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This fixes the store case, my previous patch just fixed the load case. rdar://5707076. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46932 91177308-0d34-0410-b5e6-96231b3b80d8
1361 lines
54 KiB
C++
1361 lines
54 KiB
C++
//===- ScalarReplAggregates.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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//
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// This transformation implements the well known scalar replacement of
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// aggregates transformation. This xform breaks up alloca instructions of
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// aggregate type (structure or array) into individual alloca instructions for
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// each member (if possible). Then, if possible, it transforms the individual
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// alloca instructions into nice clean scalar SSA form.
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//
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// This combines a simple SRoA algorithm with the Mem2Reg algorithm because
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// often interact, especially for C++ programs. As such, iterating between
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// SRoA, then Mem2Reg until we run out of things to promote works well.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "scalarrepl"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Constants.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/Function.h"
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#include "llvm/GlobalVariable.h"
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#include "llvm/Instructions.h"
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#include "llvm/IntrinsicInst.h"
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#include "llvm/Pass.h"
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#include "llvm/Analysis/Dominators.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/Transforms/Utils/PromoteMemToReg.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/GetElementPtrTypeIterator.h"
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#include "llvm/Support/MathExtras.h"
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#include "llvm/Support/Compiler.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/ADT/StringExtras.h"
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using namespace llvm;
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STATISTIC(NumReplaced, "Number of allocas broken up");
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STATISTIC(NumPromoted, "Number of allocas promoted");
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STATISTIC(NumConverted, "Number of aggregates converted to scalar");
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STATISTIC(NumGlobals, "Number of allocas copied from constant global");
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namespace {
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struct VISIBILITY_HIDDEN SROA : public FunctionPass {
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static char ID; // Pass identification, replacement for typeid
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explicit SROA(signed T = -1) : FunctionPass((intptr_t)&ID) {
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if (T == -1)
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SRThreshold = 128;
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else
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SRThreshold = T;
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}
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bool runOnFunction(Function &F);
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bool performScalarRepl(Function &F);
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bool performPromotion(Function &F);
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// getAnalysisUsage - This pass does not require any passes, but we know it
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// will not alter the CFG, so say so.
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addRequired<DominatorTree>();
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AU.addRequired<DominanceFrontier>();
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AU.addRequired<TargetData>();
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AU.setPreservesCFG();
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}
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private:
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/// AllocaInfo - When analyzing uses of an alloca instruction, this captures
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/// information about the uses. All these fields are initialized to false
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/// and set to true when something is learned.
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struct AllocaInfo {
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/// isUnsafe - This is set to true if the alloca cannot be SROA'd.
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bool isUnsafe : 1;
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/// needsCanon - This is set to true if there is some use of the alloca
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/// that requires canonicalization.
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bool needsCanon : 1;
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/// isMemCpySrc - This is true if this aggregate is memcpy'd from.
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bool isMemCpySrc : 1;
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/// isMemCpyDst - This is true if this aggregate is memcpy'd into.
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bool isMemCpyDst : 1;
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AllocaInfo()
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: isUnsafe(false), needsCanon(false),
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isMemCpySrc(false), isMemCpyDst(false) {}
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};
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unsigned SRThreshold;
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void MarkUnsafe(AllocaInfo &I) { I.isUnsafe = true; }
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int isSafeAllocaToScalarRepl(AllocationInst *AI);
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void isSafeUseOfAllocation(Instruction *User, AllocationInst *AI,
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AllocaInfo &Info);
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void isSafeElementUse(Value *Ptr, bool isFirstElt, AllocationInst *AI,
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AllocaInfo &Info);
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void isSafeMemIntrinsicOnAllocation(MemIntrinsic *MI, AllocationInst *AI,
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unsigned OpNo, AllocaInfo &Info);
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void isSafeUseOfBitCastedAllocation(BitCastInst *User, AllocationInst *AI,
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AllocaInfo &Info);
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void DoScalarReplacement(AllocationInst *AI,
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std::vector<AllocationInst*> &WorkList);
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void CanonicalizeAllocaUsers(AllocationInst *AI);
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AllocaInst *AddNewAlloca(Function &F, const Type *Ty, AllocationInst *Base);
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void RewriteBitCastUserOfAlloca(Instruction *BCInst, AllocationInst *AI,
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SmallVector<AllocaInst*, 32> &NewElts);
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const Type *CanConvertToScalar(Value *V, bool &IsNotTrivial);
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void ConvertToScalar(AllocationInst *AI, const Type *Ty);
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void ConvertUsesToScalar(Value *Ptr, AllocaInst *NewAI, unsigned Offset);
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static Instruction *isOnlyCopiedFromConstantGlobal(AllocationInst *AI);
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};
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char SROA::ID = 0;
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RegisterPass<SROA> X("scalarrepl", "Scalar Replacement of Aggregates");
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}
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// Public interface to the ScalarReplAggregates pass
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FunctionPass *llvm::createScalarReplAggregatesPass(signed int Threshold) {
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return new SROA(Threshold);
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}
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bool SROA::runOnFunction(Function &F) {
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bool Changed = performPromotion(F);
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while (1) {
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bool LocalChange = performScalarRepl(F);
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if (!LocalChange) break; // No need to repromote if no scalarrepl
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Changed = true;
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LocalChange = performPromotion(F);
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if (!LocalChange) break; // No need to re-scalarrepl if no promotion
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}
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return Changed;
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}
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bool SROA::performPromotion(Function &F) {
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std::vector<AllocaInst*> Allocas;
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DominatorTree &DT = getAnalysis<DominatorTree>();
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DominanceFrontier &DF = getAnalysis<DominanceFrontier>();
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BasicBlock &BB = F.getEntryBlock(); // Get the entry node for the function
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bool Changed = false;
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while (1) {
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Allocas.clear();
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// Find allocas that are safe to promote, by looking at all instructions in
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// the entry node
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for (BasicBlock::iterator I = BB.begin(), E = --BB.end(); I != E; ++I)
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if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) // Is it an alloca?
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if (isAllocaPromotable(AI))
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Allocas.push_back(AI);
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if (Allocas.empty()) break;
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PromoteMemToReg(Allocas, DT, DF);
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NumPromoted += Allocas.size();
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Changed = true;
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}
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return Changed;
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}
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// performScalarRepl - This algorithm is a simple worklist driven algorithm,
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// which runs on all of the malloc/alloca instructions in the function, removing
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// them if they are only used by getelementptr instructions.
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//
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bool SROA::performScalarRepl(Function &F) {
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std::vector<AllocationInst*> WorkList;
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// Scan the entry basic block, adding any alloca's and mallocs to the worklist
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BasicBlock &BB = F.getEntryBlock();
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for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
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if (AllocationInst *A = dyn_cast<AllocationInst>(I))
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WorkList.push_back(A);
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const TargetData &TD = getAnalysis<TargetData>();
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// Process the worklist
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bool Changed = false;
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while (!WorkList.empty()) {
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AllocationInst *AI = WorkList.back();
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WorkList.pop_back();
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// Handle dead allocas trivially. These can be formed by SROA'ing arrays
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// with unused elements.
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if (AI->use_empty()) {
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AI->eraseFromParent();
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continue;
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}
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// If we can turn this aggregate value (potentially with casts) into a
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// simple scalar value that can be mem2reg'd into a register value.
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bool IsNotTrivial = false;
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if (const Type *ActualType = CanConvertToScalar(AI, IsNotTrivial))
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if (IsNotTrivial && ActualType != Type::VoidTy) {
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ConvertToScalar(AI, ActualType);
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Changed = true;
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continue;
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}
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// Check to see if we can perform the core SROA transformation. We cannot
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// transform the allocation instruction if it is an array allocation
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// (allocations OF arrays are ok though), and an allocation of a scalar
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// value cannot be decomposed at all.
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if (!AI->isArrayAllocation() &&
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(isa<StructType>(AI->getAllocatedType()) ||
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isa<ArrayType>(AI->getAllocatedType())) &&
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AI->getAllocatedType()->isSized() &&
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TD.getABITypeSize(AI->getAllocatedType()) < SRThreshold) {
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// Check that all of the users of the allocation are capable of being
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// transformed.
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switch (isSafeAllocaToScalarRepl(AI)) {
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default: assert(0 && "Unexpected value!");
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case 0: // Not safe to scalar replace.
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break;
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case 1: // Safe, but requires cleanup/canonicalizations first
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CanonicalizeAllocaUsers(AI);
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// FALL THROUGH.
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case 3: // Safe to scalar replace.
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DoScalarReplacement(AI, WorkList);
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Changed = true;
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continue;
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}
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}
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// Check to see if this allocation is only modified by a memcpy/memmove from
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// a constant global. If this is the case, we can change all users to use
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// the constant global instead. This is commonly produced by the CFE by
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// constructs like "void foo() { int A[] = {1,2,3,4,5,6,7,8,9...}; }" if 'A'
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// is only subsequently read.
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if (Instruction *TheCopy = isOnlyCopiedFromConstantGlobal(AI)) {
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DOUT << "Found alloca equal to global: " << *AI;
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DOUT << " memcpy = " << *TheCopy;
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Constant *TheSrc = cast<Constant>(TheCopy->getOperand(2));
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AI->replaceAllUsesWith(ConstantExpr::getBitCast(TheSrc, AI->getType()));
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TheCopy->eraseFromParent(); // Don't mutate the global.
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AI->eraseFromParent();
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++NumGlobals;
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Changed = true;
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continue;
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}
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// Otherwise, couldn't process this.
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}
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return Changed;
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}
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/// DoScalarReplacement - This alloca satisfied the isSafeAllocaToScalarRepl
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/// predicate, do SROA now.
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void SROA::DoScalarReplacement(AllocationInst *AI,
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std::vector<AllocationInst*> &WorkList) {
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DOUT << "Found inst to SROA: " << *AI;
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SmallVector<AllocaInst*, 32> ElementAllocas;
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if (const StructType *ST = dyn_cast<StructType>(AI->getAllocatedType())) {
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ElementAllocas.reserve(ST->getNumContainedTypes());
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for (unsigned i = 0, e = ST->getNumContainedTypes(); i != e; ++i) {
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AllocaInst *NA = new AllocaInst(ST->getContainedType(i), 0,
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AI->getAlignment(),
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AI->getName() + "." + utostr(i), AI);
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ElementAllocas.push_back(NA);
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WorkList.push_back(NA); // Add to worklist for recursive processing
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}
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} else {
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const ArrayType *AT = cast<ArrayType>(AI->getAllocatedType());
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ElementAllocas.reserve(AT->getNumElements());
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const Type *ElTy = AT->getElementType();
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for (unsigned i = 0, e = AT->getNumElements(); i != e; ++i) {
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AllocaInst *NA = new AllocaInst(ElTy, 0, AI->getAlignment(),
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AI->getName() + "." + utostr(i), AI);
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ElementAllocas.push_back(NA);
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WorkList.push_back(NA); // Add to worklist for recursive processing
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}
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}
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// Now that we have created the alloca instructions that we want to use,
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// expand the getelementptr instructions to use them.
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//
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while (!AI->use_empty()) {
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Instruction *User = cast<Instruction>(AI->use_back());
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if (BitCastInst *BCInst = dyn_cast<BitCastInst>(User)) {
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RewriteBitCastUserOfAlloca(BCInst, AI, ElementAllocas);
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BCInst->eraseFromParent();
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continue;
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}
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GetElementPtrInst *GEPI = cast<GetElementPtrInst>(User);
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// We now know that the GEP is of the form: GEP <ptr>, 0, <cst>
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unsigned Idx =
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(unsigned)cast<ConstantInt>(GEPI->getOperand(2))->getZExtValue();
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assert(Idx < ElementAllocas.size() && "Index out of range?");
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AllocaInst *AllocaToUse = ElementAllocas[Idx];
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Value *RepValue;
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if (GEPI->getNumOperands() == 3) {
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// Do not insert a new getelementptr instruction with zero indices, only
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// to have it optimized out later.
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RepValue = AllocaToUse;
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} else {
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// We are indexing deeply into the structure, so we still need a
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// getelement ptr instruction to finish the indexing. This may be
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// expanded itself once the worklist is rerun.
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//
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SmallVector<Value*, 8> NewArgs;
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NewArgs.push_back(Constant::getNullValue(Type::Int32Ty));
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NewArgs.append(GEPI->op_begin()+3, GEPI->op_end());
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RepValue = new GetElementPtrInst(AllocaToUse, NewArgs.begin(),
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NewArgs.end(), "", GEPI);
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RepValue->takeName(GEPI);
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}
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// If this GEP is to the start of the aggregate, check for memcpys.
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if (Idx == 0) {
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bool IsStartOfAggregateGEP = true;
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for (unsigned i = 3, e = GEPI->getNumOperands(); i != e; ++i) {
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if (!isa<ConstantInt>(GEPI->getOperand(i))) {
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IsStartOfAggregateGEP = false;
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break;
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}
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if (!cast<ConstantInt>(GEPI->getOperand(i))->isZero()) {
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IsStartOfAggregateGEP = false;
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break;
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}
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}
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if (IsStartOfAggregateGEP)
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RewriteBitCastUserOfAlloca(GEPI, AI, ElementAllocas);
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}
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// Move all of the users over to the new GEP.
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GEPI->replaceAllUsesWith(RepValue);
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// Delete the old GEP
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GEPI->eraseFromParent();
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}
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// Finally, delete the Alloca instruction
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AI->eraseFromParent();
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NumReplaced++;
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}
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/// isSafeElementUse - Check to see if this use is an allowed use for a
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/// getelementptr instruction of an array aggregate allocation. isFirstElt
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/// indicates whether Ptr is known to the start of the aggregate.
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///
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void SROA::isSafeElementUse(Value *Ptr, bool isFirstElt, AllocationInst *AI,
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AllocaInfo &Info) {
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for (Value::use_iterator I = Ptr->use_begin(), E = Ptr->use_end();
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I != E; ++I) {
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Instruction *User = cast<Instruction>(*I);
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switch (User->getOpcode()) {
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case Instruction::Load: break;
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case Instruction::Store:
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// Store is ok if storing INTO the pointer, not storing the pointer
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if (User->getOperand(0) == Ptr) return MarkUnsafe(Info);
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break;
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case Instruction::GetElementPtr: {
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GetElementPtrInst *GEP = cast<GetElementPtrInst>(User);
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bool AreAllZeroIndices = isFirstElt;
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if (GEP->getNumOperands() > 1) {
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if (!isa<ConstantInt>(GEP->getOperand(1)) ||
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!cast<ConstantInt>(GEP->getOperand(1))->isZero())
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// Using pointer arithmetic to navigate the array.
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return MarkUnsafe(Info);
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if (AreAllZeroIndices) {
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for (unsigned i = 2, e = GEP->getNumOperands(); i != e; ++i) {
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if (!isa<ConstantInt>(GEP->getOperand(i)) ||
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!cast<ConstantInt>(GEP->getOperand(i))->isZero()) {
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AreAllZeroIndices = false;
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break;
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}
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}
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}
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}
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isSafeElementUse(GEP, AreAllZeroIndices, AI, Info);
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if (Info.isUnsafe) return;
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break;
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}
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case Instruction::BitCast:
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if (isFirstElt) {
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isSafeUseOfBitCastedAllocation(cast<BitCastInst>(User), AI, Info);
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if (Info.isUnsafe) return;
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break;
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}
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DOUT << " Transformation preventing inst: " << *User;
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return MarkUnsafe(Info);
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case Instruction::Call:
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if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(User)) {
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if (isFirstElt) {
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isSafeMemIntrinsicOnAllocation(MI, AI, I.getOperandNo(), Info);
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if (Info.isUnsafe) return;
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break;
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}
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}
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DOUT << " Transformation preventing inst: " << *User;
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return MarkUnsafe(Info);
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default:
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DOUT << " Transformation preventing inst: " << *User;
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return MarkUnsafe(Info);
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}
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}
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return; // All users look ok :)
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}
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/// AllUsersAreLoads - Return true if all users of this value are loads.
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static bool AllUsersAreLoads(Value *Ptr) {
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for (Value::use_iterator I = Ptr->use_begin(), E = Ptr->use_end();
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I != E; ++I)
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if (cast<Instruction>(*I)->getOpcode() != Instruction::Load)
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return false;
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return true;
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}
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/// isSafeUseOfAllocation - Check to see if this user is an allowed use for an
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/// aggregate allocation.
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///
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void SROA::isSafeUseOfAllocation(Instruction *User, AllocationInst *AI,
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AllocaInfo &Info) {
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if (BitCastInst *C = dyn_cast<BitCastInst>(User))
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return isSafeUseOfBitCastedAllocation(C, AI, Info);
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GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User);
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if (GEPI == 0)
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return MarkUnsafe(Info);
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gep_type_iterator I = gep_type_begin(GEPI), E = gep_type_end(GEPI);
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// The GEP is not safe to transform if not of the form "GEP <ptr>, 0, <cst>".
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if (I == E ||
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I.getOperand() != Constant::getNullValue(I.getOperand()->getType())) {
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return MarkUnsafe(Info);
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}
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++I;
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if (I == E) return MarkUnsafe(Info); // ran out of GEP indices??
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bool IsAllZeroIndices = true;
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// If this is a use of an array allocation, do a bit more checking for sanity.
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if (const ArrayType *AT = dyn_cast<ArrayType>(*I)) {
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uint64_t NumElements = AT->getNumElements();
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if (ConstantInt *Idx = dyn_cast<ConstantInt>(I.getOperand())) {
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IsAllZeroIndices &= Idx->isZero();
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// Check to make sure that index falls within the array. If not,
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// something funny is going on, so we won't do the optimization.
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//
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if (Idx->getZExtValue() >= NumElements)
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return MarkUnsafe(Info);
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// We cannot scalar repl this level of the array unless any array
|
|
// sub-indices are in-range constants. In particular, consider:
|
|
// A[0][i]. We cannot know that the user isn't doing invalid things like
|
|
// allowing i to index an out-of-range subscript that accesses A[1].
|
|
//
|
|
// Scalar replacing *just* the outer index of the array is probably not
|
|
// going to be a win anyway, so just give up.
|
|
for (++I; I != E && (isa<ArrayType>(*I) || isa<VectorType>(*I)); ++I) {
|
|
uint64_t NumElements;
|
|
if (const ArrayType *SubArrayTy = dyn_cast<ArrayType>(*I))
|
|
NumElements = SubArrayTy->getNumElements();
|
|
else
|
|
NumElements = cast<VectorType>(*I)->getNumElements();
|
|
|
|
ConstantInt *IdxVal = dyn_cast<ConstantInt>(I.getOperand());
|
|
if (!IdxVal) return MarkUnsafe(Info);
|
|
if (IdxVal->getZExtValue() >= NumElements)
|
|
return MarkUnsafe(Info);
|
|
IsAllZeroIndices &= IdxVal->isZero();
|
|
}
|
|
|
|
} else {
|
|
IsAllZeroIndices = 0;
|
|
|
|
// If this is an array index and the index is not constant, we cannot
|
|
// promote... that is unless the array has exactly one or two elements in
|
|
// it, in which case we CAN promote it, but we have to canonicalize this
|
|
// out if this is the only problem.
|
|
if ((NumElements == 1 || NumElements == 2) &&
|
|
AllUsersAreLoads(GEPI)) {
|
|
Info.needsCanon = true;
|
|
return; // Canonicalization required!
|
|
}
|
|
return MarkUnsafe(Info);
|
|
}
|
|
}
|
|
|
|
// If there are any non-simple uses of this getelementptr, make sure to reject
|
|
// them.
|
|
return isSafeElementUse(GEPI, IsAllZeroIndices, AI, Info);
|
|
}
|
|
|
|
/// isSafeMemIntrinsicOnAllocation - Return true if the specified memory
|
|
/// intrinsic can be promoted by SROA. At this point, we know that the operand
|
|
/// of the memintrinsic is a pointer to the beginning of the allocation.
|
|
void SROA::isSafeMemIntrinsicOnAllocation(MemIntrinsic *MI, AllocationInst *AI,
|
|
unsigned OpNo, AllocaInfo &Info) {
|
|
// If not constant length, give up.
|
|
ConstantInt *Length = dyn_cast<ConstantInt>(MI->getLength());
|
|
if (!Length) return MarkUnsafe(Info);
|
|
|
|
// If not the whole aggregate, give up.
|
|
const TargetData &TD = getAnalysis<TargetData>();
|
|
if (Length->getZExtValue() !=
|
|
TD.getABITypeSize(AI->getType()->getElementType()))
|
|
return MarkUnsafe(Info);
|
|
|
|
// We only know about memcpy/memset/memmove.
|
|
if (!isa<MemCpyInst>(MI) && !isa<MemSetInst>(MI) && !isa<MemMoveInst>(MI))
|
|
return MarkUnsafe(Info);
|
|
|
|
// Otherwise, we can transform it. Determine whether this is a memcpy/set
|
|
// into or out of the aggregate.
|
|
if (OpNo == 1)
|
|
Info.isMemCpyDst = true;
|
|
else {
|
|
assert(OpNo == 2);
|
|
Info.isMemCpySrc = true;
|
|
}
|
|
}
|
|
|
|
/// isSafeUseOfBitCastedAllocation - Return true if all users of this bitcast
|
|
/// are
|
|
void SROA::isSafeUseOfBitCastedAllocation(BitCastInst *BC, AllocationInst *AI,
|
|
AllocaInfo &Info) {
|
|
for (Value::use_iterator UI = BC->use_begin(), E = BC->use_end();
|
|
UI != E; ++UI) {
|
|
if (BitCastInst *BCU = dyn_cast<BitCastInst>(UI)) {
|
|
isSafeUseOfBitCastedAllocation(BCU, AI, Info);
|
|
} else if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(UI)) {
|
|
isSafeMemIntrinsicOnAllocation(MI, AI, UI.getOperandNo(), Info);
|
|
} else {
|
|
return MarkUnsafe(Info);
|
|
}
|
|
if (Info.isUnsafe) return;
|
|
}
|
|
}
|
|
|
|
/// RewriteBitCastUserOfAlloca - BCInst (transitively) bitcasts AI, or indexes
|
|
/// to its first element. Transform users of the cast to use the new values
|
|
/// instead.
|
|
void SROA::RewriteBitCastUserOfAlloca(Instruction *BCInst, AllocationInst *AI,
|
|
SmallVector<AllocaInst*, 32> &NewElts) {
|
|
Constant *Zero = Constant::getNullValue(Type::Int32Ty);
|
|
const TargetData &TD = getAnalysis<TargetData>();
|
|
|
|
Value::use_iterator UI = BCInst->use_begin(), UE = BCInst->use_end();
|
|
while (UI != UE) {
|
|
if (BitCastInst *BCU = dyn_cast<BitCastInst>(*UI)) {
|
|
RewriteBitCastUserOfAlloca(BCU, AI, NewElts);
|
|
++UI;
|
|
BCU->eraseFromParent();
|
|
continue;
|
|
}
|
|
|
|
// Otherwise, must be memcpy/memmove/memset of the entire aggregate. Split
|
|
// into one per element.
|
|
MemIntrinsic *MI = dyn_cast<MemIntrinsic>(*UI);
|
|
|
|
// If it's not a mem intrinsic, it must be some other user of a gep of the
|
|
// first pointer. Just leave these alone.
|
|
if (!MI) {
|
|
++UI;
|
|
continue;
|
|
}
|
|
|
|
// If this is a memcpy/memmove, construct the other pointer as the
|
|
// appropriate type.
|
|
Value *OtherPtr = 0;
|
|
if (MemCpyInst *MCI = dyn_cast<MemCpyInst>(MI)) {
|
|
if (BCInst == MCI->getRawDest())
|
|
OtherPtr = MCI->getRawSource();
|
|
else {
|
|
assert(BCInst == MCI->getRawSource());
|
|
OtherPtr = MCI->getRawDest();
|
|
}
|
|
} else if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI)) {
|
|
if (BCInst == MMI->getRawDest())
|
|
OtherPtr = MMI->getRawSource();
|
|
else {
|
|
assert(BCInst == MMI->getRawSource());
|
|
OtherPtr = MMI->getRawDest();
|
|
}
|
|
}
|
|
|
|
// If there is an other pointer, we want to convert it to the same pointer
|
|
// type as AI has, so we can GEP through it.
|
|
if (OtherPtr) {
|
|
// It is likely that OtherPtr is a bitcast, if so, remove it.
|
|
if (BitCastInst *BC = dyn_cast<BitCastInst>(OtherPtr))
|
|
OtherPtr = BC->getOperand(0);
|
|
if (ConstantExpr *BCE = dyn_cast<ConstantExpr>(OtherPtr))
|
|
if (BCE->getOpcode() == Instruction::BitCast)
|
|
OtherPtr = BCE->getOperand(0);
|
|
|
|
// If the pointer is not the right type, insert a bitcast to the right
|
|
// type.
|
|
if (OtherPtr->getType() != AI->getType())
|
|
OtherPtr = new BitCastInst(OtherPtr, AI->getType(), OtherPtr->getName(),
|
|
MI);
|
|
}
|
|
|
|
// Process each element of the aggregate.
|
|
Value *TheFn = MI->getOperand(0);
|
|
const Type *BytePtrTy = MI->getRawDest()->getType();
|
|
bool SROADest = MI->getRawDest() == BCInst;
|
|
|
|
for (unsigned i = 0, e = NewElts.size(); i != e; ++i) {
|
|
// If this is a memcpy/memmove, emit a GEP of the other element address.
|
|
Value *OtherElt = 0;
|
|
if (OtherPtr) {
|
|
Value *Idx[2];
|
|
Idx[0] = Zero;
|
|
Idx[1] = ConstantInt::get(Type::Int32Ty, i);
|
|
OtherElt = new GetElementPtrInst(OtherPtr, Idx, Idx + 2,
|
|
OtherPtr->getNameStr()+"."+utostr(i),
|
|
MI);
|
|
}
|
|
|
|
Value *EltPtr = NewElts[i];
|
|
const Type *EltTy =cast<PointerType>(EltPtr->getType())->getElementType();
|
|
|
|
// If we got down to a scalar, insert a load or store as appropriate.
|
|
if (EltTy->isFirstClassType()) {
|
|
if (isa<MemCpyInst>(MI) || isa<MemMoveInst>(MI)) {
|
|
Value *Elt = new LoadInst(SROADest ? OtherElt : EltPtr, "tmp",
|
|
MI);
|
|
new StoreInst(Elt, SROADest ? EltPtr : OtherElt, MI);
|
|
continue;
|
|
} else {
|
|
assert(isa<MemSetInst>(MI));
|
|
|
|
// If the stored element is zero (common case), just store a null
|
|
// constant.
|
|
Constant *StoreVal;
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(MI->getOperand(2))) {
|
|
if (CI->isZero()) {
|
|
StoreVal = Constant::getNullValue(EltTy); // 0.0, null, 0, <0,0>
|
|
} else {
|
|
// If EltTy is a vector type, get the element type.
|
|
const Type *ValTy = EltTy;
|
|
if (const VectorType *VTy = dyn_cast<VectorType>(ValTy))
|
|
ValTy = VTy->getElementType();
|
|
|
|
// Construct an integer with the right value.
|
|
unsigned EltSize = TD.getTypeSizeInBits(ValTy);
|
|
APInt OneVal(EltSize, CI->getZExtValue());
|
|
APInt TotalVal(OneVal);
|
|
// Set each byte.
|
|
for (unsigned i = 0; 8*i < EltSize; ++i) {
|
|
TotalVal = TotalVal.shl(8);
|
|
TotalVal |= OneVal;
|
|
}
|
|
|
|
// Convert the integer value to the appropriate type.
|
|
StoreVal = ConstantInt::get(TotalVal);
|
|
if (isa<PointerType>(ValTy))
|
|
StoreVal = ConstantExpr::getIntToPtr(StoreVal, ValTy);
|
|
else if (ValTy->isFloatingPoint())
|
|
StoreVal = ConstantExpr::getBitCast(StoreVal, ValTy);
|
|
assert(StoreVal->getType() == ValTy && "Type mismatch!");
|
|
|
|
// If the requested value was a vector constant, create it.
|
|
if (EltTy != ValTy) {
|
|
unsigned NumElts = cast<VectorType>(ValTy)->getNumElements();
|
|
SmallVector<Constant*, 16> Elts(NumElts, StoreVal);
|
|
StoreVal = ConstantVector::get(&Elts[0], NumElts);
|
|
}
|
|
}
|
|
new StoreInst(StoreVal, EltPtr, MI);
|
|
continue;
|
|
}
|
|
// Otherwise, if we're storing a byte variable, use a memset call for
|
|
// this element.
|
|
}
|
|
}
|
|
|
|
// Cast the element pointer to BytePtrTy.
|
|
if (EltPtr->getType() != BytePtrTy)
|
|
EltPtr = new BitCastInst(EltPtr, BytePtrTy, EltPtr->getNameStr(), MI);
|
|
|
|
// Cast the other pointer (if we have one) to BytePtrTy.
|
|
if (OtherElt && OtherElt->getType() != BytePtrTy)
|
|
OtherElt = new BitCastInst(OtherElt, BytePtrTy,OtherElt->getNameStr(),
|
|
MI);
|
|
|
|
unsigned EltSize = TD.getABITypeSize(EltTy);
|
|
|
|
// Finally, insert the meminst for this element.
|
|
if (isa<MemCpyInst>(MI) || isa<MemMoveInst>(MI)) {
|
|
Value *Ops[] = {
|
|
SROADest ? EltPtr : OtherElt, // Dest ptr
|
|
SROADest ? OtherElt : EltPtr, // Src ptr
|
|
ConstantInt::get(MI->getOperand(3)->getType(), EltSize), // Size
|
|
Zero // Align
|
|
};
|
|
new CallInst(TheFn, Ops, Ops + 4, "", MI);
|
|
} else {
|
|
assert(isa<MemSetInst>(MI));
|
|
Value *Ops[] = {
|
|
EltPtr, MI->getOperand(2), // Dest, Value,
|
|
ConstantInt::get(MI->getOperand(3)->getType(), EltSize), // Size
|
|
Zero // Align
|
|
};
|
|
new CallInst(TheFn, Ops, Ops + 4, "", MI);
|
|
}
|
|
}
|
|
|
|
// Finally, MI is now dead, as we've modified its actions to occur on all of
|
|
// the elements of the aggregate.
|
|
++UI;
|
|
MI->eraseFromParent();
|
|
}
|
|
}
|
|
|
|
/// HasPadding - Return true if the specified type has any structure or
|
|
/// alignment padding, false otherwise.
|
|
static bool HasPadding(const Type *Ty, const TargetData &TD,
|
|
bool inPacked = false) {
|
|
if (const StructType *STy = dyn_cast<StructType>(Ty)) {
|
|
const StructLayout *SL = TD.getStructLayout(STy);
|
|
unsigned PrevFieldBitOffset = 0;
|
|
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
|
|
unsigned FieldBitOffset = SL->getElementOffsetInBits(i);
|
|
|
|
// Padding in sub-elements?
|
|
if (HasPadding(STy->getElementType(i), TD, STy->isPacked()))
|
|
return true;
|
|
|
|
// Check to see if there is any padding between this element and the
|
|
// previous one.
|
|
if (i) {
|
|
unsigned PrevFieldEnd =
|
|
PrevFieldBitOffset+TD.getTypeSizeInBits(STy->getElementType(i-1));
|
|
if (PrevFieldEnd < FieldBitOffset)
|
|
return true;
|
|
}
|
|
|
|
PrevFieldBitOffset = FieldBitOffset;
|
|
}
|
|
|
|
// Check for tail padding.
|
|
if (unsigned EltCount = STy->getNumElements()) {
|
|
unsigned PrevFieldEnd = PrevFieldBitOffset +
|
|
TD.getTypeSizeInBits(STy->getElementType(EltCount-1));
|
|
if (PrevFieldEnd < SL->getSizeInBits())
|
|
return true;
|
|
}
|
|
|
|
} else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
|
|
return HasPadding(ATy->getElementType(), TD, false);
|
|
} else if (const VectorType *VTy = dyn_cast<VectorType>(Ty)) {
|
|
return HasPadding(VTy->getElementType(), TD, false);
|
|
}
|
|
return inPacked ?
|
|
false : TD.getTypeSizeInBits(Ty) != TD.getABITypeSizeInBits(Ty);
|
|
}
|
|
|
|
/// isSafeStructAllocaToScalarRepl - Check to see if the specified allocation of
|
|
/// an aggregate can be broken down into elements. Return 0 if not, 3 if safe,
|
|
/// or 1 if safe after canonicalization has been performed.
|
|
///
|
|
int SROA::isSafeAllocaToScalarRepl(AllocationInst *AI) {
|
|
// Loop over the use list of the alloca. We can only transform it if all of
|
|
// the users are safe to transform.
|
|
AllocaInfo Info;
|
|
|
|
for (Value::use_iterator I = AI->use_begin(), E = AI->use_end();
|
|
I != E; ++I) {
|
|
isSafeUseOfAllocation(cast<Instruction>(*I), AI, Info);
|
|
if (Info.isUnsafe) {
|
|
DOUT << "Cannot transform: " << *AI << " due to user: " << **I;
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
// Okay, we know all the users are promotable. If the aggregate is a memcpy
|
|
// source and destination, we have to be careful. In particular, the memcpy
|
|
// could be moving around elements that live in structure padding of the LLVM
|
|
// types, but may actually be used. In these cases, we refuse to promote the
|
|
// struct.
|
|
if (Info.isMemCpySrc && Info.isMemCpyDst &&
|
|
HasPadding(AI->getType()->getElementType(), getAnalysis<TargetData>()))
|
|
return 0;
|
|
|
|
// If we require cleanup, return 1, otherwise return 3.
|
|
return Info.needsCanon ? 1 : 3;
|
|
}
|
|
|
|
/// CanonicalizeAllocaUsers - If SROA reported that it can promote the specified
|
|
/// allocation, but only if cleaned up, perform the cleanups required.
|
|
void SROA::CanonicalizeAllocaUsers(AllocationInst *AI) {
|
|
// At this point, we know that the end result will be SROA'd and promoted, so
|
|
// we can insert ugly code if required so long as sroa+mem2reg will clean it
|
|
// up.
|
|
for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
|
|
UI != E; ) {
|
|
GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(*UI++);
|
|
if (!GEPI) continue;
|
|
gep_type_iterator I = gep_type_begin(GEPI);
|
|
++I;
|
|
|
|
if (const ArrayType *AT = dyn_cast<ArrayType>(*I)) {
|
|
uint64_t NumElements = AT->getNumElements();
|
|
|
|
if (!isa<ConstantInt>(I.getOperand())) {
|
|
if (NumElements == 1) {
|
|
GEPI->setOperand(2, Constant::getNullValue(Type::Int32Ty));
|
|
} else {
|
|
assert(NumElements == 2 && "Unhandled case!");
|
|
// All users of the GEP must be loads. At each use of the GEP, insert
|
|
// two loads of the appropriate indexed GEP and select between them.
|
|
Value *IsOne = new ICmpInst(ICmpInst::ICMP_NE, I.getOperand(),
|
|
Constant::getNullValue(I.getOperand()->getType()),
|
|
"isone", GEPI);
|
|
// Insert the new GEP instructions, which are properly indexed.
|
|
SmallVector<Value*, 8> Indices(GEPI->op_begin()+1, GEPI->op_end());
|
|
Indices[1] = Constant::getNullValue(Type::Int32Ty);
|
|
Value *ZeroIdx = new GetElementPtrInst(GEPI->getOperand(0),
|
|
Indices.begin(),
|
|
Indices.end(),
|
|
GEPI->getName()+".0", GEPI);
|
|
Indices[1] = ConstantInt::get(Type::Int32Ty, 1);
|
|
Value *OneIdx = new GetElementPtrInst(GEPI->getOperand(0),
|
|
Indices.begin(),
|
|
Indices.end(),
|
|
GEPI->getName()+".1", GEPI);
|
|
// Replace all loads of the variable index GEP with loads from both
|
|
// indexes and a select.
|
|
while (!GEPI->use_empty()) {
|
|
LoadInst *LI = cast<LoadInst>(GEPI->use_back());
|
|
Value *Zero = new LoadInst(ZeroIdx, LI->getName()+".0", LI);
|
|
Value *One = new LoadInst(OneIdx , LI->getName()+".1", LI);
|
|
Value *R = new SelectInst(IsOne, One, Zero, LI->getName(), LI);
|
|
LI->replaceAllUsesWith(R);
|
|
LI->eraseFromParent();
|
|
}
|
|
GEPI->eraseFromParent();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// MergeInType - Add the 'In' type to the accumulated type so far. If the
|
|
/// types are incompatible, return true, otherwise update Accum and return
|
|
/// false.
|
|
///
|
|
/// There are three cases we handle here:
|
|
/// 1) An effectively-integer union, where the pieces are stored into as
|
|
/// smaller integers (common with byte swap and other idioms).
|
|
/// 2) A union of vector types of the same size and potentially its elements.
|
|
/// Here we turn element accesses into insert/extract element operations.
|
|
/// 3) A union of scalar types, such as int/float or int/pointer. Here we
|
|
/// merge together into integers, allowing the xform to work with #1 as
|
|
/// well.
|
|
static bool MergeInType(const Type *In, const Type *&Accum,
|
|
const TargetData &TD) {
|
|
// If this is our first type, just use it.
|
|
const VectorType *PTy;
|
|
if (Accum == Type::VoidTy || In == Accum) {
|
|
Accum = In;
|
|
} else if (In == Type::VoidTy) {
|
|
// Noop.
|
|
} else if (In->isInteger() && Accum->isInteger()) { // integer union.
|
|
// Otherwise pick whichever type is larger.
|
|
if (cast<IntegerType>(In)->getBitWidth() >
|
|
cast<IntegerType>(Accum)->getBitWidth())
|
|
Accum = In;
|
|
} else if (isa<PointerType>(In) && isa<PointerType>(Accum)) {
|
|
// Pointer unions just stay as one of the pointers.
|
|
} else if (isa<VectorType>(In) || isa<VectorType>(Accum)) {
|
|
if ((PTy = dyn_cast<VectorType>(Accum)) &&
|
|
PTy->getElementType() == In) {
|
|
// Accum is a vector, and we are accessing an element: ok.
|
|
} else if ((PTy = dyn_cast<VectorType>(In)) &&
|
|
PTy->getElementType() == Accum) {
|
|
// In is a vector, and accum is an element: ok, remember In.
|
|
Accum = In;
|
|
} else if ((PTy = dyn_cast<VectorType>(In)) && isa<VectorType>(Accum) &&
|
|
PTy->getBitWidth() == cast<VectorType>(Accum)->getBitWidth()) {
|
|
// Two vectors of the same size: keep Accum.
|
|
} else {
|
|
// Cannot insert an short into a <4 x int> or handle
|
|
// <2 x int> -> <4 x int>
|
|
return true;
|
|
}
|
|
} else {
|
|
// Pointer/FP/Integer unions merge together as integers.
|
|
switch (Accum->getTypeID()) {
|
|
case Type::PointerTyID: Accum = TD.getIntPtrType(); break;
|
|
case Type::FloatTyID: Accum = Type::Int32Ty; break;
|
|
case Type::DoubleTyID: Accum = Type::Int64Ty; break;
|
|
case Type::X86_FP80TyID: return true;
|
|
case Type::FP128TyID: return true;
|
|
case Type::PPC_FP128TyID: return true;
|
|
default:
|
|
assert(Accum->isInteger() && "Unknown FP type!");
|
|
break;
|
|
}
|
|
|
|
switch (In->getTypeID()) {
|
|
case Type::PointerTyID: In = TD.getIntPtrType(); break;
|
|
case Type::FloatTyID: In = Type::Int32Ty; break;
|
|
case Type::DoubleTyID: In = Type::Int64Ty; break;
|
|
case Type::X86_FP80TyID: return true;
|
|
case Type::FP128TyID: return true;
|
|
case Type::PPC_FP128TyID: return true;
|
|
default:
|
|
assert(In->isInteger() && "Unknown FP type!");
|
|
break;
|
|
}
|
|
return MergeInType(In, Accum, TD);
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// getUIntAtLeastAsBigAs - Return an unsigned integer type that is at least
|
|
/// as big as the specified type. If there is no suitable type, this returns
|
|
/// null.
|
|
const Type *getUIntAtLeastAsBigAs(unsigned NumBits) {
|
|
if (NumBits > 64) return 0;
|
|
if (NumBits > 32) return Type::Int64Ty;
|
|
if (NumBits > 16) return Type::Int32Ty;
|
|
if (NumBits > 8) return Type::Int16Ty;
|
|
return Type::Int8Ty;
|
|
}
|
|
|
|
/// CanConvertToScalar - V is a pointer. If we can convert the pointee to a
|
|
/// single scalar integer type, return that type. Further, if the use is not
|
|
/// a completely trivial use that mem2reg could promote, set IsNotTrivial. If
|
|
/// there are no uses of this pointer, return Type::VoidTy to differentiate from
|
|
/// failure.
|
|
///
|
|
const Type *SROA::CanConvertToScalar(Value *V, bool &IsNotTrivial) {
|
|
const Type *UsedType = Type::VoidTy; // No uses, no forced type.
|
|
const TargetData &TD = getAnalysis<TargetData>();
|
|
const PointerType *PTy = cast<PointerType>(V->getType());
|
|
|
|
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI!=E; ++UI) {
|
|
Instruction *User = cast<Instruction>(*UI);
|
|
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
|
|
if (MergeInType(LI->getType(), UsedType, TD))
|
|
return 0;
|
|
|
|
} else if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
|
|
// Storing the pointer, not into the value?
|
|
if (SI->getOperand(0) == V) return 0;
|
|
|
|
// NOTE: We could handle storing of FP imms into integers here!
|
|
|
|
if (MergeInType(SI->getOperand(0)->getType(), UsedType, TD))
|
|
return 0;
|
|
} else if (BitCastInst *CI = dyn_cast<BitCastInst>(User)) {
|
|
IsNotTrivial = true;
|
|
const Type *SubTy = CanConvertToScalar(CI, IsNotTrivial);
|
|
if (!SubTy || MergeInType(SubTy, UsedType, TD)) return 0;
|
|
} else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(User)) {
|
|
// Check to see if this is stepping over an element: GEP Ptr, int C
|
|
if (GEP->getNumOperands() == 2 && isa<ConstantInt>(GEP->getOperand(1))) {
|
|
unsigned Idx = cast<ConstantInt>(GEP->getOperand(1))->getZExtValue();
|
|
unsigned ElSize = TD.getABITypeSize(PTy->getElementType());
|
|
unsigned BitOffset = Idx*ElSize*8;
|
|
if (BitOffset > 64 || !isPowerOf2_32(ElSize)) return 0;
|
|
|
|
IsNotTrivial = true;
|
|
const Type *SubElt = CanConvertToScalar(GEP, IsNotTrivial);
|
|
if (SubElt == 0) return 0;
|
|
if (SubElt != Type::VoidTy && SubElt->isInteger()) {
|
|
const Type *NewTy =
|
|
getUIntAtLeastAsBigAs(TD.getABITypeSizeInBits(SubElt)+BitOffset);
|
|
if (NewTy == 0 || MergeInType(NewTy, UsedType, TD)) return 0;
|
|
continue;
|
|
}
|
|
} else if (GEP->getNumOperands() == 3 &&
|
|
isa<ConstantInt>(GEP->getOperand(1)) &&
|
|
isa<ConstantInt>(GEP->getOperand(2)) &&
|
|
cast<ConstantInt>(GEP->getOperand(1))->isZero()) {
|
|
// We are stepping into an element, e.g. a structure or an array:
|
|
// GEP Ptr, int 0, uint C
|
|
const Type *AggTy = PTy->getElementType();
|
|
unsigned Idx = cast<ConstantInt>(GEP->getOperand(2))->getZExtValue();
|
|
|
|
if (const ArrayType *ATy = dyn_cast<ArrayType>(AggTy)) {
|
|
if (Idx >= ATy->getNumElements()) return 0; // Out of range.
|
|
} else if (const VectorType *VectorTy = dyn_cast<VectorType>(AggTy)) {
|
|
// Getting an element of the vector.
|
|
if (Idx >= VectorTy->getNumElements()) return 0; // Out of range.
|
|
|
|
// Merge in the vector type.
|
|
if (MergeInType(VectorTy, UsedType, TD)) return 0;
|
|
|
|
const Type *SubTy = CanConvertToScalar(GEP, IsNotTrivial);
|
|
if (SubTy == 0) return 0;
|
|
|
|
if (SubTy != Type::VoidTy && MergeInType(SubTy, UsedType, TD))
|
|
return 0;
|
|
|
|
// We'll need to change this to an insert/extract element operation.
|
|
IsNotTrivial = true;
|
|
continue; // Everything looks ok
|
|
|
|
} else if (isa<StructType>(AggTy)) {
|
|
// Structs are always ok.
|
|
} else {
|
|
return 0;
|
|
}
|
|
const Type *NTy = getUIntAtLeastAsBigAs(TD.getABITypeSizeInBits(AggTy));
|
|
if (NTy == 0 || MergeInType(NTy, UsedType, TD)) return 0;
|
|
const Type *SubTy = CanConvertToScalar(GEP, IsNotTrivial);
|
|
if (SubTy == 0) return 0;
|
|
if (SubTy != Type::VoidTy && MergeInType(SubTy, UsedType, TD))
|
|
return 0;
|
|
continue; // Everything looks ok
|
|
}
|
|
return 0;
|
|
} else {
|
|
// Cannot handle this!
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
return UsedType;
|
|
}
|
|
|
|
/// ConvertToScalar - The specified alloca passes the CanConvertToScalar
|
|
/// predicate and is non-trivial. Convert it to something that can be trivially
|
|
/// promoted into a register by mem2reg.
|
|
void SROA::ConvertToScalar(AllocationInst *AI, const Type *ActualTy) {
|
|
DOUT << "CONVERT TO SCALAR: " << *AI << " TYPE = "
|
|
<< *ActualTy << "\n";
|
|
++NumConverted;
|
|
|
|
BasicBlock *EntryBlock = AI->getParent();
|
|
assert(EntryBlock == &EntryBlock->getParent()->getEntryBlock() &&
|
|
"Not in the entry block!");
|
|
EntryBlock->getInstList().remove(AI); // Take the alloca out of the program.
|
|
|
|
// Create and insert the alloca.
|
|
AllocaInst *NewAI = new AllocaInst(ActualTy, 0, AI->getName(),
|
|
EntryBlock->begin());
|
|
ConvertUsesToScalar(AI, NewAI, 0);
|
|
delete AI;
|
|
}
|
|
|
|
|
|
/// ConvertUsesToScalar - Convert all of the users of Ptr to use the new alloca
|
|
/// directly. This happens when we are converting an "integer union" to a
|
|
/// single integer scalar, or when we are converting a "vector union" to a
|
|
/// vector with insert/extractelement instructions.
|
|
///
|
|
/// Offset is an offset from the original alloca, in bits that need to be
|
|
/// shifted to the right. By the end of this, there should be no uses of Ptr.
|
|
void SROA::ConvertUsesToScalar(Value *Ptr, AllocaInst *NewAI, unsigned Offset) {
|
|
const TargetData &TD = getAnalysis<TargetData>();
|
|
while (!Ptr->use_empty()) {
|
|
Instruction *User = cast<Instruction>(Ptr->use_back());
|
|
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
|
|
// The load is a bit extract from NewAI shifted right by Offset bits.
|
|
Value *NV = new LoadInst(NewAI, LI->getName(), LI);
|
|
if (NV->getType() == LI->getType() && Offset == 0) {
|
|
// We win, no conversion needed.
|
|
} else if (const VectorType *PTy = dyn_cast<VectorType>(NV->getType())) {
|
|
// If the result alloca is a vector type, this is either an element
|
|
// access or a bitcast to another vector type.
|
|
if (isa<VectorType>(LI->getType())) {
|
|
NV = new BitCastInst(NV, LI->getType(), LI->getName(), LI);
|
|
} else {
|
|
// Must be an element access.
|
|
unsigned Elt = Offset/TD.getABITypeSizeInBits(PTy->getElementType());
|
|
NV = new ExtractElementInst(
|
|
NV, ConstantInt::get(Type::Int32Ty, Elt), "tmp", LI);
|
|
}
|
|
} else if (isa<PointerType>(NV->getType())) {
|
|
assert(isa<PointerType>(LI->getType()));
|
|
// Must be ptr->ptr cast. Anything else would result in NV being
|
|
// an integer.
|
|
NV = new BitCastInst(NV, LI->getType(), LI->getName(), LI);
|
|
} else {
|
|
const IntegerType *NTy = cast<IntegerType>(NV->getType());
|
|
|
|
// If this is a big-endian system and the load is narrower than the
|
|
// full alloca type, we need to do a shift to get the right bits.
|
|
int ShAmt = 0;
|
|
if (TD.isBigEndian()) {
|
|
// On big-endian machines, the lowest bit is stored at the bit offset
|
|
// from the pointer given by getTypeStoreSizeInBits. This matters for
|
|
// integers with a bitwidth that is not a multiple of 8.
|
|
ShAmt = TD.getTypeStoreSizeInBits(NTy) -
|
|
TD.getTypeStoreSizeInBits(LI->getType()) - Offset;
|
|
} else {
|
|
ShAmt = Offset;
|
|
}
|
|
|
|
// Note: we support negative bitwidths (with shl) which are not defined.
|
|
// We do this to support (f.e.) loads off the end of a structure where
|
|
// only some bits are used.
|
|
if (ShAmt > 0 && (unsigned)ShAmt < NTy->getBitWidth())
|
|
NV = BinaryOperator::createLShr(NV,
|
|
ConstantInt::get(NV->getType(),ShAmt),
|
|
LI->getName(), LI);
|
|
else if (ShAmt < 0 && (unsigned)-ShAmt < NTy->getBitWidth())
|
|
NV = BinaryOperator::createShl(NV,
|
|
ConstantInt::get(NV->getType(),-ShAmt),
|
|
LI->getName(), LI);
|
|
|
|
// Finally, unconditionally truncate the integer to the right width.
|
|
unsigned LIBitWidth = TD.getTypeSizeInBits(LI->getType());
|
|
if (LIBitWidth < NTy->getBitWidth())
|
|
NV = new TruncInst(NV, IntegerType::get(LIBitWidth),
|
|
LI->getName(), LI);
|
|
|
|
// If the result is an integer, this is a trunc or bitcast.
|
|
if (isa<IntegerType>(LI->getType())) {
|
|
assert(NV->getType() == LI->getType() && "Truncate wasn't enough?");
|
|
} else if (LI->getType()->isFloatingPoint()) {
|
|
// Just do a bitcast, we know the sizes match up.
|
|
NV = new BitCastInst(NV, LI->getType(), LI->getName(), LI);
|
|
} else {
|
|
// Otherwise must be a pointer.
|
|
NV = new IntToPtrInst(NV, LI->getType(), LI->getName(), LI);
|
|
}
|
|
}
|
|
LI->replaceAllUsesWith(NV);
|
|
LI->eraseFromParent();
|
|
} else if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
|
|
assert(SI->getOperand(0) != Ptr && "Consistency error!");
|
|
|
|
// Convert the stored type to the actual type, shift it left to insert
|
|
// then 'or' into place.
|
|
Value *SV = SI->getOperand(0);
|
|
const Type *AllocaType = NewAI->getType()->getElementType();
|
|
if (SV->getType() == AllocaType && Offset == 0) {
|
|
// All is well.
|
|
} else if (const VectorType *PTy = dyn_cast<VectorType>(AllocaType)) {
|
|
Value *Old = new LoadInst(NewAI, NewAI->getName()+".in", SI);
|
|
|
|
// If the result alloca is a vector type, this is either an element
|
|
// access or a bitcast to another vector type.
|
|
if (isa<VectorType>(SV->getType())) {
|
|
SV = new BitCastInst(SV, AllocaType, SV->getName(), SI);
|
|
} else {
|
|
// Must be an element insertion.
|
|
unsigned Elt = Offset/TD.getABITypeSizeInBits(PTy->getElementType());
|
|
SV = new InsertElementInst(Old, SV,
|
|
ConstantInt::get(Type::Int32Ty, Elt),
|
|
"tmp", SI);
|
|
}
|
|
} else if (isa<PointerType>(AllocaType)) {
|
|
// If the alloca type is a pointer, then all the elements must be
|
|
// pointers.
|
|
if (SV->getType() != AllocaType)
|
|
SV = new BitCastInst(SV, AllocaType, SV->getName(), SI);
|
|
} else {
|
|
Value *Old = new LoadInst(NewAI, NewAI->getName()+".in", SI);
|
|
|
|
// If SV is a float, convert it to the appropriate integer type.
|
|
// If it is a pointer, do the same, and also handle ptr->ptr casts
|
|
// here.
|
|
unsigned SrcWidth = TD.getTypeSizeInBits(SV->getType());
|
|
unsigned DestWidth = TD.getTypeSizeInBits(AllocaType);
|
|
unsigned SrcStoreWidth = TD.getTypeStoreSizeInBits(SV->getType());
|
|
unsigned DestStoreWidth = TD.getTypeStoreSizeInBits(AllocaType);
|
|
if (SV->getType()->isFloatingPoint())
|
|
SV = new BitCastInst(SV, IntegerType::get(SrcWidth),
|
|
SV->getName(), SI);
|
|
else if (isa<PointerType>(SV->getType()))
|
|
SV = new PtrToIntInst(SV, TD.getIntPtrType(), SV->getName(), SI);
|
|
|
|
// Always zero extend the value if needed.
|
|
if (SV->getType() != AllocaType)
|
|
SV = new ZExtInst(SV, AllocaType, SV->getName(), SI);
|
|
|
|
// If this is a big-endian system and the store is narrower than the
|
|
// full alloca type, we need to do a shift to get the right bits.
|
|
int ShAmt = 0;
|
|
if (TD.isBigEndian()) {
|
|
// On big-endian machines, the lowest bit is stored at the bit offset
|
|
// from the pointer given by getTypeStoreSizeInBits. This matters for
|
|
// integers with a bitwidth that is not a multiple of 8.
|
|
ShAmt = DestStoreWidth - SrcStoreWidth - Offset;
|
|
} else {
|
|
ShAmt = Offset;
|
|
}
|
|
|
|
// Note: we support negative bitwidths (with shr) which are not defined.
|
|
// We do this to support (f.e.) stores off the end of a structure where
|
|
// only some bits in the structure are set.
|
|
APInt Mask(APInt::getLowBitsSet(DestWidth, SrcWidth));
|
|
if (ShAmt > 0 && (unsigned)ShAmt < DestWidth) {
|
|
SV = BinaryOperator::createShl(SV,
|
|
ConstantInt::get(SV->getType(), ShAmt),
|
|
SV->getName(), SI);
|
|
Mask <<= ShAmt;
|
|
} else if (ShAmt < 0 && (unsigned)-ShAmt < DestWidth) {
|
|
SV = BinaryOperator::createLShr(SV,
|
|
ConstantInt::get(SV->getType(),-ShAmt),
|
|
SV->getName(), SI);
|
|
Mask = Mask.lshr(ShAmt);
|
|
}
|
|
|
|
// Mask out the bits we are about to insert from the old value, and or
|
|
// in the new bits.
|
|
if (SrcWidth != DestWidth) {
|
|
assert(DestWidth > SrcWidth);
|
|
Old = BinaryOperator::createAnd(Old, ConstantInt::get(~Mask),
|
|
Old->getName()+".mask", SI);
|
|
SV = BinaryOperator::createOr(Old, SV, SV->getName()+".ins", SI);
|
|
}
|
|
}
|
|
new StoreInst(SV, NewAI, SI);
|
|
SI->eraseFromParent();
|
|
|
|
} else if (BitCastInst *CI = dyn_cast<BitCastInst>(User)) {
|
|
ConvertUsesToScalar(CI, NewAI, Offset);
|
|
CI->eraseFromParent();
|
|
} else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(User)) {
|
|
const PointerType *AggPtrTy =
|
|
cast<PointerType>(GEP->getOperand(0)->getType());
|
|
const TargetData &TD = getAnalysis<TargetData>();
|
|
unsigned AggSizeInBits =
|
|
TD.getABITypeSizeInBits(AggPtrTy->getElementType());
|
|
|
|
// Check to see if this is stepping over an element: GEP Ptr, int C
|
|
unsigned NewOffset = Offset;
|
|
if (GEP->getNumOperands() == 2) {
|
|
unsigned Idx = cast<ConstantInt>(GEP->getOperand(1))->getZExtValue();
|
|
unsigned BitOffset = Idx*AggSizeInBits;
|
|
|
|
NewOffset += BitOffset;
|
|
} else if (GEP->getNumOperands() == 3) {
|
|
// We know that operand #2 is zero.
|
|
unsigned Idx = cast<ConstantInt>(GEP->getOperand(2))->getZExtValue();
|
|
const Type *AggTy = AggPtrTy->getElementType();
|
|
if (const SequentialType *SeqTy = dyn_cast<SequentialType>(AggTy)) {
|
|
unsigned ElSizeBits =
|
|
TD.getABITypeSizeInBits(SeqTy->getElementType());
|
|
|
|
NewOffset += ElSizeBits*Idx;
|
|
} else if (const StructType *STy = dyn_cast<StructType>(AggTy)) {
|
|
unsigned EltBitOffset =
|
|
TD.getStructLayout(STy)->getElementOffsetInBits(Idx);
|
|
|
|
NewOffset += EltBitOffset;
|
|
} else {
|
|
assert(0 && "Unsupported operation!");
|
|
abort();
|
|
}
|
|
} else {
|
|
assert(0 && "Unsupported operation!");
|
|
abort();
|
|
}
|
|
ConvertUsesToScalar(GEP, NewAI, NewOffset);
|
|
GEP->eraseFromParent();
|
|
} else {
|
|
assert(0 && "Unsupported operation!");
|
|
abort();
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/// PointsToConstantGlobal - Return true if V (possibly indirectly) points to
|
|
/// some part of a constant global variable. This intentionally only accepts
|
|
/// constant expressions because we don't can't rewrite arbitrary instructions.
|
|
static bool PointsToConstantGlobal(Value *V) {
|
|
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
|
|
return GV->isConstant();
|
|
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
|
|
if (CE->getOpcode() == Instruction::BitCast ||
|
|
CE->getOpcode() == Instruction::GetElementPtr)
|
|
return PointsToConstantGlobal(CE->getOperand(0));
|
|
return false;
|
|
}
|
|
|
|
/// isOnlyCopiedFromConstantGlobal - Recursively walk the uses of a (derived)
|
|
/// pointer to an alloca. Ignore any reads of the pointer, return false if we
|
|
/// see any stores or other unknown uses. If we see pointer arithmetic, keep
|
|
/// track of whether it moves the pointer (with isOffset) but otherwise traverse
|
|
/// the uses. If we see a memcpy/memmove that targets an unoffseted pointer to
|
|
/// the alloca, and if the source pointer is a pointer to a constant global, we
|
|
/// can optimize this.
|
|
static bool isOnlyCopiedFromConstantGlobal(Value *V, Instruction *&TheCopy,
|
|
bool isOffset) {
|
|
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI!=E; ++UI) {
|
|
if (isa<LoadInst>(*UI)) {
|
|
// Ignore loads, they are always ok.
|
|
continue;
|
|
}
|
|
if (BitCastInst *BCI = dyn_cast<BitCastInst>(*UI)) {
|
|
// If uses of the bitcast are ok, we are ok.
|
|
if (!isOnlyCopiedFromConstantGlobal(BCI, TheCopy, isOffset))
|
|
return false;
|
|
continue;
|
|
}
|
|
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(*UI)) {
|
|
// If the GEP has all zero indices, it doesn't offset the pointer. If it
|
|
// doesn't, it does.
|
|
if (!isOnlyCopiedFromConstantGlobal(GEP, TheCopy,
|
|
isOffset || !GEP->hasAllZeroIndices()))
|
|
return false;
|
|
continue;
|
|
}
|
|
|
|
// If this is isn't our memcpy/memmove, reject it as something we can't
|
|
// handle.
|
|
if (!isa<MemCpyInst>(*UI) && !isa<MemMoveInst>(*UI))
|
|
return false;
|
|
|
|
// If we already have seen a copy, reject the second one.
|
|
if (TheCopy) return false;
|
|
|
|
// If the pointer has been offset from the start of the alloca, we can't
|
|
// safely handle this.
|
|
if (isOffset) return false;
|
|
|
|
// If the memintrinsic isn't using the alloca as the dest, reject it.
|
|
if (UI.getOperandNo() != 1) return false;
|
|
|
|
MemIntrinsic *MI = cast<MemIntrinsic>(*UI);
|
|
|
|
// If the source of the memcpy/move is not a constant global, reject it.
|
|
if (!PointsToConstantGlobal(MI->getOperand(2)))
|
|
return false;
|
|
|
|
// Otherwise, the transform is safe. Remember the copy instruction.
|
|
TheCopy = MI;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/// isOnlyCopiedFromConstantGlobal - Return true if the specified alloca is only
|
|
/// modified by a copy from a constant global. If we can prove this, we can
|
|
/// replace any uses of the alloca with uses of the global directly.
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Instruction *SROA::isOnlyCopiedFromConstantGlobal(AllocationInst *AI) {
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Instruction *TheCopy = 0;
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if (::isOnlyCopiedFromConstantGlobal(AI, TheCopy, false))
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return TheCopy;
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return 0;
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}
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