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https://github.com/c64scene-ar/llvm-6502.git
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@137650 91177308-0d34-0410-b5e6-96231b3b80d8
1486 lines
60 KiB
C++
1486 lines
60 KiB
C++
//===- MemoryDependenceAnalysis.cpp - Mem Deps Implementation --*- C++ -*-===//
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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 file implements an analysis that determines, for a given memory
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// operation, what preceding memory operations it depends on. It builds on
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// alias analysis information, and tries to provide a lazy, caching interface to
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// a common kind of alias information query.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "memdep"
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#include "llvm/Analysis/MemoryDependenceAnalysis.h"
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#include "llvm/Analysis/ValueTracking.h"
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#include "llvm/Instructions.h"
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#include "llvm/IntrinsicInst.h"
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#include "llvm/Function.h"
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#include "llvm/LLVMContext.h"
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#include "llvm/Analysis/AliasAnalysis.h"
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#include "llvm/Analysis/Dominators.h"
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#include "llvm/Analysis/InstructionSimplify.h"
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#include "llvm/Analysis/MemoryBuiltins.h"
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#include "llvm/Analysis/PHITransAddr.h"
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#include "llvm/Analysis/ValueTracking.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/Support/PredIteratorCache.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Target/TargetData.h"
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using namespace llvm;
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STATISTIC(NumCacheNonLocal, "Number of fully cached non-local responses");
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STATISTIC(NumCacheDirtyNonLocal, "Number of dirty cached non-local responses");
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STATISTIC(NumUncacheNonLocal, "Number of uncached non-local responses");
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STATISTIC(NumCacheNonLocalPtr,
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"Number of fully cached non-local ptr responses");
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STATISTIC(NumCacheDirtyNonLocalPtr,
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"Number of cached, but dirty, non-local ptr responses");
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STATISTIC(NumUncacheNonLocalPtr,
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"Number of uncached non-local ptr responses");
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STATISTIC(NumCacheCompleteNonLocalPtr,
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"Number of block queries that were completely cached");
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// Limit for the number of instructions to scan in a block.
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// FIXME: Figure out what a sane value is for this.
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// (500 is relatively insane.)
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static const int BlockScanLimit = 500;
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char MemoryDependenceAnalysis::ID = 0;
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// Register this pass...
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INITIALIZE_PASS_BEGIN(MemoryDependenceAnalysis, "memdep",
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"Memory Dependence Analysis", false, true)
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INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
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INITIALIZE_PASS_END(MemoryDependenceAnalysis, "memdep",
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"Memory Dependence Analysis", false, true)
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MemoryDependenceAnalysis::MemoryDependenceAnalysis()
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: FunctionPass(ID), PredCache(0) {
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initializeMemoryDependenceAnalysisPass(*PassRegistry::getPassRegistry());
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}
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MemoryDependenceAnalysis::~MemoryDependenceAnalysis() {
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}
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/// Clean up memory in between runs
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void MemoryDependenceAnalysis::releaseMemory() {
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LocalDeps.clear();
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NonLocalDeps.clear();
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NonLocalPointerDeps.clear();
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ReverseLocalDeps.clear();
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ReverseNonLocalDeps.clear();
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ReverseNonLocalPtrDeps.clear();
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PredCache->clear();
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}
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/// getAnalysisUsage - Does not modify anything. It uses Alias Analysis.
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///
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void MemoryDependenceAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesAll();
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AU.addRequiredTransitive<AliasAnalysis>();
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}
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bool MemoryDependenceAnalysis::runOnFunction(Function &) {
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AA = &getAnalysis<AliasAnalysis>();
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TD = getAnalysisIfAvailable<TargetData>();
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if (PredCache == 0)
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PredCache.reset(new PredIteratorCache());
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return false;
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}
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/// RemoveFromReverseMap - This is a helper function that removes Val from
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/// 'Inst's set in ReverseMap. If the set becomes empty, remove Inst's entry.
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template <typename KeyTy>
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static void RemoveFromReverseMap(DenseMap<Instruction*,
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SmallPtrSet<KeyTy, 4> > &ReverseMap,
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Instruction *Inst, KeyTy Val) {
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typename DenseMap<Instruction*, SmallPtrSet<KeyTy, 4> >::iterator
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InstIt = ReverseMap.find(Inst);
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assert(InstIt != ReverseMap.end() && "Reverse map out of sync?");
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bool Found = InstIt->second.erase(Val);
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assert(Found && "Invalid reverse map!"); (void)Found;
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if (InstIt->second.empty())
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ReverseMap.erase(InstIt);
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}
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/// GetLocation - If the given instruction references a specific memory
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/// location, fill in Loc with the details, otherwise set Loc.Ptr to null.
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/// Return a ModRefInfo value describing the general behavior of the
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/// instruction.
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static
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AliasAnalysis::ModRefResult GetLocation(const Instruction *Inst,
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AliasAnalysis::Location &Loc,
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AliasAnalysis *AA) {
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if (const LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
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if (LI->isUnordered()) {
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Loc = AA->getLocation(LI);
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return AliasAnalysis::Ref;
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} else if (LI->getOrdering() == Monotonic) {
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Loc = AA->getLocation(LI);
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return AliasAnalysis::ModRef;
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}
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Loc = AliasAnalysis::Location();
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return AliasAnalysis::ModRef;
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}
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if (const StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
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if (SI->isUnordered()) {
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Loc = AA->getLocation(SI);
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return AliasAnalysis::Mod;
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} else if (SI->getOrdering() == Monotonic) {
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Loc = AA->getLocation(SI);
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return AliasAnalysis::ModRef;
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}
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Loc = AliasAnalysis::Location();
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return AliasAnalysis::ModRef;
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}
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if (const VAArgInst *V = dyn_cast<VAArgInst>(Inst)) {
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Loc = AA->getLocation(V);
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return AliasAnalysis::ModRef;
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}
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if (const CallInst *CI = isFreeCall(Inst)) {
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// calls to free() deallocate the entire structure
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Loc = AliasAnalysis::Location(CI->getArgOperand(0));
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return AliasAnalysis::Mod;
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}
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if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst))
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switch (II->getIntrinsicID()) {
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case Intrinsic::lifetime_start:
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case Intrinsic::lifetime_end:
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case Intrinsic::invariant_start:
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Loc = AliasAnalysis::Location(II->getArgOperand(1),
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cast<ConstantInt>(II->getArgOperand(0))
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->getZExtValue(),
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II->getMetadata(LLVMContext::MD_tbaa));
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// These intrinsics don't really modify the memory, but returning Mod
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// will allow them to be handled conservatively.
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return AliasAnalysis::Mod;
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case Intrinsic::invariant_end:
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Loc = AliasAnalysis::Location(II->getArgOperand(2),
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cast<ConstantInt>(II->getArgOperand(1))
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->getZExtValue(),
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II->getMetadata(LLVMContext::MD_tbaa));
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// These intrinsics don't really modify the memory, but returning Mod
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// will allow them to be handled conservatively.
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return AliasAnalysis::Mod;
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default:
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break;
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}
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// Otherwise, just do the coarse-grained thing that always works.
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if (Inst->mayWriteToMemory())
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return AliasAnalysis::ModRef;
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if (Inst->mayReadFromMemory())
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return AliasAnalysis::Ref;
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return AliasAnalysis::NoModRef;
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}
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/// getCallSiteDependencyFrom - Private helper for finding the local
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/// dependencies of a call site.
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MemDepResult MemoryDependenceAnalysis::
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getCallSiteDependencyFrom(CallSite CS, bool isReadOnlyCall,
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BasicBlock::iterator ScanIt, BasicBlock *BB) {
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unsigned Limit = BlockScanLimit;
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// Walk backwards through the block, looking for dependencies
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while (ScanIt != BB->begin()) {
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// Limit the amount of scanning we do so we don't end up with quadratic
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// running time on extreme testcases.
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--Limit;
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if (!Limit)
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return MemDepResult::getUnknown();
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Instruction *Inst = --ScanIt;
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// If this inst is a memory op, get the pointer it accessed
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AliasAnalysis::Location Loc;
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AliasAnalysis::ModRefResult MR = GetLocation(Inst, Loc, AA);
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if (Loc.Ptr) {
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// A simple instruction.
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if (AA->getModRefInfo(CS, Loc) != AliasAnalysis::NoModRef)
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return MemDepResult::getClobber(Inst);
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continue;
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}
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if (CallSite InstCS = cast<Value>(Inst)) {
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// Debug intrinsics don't cause dependences.
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if (isa<DbgInfoIntrinsic>(Inst)) continue;
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// If these two calls do not interfere, look past it.
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switch (AA->getModRefInfo(CS, InstCS)) {
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case AliasAnalysis::NoModRef:
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// If the two calls are the same, return InstCS as a Def, so that
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// CS can be found redundant and eliminated.
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if (isReadOnlyCall && !(MR & AliasAnalysis::Mod) &&
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CS.getInstruction()->isIdenticalToWhenDefined(Inst))
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return MemDepResult::getDef(Inst);
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// Otherwise if the two calls don't interact (e.g. InstCS is readnone)
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// keep scanning.
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break;
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default:
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return MemDepResult::getClobber(Inst);
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}
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}
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}
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// No dependence found. If this is the entry block of the function, it is
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// unknown, otherwise it is non-local.
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if (BB != &BB->getParent()->getEntryBlock())
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return MemDepResult::getNonLocal();
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return MemDepResult::getUnknown();
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}
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/// isLoadLoadClobberIfExtendedToFullWidth - Return true if LI is a load that
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/// would fully overlap MemLoc if done as a wider legal integer load.
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///
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/// MemLocBase, MemLocOffset are lazily computed here the first time the
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/// base/offs of memloc is needed.
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static bool
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isLoadLoadClobberIfExtendedToFullWidth(const AliasAnalysis::Location &MemLoc,
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const Value *&MemLocBase,
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int64_t &MemLocOffs,
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const LoadInst *LI,
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const TargetData *TD) {
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// If we have no target data, we can't do this.
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if (TD == 0) return false;
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// If we haven't already computed the base/offset of MemLoc, do so now.
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if (MemLocBase == 0)
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MemLocBase = GetPointerBaseWithConstantOffset(MemLoc.Ptr, MemLocOffs, *TD);
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unsigned Size = MemoryDependenceAnalysis::
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getLoadLoadClobberFullWidthSize(MemLocBase, MemLocOffs, MemLoc.Size,
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LI, *TD);
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return Size != 0;
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}
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/// getLoadLoadClobberFullWidthSize - This is a little bit of analysis that
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/// looks at a memory location for a load (specified by MemLocBase, Offs,
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/// and Size) and compares it against a load. If the specified load could
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/// be safely widened to a larger integer load that is 1) still efficient,
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/// 2) safe for the target, and 3) would provide the specified memory
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/// location value, then this function returns the size in bytes of the
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/// load width to use. If not, this returns zero.
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unsigned MemoryDependenceAnalysis::
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getLoadLoadClobberFullWidthSize(const Value *MemLocBase, int64_t MemLocOffs,
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unsigned MemLocSize, const LoadInst *LI,
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const TargetData &TD) {
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// We can only extend simple integer loads.
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if (!isa<IntegerType>(LI->getType()) || !LI->isSimple()) return 0;
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// Get the base of this load.
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int64_t LIOffs = 0;
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const Value *LIBase =
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GetPointerBaseWithConstantOffset(LI->getPointerOperand(), LIOffs, TD);
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// If the two pointers are not based on the same pointer, we can't tell that
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// they are related.
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if (LIBase != MemLocBase) return 0;
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// Okay, the two values are based on the same pointer, but returned as
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// no-alias. This happens when we have things like two byte loads at "P+1"
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// and "P+3". Check to see if increasing the size of the "LI" load up to its
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// alignment (or the largest native integer type) will allow us to load all
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// the bits required by MemLoc.
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// If MemLoc is before LI, then no widening of LI will help us out.
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if (MemLocOffs < LIOffs) return 0;
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// Get the alignment of the load in bytes. We assume that it is safe to load
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// any legal integer up to this size without a problem. For example, if we're
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// looking at an i8 load on x86-32 that is known 1024 byte aligned, we can
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// widen it up to an i32 load. If it is known 2-byte aligned, we can widen it
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// to i16.
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unsigned LoadAlign = LI->getAlignment();
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int64_t MemLocEnd = MemLocOffs+MemLocSize;
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// If no amount of rounding up will let MemLoc fit into LI, then bail out.
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if (LIOffs+LoadAlign < MemLocEnd) return 0;
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// This is the size of the load to try. Start with the next larger power of
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// two.
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unsigned NewLoadByteSize = LI->getType()->getPrimitiveSizeInBits()/8U;
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NewLoadByteSize = NextPowerOf2(NewLoadByteSize);
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while (1) {
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// If this load size is bigger than our known alignment or would not fit
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// into a native integer register, then we fail.
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if (NewLoadByteSize > LoadAlign ||
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!TD.fitsInLegalInteger(NewLoadByteSize*8))
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return 0;
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// If a load of this width would include all of MemLoc, then we succeed.
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if (LIOffs+NewLoadByteSize >= MemLocEnd)
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return NewLoadByteSize;
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NewLoadByteSize <<= 1;
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}
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return 0;
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}
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/// getPointerDependencyFrom - Return the instruction on which a memory
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/// location depends. If isLoad is true, this routine ignores may-aliases with
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/// read-only operations. If isLoad is false, this routine ignores may-aliases
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/// with reads from read-only locations.
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MemDepResult MemoryDependenceAnalysis::
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getPointerDependencyFrom(const AliasAnalysis::Location &MemLoc, bool isLoad,
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BasicBlock::iterator ScanIt, BasicBlock *BB) {
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const Value *MemLocBase = 0;
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int64_t MemLocOffset = 0;
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unsigned Limit = BlockScanLimit;
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// Walk backwards through the basic block, looking for dependencies.
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while (ScanIt != BB->begin()) {
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// Limit the amount of scanning we do so we don't end up with quadratic
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// running time on extreme testcases.
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--Limit;
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if (!Limit)
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return MemDepResult::getUnknown();
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Instruction *Inst = --ScanIt;
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if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
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// Debug intrinsics don't (and can't) cause dependences.
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if (isa<DbgInfoIntrinsic>(II)) continue;
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// If we reach a lifetime begin or end marker, then the query ends here
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// because the value is undefined.
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if (II->getIntrinsicID() == Intrinsic::lifetime_start) {
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// FIXME: This only considers queries directly on the invariant-tagged
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// pointer, not on query pointers that are indexed off of them. It'd
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// be nice to handle that at some point (the right approach is to use
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// GetPointerBaseWithConstantOffset).
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if (AA->isMustAlias(AliasAnalysis::Location(II->getArgOperand(1)),
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MemLoc))
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return MemDepResult::getDef(II);
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continue;
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}
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}
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// Values depend on loads if the pointers are must aliased. This means that
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// a load depends on another must aliased load from the same value.
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if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
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// Atomic loads have complications involved.
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// FIXME: This is overly conservative.
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if (!LI->isUnordered())
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return MemDepResult::getClobber(LI);
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AliasAnalysis::Location LoadLoc = AA->getLocation(LI);
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// If we found a pointer, check if it could be the same as our pointer.
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AliasAnalysis::AliasResult R = AA->alias(LoadLoc, MemLoc);
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if (isLoad) {
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if (R == AliasAnalysis::NoAlias) {
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// If this is an over-aligned integer load (for example,
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// "load i8* %P, align 4") see if it would obviously overlap with the
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// queried location if widened to a larger load (e.g. if the queried
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// location is 1 byte at P+1). If so, return it as a load/load
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// clobber result, allowing the client to decide to widen the load if
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// it wants to.
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if (IntegerType *ITy = dyn_cast<IntegerType>(LI->getType()))
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if (LI->getAlignment()*8 > ITy->getPrimitiveSizeInBits() &&
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isLoadLoadClobberIfExtendedToFullWidth(MemLoc, MemLocBase,
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MemLocOffset, LI, TD))
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return MemDepResult::getClobber(Inst);
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continue;
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}
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// Must aliased loads are defs of each other.
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if (R == AliasAnalysis::MustAlias)
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return MemDepResult::getDef(Inst);
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#if 0 // FIXME: Temporarily disabled. GVN is cleverly rewriting loads
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// in terms of clobbering loads, but since it does this by looking
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// at the clobbering load directly, it doesn't know about any
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// phi translation that may have happened along the way.
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// If we have a partial alias, then return this as a clobber for the
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// client to handle.
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if (R == AliasAnalysis::PartialAlias)
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return MemDepResult::getClobber(Inst);
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#endif
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// Random may-alias loads don't depend on each other without a
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// dependence.
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continue;
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}
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// Stores don't depend on other no-aliased accesses.
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if (R == AliasAnalysis::NoAlias)
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continue;
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// Stores don't alias loads from read-only memory.
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if (AA->pointsToConstantMemory(LoadLoc))
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continue;
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// Stores depend on may/must aliased loads.
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return MemDepResult::getDef(Inst);
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}
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if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
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// Atomic stores have complications involved.
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// FIXME: This is overly conservative.
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if (!SI->isUnordered())
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return MemDepResult::getClobber(SI);
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// If alias analysis can tell that this store is guaranteed to not modify
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// the query pointer, ignore it. Use getModRefInfo to handle cases where
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// the query pointer points to constant memory etc.
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if (AA->getModRefInfo(SI, MemLoc) == AliasAnalysis::NoModRef)
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continue;
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// Ok, this store might clobber the query pointer. Check to see if it is
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// a must alias: in this case, we want to return this as a def.
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AliasAnalysis::Location StoreLoc = AA->getLocation(SI);
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// If we found a pointer, check if it could be the same as our pointer.
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AliasAnalysis::AliasResult R = AA->alias(StoreLoc, MemLoc);
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if (R == AliasAnalysis::NoAlias)
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continue;
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if (R == AliasAnalysis::MustAlias)
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return MemDepResult::getDef(Inst);
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return MemDepResult::getClobber(Inst);
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}
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// If this is an allocation, and if we know that the accessed pointer is to
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// the allocation, return Def. This means that there is no dependence and
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// the access can be optimized based on that. For example, a load could
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// turn into undef.
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// Note: Only determine this to be a malloc if Inst is the malloc call, not
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// a subsequent bitcast of the malloc call result. There can be stores to
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// the malloced memory between the malloc call and its bitcast uses, and we
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// need to continue scanning until the malloc call.
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if (isa<AllocaInst>(Inst) ||
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(isa<CallInst>(Inst) && extractMallocCall(Inst))) {
|
|
const Value *AccessPtr = GetUnderlyingObject(MemLoc.Ptr, TD);
|
|
|
|
if (AccessPtr == Inst || AA->isMustAlias(Inst, AccessPtr))
|
|
return MemDepResult::getDef(Inst);
|
|
continue;
|
|
}
|
|
|
|
// See if this instruction (e.g. a call or vaarg) mod/ref's the pointer.
|
|
switch (AA->getModRefInfo(Inst, MemLoc)) {
|
|
case AliasAnalysis::NoModRef:
|
|
// If the call has no effect on the queried pointer, just ignore it.
|
|
continue;
|
|
case AliasAnalysis::Mod:
|
|
return MemDepResult::getClobber(Inst);
|
|
case AliasAnalysis::Ref:
|
|
// If the call is known to never store to the pointer, and if this is a
|
|
// load query, we can safely ignore it (scan past it).
|
|
if (isLoad)
|
|
continue;
|
|
default:
|
|
// Otherwise, there is a potential dependence. Return a clobber.
|
|
return MemDepResult::getClobber(Inst);
|
|
}
|
|
}
|
|
|
|
// No dependence found. If this is the entry block of the function, it is
|
|
// unknown, otherwise it is non-local.
|
|
if (BB != &BB->getParent()->getEntryBlock())
|
|
return MemDepResult::getNonLocal();
|
|
return MemDepResult::getUnknown();
|
|
}
|
|
|
|
/// getDependency - Return the instruction on which a memory operation
|
|
/// depends.
|
|
MemDepResult MemoryDependenceAnalysis::getDependency(Instruction *QueryInst) {
|
|
Instruction *ScanPos = QueryInst;
|
|
|
|
// Check for a cached result
|
|
MemDepResult &LocalCache = LocalDeps[QueryInst];
|
|
|
|
// If the cached entry is non-dirty, just return it. Note that this depends
|
|
// on MemDepResult's default constructing to 'dirty'.
|
|
if (!LocalCache.isDirty())
|
|
return LocalCache;
|
|
|
|
// Otherwise, if we have a dirty entry, we know we can start the scan at that
|
|
// instruction, which may save us some work.
|
|
if (Instruction *Inst = LocalCache.getInst()) {
|
|
ScanPos = Inst;
|
|
|
|
RemoveFromReverseMap(ReverseLocalDeps, Inst, QueryInst);
|
|
}
|
|
|
|
BasicBlock *QueryParent = QueryInst->getParent();
|
|
|
|
// Do the scan.
|
|
if (BasicBlock::iterator(QueryInst) == QueryParent->begin()) {
|
|
// No dependence found. If this is the entry block of the function, it is
|
|
// unknown, otherwise it is non-local.
|
|
if (QueryParent != &QueryParent->getParent()->getEntryBlock())
|
|
LocalCache = MemDepResult::getNonLocal();
|
|
else
|
|
LocalCache = MemDepResult::getUnknown();
|
|
} else {
|
|
AliasAnalysis::Location MemLoc;
|
|
AliasAnalysis::ModRefResult MR = GetLocation(QueryInst, MemLoc, AA);
|
|
if (MemLoc.Ptr) {
|
|
// If we can do a pointer scan, make it happen.
|
|
bool isLoad = !(MR & AliasAnalysis::Mod);
|
|
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(QueryInst))
|
|
isLoad |= II->getIntrinsicID() == Intrinsic::lifetime_start;
|
|
|
|
LocalCache = getPointerDependencyFrom(MemLoc, isLoad, ScanPos,
|
|
QueryParent);
|
|
} else if (isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst)) {
|
|
CallSite QueryCS(QueryInst);
|
|
bool isReadOnly = AA->onlyReadsMemory(QueryCS);
|
|
LocalCache = getCallSiteDependencyFrom(QueryCS, isReadOnly, ScanPos,
|
|
QueryParent);
|
|
} else
|
|
// Non-memory instruction.
|
|
LocalCache = MemDepResult::getUnknown();
|
|
}
|
|
|
|
// Remember the result!
|
|
if (Instruction *I = LocalCache.getInst())
|
|
ReverseLocalDeps[I].insert(QueryInst);
|
|
|
|
return LocalCache;
|
|
}
|
|
|
|
#ifndef NDEBUG
|
|
/// AssertSorted - This method is used when -debug is specified to verify that
|
|
/// cache arrays are properly kept sorted.
|
|
static void AssertSorted(MemoryDependenceAnalysis::NonLocalDepInfo &Cache,
|
|
int Count = -1) {
|
|
if (Count == -1) Count = Cache.size();
|
|
if (Count == 0) return;
|
|
|
|
for (unsigned i = 1; i != unsigned(Count); ++i)
|
|
assert(!(Cache[i] < Cache[i-1]) && "Cache isn't sorted!");
|
|
}
|
|
#endif
|
|
|
|
/// getNonLocalCallDependency - Perform a full dependency query for the
|
|
/// specified call, returning the set of blocks that the value is
|
|
/// potentially live across. The returned set of results will include a
|
|
/// "NonLocal" result for all blocks where the value is live across.
|
|
///
|
|
/// This method assumes the instruction returns a "NonLocal" dependency
|
|
/// within its own block.
|
|
///
|
|
/// This returns a reference to an internal data structure that may be
|
|
/// invalidated on the next non-local query or when an instruction is
|
|
/// removed. Clients must copy this data if they want it around longer than
|
|
/// that.
|
|
const MemoryDependenceAnalysis::NonLocalDepInfo &
|
|
MemoryDependenceAnalysis::getNonLocalCallDependency(CallSite QueryCS) {
|
|
assert(getDependency(QueryCS.getInstruction()).isNonLocal() &&
|
|
"getNonLocalCallDependency should only be used on calls with non-local deps!");
|
|
PerInstNLInfo &CacheP = NonLocalDeps[QueryCS.getInstruction()];
|
|
NonLocalDepInfo &Cache = CacheP.first;
|
|
|
|
/// DirtyBlocks - This is the set of blocks that need to be recomputed. In
|
|
/// the cached case, this can happen due to instructions being deleted etc. In
|
|
/// the uncached case, this starts out as the set of predecessors we care
|
|
/// about.
|
|
SmallVector<BasicBlock*, 32> DirtyBlocks;
|
|
|
|
if (!Cache.empty()) {
|
|
// Okay, we have a cache entry. If we know it is not dirty, just return it
|
|
// with no computation.
|
|
if (!CacheP.second) {
|
|
++NumCacheNonLocal;
|
|
return Cache;
|
|
}
|
|
|
|
// If we already have a partially computed set of results, scan them to
|
|
// determine what is dirty, seeding our initial DirtyBlocks worklist.
|
|
for (NonLocalDepInfo::iterator I = Cache.begin(), E = Cache.end();
|
|
I != E; ++I)
|
|
if (I->getResult().isDirty())
|
|
DirtyBlocks.push_back(I->getBB());
|
|
|
|
// Sort the cache so that we can do fast binary search lookups below.
|
|
std::sort(Cache.begin(), Cache.end());
|
|
|
|
++NumCacheDirtyNonLocal;
|
|
//cerr << "CACHED CASE: " << DirtyBlocks.size() << " dirty: "
|
|
// << Cache.size() << " cached: " << *QueryInst;
|
|
} else {
|
|
// Seed DirtyBlocks with each of the preds of QueryInst's block.
|
|
BasicBlock *QueryBB = QueryCS.getInstruction()->getParent();
|
|
for (BasicBlock **PI = PredCache->GetPreds(QueryBB); *PI; ++PI)
|
|
DirtyBlocks.push_back(*PI);
|
|
++NumUncacheNonLocal;
|
|
}
|
|
|
|
// isReadonlyCall - If this is a read-only call, we can be more aggressive.
|
|
bool isReadonlyCall = AA->onlyReadsMemory(QueryCS);
|
|
|
|
SmallPtrSet<BasicBlock*, 64> Visited;
|
|
|
|
unsigned NumSortedEntries = Cache.size();
|
|
DEBUG(AssertSorted(Cache));
|
|
|
|
// Iterate while we still have blocks to update.
|
|
while (!DirtyBlocks.empty()) {
|
|
BasicBlock *DirtyBB = DirtyBlocks.back();
|
|
DirtyBlocks.pop_back();
|
|
|
|
// Already processed this block?
|
|
if (!Visited.insert(DirtyBB))
|
|
continue;
|
|
|
|
// Do a binary search to see if we already have an entry for this block in
|
|
// the cache set. If so, find it.
|
|
DEBUG(AssertSorted(Cache, NumSortedEntries));
|
|
NonLocalDepInfo::iterator Entry =
|
|
std::upper_bound(Cache.begin(), Cache.begin()+NumSortedEntries,
|
|
NonLocalDepEntry(DirtyBB));
|
|
if (Entry != Cache.begin() && prior(Entry)->getBB() == DirtyBB)
|
|
--Entry;
|
|
|
|
NonLocalDepEntry *ExistingResult = 0;
|
|
if (Entry != Cache.begin()+NumSortedEntries &&
|
|
Entry->getBB() == DirtyBB) {
|
|
// If we already have an entry, and if it isn't already dirty, the block
|
|
// is done.
|
|
if (!Entry->getResult().isDirty())
|
|
continue;
|
|
|
|
// Otherwise, remember this slot so we can update the value.
|
|
ExistingResult = &*Entry;
|
|
}
|
|
|
|
// If the dirty entry has a pointer, start scanning from it so we don't have
|
|
// to rescan the entire block.
|
|
BasicBlock::iterator ScanPos = DirtyBB->end();
|
|
if (ExistingResult) {
|
|
if (Instruction *Inst = ExistingResult->getResult().getInst()) {
|
|
ScanPos = Inst;
|
|
// We're removing QueryInst's use of Inst.
|
|
RemoveFromReverseMap(ReverseNonLocalDeps, Inst,
|
|
QueryCS.getInstruction());
|
|
}
|
|
}
|
|
|
|
// Find out if this block has a local dependency for QueryInst.
|
|
MemDepResult Dep;
|
|
|
|
if (ScanPos != DirtyBB->begin()) {
|
|
Dep = getCallSiteDependencyFrom(QueryCS, isReadonlyCall,ScanPos, DirtyBB);
|
|
} else if (DirtyBB != &DirtyBB->getParent()->getEntryBlock()) {
|
|
// No dependence found. If this is the entry block of the function, it is
|
|
// a clobber, otherwise it is unknown.
|
|
Dep = MemDepResult::getNonLocal();
|
|
} else {
|
|
Dep = MemDepResult::getUnknown();
|
|
}
|
|
|
|
// If we had a dirty entry for the block, update it. Otherwise, just add
|
|
// a new entry.
|
|
if (ExistingResult)
|
|
ExistingResult->setResult(Dep);
|
|
else
|
|
Cache.push_back(NonLocalDepEntry(DirtyBB, Dep));
|
|
|
|
// If the block has a dependency (i.e. it isn't completely transparent to
|
|
// the value), remember the association!
|
|
if (!Dep.isNonLocal()) {
|
|
// Keep the ReverseNonLocalDeps map up to date so we can efficiently
|
|
// update this when we remove instructions.
|
|
if (Instruction *Inst = Dep.getInst())
|
|
ReverseNonLocalDeps[Inst].insert(QueryCS.getInstruction());
|
|
} else {
|
|
|
|
// If the block *is* completely transparent to the load, we need to check
|
|
// the predecessors of this block. Add them to our worklist.
|
|
for (BasicBlock **PI = PredCache->GetPreds(DirtyBB); *PI; ++PI)
|
|
DirtyBlocks.push_back(*PI);
|
|
}
|
|
}
|
|
|
|
return Cache;
|
|
}
|
|
|
|
/// getNonLocalPointerDependency - Perform a full dependency query for an
|
|
/// access to the specified (non-volatile) memory location, returning the
|
|
/// set of instructions that either define or clobber the value.
|
|
///
|
|
/// This method assumes the pointer has a "NonLocal" dependency within its
|
|
/// own block.
|
|
///
|
|
void MemoryDependenceAnalysis::
|
|
getNonLocalPointerDependency(const AliasAnalysis::Location &Loc, bool isLoad,
|
|
BasicBlock *FromBB,
|
|
SmallVectorImpl<NonLocalDepResult> &Result) {
|
|
assert(Loc.Ptr->getType()->isPointerTy() &&
|
|
"Can't get pointer deps of a non-pointer!");
|
|
Result.clear();
|
|
|
|
PHITransAddr Address(const_cast<Value *>(Loc.Ptr), TD);
|
|
|
|
// This is the set of blocks we've inspected, and the pointer we consider in
|
|
// each block. Because of critical edges, we currently bail out if querying
|
|
// a block with multiple different pointers. This can happen during PHI
|
|
// translation.
|
|
DenseMap<BasicBlock*, Value*> Visited;
|
|
if (!getNonLocalPointerDepFromBB(Address, Loc, isLoad, FromBB,
|
|
Result, Visited, true))
|
|
return;
|
|
Result.clear();
|
|
Result.push_back(NonLocalDepResult(FromBB,
|
|
MemDepResult::getUnknown(),
|
|
const_cast<Value *>(Loc.Ptr)));
|
|
}
|
|
|
|
/// GetNonLocalInfoForBlock - Compute the memdep value for BB with
|
|
/// Pointer/PointeeSize using either cached information in Cache or by doing a
|
|
/// lookup (which may use dirty cache info if available). If we do a lookup,
|
|
/// add the result to the cache.
|
|
MemDepResult MemoryDependenceAnalysis::
|
|
GetNonLocalInfoForBlock(const AliasAnalysis::Location &Loc,
|
|
bool isLoad, BasicBlock *BB,
|
|
NonLocalDepInfo *Cache, unsigned NumSortedEntries) {
|
|
|
|
// Do a binary search to see if we already have an entry for this block in
|
|
// the cache set. If so, find it.
|
|
NonLocalDepInfo::iterator Entry =
|
|
std::upper_bound(Cache->begin(), Cache->begin()+NumSortedEntries,
|
|
NonLocalDepEntry(BB));
|
|
if (Entry != Cache->begin() && (Entry-1)->getBB() == BB)
|
|
--Entry;
|
|
|
|
NonLocalDepEntry *ExistingResult = 0;
|
|
if (Entry != Cache->begin()+NumSortedEntries && Entry->getBB() == BB)
|
|
ExistingResult = &*Entry;
|
|
|
|
// If we have a cached entry, and it is non-dirty, use it as the value for
|
|
// this dependency.
|
|
if (ExistingResult && !ExistingResult->getResult().isDirty()) {
|
|
++NumCacheNonLocalPtr;
|
|
return ExistingResult->getResult();
|
|
}
|
|
|
|
// Otherwise, we have to scan for the value. If we have a dirty cache
|
|
// entry, start scanning from its position, otherwise we scan from the end
|
|
// of the block.
|
|
BasicBlock::iterator ScanPos = BB->end();
|
|
if (ExistingResult && ExistingResult->getResult().getInst()) {
|
|
assert(ExistingResult->getResult().getInst()->getParent() == BB &&
|
|
"Instruction invalidated?");
|
|
++NumCacheDirtyNonLocalPtr;
|
|
ScanPos = ExistingResult->getResult().getInst();
|
|
|
|
// Eliminating the dirty entry from 'Cache', so update the reverse info.
|
|
ValueIsLoadPair CacheKey(Loc.Ptr, isLoad);
|
|
RemoveFromReverseMap(ReverseNonLocalPtrDeps, ScanPos, CacheKey);
|
|
} else {
|
|
++NumUncacheNonLocalPtr;
|
|
}
|
|
|
|
// Scan the block for the dependency.
|
|
MemDepResult Dep = getPointerDependencyFrom(Loc, isLoad, ScanPos, BB);
|
|
|
|
// If we had a dirty entry for the block, update it. Otherwise, just add
|
|
// a new entry.
|
|
if (ExistingResult)
|
|
ExistingResult->setResult(Dep);
|
|
else
|
|
Cache->push_back(NonLocalDepEntry(BB, Dep));
|
|
|
|
// If the block has a dependency (i.e. it isn't completely transparent to
|
|
// the value), remember the reverse association because we just added it
|
|
// to Cache!
|
|
if (Dep.isNonLocal() || Dep.isUnknown())
|
|
return Dep;
|
|
|
|
// Keep the ReverseNonLocalPtrDeps map up to date so we can efficiently
|
|
// update MemDep when we remove instructions.
|
|
Instruction *Inst = Dep.getInst();
|
|
assert(Inst && "Didn't depend on anything?");
|
|
ValueIsLoadPair CacheKey(Loc.Ptr, isLoad);
|
|
ReverseNonLocalPtrDeps[Inst].insert(CacheKey);
|
|
return Dep;
|
|
}
|
|
|
|
/// SortNonLocalDepInfoCache - Sort the a NonLocalDepInfo cache, given a certain
|
|
/// number of elements in the array that are already properly ordered. This is
|
|
/// optimized for the case when only a few entries are added.
|
|
static void
|
|
SortNonLocalDepInfoCache(MemoryDependenceAnalysis::NonLocalDepInfo &Cache,
|
|
unsigned NumSortedEntries) {
|
|
switch (Cache.size() - NumSortedEntries) {
|
|
case 0:
|
|
// done, no new entries.
|
|
break;
|
|
case 2: {
|
|
// Two new entries, insert the last one into place.
|
|
NonLocalDepEntry Val = Cache.back();
|
|
Cache.pop_back();
|
|
MemoryDependenceAnalysis::NonLocalDepInfo::iterator Entry =
|
|
std::upper_bound(Cache.begin(), Cache.end()-1, Val);
|
|
Cache.insert(Entry, Val);
|
|
// FALL THROUGH.
|
|
}
|
|
case 1:
|
|
// One new entry, Just insert the new value at the appropriate position.
|
|
if (Cache.size() != 1) {
|
|
NonLocalDepEntry Val = Cache.back();
|
|
Cache.pop_back();
|
|
MemoryDependenceAnalysis::NonLocalDepInfo::iterator Entry =
|
|
std::upper_bound(Cache.begin(), Cache.end(), Val);
|
|
Cache.insert(Entry, Val);
|
|
}
|
|
break;
|
|
default:
|
|
// Added many values, do a full scale sort.
|
|
std::sort(Cache.begin(), Cache.end());
|
|
break;
|
|
}
|
|
}
|
|
|
|
/// getNonLocalPointerDepFromBB - Perform a dependency query based on
|
|
/// pointer/pointeesize starting at the end of StartBB. Add any clobber/def
|
|
/// results to the results vector and keep track of which blocks are visited in
|
|
/// 'Visited'.
|
|
///
|
|
/// This has special behavior for the first block queries (when SkipFirstBlock
|
|
/// is true). In this special case, it ignores the contents of the specified
|
|
/// block and starts returning dependence info for its predecessors.
|
|
///
|
|
/// This function returns false on success, or true to indicate that it could
|
|
/// not compute dependence information for some reason. This should be treated
|
|
/// as a clobber dependence on the first instruction in the predecessor block.
|
|
bool MemoryDependenceAnalysis::
|
|
getNonLocalPointerDepFromBB(const PHITransAddr &Pointer,
|
|
const AliasAnalysis::Location &Loc,
|
|
bool isLoad, BasicBlock *StartBB,
|
|
SmallVectorImpl<NonLocalDepResult> &Result,
|
|
DenseMap<BasicBlock*, Value*> &Visited,
|
|
bool SkipFirstBlock) {
|
|
|
|
// Look up the cached info for Pointer.
|
|
ValueIsLoadPair CacheKey(Pointer.getAddr(), isLoad);
|
|
|
|
// Set up a temporary NLPI value. If the map doesn't yet have an entry for
|
|
// CacheKey, this value will be inserted as the associated value. Otherwise,
|
|
// it'll be ignored, and we'll have to check to see if the cached size and
|
|
// tbaa tag are consistent with the current query.
|
|
NonLocalPointerInfo InitialNLPI;
|
|
InitialNLPI.Size = Loc.Size;
|
|
InitialNLPI.TBAATag = Loc.TBAATag;
|
|
|
|
// Get the NLPI for CacheKey, inserting one into the map if it doesn't
|
|
// already have one.
|
|
std::pair<CachedNonLocalPointerInfo::iterator, bool> Pair =
|
|
NonLocalPointerDeps.insert(std::make_pair(CacheKey, InitialNLPI));
|
|
NonLocalPointerInfo *CacheInfo = &Pair.first->second;
|
|
|
|
// If we already have a cache entry for this CacheKey, we may need to do some
|
|
// work to reconcile the cache entry and the current query.
|
|
if (!Pair.second) {
|
|
if (CacheInfo->Size < Loc.Size) {
|
|
// The query's Size is greater than the cached one. Throw out the
|
|
// cached data and procede with the query at the greater size.
|
|
CacheInfo->Pair = BBSkipFirstBlockPair();
|
|
CacheInfo->Size = Loc.Size;
|
|
for (NonLocalDepInfo::iterator DI = CacheInfo->NonLocalDeps.begin(),
|
|
DE = CacheInfo->NonLocalDeps.end(); DI != DE; ++DI)
|
|
if (Instruction *Inst = DI->getResult().getInst())
|
|
RemoveFromReverseMap(ReverseNonLocalPtrDeps, Inst, CacheKey);
|
|
CacheInfo->NonLocalDeps.clear();
|
|
} else if (CacheInfo->Size > Loc.Size) {
|
|
// This query's Size is less than the cached one. Conservatively restart
|
|
// the query using the greater size.
|
|
return getNonLocalPointerDepFromBB(Pointer,
|
|
Loc.getWithNewSize(CacheInfo->Size),
|
|
isLoad, StartBB, Result, Visited,
|
|
SkipFirstBlock);
|
|
}
|
|
|
|
// If the query's TBAATag is inconsistent with the cached one,
|
|
// conservatively throw out the cached data and restart the query with
|
|
// no tag if needed.
|
|
if (CacheInfo->TBAATag != Loc.TBAATag) {
|
|
if (CacheInfo->TBAATag) {
|
|
CacheInfo->Pair = BBSkipFirstBlockPair();
|
|
CacheInfo->TBAATag = 0;
|
|
for (NonLocalDepInfo::iterator DI = CacheInfo->NonLocalDeps.begin(),
|
|
DE = CacheInfo->NonLocalDeps.end(); DI != DE; ++DI)
|
|
if (Instruction *Inst = DI->getResult().getInst())
|
|
RemoveFromReverseMap(ReverseNonLocalPtrDeps, Inst, CacheKey);
|
|
CacheInfo->NonLocalDeps.clear();
|
|
}
|
|
if (Loc.TBAATag)
|
|
return getNonLocalPointerDepFromBB(Pointer, Loc.getWithoutTBAATag(),
|
|
isLoad, StartBB, Result, Visited,
|
|
SkipFirstBlock);
|
|
}
|
|
}
|
|
|
|
NonLocalDepInfo *Cache = &CacheInfo->NonLocalDeps;
|
|
|
|
// If we have valid cached information for exactly the block we are
|
|
// investigating, just return it with no recomputation.
|
|
if (CacheInfo->Pair == BBSkipFirstBlockPair(StartBB, SkipFirstBlock)) {
|
|
// We have a fully cached result for this query then we can just return the
|
|
// cached results and populate the visited set. However, we have to verify
|
|
// that we don't already have conflicting results for these blocks. Check
|
|
// to ensure that if a block in the results set is in the visited set that
|
|
// it was for the same pointer query.
|
|
if (!Visited.empty()) {
|
|
for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end();
|
|
I != E; ++I) {
|
|
DenseMap<BasicBlock*, Value*>::iterator VI = Visited.find(I->getBB());
|
|
if (VI == Visited.end() || VI->second == Pointer.getAddr())
|
|
continue;
|
|
|
|
// We have a pointer mismatch in a block. Just return clobber, saying
|
|
// that something was clobbered in this result. We could also do a
|
|
// non-fully cached query, but there is little point in doing this.
|
|
return true;
|
|
}
|
|
}
|
|
|
|
Value *Addr = Pointer.getAddr();
|
|
for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end();
|
|
I != E; ++I) {
|
|
Visited.insert(std::make_pair(I->getBB(), Addr));
|
|
if (!I->getResult().isNonLocal())
|
|
Result.push_back(NonLocalDepResult(I->getBB(), I->getResult(), Addr));
|
|
}
|
|
++NumCacheCompleteNonLocalPtr;
|
|
return false;
|
|
}
|
|
|
|
// Otherwise, either this is a new block, a block with an invalid cache
|
|
// pointer or one that we're about to invalidate by putting more info into it
|
|
// than its valid cache info. If empty, the result will be valid cache info,
|
|
// otherwise it isn't.
|
|
if (Cache->empty())
|
|
CacheInfo->Pair = BBSkipFirstBlockPair(StartBB, SkipFirstBlock);
|
|
else
|
|
CacheInfo->Pair = BBSkipFirstBlockPair();
|
|
|
|
SmallVector<BasicBlock*, 32> Worklist;
|
|
Worklist.push_back(StartBB);
|
|
|
|
// PredList used inside loop.
|
|
SmallVector<std::pair<BasicBlock*, PHITransAddr>, 16> PredList;
|
|
|
|
// Keep track of the entries that we know are sorted. Previously cached
|
|
// entries will all be sorted. The entries we add we only sort on demand (we
|
|
// don't insert every element into its sorted position). We know that we
|
|
// won't get any reuse from currently inserted values, because we don't
|
|
// revisit blocks after we insert info for them.
|
|
unsigned NumSortedEntries = Cache->size();
|
|
DEBUG(AssertSorted(*Cache));
|
|
|
|
while (!Worklist.empty()) {
|
|
BasicBlock *BB = Worklist.pop_back_val();
|
|
|
|
// Skip the first block if we have it.
|
|
if (!SkipFirstBlock) {
|
|
// Analyze the dependency of *Pointer in FromBB. See if we already have
|
|
// been here.
|
|
assert(Visited.count(BB) && "Should check 'visited' before adding to WL");
|
|
|
|
// Get the dependency info for Pointer in BB. If we have cached
|
|
// information, we will use it, otherwise we compute it.
|
|
DEBUG(AssertSorted(*Cache, NumSortedEntries));
|
|
MemDepResult Dep = GetNonLocalInfoForBlock(Loc, isLoad, BB, Cache,
|
|
NumSortedEntries);
|
|
|
|
// If we got a Def or Clobber, add this to the list of results.
|
|
if (!Dep.isNonLocal()) {
|
|
Result.push_back(NonLocalDepResult(BB, Dep, Pointer.getAddr()));
|
|
continue;
|
|
}
|
|
}
|
|
|
|
// If 'Pointer' is an instruction defined in this block, then we need to do
|
|
// phi translation to change it into a value live in the predecessor block.
|
|
// If not, we just add the predecessors to the worklist and scan them with
|
|
// the same Pointer.
|
|
if (!Pointer.NeedsPHITranslationFromBlock(BB)) {
|
|
SkipFirstBlock = false;
|
|
SmallVector<BasicBlock*, 16> NewBlocks;
|
|
for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
|
|
// Verify that we haven't looked at this block yet.
|
|
std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool>
|
|
InsertRes = Visited.insert(std::make_pair(*PI, Pointer.getAddr()));
|
|
if (InsertRes.second) {
|
|
// First time we've looked at *PI.
|
|
NewBlocks.push_back(*PI);
|
|
continue;
|
|
}
|
|
|
|
// If we have seen this block before, but it was with a different
|
|
// pointer then we have a phi translation failure and we have to treat
|
|
// this as a clobber.
|
|
if (InsertRes.first->second != Pointer.getAddr()) {
|
|
// Make sure to clean up the Visited map before continuing on to
|
|
// PredTranslationFailure.
|
|
for (unsigned i = 0; i < NewBlocks.size(); i++)
|
|
Visited.erase(NewBlocks[i]);
|
|
goto PredTranslationFailure;
|
|
}
|
|
}
|
|
Worklist.append(NewBlocks.begin(), NewBlocks.end());
|
|
continue;
|
|
}
|
|
|
|
// We do need to do phi translation, if we know ahead of time we can't phi
|
|
// translate this value, don't even try.
|
|
if (!Pointer.IsPotentiallyPHITranslatable())
|
|
goto PredTranslationFailure;
|
|
|
|
// We may have added values to the cache list before this PHI translation.
|
|
// If so, we haven't done anything to ensure that the cache remains sorted.
|
|
// Sort it now (if needed) so that recursive invocations of
|
|
// getNonLocalPointerDepFromBB and other routines that could reuse the cache
|
|
// value will only see properly sorted cache arrays.
|
|
if (Cache && NumSortedEntries != Cache->size()) {
|
|
SortNonLocalDepInfoCache(*Cache, NumSortedEntries);
|
|
NumSortedEntries = Cache->size();
|
|
}
|
|
Cache = 0;
|
|
|
|
PredList.clear();
|
|
for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
|
|
BasicBlock *Pred = *PI;
|
|
PredList.push_back(std::make_pair(Pred, Pointer));
|
|
|
|
// Get the PHI translated pointer in this predecessor. This can fail if
|
|
// not translatable, in which case the getAddr() returns null.
|
|
PHITransAddr &PredPointer = PredList.back().second;
|
|
PredPointer.PHITranslateValue(BB, Pred, 0);
|
|
|
|
Value *PredPtrVal = PredPointer.getAddr();
|
|
|
|
// Check to see if we have already visited this pred block with another
|
|
// pointer. If so, we can't do this lookup. This failure can occur
|
|
// with PHI translation when a critical edge exists and the PHI node in
|
|
// the successor translates to a pointer value different than the
|
|
// pointer the block was first analyzed with.
|
|
std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool>
|
|
InsertRes = Visited.insert(std::make_pair(Pred, PredPtrVal));
|
|
|
|
if (!InsertRes.second) {
|
|
// We found the pred; take it off the list of preds to visit.
|
|
PredList.pop_back();
|
|
|
|
// If the predecessor was visited with PredPtr, then we already did
|
|
// the analysis and can ignore it.
|
|
if (InsertRes.first->second == PredPtrVal)
|
|
continue;
|
|
|
|
// Otherwise, the block was previously analyzed with a different
|
|
// pointer. We can't represent the result of this case, so we just
|
|
// treat this as a phi translation failure.
|
|
|
|
// Make sure to clean up the Visited map before continuing on to
|
|
// PredTranslationFailure.
|
|
for (unsigned i = 0; i < PredList.size(); i++)
|
|
Visited.erase(PredList[i].first);
|
|
|
|
goto PredTranslationFailure;
|
|
}
|
|
}
|
|
|
|
// Actually process results here; this need to be a separate loop to avoid
|
|
// calling getNonLocalPointerDepFromBB for blocks we don't want to return
|
|
// any results for. (getNonLocalPointerDepFromBB will modify our
|
|
// datastructures in ways the code after the PredTranslationFailure label
|
|
// doesn't expect.)
|
|
for (unsigned i = 0; i < PredList.size(); i++) {
|
|
BasicBlock *Pred = PredList[i].first;
|
|
PHITransAddr &PredPointer = PredList[i].second;
|
|
Value *PredPtrVal = PredPointer.getAddr();
|
|
|
|
bool CanTranslate = true;
|
|
// If PHI translation was unable to find an available pointer in this
|
|
// predecessor, then we have to assume that the pointer is clobbered in
|
|
// that predecessor. We can still do PRE of the load, which would insert
|
|
// a computation of the pointer in this predecessor.
|
|
if (PredPtrVal == 0)
|
|
CanTranslate = false;
|
|
|
|
// FIXME: it is entirely possible that PHI translating will end up with
|
|
// the same value. Consider PHI translating something like:
|
|
// X = phi [x, bb1], [y, bb2]. PHI translating for bb1 doesn't *need*
|
|
// to recurse here, pedantically speaking.
|
|
|
|
// If getNonLocalPointerDepFromBB fails here, that means the cached
|
|
// result conflicted with the Visited list; we have to conservatively
|
|
// assume it is unknown, but this also does not block PRE of the load.
|
|
if (!CanTranslate ||
|
|
getNonLocalPointerDepFromBB(PredPointer,
|
|
Loc.getWithNewPtr(PredPtrVal),
|
|
isLoad, Pred,
|
|
Result, Visited)) {
|
|
// Add the entry to the Result list.
|
|
NonLocalDepResult Entry(Pred, MemDepResult::getUnknown(), PredPtrVal);
|
|
Result.push_back(Entry);
|
|
|
|
// Since we had a phi translation failure, the cache for CacheKey won't
|
|
// include all of the entries that we need to immediately satisfy future
|
|
// queries. Mark this in NonLocalPointerDeps by setting the
|
|
// BBSkipFirstBlockPair pointer to null. This requires reuse of the
|
|
// cached value to do more work but not miss the phi trans failure.
|
|
NonLocalPointerInfo &NLPI = NonLocalPointerDeps[CacheKey];
|
|
NLPI.Pair = BBSkipFirstBlockPair();
|
|
continue;
|
|
}
|
|
}
|
|
|
|
// Refresh the CacheInfo/Cache pointer so that it isn't invalidated.
|
|
CacheInfo = &NonLocalPointerDeps[CacheKey];
|
|
Cache = &CacheInfo->NonLocalDeps;
|
|
NumSortedEntries = Cache->size();
|
|
|
|
// Since we did phi translation, the "Cache" set won't contain all of the
|
|
// results for the query. This is ok (we can still use it to accelerate
|
|
// specific block queries) but we can't do the fastpath "return all
|
|
// results from the set" Clear out the indicator for this.
|
|
CacheInfo->Pair = BBSkipFirstBlockPair();
|
|
SkipFirstBlock = false;
|
|
continue;
|
|
|
|
PredTranslationFailure:
|
|
// The following code is "failure"; we can't produce a sane translation
|
|
// for the given block. It assumes that we haven't modified any of
|
|
// our datastructures while processing the current block.
|
|
|
|
if (Cache == 0) {
|
|
// Refresh the CacheInfo/Cache pointer if it got invalidated.
|
|
CacheInfo = &NonLocalPointerDeps[CacheKey];
|
|
Cache = &CacheInfo->NonLocalDeps;
|
|
NumSortedEntries = Cache->size();
|
|
}
|
|
|
|
// Since we failed phi translation, the "Cache" set won't contain all of the
|
|
// results for the query. This is ok (we can still use it to accelerate
|
|
// specific block queries) but we can't do the fastpath "return all
|
|
// results from the set". Clear out the indicator for this.
|
|
CacheInfo->Pair = BBSkipFirstBlockPair();
|
|
|
|
// If *nothing* works, mark the pointer as unknown.
|
|
//
|
|
// If this is the magic first block, return this as a clobber of the whole
|
|
// incoming value. Since we can't phi translate to one of the predecessors,
|
|
// we have to bail out.
|
|
if (SkipFirstBlock)
|
|
return true;
|
|
|
|
for (NonLocalDepInfo::reverse_iterator I = Cache->rbegin(); ; ++I) {
|
|
assert(I != Cache->rend() && "Didn't find current block??");
|
|
if (I->getBB() != BB)
|
|
continue;
|
|
|
|
assert(I->getResult().isNonLocal() &&
|
|
"Should only be here with transparent block");
|
|
I->setResult(MemDepResult::getUnknown());
|
|
Result.push_back(NonLocalDepResult(I->getBB(), I->getResult(),
|
|
Pointer.getAddr()));
|
|
break;
|
|
}
|
|
}
|
|
|
|
// Okay, we're done now. If we added new values to the cache, re-sort it.
|
|
SortNonLocalDepInfoCache(*Cache, NumSortedEntries);
|
|
DEBUG(AssertSorted(*Cache));
|
|
return false;
|
|
}
|
|
|
|
/// RemoveCachedNonLocalPointerDependencies - If P exists in
|
|
/// CachedNonLocalPointerInfo, remove it.
|
|
void MemoryDependenceAnalysis::
|
|
RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair P) {
|
|
CachedNonLocalPointerInfo::iterator It =
|
|
NonLocalPointerDeps.find(P);
|
|
if (It == NonLocalPointerDeps.end()) return;
|
|
|
|
// Remove all of the entries in the BB->val map. This involves removing
|
|
// instructions from the reverse map.
|
|
NonLocalDepInfo &PInfo = It->second.NonLocalDeps;
|
|
|
|
for (unsigned i = 0, e = PInfo.size(); i != e; ++i) {
|
|
Instruction *Target = PInfo[i].getResult().getInst();
|
|
if (Target == 0) continue; // Ignore non-local dep results.
|
|
assert(Target->getParent() == PInfo[i].getBB());
|
|
|
|
// Eliminating the dirty entry from 'Cache', so update the reverse info.
|
|
RemoveFromReverseMap(ReverseNonLocalPtrDeps, Target, P);
|
|
}
|
|
|
|
// Remove P from NonLocalPointerDeps (which deletes NonLocalDepInfo).
|
|
NonLocalPointerDeps.erase(It);
|
|
}
|
|
|
|
|
|
/// invalidateCachedPointerInfo - This method is used to invalidate cached
|
|
/// information about the specified pointer, because it may be too
|
|
/// conservative in memdep. This is an optional call that can be used when
|
|
/// the client detects an equivalence between the pointer and some other
|
|
/// value and replaces the other value with ptr. This can make Ptr available
|
|
/// in more places that cached info does not necessarily keep.
|
|
void MemoryDependenceAnalysis::invalidateCachedPointerInfo(Value *Ptr) {
|
|
// If Ptr isn't really a pointer, just ignore it.
|
|
if (!Ptr->getType()->isPointerTy()) return;
|
|
// Flush store info for the pointer.
|
|
RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, false));
|
|
// Flush load info for the pointer.
|
|
RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, true));
|
|
}
|
|
|
|
/// invalidateCachedPredecessors - Clear the PredIteratorCache info.
|
|
/// This needs to be done when the CFG changes, e.g., due to splitting
|
|
/// critical edges.
|
|
void MemoryDependenceAnalysis::invalidateCachedPredecessors() {
|
|
PredCache->clear();
|
|
}
|
|
|
|
/// removeInstruction - Remove an instruction from the dependence analysis,
|
|
/// updating the dependence of instructions that previously depended on it.
|
|
/// This method attempts to keep the cache coherent using the reverse map.
|
|
void MemoryDependenceAnalysis::removeInstruction(Instruction *RemInst) {
|
|
// Walk through the Non-local dependencies, removing this one as the value
|
|
// for any cached queries.
|
|
NonLocalDepMapType::iterator NLDI = NonLocalDeps.find(RemInst);
|
|
if (NLDI != NonLocalDeps.end()) {
|
|
NonLocalDepInfo &BlockMap = NLDI->second.first;
|
|
for (NonLocalDepInfo::iterator DI = BlockMap.begin(), DE = BlockMap.end();
|
|
DI != DE; ++DI)
|
|
if (Instruction *Inst = DI->getResult().getInst())
|
|
RemoveFromReverseMap(ReverseNonLocalDeps, Inst, RemInst);
|
|
NonLocalDeps.erase(NLDI);
|
|
}
|
|
|
|
// If we have a cached local dependence query for this instruction, remove it.
|
|
//
|
|
LocalDepMapType::iterator LocalDepEntry = LocalDeps.find(RemInst);
|
|
if (LocalDepEntry != LocalDeps.end()) {
|
|
// Remove us from DepInst's reverse set now that the local dep info is gone.
|
|
if (Instruction *Inst = LocalDepEntry->second.getInst())
|
|
RemoveFromReverseMap(ReverseLocalDeps, Inst, RemInst);
|
|
|
|
// Remove this local dependency info.
|
|
LocalDeps.erase(LocalDepEntry);
|
|
}
|
|
|
|
// If we have any cached pointer dependencies on this instruction, remove
|
|
// them. If the instruction has non-pointer type, then it can't be a pointer
|
|
// base.
|
|
|
|
// Remove it from both the load info and the store info. The instruction
|
|
// can't be in either of these maps if it is non-pointer.
|
|
if (RemInst->getType()->isPointerTy()) {
|
|
RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, false));
|
|
RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, true));
|
|
}
|
|
|
|
// Loop over all of the things that depend on the instruction we're removing.
|
|
//
|
|
SmallVector<std::pair<Instruction*, Instruction*>, 8> ReverseDepsToAdd;
|
|
|
|
// If we find RemInst as a clobber or Def in any of the maps for other values,
|
|
// we need to replace its entry with a dirty version of the instruction after
|
|
// it. If RemInst is a terminator, we use a null dirty value.
|
|
//
|
|
// Using a dirty version of the instruction after RemInst saves having to scan
|
|
// the entire block to get to this point.
|
|
MemDepResult NewDirtyVal;
|
|
if (!RemInst->isTerminator())
|
|
NewDirtyVal = MemDepResult::getDirty(++BasicBlock::iterator(RemInst));
|
|
|
|
ReverseDepMapType::iterator ReverseDepIt = ReverseLocalDeps.find(RemInst);
|
|
if (ReverseDepIt != ReverseLocalDeps.end()) {
|
|
SmallPtrSet<Instruction*, 4> &ReverseDeps = ReverseDepIt->second;
|
|
// RemInst can't be the terminator if it has local stuff depending on it.
|
|
assert(!ReverseDeps.empty() && !isa<TerminatorInst>(RemInst) &&
|
|
"Nothing can locally depend on a terminator");
|
|
|
|
for (SmallPtrSet<Instruction*, 4>::iterator I = ReverseDeps.begin(),
|
|
E = ReverseDeps.end(); I != E; ++I) {
|
|
Instruction *InstDependingOnRemInst = *I;
|
|
assert(InstDependingOnRemInst != RemInst &&
|
|
"Already removed our local dep info");
|
|
|
|
LocalDeps[InstDependingOnRemInst] = NewDirtyVal;
|
|
|
|
// Make sure to remember that new things depend on NewDepInst.
|
|
assert(NewDirtyVal.getInst() && "There is no way something else can have "
|
|
"a local dep on this if it is a terminator!");
|
|
ReverseDepsToAdd.push_back(std::make_pair(NewDirtyVal.getInst(),
|
|
InstDependingOnRemInst));
|
|
}
|
|
|
|
ReverseLocalDeps.erase(ReverseDepIt);
|
|
|
|
// Add new reverse deps after scanning the set, to avoid invalidating the
|
|
// 'ReverseDeps' reference.
|
|
while (!ReverseDepsToAdd.empty()) {
|
|
ReverseLocalDeps[ReverseDepsToAdd.back().first]
|
|
.insert(ReverseDepsToAdd.back().second);
|
|
ReverseDepsToAdd.pop_back();
|
|
}
|
|
}
|
|
|
|
ReverseDepIt = ReverseNonLocalDeps.find(RemInst);
|
|
if (ReverseDepIt != ReverseNonLocalDeps.end()) {
|
|
SmallPtrSet<Instruction*, 4> &Set = ReverseDepIt->second;
|
|
for (SmallPtrSet<Instruction*, 4>::iterator I = Set.begin(), E = Set.end();
|
|
I != E; ++I) {
|
|
assert(*I != RemInst && "Already removed NonLocalDep info for RemInst");
|
|
|
|
PerInstNLInfo &INLD = NonLocalDeps[*I];
|
|
// The information is now dirty!
|
|
INLD.second = true;
|
|
|
|
for (NonLocalDepInfo::iterator DI = INLD.first.begin(),
|
|
DE = INLD.first.end(); DI != DE; ++DI) {
|
|
if (DI->getResult().getInst() != RemInst) continue;
|
|
|
|
// Convert to a dirty entry for the subsequent instruction.
|
|
DI->setResult(NewDirtyVal);
|
|
|
|
if (Instruction *NextI = NewDirtyVal.getInst())
|
|
ReverseDepsToAdd.push_back(std::make_pair(NextI, *I));
|
|
}
|
|
}
|
|
|
|
ReverseNonLocalDeps.erase(ReverseDepIt);
|
|
|
|
// Add new reverse deps after scanning the set, to avoid invalidating 'Set'
|
|
while (!ReverseDepsToAdd.empty()) {
|
|
ReverseNonLocalDeps[ReverseDepsToAdd.back().first]
|
|
.insert(ReverseDepsToAdd.back().second);
|
|
ReverseDepsToAdd.pop_back();
|
|
}
|
|
}
|
|
|
|
// If the instruction is in ReverseNonLocalPtrDeps then it appears as a
|
|
// value in the NonLocalPointerDeps info.
|
|
ReverseNonLocalPtrDepTy::iterator ReversePtrDepIt =
|
|
ReverseNonLocalPtrDeps.find(RemInst);
|
|
if (ReversePtrDepIt != ReverseNonLocalPtrDeps.end()) {
|
|
SmallPtrSet<ValueIsLoadPair, 4> &Set = ReversePtrDepIt->second;
|
|
SmallVector<std::pair<Instruction*, ValueIsLoadPair>,8> ReversePtrDepsToAdd;
|
|
|
|
for (SmallPtrSet<ValueIsLoadPair, 4>::iterator I = Set.begin(),
|
|
E = Set.end(); I != E; ++I) {
|
|
ValueIsLoadPair P = *I;
|
|
assert(P.getPointer() != RemInst &&
|
|
"Already removed NonLocalPointerDeps info for RemInst");
|
|
|
|
NonLocalDepInfo &NLPDI = NonLocalPointerDeps[P].NonLocalDeps;
|
|
|
|
// The cache is not valid for any specific block anymore.
|
|
NonLocalPointerDeps[P].Pair = BBSkipFirstBlockPair();
|
|
|
|
// Update any entries for RemInst to use the instruction after it.
|
|
for (NonLocalDepInfo::iterator DI = NLPDI.begin(), DE = NLPDI.end();
|
|
DI != DE; ++DI) {
|
|
if (DI->getResult().getInst() != RemInst) continue;
|
|
|
|
// Convert to a dirty entry for the subsequent instruction.
|
|
DI->setResult(NewDirtyVal);
|
|
|
|
if (Instruction *NewDirtyInst = NewDirtyVal.getInst())
|
|
ReversePtrDepsToAdd.push_back(std::make_pair(NewDirtyInst, P));
|
|
}
|
|
|
|
// Re-sort the NonLocalDepInfo. Changing the dirty entry to its
|
|
// subsequent value may invalidate the sortedness.
|
|
std::sort(NLPDI.begin(), NLPDI.end());
|
|
}
|
|
|
|
ReverseNonLocalPtrDeps.erase(ReversePtrDepIt);
|
|
|
|
while (!ReversePtrDepsToAdd.empty()) {
|
|
ReverseNonLocalPtrDeps[ReversePtrDepsToAdd.back().first]
|
|
.insert(ReversePtrDepsToAdd.back().second);
|
|
ReversePtrDepsToAdd.pop_back();
|
|
}
|
|
}
|
|
|
|
|
|
assert(!NonLocalDeps.count(RemInst) && "RemInst got reinserted?");
|
|
AA->deleteValue(RemInst);
|
|
DEBUG(verifyRemoved(RemInst));
|
|
}
|
|
/// verifyRemoved - Verify that the specified instruction does not occur
|
|
/// in our internal data structures.
|
|
void MemoryDependenceAnalysis::verifyRemoved(Instruction *D) const {
|
|
for (LocalDepMapType::const_iterator I = LocalDeps.begin(),
|
|
E = LocalDeps.end(); I != E; ++I) {
|
|
assert(I->first != D && "Inst occurs in data structures");
|
|
assert(I->second.getInst() != D &&
|
|
"Inst occurs in data structures");
|
|
}
|
|
|
|
for (CachedNonLocalPointerInfo::const_iterator I =NonLocalPointerDeps.begin(),
|
|
E = NonLocalPointerDeps.end(); I != E; ++I) {
|
|
assert(I->first.getPointer() != D && "Inst occurs in NLPD map key");
|
|
const NonLocalDepInfo &Val = I->second.NonLocalDeps;
|
|
for (NonLocalDepInfo::const_iterator II = Val.begin(), E = Val.end();
|
|
II != E; ++II)
|
|
assert(II->getResult().getInst() != D && "Inst occurs as NLPD value");
|
|
}
|
|
|
|
for (NonLocalDepMapType::const_iterator I = NonLocalDeps.begin(),
|
|
E = NonLocalDeps.end(); I != E; ++I) {
|
|
assert(I->first != D && "Inst occurs in data structures");
|
|
const PerInstNLInfo &INLD = I->second;
|
|
for (NonLocalDepInfo::const_iterator II = INLD.first.begin(),
|
|
EE = INLD.first.end(); II != EE; ++II)
|
|
assert(II->getResult().getInst() != D && "Inst occurs in data structures");
|
|
}
|
|
|
|
for (ReverseDepMapType::const_iterator I = ReverseLocalDeps.begin(),
|
|
E = ReverseLocalDeps.end(); I != E; ++I) {
|
|
assert(I->first != D && "Inst occurs in data structures");
|
|
for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
|
|
EE = I->second.end(); II != EE; ++II)
|
|
assert(*II != D && "Inst occurs in data structures");
|
|
}
|
|
|
|
for (ReverseDepMapType::const_iterator I = ReverseNonLocalDeps.begin(),
|
|
E = ReverseNonLocalDeps.end();
|
|
I != E; ++I) {
|
|
assert(I->first != D && "Inst occurs in data structures");
|
|
for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
|
|
EE = I->second.end(); II != EE; ++II)
|
|
assert(*II != D && "Inst occurs in data structures");
|
|
}
|
|
|
|
for (ReverseNonLocalPtrDepTy::const_iterator
|
|
I = ReverseNonLocalPtrDeps.begin(),
|
|
E = ReverseNonLocalPtrDeps.end(); I != E; ++I) {
|
|
assert(I->first != D && "Inst occurs in rev NLPD map");
|
|
|
|
for (SmallPtrSet<ValueIsLoadPair, 4>::const_iterator II = I->second.begin(),
|
|
E = I->second.end(); II != E; ++II)
|
|
assert(*II != ValueIsLoadPair(D, false) &&
|
|
*II != ValueIsLoadPair(D, true) &&
|
|
"Inst occurs in ReverseNonLocalPtrDeps map");
|
|
}
|
|
|
|
}
|