-//===- MemoryDependenceAnalysis.cpp - Mem Deps Implementation --*- C++ -*-===//
+//===- MemoryDependenceAnalysis.cpp - Mem Deps Implementation -------------===//
//
// The LLVM Compiler Infrastructure
//
//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "memdep"
#include "llvm/Analysis/MemoryDependenceAnalysis.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
-#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/PHITransAddr.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/PredIteratorCache.h"
#include "llvm/Support/Debug.h"
-#include "llvm/Support/PredIteratorCache.h"
using namespace llvm;
+#define DEBUG_TYPE "memdep"
+
STATISTIC(NumCacheNonLocal, "Number of fully cached non-local responses");
STATISTIC(NumCacheDirtyNonLocal, "Number of dirty cached non-local responses");
STATISTIC(NumUncacheNonLocal, "Number of uncached non-local responses");
"Memory Dependence Analysis", false, true)
MemoryDependenceAnalysis::MemoryDependenceAnalysis()
-: FunctionPass(ID), PredCache(0) {
+ : FunctionPass(ID), PredCache() {
initializeMemoryDependenceAnalysisPass(*PassRegistry::getPassRegistry());
}
MemoryDependenceAnalysis::~MemoryDependenceAnalysis() {
bool MemoryDependenceAnalysis::runOnFunction(Function &) {
AA = &getAnalysis<AliasAnalysis>();
- TD = getAnalysisIfAvailable<DataLayout>();
- DT = getAnalysisIfAvailable<DominatorTree>();
- if (PredCache == 0)
+ DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
+ DL = DLP ? &DLP->getDataLayout() : nullptr;
+ DominatorTreeWrapperPass *DTWP =
+ getAnalysisIfAvailable<DominatorTreeWrapperPass>();
+ DT = DTWP ? &DTWP->getDomTree() : nullptr;
+ if (!PredCache)
PredCache.reset(new PredIteratorCache());
return false;
}
return AliasAnalysis::Mod;
}
- if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst))
+ if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
+ AAMDNodes AAInfo;
+
switch (II->getIntrinsicID()) {
case Intrinsic::lifetime_start:
case Intrinsic::lifetime_end:
case Intrinsic::invariant_start:
+ II->getAAMetadata(AAInfo);
Loc = AliasAnalysis::Location(II->getArgOperand(1),
cast<ConstantInt>(II->getArgOperand(0))
- ->getZExtValue(),
- II->getMetadata(LLVMContext::MD_tbaa));
+ ->getZExtValue(), AAInfo);
// These intrinsics don't really modify the memory, but returning Mod
// will allow them to be handled conservatively.
return AliasAnalysis::Mod;
case Intrinsic::invariant_end:
+ II->getAAMetadata(AAInfo);
Loc = AliasAnalysis::Location(II->getArgOperand(2),
cast<ConstantInt>(II->getArgOperand(1))
- ->getZExtValue(),
- II->getMetadata(LLVMContext::MD_tbaa));
+ ->getZExtValue(), AAInfo);
// These intrinsics don't really modify the memory, but returning Mod
// will allow them to be handled conservatively.
return AliasAnalysis::Mod;
default:
break;
}
+ }
// Otherwise, just do the coarse-grained thing that always works.
if (Inst->mayWriteToMemory())
const Value *&MemLocBase,
int64_t &MemLocOffs,
const LoadInst *LI,
- const DataLayout *TD) {
+ const DataLayout *DL) {
// If we have no target data, we can't do this.
- if (TD == 0) return false;
+ if (!DL) return false;
// If we haven't already computed the base/offset of MemLoc, do so now.
- if (MemLocBase == 0)
- MemLocBase = GetPointerBaseWithConstantOffset(MemLoc.Ptr, MemLocOffs, TD);
+ if (!MemLocBase)
+ MemLocBase = GetPointerBaseWithConstantOffset(MemLoc.Ptr, MemLocOffs, DL);
unsigned Size = MemoryDependenceAnalysis::
getLoadLoadClobberFullWidthSize(MemLocBase, MemLocOffs, MemLoc.Size,
- LI, *TD);
+ LI, *DL);
return Size != 0;
}
unsigned MemoryDependenceAnalysis::
getLoadLoadClobberFullWidthSize(const Value *MemLocBase, int64_t MemLocOffs,
unsigned MemLocSize, const LoadInst *LI,
- const DataLayout &TD) {
+ const DataLayout &DL) {
// We can only extend simple integer loads.
if (!isa<IntegerType>(LI->getType()) || !LI->isSimple()) return 0;
// Get the base of this load.
int64_t LIOffs = 0;
const Value *LIBase =
- GetPointerBaseWithConstantOffset(LI->getPointerOperand(), LIOffs, &TD);
+ GetPointerBaseWithConstantOffset(LI->getPointerOperand(), LIOffs, &DL);
// If the two pointers are not based on the same pointer, we can't tell that
// they are related.
// If this load size is bigger than our known alignment or would not fit
// into a native integer register, then we fail.
if (NewLoadByteSize > LoadAlign ||
- !TD.fitsInLegalInteger(NewLoadByteSize*8))
+ !DL.fitsInLegalInteger(NewLoadByteSize*8))
return 0;
if (LIOffs+NewLoadByteSize > MemLocEnd &&
BasicBlock::iterator ScanIt, BasicBlock *BB,
Instruction *QueryInst) {
- const Value *MemLocBase = 0;
+ const Value *MemLocBase = nullptr;
int64_t MemLocOffset = 0;
unsigned Limit = BlockScanLimit;
bool isInvariantLoad = false;
if (isLoad && QueryInst) {
LoadInst *LI = dyn_cast<LoadInst>(QueryInst);
- if (LI && LI->getMetadata(LLVMContext::MD_invariant_load) != 0)
+ if (LI && LI->getMetadata(LLVMContext::MD_invariant_load) != nullptr)
isInvariantLoad = true;
}
// Walk backwards through the basic block, looking for dependencies.
while (ScanIt != BB->begin()) {
+ Instruction *Inst = --ScanIt;
+
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst))
+ // Debug intrinsics don't (and can't) cause dependencies.
+ if (isa<DbgInfoIntrinsic>(II)) continue;
+
// Limit the amount of scanning we do so we don't end up with quadratic
// running time on extreme testcases.
--Limit;
if (!Limit)
return MemDepResult::getUnknown();
- Instruction *Inst = --ScanIt;
-
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
- // Debug intrinsics don't (and can't) cause dependences.
- if (isa<DbgInfoIntrinsic>(II)) continue;
-
// If we reach a lifetime begin or end marker, then the query ends here
// because the value is undefined.
if (II->getIntrinsicID() == Intrinsic::lifetime_start) {
// Values depend on loads if the pointers are must aliased. This means that
// a load depends on another must aliased load from the same value.
+ // One exception is atomic loads: a value can depend on an atomic load that it
+ // does not alias with when this atomic load indicates that another thread may
+ // be accessing the location.
if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
// Atomic loads have complications involved.
+ // A monotonic load is OK if the query inst is itself not atomic.
// FIXME: This is overly conservative.
- if (!LI->isUnordered())
+ if (!LI->isUnordered()) {
+ if (!QueryInst)
+ return MemDepResult::getClobber(LI);
+ if (LI->getOrdering() != Monotonic)
+ return MemDepResult::getClobber(LI);
+ if (auto *QueryLI = dyn_cast<LoadInst>(QueryInst))
+ if (!QueryLI->isSimple())
+ return MemDepResult::getClobber(LI);
+ if (auto *QuerySI = dyn_cast<StoreInst>(QueryInst))
+ if (!QuerySI->isSimple())
+ return MemDepResult::getClobber(LI);
+ }
+
+ // FIXME: this is overly conservative.
+ // While volatile access cannot be eliminated, they do not have to clobber
+ // non-aliasing locations, as normal accesses can for example be reordered
+ // with volatile accesses.
+ if (LI->isVolatile())
return MemDepResult::getClobber(LI);
AliasAnalysis::Location LoadLoc = AA->getLocation(LI);
if (IntegerType *ITy = dyn_cast<IntegerType>(LI->getType()))
if (LI->getAlignment()*8 > ITy->getPrimitiveSizeInBits() &&
isLoadLoadClobberIfExtendedToFullWidth(MemLoc, MemLocBase,
- MemLocOffset, LI, TD))
+ MemLocOffset, LI, DL))
return MemDepResult::getClobber(Inst);
continue;
if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
// Atomic stores have complications involved.
+ // A monotonic store is OK if the query inst is itself not atomic.
// FIXME: This is overly conservative.
- if (!SI->isUnordered())
+ if (!SI->isUnordered()) {
+ if (!QueryInst)
+ return MemDepResult::getClobber(SI);
+ if (SI->getOrdering() != Monotonic)
+ return MemDepResult::getClobber(SI);
+ if (auto *QueryLI = dyn_cast<LoadInst>(QueryInst))
+ if (!QueryLI->isSimple())
+ return MemDepResult::getClobber(SI);
+ if (auto *QuerySI = dyn_cast<StoreInst>(QueryInst))
+ if (!QuerySI->isSimple())
+ return MemDepResult::getClobber(SI);
+ }
+
+ // FIXME: this is overly conservative.
+ // While volatile access cannot be eliminated, they do not have to clobber
+ // non-aliasing locations, as normal accesses can for example be reordered
+ // with volatile accesses.
+ if (SI->isVolatile())
return MemDepResult::getClobber(SI);
// If alias analysis can tell that this store is guaranteed to not modify
// need to continue scanning until the malloc call.
const TargetLibraryInfo *TLI = AA->getTargetLibraryInfo();
if (isa<AllocaInst>(Inst) || isNoAliasFn(Inst, TLI)) {
- const Value *AccessPtr = GetUnderlyingObject(MemLoc.Ptr, TD);
+ const Value *AccessPtr = GetUnderlyingObject(MemLoc.Ptr, DL);
if (AccessPtr == Inst || AA->isMustAlias(Inst, AccessPtr))
return MemDepResult::getDef(Inst);
NonLocalDepInfo::iterator Entry =
std::upper_bound(Cache.begin(), Cache.begin()+NumSortedEntries,
NonLocalDepEntry(DirtyBB));
- if (Entry != Cache.begin() && prior(Entry)->getBB() == DirtyBB)
+ if (Entry != Cache.begin() && std::prev(Entry)->getBB() == DirtyBB)
--Entry;
- NonLocalDepEntry *ExistingResult = 0;
+ NonLocalDepEntry *ExistingResult = nullptr;
if (Entry != Cache.begin()+NumSortedEntries &&
Entry->getBB() == DirtyBB) {
// If we already have an entry, and if it isn't already dirty, the block
"Can't get pointer deps of a non-pointer!");
Result.clear();
- PHITransAddr Address(const_cast<Value *>(Loc.Ptr), TD);
+ PHITransAddr Address(const_cast<Value *>(Loc.Ptr), DL);
// 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
if (Entry != Cache->begin() && (Entry-1)->getBB() == BB)
--Entry;
- NonLocalDepEntry *ExistingResult = 0;
+ NonLocalDepEntry *ExistingResult = nullptr;
if (Entry != Cache->begin()+NumSortedEntries && Entry->getBB() == BB)
ExistingResult = &*Entry;
// 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.
+ // aa tags are consistent with the current query.
NonLocalPointerInfo InitialNLPI;
InitialNLPI.Size = Loc.Size;
- InitialNLPI.TBAATag = Loc.TBAATag;
+ InitialNLPI.AATags = Loc.AATags;
// Get the NLPI for CacheKey, inserting one into the map if it doesn't
// already have one.
SkipFirstBlock);
}
- // If the query's TBAATag is inconsistent with the cached one,
+ // If the query's AATags are 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) {
+ if (CacheInfo->AATags != Loc.AATags) {
+ if (CacheInfo->AATags) {
CacheInfo->Pair = BBSkipFirstBlockPair();
- CacheInfo->TBAATag = 0;
+ CacheInfo->AATags = AAMDNodes();
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(),
+ if (Loc.AATags)
+ return getNonLocalPointerDepFromBB(Pointer, Loc.getWithoutAATags(),
isLoad, StartBB, Result, Visited,
SkipFirstBlock);
}
SortNonLocalDepInfoCache(*Cache, NumSortedEntries);
NumSortedEntries = Cache->size();
}
- Cache = 0;
+ Cache = nullptr;
PredList.clear();
for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
// 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);
+ PredPointer.PHITranslateValue(BB, Pred, nullptr);
Value *PredPtrVal = PredPointer.getAddr();
// 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)
+ if (!PredPtrVal)
CanTranslate = false;
// FIXME: it is entirely possible that PHI translating will end up with
// for the given block. It assumes that we haven't modified any of
// our datastructures while processing the current block.
- if (Cache == 0) {
+ if (!Cache) {
// Refresh the CacheInfo/Cache pointer if it got invalidated.
CacheInfo = &NonLocalPointerDeps[CacheKey];
Cache = &CacheInfo->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.
+ if (!Target) continue; // Ignore non-local dep results.
assert(Target->getParent() == PInfo[i].getBB());
// Eliminating the dirty entry from 'Cache', so update the reverse info.
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) &&
+ assert(!ReverseDepIt->second.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;
+ for (Instruction *InstDependingOnRemInst : ReverseDepIt->second) {
assert(InstDependingOnRemInst != RemInst &&
"Already removed our local dep info");
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");
+ for (Instruction *I : ReverseDepIt->second) {
+ assert(I != RemInst && "Already removed NonLocalDep info for RemInst");
- PerInstNLInfo &INLD = NonLocalDeps[*I];
+ PerInstNLInfo &INLD = NonLocalDeps[I];
// The information is now dirty!
INLD.second = true;
DI->setResult(NewDirtyVal);
if (Instruction *NextI = NewDirtyVal.getInst())
- ReverseDepsToAdd.push_back(std::make_pair(NextI, *I));
+ ReverseDepsToAdd.push_back(std::make_pair(NextI, I));
}
}
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;
+ for (ValueIsLoadPair P : ReversePtrDepIt->second) {
assert(P.getPointer() != RemInst &&
"Already removed NonLocalPointerDeps info for RemInst");
DEBUG(verifyRemoved(RemInst));
}
/// verifyRemoved - Verify that the specified instruction does not occur
-/// in our internal data structures.
+/// in our internal data structures. This function verifies by asserting in
+/// debug builds.
void MemoryDependenceAnalysis::verifyRemoved(Instruction *D) const {
+#ifndef NDEBUG
for (LocalDepMapType::const_iterator I = LocalDeps.begin(),
E = LocalDeps.end(); I != E; ++I) {
assert(I->first != 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 (Instruction *Inst : I->second)
+ assert(Inst != 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 (Instruction *Inst : I->second)
+ assert(Inst != D && "Inst occurs in data structures");
}
for (ReverseNonLocalPtrDepTy::const_iterator
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) &&
+ for (ValueIsLoadPair P : I->second)
+ assert(P != ValueIsLoadPair(D, false) &&
+ P != ValueIsLoadPair(D, true) &&
"Inst occurs in ReverseNonLocalPtrDeps map");
}
-
+#endif
}
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