a subtype
|
|
/// based on the offset and size. When the offset and size span a sub-section
|
|
/// of an array, it will even compute a new array type for that sub-section,
|
|
/// and the same for structs.
|
|
///
|
|
/// Note that this routine is very strict and tries to find a partition of the
|
|
/// type which produces the *exact* right offset and size. It is not forgiving
|
|
/// when the size or offset cause either end of type-based partition to be off.
|
|
/// Also, this is a best-effort routine. It is reasonable to give up and not
|
|
/// return a type if necessary.
|
|
static Type *getTypePartition(const DataLayout &DL, Type *Ty, uint64_t Offset,
|
|
uint64_t Size) {
|
|
if (Offset == 0 && DL.getTypeAllocSize(Ty) == Size)
|
|
return stripAggregateTypeWrapping(DL, Ty);
|
|
if (Offset > DL.getTypeAllocSize(Ty) ||
|
|
(DL.getTypeAllocSize(Ty) - Offset) < Size)
|
|
return nullptr;
|
|
|
|
if (SequentialType *SeqTy = dyn_cast<SequentialType>(Ty)) {
|
|
// We can't partition pointers...
|
|
if (SeqTy->isPointerTy())
|
|
return nullptr;
|
|
|
|
Type *ElementTy = SeqTy->getElementType();
|
|
uint64_t ElementSize = DL.getTypeAllocSize(ElementTy);
|
|
uint64_t NumSkippedElements = Offset / ElementSize;
|
|
if (ArrayType *ArrTy = dyn_cast<ArrayType>(SeqTy)) {
|
|
if (NumSkippedElements >= ArrTy->getNumElements())
|
|
return nullptr;
|
|
} else if (VectorType *VecTy = dyn_cast<VectorType>(SeqTy)) {
|
|
if (NumSkippedElements >= VecTy->getNumElements())
|
|
return nullptr;
|
|
}
|
|
Offset -= NumSkippedElements * ElementSize;
|
|
|
|
// First check if we need to recurse.
|
|
if (Offset > 0 || Size < ElementSize) {
|
|
// Bail if the partition ends in a different array element.
|
|
if ((Offset + Size) > ElementSize)
|
|
return nullptr;
|
|
// Recurse through the element type trying to peel off offset bytes.
|
|
return getTypePartition(DL, ElementTy, Offset, Size);
|
|
}
|
|
assert(Offset == 0);
|
|
|
|
if (Size == ElementSize)
|
|
return stripAggregateTypeWrapping(DL, ElementTy);
|
|
assert(Size > ElementSize);
|
|
uint64_t NumElements = Size / ElementSize;
|
|
if (NumElements * ElementSize != Size)
|
|
return nullptr;
|
|
return ArrayType::get(ElementTy, NumElements);
|
|
}
|
|
|
|
StructType *STy = dyn_cast<StructType>(Ty);
|
|
if (!STy)
|
|
return nullptr;
|
|
|
|
const StructLayout *SL = DL.getStructLayout(STy);
|
|
if (Offset >= SL->getSizeInBytes())
|
|
return nullptr;
|
|
uint64_t EndOffset = Offset + Size;
|
|
if (EndOffset > SL->getSizeInBytes())
|
|
return nullptr;
|
|
|
|
unsigned Index = SL->getElementContainingOffset(Offset);
|
|
Offset -= SL->getElementOffset(Index);
|
|
|
|
Type *ElementTy = STy->getElementType(Index);
|
|
uint64_t ElementSize = DL.getTypeAllocSize(ElementTy);
|
|
if (Offset >= ElementSize)
|
|
return nullptr; // The offset points into alignment padding.
|
|
|
|
// See if any partition must be contained by the element.
|
|
if (Offset > 0 || Size < ElementSize) {
|
|
if ((Offset + Size) > ElementSize)
|
|
return nullptr;
|
|
return getTypePartition(DL, ElementTy, Offset, Size);
|
|
}
|
|
assert(Offset == 0);
|
|
|
|
if (Size == ElementSize)
|
|
return stripAggregateTypeWrapping(DL, ElementTy);
|
|
|
|
StructType::element_iterator EI = STy->element_begin() + Index,
|
|
EE = STy->element_end();
|
|
if (EndOffset < SL->getSizeInBytes()) {
|
|
unsigned EndIndex = SL->getElementContainingOffset(EndOffset);
|
|
if (Index == EndIndex)
|
|
return nullptr; // Within a single element and its padding.
|
|
|
|
// Don't try to form "natural" types if the elements don't line up with the
|
|
// expected size.
|
|
// FIXME: We could potentially recurse down through the last element in the
|
|
// sub-struct to find a natural end point.
|
|
if (SL->getElementOffset(EndIndex) != EndOffset)
|
|
return nullptr;
|
|
|
|
assert(Index < EndIndex);
|
|
EE = STy->element_begin() + EndIndex;
|
|
}
|
|
|
|
// Try to build up a sub-structure.
|
|
StructType *SubTy =
|
|
StructType::get(STy->getContext(), makeArrayRef(EI, EE), STy->isPacked());
|
|
const StructLayout *SubSL = DL.getStructLayout(SubTy);
|
|
if (Size != SubSL->getSizeInBytes())
|
|
return nullptr; // The sub-struct doesn't have quite the size needed.
|
|
|
|
return SubTy;
|
|
}
|
|
|
|
/// \brief Pre-split loads and stores to simplify rewriting.
|
|
///
|
|
/// We want to break up the splittable load+store pairs as much as
|
|
/// possible. This is important to do as a preprocessing step, as once we
|
|
/// start rewriting the accesses to partitions of the alloca we lose the
|
|
/// necessary information to correctly split apart paired loads and stores
|
|
/// which both point into this alloca. The case to consider is something like
|
|
/// the following:
|
|
///
|
|
/// %a = alloca [12 x i8]
|
|
/// %gep1 = getelementptr [12 x i8]* %a, i32 0, i32 0
|
|
/// %gep2 = getelementptr [12 x i8]* %a, i32 0, i32 4
|
|
/// %gep3 = getelementptr [12 x i8]* %a, i32 0, i32 8
|
|
/// %iptr1 = bitcast i8* %gep1 to i64*
|
|
/// %iptr2 = bitcast i8* %gep2 to i64*
|
|
/// %fptr1 = bitcast i8* %gep1 to float*
|
|
/// %fptr2 = bitcast i8* %gep2 to float*
|
|
/// %fptr3 = bitcast i8* %gep3 to float*
|
|
/// store float 0.0, float* %fptr1
|
|
/// store float 1.0, float* %fptr2
|
|
/// %v = load i64* %iptr1
|
|
/// store i64 %v, i64* %iptr2
|
|
/// %f1 = load float* %fptr2
|
|
/// %f2 = load float* %fptr3
|
|
///
|
|
/// Here we want to form 3 partitions of the alloca, each 4 bytes large, and
|
|
/// promote everything so we recover the 2 SSA values that should have been
|
|
/// there all along.
|
|
///
|
|
/// \returns true if any changes are made.
|
|
bool SROA::presplitLoadsAndStores(AllocaInst &AI, AllocaSlices &AS) {
|
|
DEBUG(dbgs() << "Pre-splitting loads and stores\n");
|
|
|
|
// Track the loads and stores which are candidates for pre-splitting here, in
|
|
// the order they first appear during the partition scan. These give stable
|
|
// iteration order and a basis for tracking which loads and stores we
|
|
// actually split.
|
|
SmallVector<LoadInst *, 4> Loads;
|
|
SmallVector<StoreInst *, 4> Stores;
|
|
|
|
// We need to accumulate the splits required of each load or store where we
|
|
// can find them via a direct lookup. This is important to cross-check loads
|
|
// and stores against each other. We also track the slice so that we can kill
|
|
// all the slices that end up split.
|
|
struct SplitOffsets {
|
|
Slice *S;
|
|
std::vector<uint64_t> Splits;
|
|
};
|
|
SmallDenseMap<Instruction *, SplitOffsets, 8> SplitOffsetsMap;
|
|
|
|
// Track loads out of this alloca which cannot, for any reason, be pre-split.
|
|
// This is important as we also cannot pre-split stores of those loads!
|
|
// FIXME: This is all pretty gross. It means that we can be more aggressive
|
|
// in pre-splitting when the load feeding the store happens to come from
|
|
// a separate alloca. Put another way, the effectiveness of SROA would be
|
|
// decreased by a frontend which just concatenated all of its local allocas
|
|
// into one big flat alloca. But defeating such patterns is exactly the job
|
|
// SROA is tasked with! Sadly, to not have this discrepancy we would have
|
|
// change store pre-splitting to actually force pre-splitting of the load
|
|
// that feeds it *and all stores*. That makes pre-splitting much harder, but
|
|
// maybe it would make it more principled?
|
|
SmallPtrSet<LoadInst *, 8> UnsplittableLoads;
|
|
|
|
DEBUG(dbgs() << " Searching for candidate loads and stores\n");
|
|
for (auto &P : AS.partitions()) {
|
|
for (Slice &S : P) {
|
|
Instruction *I = cast<Instruction>(S.getUse()->getUser());
|
|
if (!S.isSplittable() ||S.endOffset() <= P.endOffset()) {
|
|
// If this was a load we have to track that it can't participate in any
|
|
// pre-splitting!
|
|
if (auto *LI = dyn_cast<LoadInst>(I))
|
|
UnsplittableLoads.insert(LI);
|
|
continue;
|
|
}
|
|
assert(P.endOffset() > S.beginOffset() &&
|
|
"Empty or backwards partition!");
|
|
|
|
// Determine if this is a pre-splittable slice.
|
|
if (auto *LI = dyn_cast<LoadInst>(I)) {
|
|
assert(!LI->isVolatile() && "Cannot split volatile loads!");
|
|
|
|
// The load must be used exclusively to store into other pointers for
|
|
// us to be able to arbitrarily pre-split it. The stores must also be
|
|
// simple to avoid changing semantics.
|
|
auto IsLoadSimplyStored = [](LoadInst *LI) {
|
|
for (User *LU : LI->users()) {
|
|
auto *SI = dyn_cast<StoreInst>(LU);
|
|
if (!SI || !SI->isSimple())
|
|
return false;
|
|
}
|
|
return true;
|
|
};
|
|
if (!IsLoadSimplyStored(LI)) {
|
|
UnsplittableLoads.insert(LI);
|
|
continue;
|
|
}
|
|
|
|
Loads.push_back(LI);
|
|
} else if (auto *SI = dyn_cast<StoreInst>(S.getUse()->getUser())) {
|
|
if (!SI ||
|
|
S.getUse() != &SI->getOperandUse(SI->getPointerOperandIndex()))
|
|
continue;
|
|
auto *StoredLoad = dyn_cast<LoadInst>(SI->getValueOperand());
|
|
if (!StoredLoad || !StoredLoad->isSimple())
|
|
continue;
|
|
assert(!SI->isVolatile() && "Cannot split volatile stores!");
|
|
|
|
Stores.push_back(SI);
|
|
} else {
|
|
// Other uses cannot be pre-split.
|
|
continue;
|
|
}
|
|
|
|
// Record the initial split.
|
|
DEBUG(dbgs() << " Candidate: " << *I << "\n");
|
|
auto &Offsets = SplitOffsetsMap[I];
|
|
assert(Offsets.Splits.empty() &&
|
|
"Should not have splits the first time we see an instruction!");
|
|
Offsets.S = &S;
|
|
Offsets.Splits.push_back(P.endOffset() - S.beginOffset());
|
|
}
|
|
|
|
// Now scan the already split slices, and add a split for any of them which
|
|
// we're going to pre-split.
|
|
for (Slice *S : P.splitSliceTails()) {
|
|
auto SplitOffsetsMapI =
|
|
SplitOffsetsMap.find(cast<Instruction>(S->getUse()->getUser()));
|
|
if (SplitOffsetsMapI == SplitOffsetsMap.end())
|
|
continue;
|
|
auto &Offsets = SplitOffsetsMapI->second;
|
|
|
|
assert(Offsets.S == S && "Found a mismatched slice!");
|
|
assert(!Offsets.Splits.empty() &&
|
|
"Cannot have an empty set of splits on the second partition!");
|
|
assert(Offsets.Splits.back() ==
|
|
P.beginOffset() - Offsets.S->beginOffset() &&
|
|
"Previous split does not end where this one begins!");
|
|
|
|
// Record each split. The last partition's end isn't needed as the size
|
|
// of the slice dictates that.
|
|
if (S->endOffset() > P.endOffset())
|
|
Offsets.Splits.push_back(P.endOffset() - Offsets.S->beginOffset());
|
|
}
|
|
}
|
|
|
|
// We may have split loads where some of their stores are split stores. For
|
|
// such loads and stores, we can only pre-split them if their splits exactly
|
|
// match relative to their starting offset. We have to verify this prior to
|
|
// any rewriting.
|
|
Stores.erase(
|
|
std::remove_if(Stores.begin(), Stores.end(),
|
|
[&UnsplittableLoads, &SplitOffsetsMap](StoreInst *SI) {
|
|
// Lookup the load we are storing in our map of split
|
|
// offsets.
|
|
auto *LI = cast<LoadInst>(SI->getValueOperand());
|
|
// If it was completely unsplittable, then we're done,
|
|
// and this store can't be pre-split.
|
|
if (UnsplittableLoads.count(LI))
|
|
return true;
|
|
|
|
auto LoadOffsetsI = SplitOffsetsMap.find(LI);
|
|
if (LoadOffsetsI == SplitOffsetsMap.end())
|
|
return false; // Unrelated loads are definitely safe.
|
|
auto &LoadOffsets = LoadOffsetsI->second;
|
|
|
|
// Now lookup the store's offsets.
|
|
auto &StoreOffsets = SplitOffsetsMap[SI];
|
|
|
|
// If the relative offsets of each split in the load and
|
|
// store match exactly, then we can split them and we
|
|
// don't need to remove them here.
|
|
if (LoadOffsets.Splits == StoreOffsets.Splits)
|
|
return false;
|
|
|
|
DEBUG(dbgs()
|
|
<< " Mismatched splits for load and store:\n"
|
|
<< " " << *LI << "\n"
|
|
<< " " << *SI << "\n");
|
|
|
|
// We've found a store and load that we need to split
|
|
// with mismatched relative splits. Just give up on them
|
|
// and remove both instructions from our list of
|
|
// candidates.
|
|
UnsplittableLoads.insert(LI);
|
|
return true;
|
|
}),
|
|
Stores.end());
|
|
// Now we have to go *back* through all te stores, because a later store may
|
|
// have caused an earlier store's load to become unsplittable and if it is
|
|
// unsplittable for the later store, then we can't rely on it being split in
|
|
// the earlier store either.
|
|
Stores.erase(std::remove_if(Stores.begin(), Stores.end(),
|
|
[&UnsplittableLoads](StoreInst *SI) {
|
|
auto *LI =
|
|
cast<LoadInst>(SI->getValueOperand());
|
|
return UnsplittableLoads.count(LI);
|
|
}),
|
|
Stores.end());
|
|
// Once we've established all the loads that can't be split for some reason,
|
|
// filter any that made it into our list out.
|
|
Loads.erase(std::remove_if(Loads.begin(), Loads.end(),
|
|
[&UnsplittableLoads](LoadInst *LI) {
|
|
return UnsplittableLoads.count(LI);
|
|
}),
|
|
Loads.end());
|
|
|
|
|
|
// If no loads or stores are left, there is no pre-splitting to be done for
|
|
// this alloca.
|
|
if (Loads.empty() && Stores.empty())
|
|
return false;
|
|
|
|
// From here on, we can't fail and will be building new accesses, so rig up
|
|
// an IR builder.
|
|
IRBuilderTy IRB(&AI);
|
|
|
|
// Collect the new slices which we will merge into the alloca slices.
|
|
SmallVector<Slice, 4> NewSlices;
|
|
|
|
// Track any allocas we end up splitting loads and stores for so we iterate
|
|
// on them.
|
|
SmallPtrSet<AllocaInst *, 4> ResplitPromotableAllocas;
|
|
|
|
// At this point, we have collected all of the loads and stores we can
|
|
// pre-split, and the specific splits needed for them. We actually do the
|
|
// splitting in a specific order in order to handle when one of the loads in
|
|
// the value operand to one of the stores.
|
|
//
|
|
// First, we rewrite all of the split loads, and just accumulate each split
|
|
// load in a parallel structure. We also build the slices for them and append
|
|
// them to the alloca slices.
|
|
SmallDenseMap<LoadInst *, std::vector<LoadInst *>, 1> SplitLoadsMap;
|
|
std::vector<LoadInst *> SplitLoads;
|
|
const DataLayout &DL = AI.getModule()->getDataLayout();
|
|
for (LoadInst *LI : Loads) {
|
|
SplitLoads.clear();
|
|
|
|
IntegerType *Ty = cast<IntegerType>(LI->getType());
|
|
uint64_t LoadSize = Ty->getBitWidth() / 8;
|
|
assert(LoadSize > 0 && "Cannot have a zero-sized integer load!");
|
|
|
|
auto &Offsets = SplitOffsetsMap[LI];
|
|
assert(LoadSize == Offsets.S->endOffset() - Offsets.S->beginOffset() &&
|
|
"Slice size should always match load size exactly!");
|
|
uint64_t BaseOffset = Offsets.S->beginOffset();
|
|
assert(BaseOffset + LoadSize > BaseOffset &&
|
|
"Cannot represent alloca access size using 64-bit integers!");
|
|
|
|
Instruction *BasePtr = cast<Instruction>(LI->getPointerOperand());
|
|
IRB.SetInsertPoint(BasicBlock::iterator(LI));
|
|
|
|
DEBUG(dbgs() << " Splitting load: " << *LI << "\n");
|
|
|
|
uint64_t PartOffset = 0, PartSize = Offsets.Splits.front();
|
|
int Idx = 0, Size = Offsets.Splits.size();
|
|
for (;;) {
|
|
auto *PartTy = Type::getIntNTy(Ty->getContext(), PartSize * 8);
|
|
auto *PartPtrTy = PartTy->getPointerTo(LI->getPointerAddressSpace());
|
|
LoadInst *PLoad = IRB.CreateAlignedLoad(
|
|
getAdjustedPtr(IRB, DL, BasePtr,
|
|
APInt(DL.getPointerSizeInBits(), PartOffset),
|
|
PartPtrTy, BasePtr->getName() + "."),
|
|
getAdjustedAlignment(LI, PartOffset, DL), /*IsVolatile*/ false,
|
|
LI->getName());
|
|
|
|
// Append this load onto the list of split loads so we can find it later
|
|
// to rewrite the stores.
|
|
SplitLoads.push_back(PLoad);
|
|
|
|
// Now build a new slice for the alloca.
|
|
NewSlices.push_back(
|
|
Slice(BaseOffset + PartOffset, BaseOffset + PartOffset + PartSize,
|
|
&PLoad->getOperandUse(PLoad->getPointerOperandIndex()),
|
|
/*IsSplittable*/ false));
|
|
DEBUG(dbgs() << " new slice [" << NewSlices.back().beginOffset()
|
|
<< ", " << NewSlices.back().endOffset() << "): " << *PLoad
|
|
<< "\n");
|
|
|
|
// See if we've handled all the splits.
|
|
if (Idx >= Size)
|
|
break;
|
|
|
|
// Setup the next partition.
|
|
PartOffset = Offsets.Splits[Idx];
|
|
++Idx;
|
|
PartSize = (Idx < Size ? Offsets.Splits[Idx] : LoadSize) - PartOffset;
|
|
}
|
|
|
|
// Now that we have the split loads, do the slow walk over all uses of the
|
|
// load and rewrite them as split stores, or save the split loads to use
|
|
// below if the store is going to be split there anyways.
|
|
bool DeferredStores = false;
|
|
for (User *LU : LI->users()) {
|
|
StoreInst *SI = cast<StoreInst>(LU);
|
|
if (!Stores.empty() && SplitOffsetsMap.count(SI)) {
|
|
DeferredStores = true;
|
|
DEBUG(dbgs() << " Deferred splitting of store: " << *SI << "\n");
|
|
continue;
|
|
}
|
|
|
|
Value *StoreBasePtr = SI->getPointerOperand();
|
|
IRB.SetInsertPoint(BasicBlock::iterator(SI));
|
|
|
|
DEBUG(dbgs() << " Splitting store of load: " << *SI << "\n");
|
|
|
|
for (int Idx = 0, Size = SplitLoads.size(); Idx < Size; ++Idx) {
|
|
LoadInst *PLoad = SplitLoads[Idx];
|
|
uint64_t PartOffset = Idx == 0 ? 0 : Offsets.Splits[Idx - 1];
|
|
auto *PartPtrTy =
|
|
PLoad->getType()->getPointerTo(SI->getPointerAddressSpace());
|
|
|
|
StoreInst *PStore = IRB.CreateAlignedStore(
|
|
PLoad, getAdjustedPtr(IRB, DL, StoreBasePtr,
|
|
APInt(DL.getPointerSizeInBits(), PartOffset),
|
|
PartPtrTy, StoreBasePtr->getName() + "."),
|
|
getAdjustedAlignment(SI, PartOffset, DL), /*IsVolatile*/ false);
|
|
(void)PStore;
|
|
DEBUG(dbgs() << " +" << PartOffset << ":" << *PStore << "\n");
|
|
}
|
|
|
|
// We want to immediately iterate on any allocas impacted by splitting
|
|
// this store, and we have to track any promotable alloca (indicated by
|
|
// a direct store) as needing to be resplit because it is no longer
|
|
// promotable.
|
|
if (AllocaInst *OtherAI = dyn_cast<AllocaInst>(StoreBasePtr)) {
|
|
ResplitPromotableAllocas.insert(OtherAI);
|
|
Worklist.insert(OtherAI);
|
|
} else if (AllocaInst *OtherAI = dyn_cast<AllocaInst>(
|
|
StoreBasePtr->stripInBoundsOffsets())) {
|
|
Worklist.insert(OtherAI);
|
|
}
|
|
|
|
// Mark the original store as dead.
|
|
DeadInsts.insert(SI);
|
|
}
|
|
|
|
// Save the split loads if there are deferred stores among the users.
|
|
if (DeferredStores)
|
|
SplitLoadsMap.insert(std::make_pair(LI, std::move(SplitLoads)));
|
|
|
|
// Mark the original load as dead and kill the original slice.
|
|
DeadInsts.insert(LI);
|
|
Offsets.S->kill();
|
|
}
|
|
|
|
// Second, we rewrite all of the split stores. At this point, we know that
|
|
// all loads from this alloca have been split already. For stores of such
|
|
// loads, we can simply look up the pre-existing split loads. For stores of
|
|
// other loads, we split those loads first and then write split stores of
|
|
// them.
|
|
for (StoreInst *SI : Stores) {
|
|
auto *LI = cast<LoadInst>(SI->getValueOperand());
|
|
IntegerType *Ty = cast<IntegerType>(LI->getType());
|
|
uint64_t StoreSize = Ty->getBitWidth() / 8;
|
|
assert(StoreSize > 0 && "Cannot have a zero-sized integer store!");
|
|
|
|
auto &Offsets = SplitOffsetsMap[SI];
|
|
assert(StoreSize == Offsets.S->endOffset() - Offsets.S->beginOffset() &&
|
|
"Slice size should always match load size exactly!");
|
|
uint64_t BaseOffset = Offsets.S->beginOffset();
|
|
assert(BaseOffset + StoreSize > BaseOffset &&
|
|
"Cannot represent alloca access size using 64-bit integers!");
|
|
|
|
Value *LoadBasePtr = LI->getPointerOperand();
|
|
Instruction *StoreBasePtr = cast<Instruction>(SI->getPointerOperand());
|
|
|
|
DEBUG(dbgs() << " Splitting store: " << *SI << "\n");
|
|
|
|
// Check whether we have an already split load.
|
|
auto SplitLoadsMapI = SplitLoadsMap.find(LI);
|
|
std::vector<LoadInst *> *SplitLoads = nullptr;
|
|
if (SplitLoadsMapI != SplitLoadsMap.end()) {
|
|
SplitLoads = &SplitLoadsMapI->second;
|
|
assert(SplitLoads->size() == Offsets.Splits.size() + 1 &&
|
|
"Too few split loads for the number of splits in the store!");
|
|
} else {
|
|
DEBUG(dbgs() << " of load: " << *LI << "\n");
|
|
}
|
|
|
|
uint64_t PartOffset = 0, PartSize = Offsets.Splits.front();
|
|
int Idx = 0, Size = Offsets.Splits.size();
|
|
for (;;) {
|
|
auto *PartTy = Type::getIntNTy(Ty->getContext(), PartSize * 8);
|
|
auto *PartPtrTy = PartTy->getPointerTo(SI->getPointerAddressSpace());
|
|
|
|
// Either lookup a split load or create one.
|
|
LoadInst *PLoad;
|
|
if (SplitLoads) {
|
|
PLoad = (*SplitLoads)[Idx];
|
|
} else {
|
|
IRB.SetInsertPoint(BasicBlock::iterator(LI));
|
|
PLoad = IRB.CreateAlignedLoad(
|
|
getAdjustedPtr(IRB, DL, LoadBasePtr,
|
|
APInt(DL.getPointerSizeInBits(), PartOffset),
|
|
PartPtrTy, LoadBasePtr->getName() + "."),
|
|
getAdjustedAlignment(LI, PartOffset, DL), /*IsVolatile*/ false,
|
|
LI->getName());
|
|
}
|
|
|
|
// And store this partition.
|
|
IRB.SetInsertPoint(BasicBlock::iterator(SI));
|
|
StoreInst *PStore = IRB.CreateAlignedStore(
|
|
PLoad, getAdjustedPtr(IRB, DL, StoreBasePtr,
|
|
APInt(DL.getPointerSizeInBits(), PartOffset),
|
|
PartPtrTy, StoreBasePtr->getName() + "."),
|
|
getAdjustedAlignment(SI, PartOffset, DL), /*IsVolatile*/ false);
|
|
|
|
// Now build a new slice for the alloca.
|
|
NewSlices.push_back(
|
|
Slice(BaseOffset + PartOffset, BaseOffset + PartOffset + PartSize,
|
|
&PStore->getOperandUse(PStore->getPointerOperandIndex()),
|
|
/*IsSplittable*/ false));
|
|
DEBUG(dbgs() << " new slice [" << NewSlices.back().beginOffset()
|
|
<< ", " << NewSlices.back().endOffset() << "): " << *PStore
|
|
<< "\n");
|
|
if (!SplitLoads) {
|
|
DEBUG(dbgs() << " of split load: " << *PLoad << "\n");
|
|
}
|
|
|
|
// See if we've finished all the splits.
|
|
if (Idx >= Size)
|
|
break;
|
|
|
|
// Setup the next partition.
|
|
PartOffset = Offsets.Splits[Idx];
|
|
++Idx;
|
|
PartSize = (Idx < Size ? Offsets.Splits[Idx] : StoreSize) - PartOffset;
|
|
}
|
|
|
|
// We want to immediately iterate on any allocas impacted by splitting
|
|
// this load, which is only relevant if it isn't a load of this alloca and
|
|
// thus we didn't already split the loads above. We also have to keep track
|
|
// of any promotable allocas we split loads on as they can no longer be
|
|
// promoted.
|
|
if (!SplitLoads) {
|
|
if (AllocaInst *OtherAI = dyn_cast<AllocaInst>(LoadBasePtr)) {
|
|
assert(OtherAI != &AI && "We can't re-split our own alloca!");
|
|
ResplitPromotableAllocas.insert(OtherAI);
|
|
Worklist.insert(OtherAI);
|
|
} else if (AllocaInst *OtherAI = dyn_cast<AllocaInst>(
|
|
LoadBasePtr->stripInBoundsOffsets())) {
|
|
assert(OtherAI != &AI && "We can't re-split our own alloca!");
|
|
Worklist.insert(OtherAI);
|
|
}
|
|
}
|
|
|
|
// Mark the original store as dead now that we've split it up and kill its
|
|
// slice. Note that we leave the original load in place unless this store
|
|
// was its ownly use. It may in turn be split up if it is an alloca load
|
|
// for some other alloca, but it may be a normal load. This may introduce
|
|
// redundant loads, but where those can be merged the rest of the optimizer
|
|
// should handle the merging, and this uncovers SSA splits which is more
|
|
// important. In practice, the original loads will almost always be fully
|
|
// split and removed eventually, and the splits will be merged by any
|
|
// trivial CSE, including instcombine.
|
|
if (LI->hasOneUse()) {
|
|
assert(*LI->user_begin() == SI && "Single use isn't this store!");
|
|
DeadInsts.insert(LI);
|
|
}
|
|
DeadInsts.insert(SI);
|
|
Offsets.S->kill();
|
|
}
|
|
|
|
// Remove the killed slices that have ben pre-split.
|
|
AS.erase(std::remove_if(AS.begin(), AS.end(), [](const Slice &S) {
|
|
return S.isDead();
|
|
}), AS.end());
|
|
|
|
// Insert our new slices. This will sort and merge them into the sorted
|
|
// sequence.
|
|
AS.insert(NewSlices);
|
|
|
|
DEBUG(dbgs() << " Pre-split slices:\n");
|
|
#ifndef NDEBUG
|
|
for (auto I = AS.begin(), E = AS.end(); I != E; ++I)
|
|
DEBUG(AS.print(dbgs(), I, " "));
|
|
#endif
|
|
|
|
// Finally, don't try to promote any allocas that new require re-splitting.
|
|
// They have already been added to the worklist above.
|
|
PromotableAllocas.erase(
|
|
std::remove_if(
|
|
PromotableAllocas.begin(), PromotableAllocas.end(),
|
|
[&](AllocaInst *AI) { return ResplitPromotableAllocas.count(AI); }),
|
|
PromotableAllocas.end());
|
|
|
|
return true;
|
|
}
|
|
|
|
/// \brief Rewrite an alloca partition's users.
|
|
///
|
|
/// This routine drives both of the rewriting goals of the SROA pass. It tries
|
|
/// to rewrite uses of an alloca partition to be conducive for SSA value
|
|
/// promotion. If the partition needs a new, more refined alloca, this will
|
|
/// build that new alloca, preserving as much type information as possible, and
|
|
/// rewrite the uses of the old alloca to point at the new one and have the
|
|
/// appropriate new offsets. It also evaluates how successful the rewrite was
|
|
/// at enabling promotion and if it was successful queues the alloca to be
|
|
/// promoted.
|
|
AllocaInst *SROA::rewritePartition(AllocaInst &AI, AllocaSlices &AS,
|
|
AllocaSlices::Partition &P) {
|
|
// Try to compute a friendly type for this partition of the alloca. This
|
|
// won't always succeed, in which case we fall back to a legal integer type
|
|
// or an i8 array of an appropriate size.
|
|
Type *SliceTy = nullptr;
|
|
const DataLayout &DL = AI.getModule()->getDataLayout();
|
|
if (Type *CommonUseTy = findCommonType(P.begin(), P.end(), P.endOffset()))
|
|
if (DL.getTypeAllocSize(CommonUseTy) >= P.size())
|
|
SliceTy = CommonUseTy;
|
|
if (!SliceTy)
|
|
if (Type *TypePartitionTy = getTypePartition(DL, AI.getAllocatedType(),
|
|
P.beginOffset(), P.size()))
|
|
SliceTy = TypePartitionTy;
|
|
if ((!SliceTy || (SliceTy->isArrayTy() &&
|
|
SliceTy->getArrayElementType()->isIntegerTy())) &&
|
|
DL.isLegalInteger(P.size() * 8))
|
|
SliceTy = Type::getIntNTy(*C, P.size() * 8);
|
|
if (!SliceTy)
|
|
SliceTy = ArrayType::get(Type::getInt8Ty(*C), P.size());
|
|
assert(DL.getTypeAllocSize(SliceTy) >= P.size());
|
|
|
|
bool IsIntegerPromotable = isIntegerWideningViable(P, SliceTy, DL);
|
|
|
|
VectorType *VecTy =
|
|
IsIntegerPromotable ? nullptr : isVectorPromotionViable(P, DL);
|
|
if (VecTy)
|
|
SliceTy = VecTy;
|
|
|
|
// Check for the case where we're going to rewrite to a new alloca of the
|
|
// exact same type as the original, and with the same access offsets. In that
|
|
// case, re-use the existing alloca, but still run through the rewriter to
|
|
// perform phi and select speculation.
|
|
AllocaInst *NewAI;
|
|
if (SliceTy == AI.getAllocatedType()) {
|
|
assert(P.beginOffset() == 0 &&
|
|
"Non-zero begin offset but same alloca type");
|
|
NewAI = &AI;
|
|
// FIXME: We should be able to bail at this point with "nothing changed".
|
|
// FIXME: We might want to defer PHI speculation until after here.
|
|
// FIXME: return nullptr;
|
|
} else {
|
|
unsigned Alignment = AI.getAlignment();
|
|
if (!Alignment) {
|
|
// The minimum alignment which users can rely on when the explicit
|
|
// alignment is omitted or zero is that required by the ABI for this
|
|
// type.
|
|
Alignment = DL.getABITypeAlignment(AI.getAllocatedType());
|
|
}
|
|
Alignment = MinAlign(Alignment, P.beginOffset());
|
|
// If we will get at least this much alignment from the type alone, leave
|
|
// the alloca's alignment unconstrained.
|
|
if (Alignment <= DL.getABITypeAlignment(SliceTy))
|
|
Alignment = 0;
|
|
NewAI = new AllocaInst(
|
|
SliceTy, nullptr, Alignment,
|
|
AI.getName() + ".sroa." + Twine(P.begin() - AS.begin()), &AI);
|
|
++NumNewAllocas;
|
|
}
|
|
|
|
DEBUG(dbgs() << "Rewriting alloca partition "
|
|
<< "[" << P.beginOffset() << "," << P.endOffset()
|
|
<< ") to: " << *NewAI << "\n");
|
|
|
|
// Track the high watermark on the worklist as it is only relevant for
|
|
// promoted allocas. We will reset it to this point if the alloca is not in
|
|
// fact scheduled for promotion.
|
|
unsigned PPWOldSize = PostPromotionWorklist.size();
|
|
unsigned NumUses = 0;
|
|
SmallPtrSet<PHINode *, 8> PHIUsers;
|
|
SmallPtrSet<SelectInst *, 8> SelectUsers;
|
|
|
|
AllocaSliceRewriter Rewriter(DL, AS, *this, AI, *NewAI, P.beginOffset(),
|
|
P.endOffset(), IsIntegerPromotable, VecTy,
|
|
PHIUsers, SelectUsers);
|
|
bool Promotable = true;
|
|
for (Slice *S : P.splitSliceTails()) {
|
|
Promotable &= Rewriter.visit(S);
|
|
++NumUses;
|
|
}
|
|
for (Slice &S : P) {
|
|
Promotable &= Rewriter.visit(&S);
|
|
++NumUses;
|
|
}
|
|
|
|
NumAllocaPartitionUses += NumUses;
|
|
MaxUsesPerAllocaPartition =
|
|
std::max<unsigned>(NumUses, MaxUsesPerAllocaPartition);
|
|
|
|
// Now that we've processed all the slices in the new partition, check if any
|
|
// PHIs or Selects would block promotion.
|
|
for (SmallPtrSetImpl<PHINode *>::iterator I = PHIUsers.begin(),
|
|
E = PHIUsers.end();
|
|
I != E; ++I)
|
|
if (!isSafePHIToSpeculate(**I)) {
|
|
Promotable = false;
|
|
PHIUsers.clear();
|
|
SelectUsers.clear();
|
|
break;
|
|
}
|
|
for (SmallPtrSetImpl<SelectInst *>::iterator I = SelectUsers.begin(),
|
|
E = SelectUsers.end();
|
|
I != E; ++I)
|
|
if (!isSafeSelectToSpeculate(**I)) {
|
|
Promotable = false;
|
|
PHIUsers.clear();
|
|
SelectUsers.clear();
|
|
break;
|
|
}
|
|
|
|
if (Promotable) {
|
|
if (PHIUsers.empty() && SelectUsers.empty()) {
|
|
// Promote the alloca.
|
|
PromotableAllocas.push_back(NewAI);
|
|
} else {
|
|
// If we have either PHIs or Selects to speculate, add them to those
|
|
// worklists and re-queue the new alloca so that we promote in on the
|
|
// next iteration.
|
|
for (PHINode *PHIUser : PHIUsers)
|
|
SpeculatablePHIs.insert(PHIUser);
|
|
for (SelectInst *SelectUser : SelectUsers)
|
|
SpeculatableSelects.insert(SelectUser);
|
|
Worklist.insert(NewAI);
|
|
}
|
|
} else {
|
|
// If we can't promote the alloca, iterate on it to check for new
|
|
// refinements exposed by splitting the current alloca. Don't iterate on an
|
|
// alloca which didn't actually change and didn't get promoted.
|
|
if (NewAI != &AI)
|
|
Worklist.insert(NewAI);
|
|
|
|
// Drop any post-promotion work items if promotion didn't happen.
|
|
while (PostPromotionWorklist.size() > PPWOldSize)
|
|
PostPromotionWorklist.pop_back();
|
|
}
|
|
|
|
return NewAI;
|
|
}
|
|
|
|
/// \brief Walks the slices of an alloca and form partitions based on them,
|
|
/// rewriting each of their uses.
|
|
bool SROA::splitAlloca(AllocaInst &AI, AllocaSlices &AS) {
|
|
if (AS.begin() == AS.end())
|
|
return false;
|
|
|
|
unsigned NumPartitions = 0;
|
|
bool Changed = false;
|
|
const DataLayout &DL = AI.getModule()->getDataLayout();
|
|
|
|
// First try to pre-split loads and stores.
|
|
Changed |= presplitLoadsAndStores(AI, AS);
|
|
|
|
// Now that we have identified any pre-splitting opportunities, mark any
|
|
// splittable (non-whole-alloca) loads and stores as unsplittable. If we fail
|
|
// to split these during pre-splitting, we want to force them to be
|
|
// rewritten into a partition.
|
|
bool IsSorted = true;
|
|
for (Slice &S : AS) {
|
|
if (!S.isSplittable())
|
|
continue;
|
|
// FIXME: We currently leave whole-alloca splittable loads and stores. This
|
|
// used to be the only splittable loads and stores and we need to be
|
|
// confident that the above handling of splittable loads and stores is
|
|
// completely sufficient before we forcibly disable the remaining handling.
|
|
if (S.beginOffset() == 0 &&
|
|
S.endOffset() >= DL.getTypeAllocSize(AI.getAllocatedType()))
|
|
continue;
|
|
if (isa<LoadInst>(S.getUse()->getUser()) ||
|
|
isa<StoreInst>(S.getUse()->getUser())) {
|
|
S.makeUnsplittable();
|
|
IsSorted = false;
|
|
}
|
|
}
|
|
if (!IsSorted)
|
|
std::sort(AS.begin(), AS.end());
|
|
|
|
/// \brief Describes the allocas introduced by rewritePartition
|
|
/// in order to migrate the debug info.
|
|
struct Piece {
|
|
AllocaInst *Alloca;
|
|
uint64_t Offset;
|
|
uint64_t Size;
|
|
Piece(AllocaInst *AI, uint64_t O, uint64_t S)
|
|
: Alloca(AI), Offset(O), Size(S) {}
|
|
};
|
|
SmallVector<Piece, 4> Pieces;
|
|
|
|
// Rewrite each partition.
|
|
for (auto &P : AS.partitions()) {
|
|
if (AllocaInst *NewAI = rewritePartition(AI, AS, P)) {
|
|
Changed = true;
|
|
if (NewAI != &AI) {
|
|
uint64_t SizeOfByte = 8;
|
|
uint64_t AllocaSize = DL.getTypeSizeInBits(NewAI->getAllocatedType());
|
|
// Don't include any padding.
|
|
uint64_t Size = std::min(AllocaSize, P.size() * SizeOfByte);
|
|
Pieces.push_back(Piece(NewAI, P.beginOffset() * SizeOfByte, Size));
|
|
}
|
|
}
|
|
++NumPartitions;
|
|
}
|
|
|
|
NumAllocaPartitions += NumPartitions;
|
|
MaxPartitionsPerAlloca =
|
|
std::max<unsigned>(NumPartitions, MaxPartitionsPerAlloca);
|
|
|
|
// Migrate debug information from the old alloca to the new alloca(s)
|
|
// and the individial partitions.
|
|
if (DbgDeclareInst *DbgDecl = FindAllocaDbgDeclare(&AI)) {
|
|
auto *Var = DbgDecl->getVariable();
|
|
auto *Expr = DbgDecl->getExpression();
|
|
DIBuilder DIB(*AI.getParent()->getParent()->getParent(),
|
|
/*AllowUnresolved*/ false);
|
|
bool IsSplit = Pieces.size() > 1;
|
|
for (auto Piece : Pieces) {
|
|
// Create a piece expression describing the new partition or reuse AI's
|
|
// expression if there is only one partition.
|
|
auto *PieceExpr = Expr;
|
|
if (IsSplit || Expr->isBitPiece()) {
|
|
// If this alloca is already a scalar replacement of a larger aggregate,
|
|
// Piece.Offset describes the offset inside the scalar.
|
|
uint64_t Offset = Expr->isBitPiece() ? Expr->getBitPieceOffset() : 0;
|
|
uint64_t Start = Offset + Piece.Offset;
|
|
uint64_t Size = Piece.Size;
|
|
if (Expr->isBitPiece()) {
|
|
uint64_t AbsEnd = Expr->getBitPieceOffset() + Expr->getBitPieceSize();
|
|
if (Start >= AbsEnd)
|
|
// No need to describe a SROAed padding.
|
|
continue;
|
|
Size = std::min(Size, AbsEnd - Start);
|
|
}
|
|
PieceExpr = DIB.createBitPieceExpression(Start, Size);
|
|
}
|
|
|
|
// Remove any existing dbg.declare intrinsic describing the same alloca.
|
|
if (DbgDeclareInst *OldDDI = FindAllocaDbgDeclare(Piece.Alloca))
|
|
OldDDI->eraseFromParent();
|
|
|
|
DIB.insertDeclare(Piece.Alloca, Var, PieceExpr, DbgDecl->getDebugLoc(),
|
|
&AI);
|
|
}
|
|
}
|
|
return Changed;
|
|
}
|
|
|
|
/// \brief Clobber a use with undef, deleting the used value if it becomes dead.
|
|
void SROA::clobberUse(Use &U) {
|
|
Value *OldV = U;
|
|
// Replace the use with an undef value.
|
|
U = UndefValue::get(OldV->getType());
|
|
|
|
// Check for this making an instruction dead. We have to garbage collect
|
|
// all the dead instructions to ensure the uses of any alloca end up being
|
|
// minimal.
|
|
if (Instruction *OldI = dyn_cast<Instruction>(OldV))
|
|
if (isInstructionTriviallyDead(OldI)) {
|
|
DeadInsts.insert(OldI);
|
|
}
|
|
}
|
|
|
|
/// \brief Analyze an alloca for SROA.
|
|
///
|
|
/// This analyzes the alloca to ensure we can reason about it, builds
|
|
/// the slices of the alloca, and then hands it off to be split and
|
|
/// rewritten as needed.
|
|
bool SROA::runOnAlloca(AllocaInst &AI) {
|
|
DEBUG(dbgs() << "SROA alloca: " << AI << "\n");
|
|
++NumAllocasAnalyzed;
|
|
|
|
// Special case dead allocas, as they're trivial.
|
|
if (AI.use_empty()) {
|
|
AI.eraseFromParent();
|
|
return true;
|
|
}
|
|
const DataLayout &DL = AI.getModule()->getDataLayout();
|
|
|
|
// Skip alloca forms that this analysis can't handle.
|
|
if (AI.isArrayAllocation() || !AI.getAllocatedType()->isSized() ||
|
|
DL.getTypeAllocSize(AI.getAllocatedType()) == 0)
|
|
return false;
|
|
|
|
bool Changed = false;
|
|
|
|
// First, split any FCA loads and stores touching this alloca to promote
|
|
// better splitting and promotion opportunities.
|
|
AggLoadStoreRewriter AggRewriter(DL);
|
|
Changed |= AggRewriter.rewrite(AI);
|
|
|
|
// Build the slices using a recursive instruction-visiting builder.
|
|
AllocaSlices AS(DL, AI);
|
|
DEBUG(AS.print(dbgs()));
|
|
if (AS.isEscaped())
|
|
return Changed;
|
|
|
|
// Delete all the dead users of this alloca before splitting and rewriting it.
|
|
for (Instruction *DeadUser : AS.getDeadUsers()) {
|
|
// Free up everything used by this instruction.
|
|
for (Use &DeadOp : DeadUser->operands())
|
|
clobberUse(DeadOp);
|
|
|
|
// Now replace the uses of this instruction.
|
|
DeadUser->replaceAllUsesWith(UndefValue::get(DeadUser->getType()));
|
|
|
|
// And mark it for deletion.
|
|
DeadInsts.insert(DeadUser);
|
|
Changed = true;
|
|
}
|
|
for (Use *DeadOp : AS.getDeadOperands()) {
|
|
clobberUse(*DeadOp);
|
|
Changed = true;
|
|
}
|
|
|
|
// No slices to split. Leave the dead alloca for a later pass to clean up.
|
|
if (AS.begin() == AS.end())
|
|
return Changed;
|
|
|
|
Changed |= splitAlloca(AI, AS);
|
|
|
|
DEBUG(dbgs() << " Speculating PHIs\n");
|
|
while (!SpeculatablePHIs.empty())
|
|
speculatePHINodeLoads(*SpeculatablePHIs.pop_back_val());
|
|
|
|
DEBUG(dbgs() << " Speculating Selects\n");
|
|
while (!SpeculatableSelects.empty())
|
|
speculateSelectInstLoads(*SpeculatableSelects.pop_back_val());
|
|
|
|
return Changed;
|
|
}
|
|
|
|
/// \brief Delete the dead instructions accumulated in this run.
|
|
///
|
|
/// Recursively deletes the dead instructions we've accumulated. This is done
|
|
/// at the very end to maximize locality of the recursive delete and to
|
|
/// minimize the problems of invalidated instruction pointers as such pointers
|
|
/// are used heavily in the intermediate stages of the algorithm.
|
|
///
|
|
/// We also record the alloca instructions deleted here so that they aren't
|
|
/// subsequently handed to mem2reg to promote.
|
|
void SROA::deleteDeadInstructions(
|
|
SmallPtrSetImpl<AllocaInst *> &DeletedAllocas) {
|
|
while (!DeadInsts.empty()) {
|
|
Instruction *I = DeadInsts.pop_back_val();
|
|
DEBUG(dbgs() << "Deleting dead instruction: " << *I << "\n");
|
|
|
|
I->replaceAllUsesWith(UndefValue::get(I->getType()));
|
|
|
|
for (Use &Operand : I->operands())
|
|
if (Instruction *U = dyn_cast<Instruction>(Operand)) {
|
|
// Zero out the operand and see if it becomes trivially dead.
|
|
Operand = nullptr;
|
|
if (isInstructionTriviallyDead(U))
|
|
DeadInsts.insert(U);
|
|
}
|
|
|
|
if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
|
|
DeletedAllocas.insert(AI);
|
|
if (DbgDeclareInst *DbgDecl = FindAllocaDbgDeclare(AI))
|
|
DbgDecl->eraseFromParent();
|
|
}
|
|
|
|
++NumDeleted;
|
|
I->eraseFromParent();
|
|
}
|
|
}
|
|
|
|
static void enqueueUsersInWorklist(Instruction &I,
|
|
SmallVectorImpl<Instruction *> &Worklist,
|
|
SmallPtrSetImpl<Instruction *> &Visited) {
|
|
for (User *U : I.users())
|
|
if (Visited.insert(cast<Instruction>(U)).second)
|
|
Worklist.push_back(cast<Instruction>(U));
|
|
}
|
|
|
|
/// \brief Promote the allocas, using the best available technique.
|
|
///
|
|
/// This attempts to promote whatever allocas have been identified as viable in
|
|
/// the PromotableAllocas list. If that list is empty, there is nothing to do.
|
|
/// If there is a domtree available, we attempt to promote using the full power
|
|
/// of mem2reg. Otherwise, we build and use the AllocaPromoter above which is
|
|
/// based on the SSAUpdater utilities. This function returns whether any
|
|
/// promotion occurred.
|
|
bool SROA::promoteAllocas(Function &F) {
|
|
if (PromotableAllocas.empty())
|
|
return false;
|
|
|
|
NumPromoted += PromotableAllocas.size();
|
|
|
|
if (DT && !ForceSSAUpdater) {
|
|
DEBUG(dbgs() << "Promoting allocas with mem2reg...\n");
|
|
PromoteMemToReg(PromotableAllocas, *DT, nullptr, AC);
|
|
PromotableAllocas.clear();
|
|
return true;
|
|
}
|
|
|
|
DEBUG(dbgs() << "Promoting allocas with SSAUpdater...\n");
|
|
SSAUpdater SSA;
|
|
DIBuilder DIB(*F.getParent(), /*AllowUnresolved*/ false);
|
|
SmallVector<Instruction *, 64> Insts;
|
|
|
|
// We need a worklist to walk the uses of each alloca.
|
|
SmallVector<Instruction *, 8> Worklist;
|
|
SmallPtrSet<Instruction *, 8> Visited;
|
|
SmallVector<Instruction *, 32> DeadInsts;
|
|
|
|
for (unsigned Idx = 0, Size = PromotableAllocas.size(); Idx != Size; ++Idx) {
|
|
AllocaInst *AI = PromotableAllocas[Idx];
|
|
Insts.clear();
|
|
Worklist.clear();
|
|
Visited.clear();
|
|
|
|
enqueueUsersInWorklist(*AI, Worklist, Visited);
|
|
|
|
while (!Worklist.empty()) {
|
|
Instruction *I = Worklist.pop_back_val();
|
|
|
|
// FIXME: Currently the SSAUpdater infrastructure doesn't reason about
|
|
// lifetime intrinsics and so we strip them (and the bitcasts+GEPs
|
|
// leading to them) here. Eventually it should use them to optimize the
|
|
// scalar values produced.
|
|
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
|
|
assert(II->getIntrinsicID() == Intrinsic::lifetime_start ||
|
|
II->getIntrinsicID() == Intrinsic::lifetime_end);
|
|
II->eraseFromParent();
|
|
continue;
|
|
}
|
|
|
|
// Push the loads and stores we find onto the list. SROA will already
|
|
// have validated that all loads and stores are viable candidates for
|
|
// promotion.
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
|
|
assert(LI->getType() == AI->getAllocatedType());
|
|
Insts.push_back(LI);
|
|
continue;
|
|
}
|
|
if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
|
|
assert(SI->getValueOperand()->getType() == AI->getAllocatedType());
|
|
Insts.push_back(SI);
|
|
continue;
|
|
}
|
|
|
|
// For everything else, we know that only no-op bitcasts and GEPs will
|
|
// make it this far, just recurse through them and recall them for later
|
|
// removal.
|
|
DeadInsts.push_back(I);
|
|
enqueueUsersInWorklist(*I, Worklist, Visited);
|
|
}
|
|
AllocaPromoter(Insts, SSA, *AI, DIB).run(Insts);
|
|
while (!DeadInsts.empty())
|
|
DeadInsts.pop_back_val()->eraseFromParent();
|
|
AI->eraseFromParent();
|
|
}
|
|
|
|
PromotableAllocas.clear();
|
|
return true;
|
|
}
|
|
|
|
bool SROA::runOnFunction(Function &F) {
|
|
if (skipOptnoneFunction(F))
|
|
return false;
|
|
|
|
DEBUG(dbgs() << "SROA function: " << F.getName() << "\n");
|
|
C = &F.getContext();
|
|
DominatorTreeWrapperPass *DTWP =
|
|
getAnalysisIfAvailable<DominatorTreeWrapperPass>();
|
|
DT = DTWP ? &DTWP->getDomTree() : nullptr;
|
|
AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
|
|
|
|
BasicBlock &EntryBB = F.getEntryBlock();
|
|
for (BasicBlock::iterator I = EntryBB.begin(), E = std::prev(EntryBB.end());
|
|
I != E; ++I) {
|
|
if (AllocaInst *AI = dyn_cast<AllocaInst>(I))
|
|
Worklist.insert(AI);
|
|
}
|
|
|
|
bool Changed = false;
|
|
// A set of deleted alloca instruction pointers which should be removed from
|
|
// the list of promotable allocas.
|
|
SmallPtrSet<AllocaInst *, 4> DeletedAllocas;
|
|
|
|
do {
|
|
while (!Worklist.empty()) {
|
|
Changed |= runOnAlloca(*Worklist.pop_back_val());
|
|
deleteDeadInstructions(DeletedAllocas);
|
|
|
|
// Remove the deleted allocas from various lists so that we don't try to
|
|
// continue processing them.
|
|
if (!DeletedAllocas.empty()) {
|
|
auto IsInSet = [&](AllocaInst *AI) { return DeletedAllocas.count(AI); };
|
|
Worklist.remove_if(IsInSet);
|
|
PostPromotionWorklist.remove_if(IsInSet);
|
|
PromotableAllocas.erase(std::remove_if(PromotableAllocas.begin(),
|
|
PromotableAllocas.end(),
|
|
IsInSet),
|
|
PromotableAllocas.end());
|
|
DeletedAllocas.clear();
|
|
}
|
|
}
|
|
|
|
Changed |= promoteAllocas(F);
|
|
|
|
Worklist = PostPromotionWorklist;
|
|
PostPromotionWorklist.clear();
|
|
} while (!Worklist.empty());
|
|
|
|
return Changed;
|
|
}
|
|
|
|
void SROA::getAnalysisUsage(AnalysisUsage &AU) const {
|
|
AU.addRequired<AssumptionCacheTracker>();
|
|
if (RequiresDomTree)
|
|
AU.addRequired<DominatorTreeWrapperPass>();
|
|
AU.setPreservesCFG();
|
|
}
|