//===----------------------------------------------------------------------===//
#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/CFG.h"
#include "llvm/Analysis/CaptureTracking.h"
-#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/BasicBlock.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"
return AA->pointsToConstantMemory(Loc, OrLocal);
}
+AliasAnalysis::Location
+AliasAnalysis::getArgLocation(ImmutableCallSite CS, unsigned ArgIdx,
+ AliasAnalysis::ModRefResult &Mask) {
+ assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
+ return AA->getArgLocation(CS, ArgIdx, Mask);
+}
+
void AliasAnalysis::deleteValue(Value *V) {
assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
AA->deleteValue(V);
if (onlyAccessesArgPointees(MRB)) {
bool doesAlias = false;
+ ModRefResult AllArgsMask = NoModRef;
if (doesAccessArgPointees(MRB)) {
- MDNode *CSTag = CS.getInstruction()->getMetadata(LLVMContext::MD_tbaa);
for (ImmutableCallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end();
AI != AE; ++AI) {
const Value *Arg = *AI;
if (!Arg->getType()->isPointerTy())
continue;
- Location CSLoc(Arg, UnknownSize, CSTag);
+ ModRefResult ArgMask;
+ Location CSLoc =
+ getArgLocation(CS, (unsigned) std::distance(CS.arg_begin(), AI),
+ ArgMask);
if (!isNoAlias(CSLoc, Loc)) {
doesAlias = true;
- break;
+ AllArgsMask = ModRefResult(AllArgsMask | ArgMask);
}
}
}
if (!doesAlias)
return NoModRef;
+ Mask = ModRefResult(Mask & AllArgsMask);
}
// If Loc is a constant memory location, the call definitely could not
if (onlyAccessesArgPointees(CS2B)) {
AliasAnalysis::ModRefResult R = NoModRef;
if (doesAccessArgPointees(CS2B)) {
- MDNode *CS2Tag = CS2.getInstruction()->getMetadata(LLVMContext::MD_tbaa);
for (ImmutableCallSite::arg_iterator
I = CS2.arg_begin(), E = CS2.arg_end(); I != E; ++I) {
const Value *Arg = *I;
if (!Arg->getType()->isPointerTy())
continue;
- Location CS2Loc(Arg, UnknownSize, CS2Tag);
- R = ModRefResult((R | getModRefInfo(CS1, CS2Loc)) & Mask);
+ ModRefResult ArgMask;
+ Location CS2Loc =
+ getArgLocation(CS2, (unsigned) std::distance(CS2.arg_begin(), I),
+ ArgMask);
+ // ArgMask indicates what CS2 might do to CS2Loc, and the dependence of
+ // CS1 on that location is the inverse.
+ if (ArgMask == Mod)
+ ArgMask = ModRef;
+ else if (ArgMask == Ref)
+ ArgMask = Mod;
+
+ R = ModRefResult((R | (getModRefInfo(CS1, CS2Loc) & ArgMask)) & Mask);
if (R == Mask)
break;
}
if (onlyAccessesArgPointees(CS1B)) {
AliasAnalysis::ModRefResult R = NoModRef;
if (doesAccessArgPointees(CS1B)) {
- MDNode *CS1Tag = CS1.getInstruction()->getMetadata(LLVMContext::MD_tbaa);
for (ImmutableCallSite::arg_iterator
I = CS1.arg_begin(), E = CS1.arg_end(); I != E; ++I) {
const Value *Arg = *I;
if (!Arg->getType()->isPointerTy())
continue;
- Location CS1Loc(Arg, UnknownSize, CS1Tag);
- if (getModRefInfo(CS2, CS1Loc) != NoModRef) {
- R = Mask;
+ ModRefResult ArgMask;
+ Location CS1Loc = getArgLocation(
+ CS1, (unsigned)std::distance(CS1.arg_begin(), I), ArgMask);
+ // ArgMask indicates what CS1 might do to CS1Loc; if CS1 might Mod
+ // CS1Loc, then we care about either a Mod or a Ref by CS2. If CS1
+ // might Ref, then we care only about a Mod by CS2.
+ ModRefResult ArgR = getModRefInfo(CS2, CS1Loc);
+ if (((ArgMask & Mod) != NoModRef && (ArgR & ModRef) != NoModRef) ||
+ ((ArgMask & Ref) != NoModRef && (ArgR & Mod) != NoModRef))
+ R = ModRefResult((R | ArgMask) & Mask);
+
+ if (R == Mask)
break;
- }
}
}
- if (R == NoModRef)
- return R;
+ return R;
}
// If this is the end of the chain, don't forward.
//===----------------------------------------------------------------------===//
AliasAnalysis::Location AliasAnalysis::getLocation(const LoadInst *LI) {
+ AAMDNodes AATags;
+ LI->getAAMetadata(AATags);
+
return Location(LI->getPointerOperand(),
- getTypeStoreSize(LI->getType()),
- LI->getMetadata(LLVMContext::MD_tbaa));
+ getTypeStoreSize(LI->getType()), AATags);
}
AliasAnalysis::Location AliasAnalysis::getLocation(const StoreInst *SI) {
+ AAMDNodes AATags;
+ SI->getAAMetadata(AATags);
+
return Location(SI->getPointerOperand(),
- getTypeStoreSize(SI->getValueOperand()->getType()),
- SI->getMetadata(LLVMContext::MD_tbaa));
+ getTypeStoreSize(SI->getValueOperand()->getType()), AATags);
}
AliasAnalysis::Location AliasAnalysis::getLocation(const VAArgInst *VI) {
- return Location(VI->getPointerOperand(),
- UnknownSize,
- VI->getMetadata(LLVMContext::MD_tbaa));
+ AAMDNodes AATags;
+ VI->getAAMetadata(AATags);
+
+ return Location(VI->getPointerOperand(), UnknownSize, AATags);
}
AliasAnalysis::Location
AliasAnalysis::getLocation(const AtomicCmpXchgInst *CXI) {
+ AAMDNodes AATags;
+ CXI->getAAMetadata(AATags);
+
return Location(CXI->getPointerOperand(),
getTypeStoreSize(CXI->getCompareOperand()->getType()),
- CXI->getMetadata(LLVMContext::MD_tbaa));
+ AATags);
}
AliasAnalysis::Location
AliasAnalysis::getLocation(const AtomicRMWInst *RMWI) {
+ AAMDNodes AATags;
+ RMWI->getAAMetadata(AATags);
+
return Location(RMWI->getPointerOperand(),
- getTypeStoreSize(RMWI->getValOperand()->getType()),
- RMWI->getMetadata(LLVMContext::MD_tbaa));
+ getTypeStoreSize(RMWI->getValOperand()->getType()), AATags);
}
-AliasAnalysis::Location
+AliasAnalysis::Location
AliasAnalysis::getLocationForSource(const MemTransferInst *MTI) {
uint64_t Size = UnknownSize;
if (ConstantInt *C = dyn_cast<ConstantInt>(MTI->getLength()))
Size = C->getValue().getZExtValue();
- // memcpy/memmove can have TBAA tags. For memcpy, they apply
+ // memcpy/memmove can have AA tags. For memcpy, they apply
// to both the source and the destination.
- MDNode *TBAATag = MTI->getMetadata(LLVMContext::MD_tbaa);
+ AAMDNodes AATags;
+ MTI->getAAMetadata(AATags);
- return Location(MTI->getRawSource(), Size, TBAATag);
+ return Location(MTI->getRawSource(), Size, AATags);
}
-AliasAnalysis::Location
+AliasAnalysis::Location
AliasAnalysis::getLocationForDest(const MemIntrinsic *MTI) {
uint64_t Size = UnknownSize;
if (ConstantInt *C = dyn_cast<ConstantInt>(MTI->getLength()))
Size = C->getValue().getZExtValue();
- // memcpy/memmove can have TBAA tags. For memcpy, they apply
+ // memcpy/memmove can have AA tags. For memcpy, they apply
// to both the source and the destination.
- MDNode *TBAATag = MTI->getMetadata(LLVMContext::MD_tbaa);
-
- return Location(MTI->getRawDest(), Size, TBAATag);
+ AAMDNodes AATags;
+ MTI->getAAMetadata(AATags);
+
+ return Location(MTI->getRawDest(), Size, AATags);
}
AliasAnalysis::ModRefResult
AliasAnalysis::getModRefInfo(const AtomicCmpXchgInst *CX, const Location &Loc) {
// Acquire/Release cmpxchg has properties that matter for arbitrary addresses.
- if (CX->getOrdering() > Monotonic)
+ if (CX->getSuccessOrdering() > Monotonic)
return ModRef;
// If the cmpxchg address does not alias the location, it does not access it.
return ModRef;
}
-namespace {
- // Conservatively return true. Return false, if there is a single path
- // starting from "From" and the path does not reach "To".
- static bool hasPath(const BasicBlock *From, const BasicBlock *To) {
- const unsigned MaxCheck = 5;
- const BasicBlock *Current = From;
- for (unsigned I = 0; I < MaxCheck; I++) {
- unsigned NumSuccs = Current->getTerminator()->getNumSuccessors();
- if (NumSuccs > 1)
- return true;
- if (NumSuccs == 0)
- return false;
- Current = Current->getTerminator()->getSuccessor(0);
- if (Current == To)
- return true;
- }
- return true;
- }
-
- /// Only find pointer captures which happen before the given instruction. Uses
- /// the dominator tree to determine whether one instruction is before another.
- /// Only support the case where the Value is defined in the same basic block
- /// as the given instruction and the use.
- struct CapturesBefore : public CaptureTracker {
- CapturesBefore(const Instruction *I, DominatorTree *DT)
- : BeforeHere(I), DT(DT), Captured(false) {}
-
- void tooManyUses() { Captured = true; }
-
- bool shouldExplore(Use *U) {
- Instruction *I = cast<Instruction>(U->getUser());
- BasicBlock *BB = I->getParent();
- // We explore this usage only if the usage can reach "BeforeHere".
- // If use is not reachable from entry, there is no need to explore.
- if (BeforeHere != I && !DT->isReachableFromEntry(BB))
- return false;
- // If the value is defined in the same basic block as use and BeforeHere,
- // there is no need to explore the use if BeforeHere dominates use.
- // Check whether there is a path from I to BeforeHere.
- if (BeforeHere != I && DT->dominates(BeforeHere, I) &&
- !hasPath(BB, BeforeHere->getParent()))
- return false;
- return true;
- }
-
- bool captured(Use *U) {
- Instruction *I = cast<Instruction>(U->getUser());
- BasicBlock *BB = I->getParent();
- // Same logic as in shouldExplore.
- if (BeforeHere != I && !DT->isReachableFromEntry(BB))
- return false;
- if (BeforeHere != I && DT->dominates(BeforeHere, I) &&
- !hasPath(BB, BeforeHere->getParent()))
- return false;
- Captured = true;
- return true;
- }
-
- const Instruction *BeforeHere;
- DominatorTree *DT;
-
- bool Captured;
- };
-}
-
// FIXME: this is really just shoring-up a deficiency in alias analysis.
// BasicAA isn't willing to spend linear time determining whether an alloca
// was captured before or after this particular call, while we are. However,
AliasAnalysis::callCapturesBefore(const Instruction *I,
const AliasAnalysis::Location &MemLoc,
DominatorTree *DT) {
- if (!DT || !TD) return AliasAnalysis::ModRef;
+ if (!DT || !DL) return AliasAnalysis::ModRef;
- const Value *Object = GetUnderlyingObject(MemLoc.Ptr, TD);
+ const Value *Object = GetUnderlyingObject(MemLoc.Ptr, DL);
if (!isIdentifiedObject(Object) || isa<GlobalValue>(Object) ||
isa<Constant>(Object))
return AliasAnalysis::ModRef;
if (!CS.getInstruction() || CS.getInstruction() == Object)
return AliasAnalysis::ModRef;
- CapturesBefore CB(I, DT);
- llvm::PointerMayBeCaptured(Object, &CB);
- if (CB.Captured)
+ if (llvm::PointerMayBeCapturedBefore(Object, /* ReturnCaptures */ true,
+ /* StoreCaptures */ true, I, DT,
+ /* include Object */ true))
return AliasAnalysis::ModRef;
unsigned ArgNo = 0;
+ AliasAnalysis::ModRefResult R = AliasAnalysis::NoModRef;
for (ImmutableCallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
CI != CE; ++CI, ++ArgNo) {
// Only look at the no-capture or byval pointer arguments. If this
// is impossible to alias the pointer we're checking. If not, we have to
// assume that the call could touch the pointer, even though it doesn't
// escape.
- if (!isNoAlias(AliasAnalysis::Location(*CI),
- AliasAnalysis::Location(Object))) {
- return AliasAnalysis::ModRef;
+ if (isNoAlias(AliasAnalysis::Location(*CI),
+ AliasAnalysis::Location(Object)))
+ continue;
+ if (CS.doesNotAccessMemory(ArgNo))
+ continue;
+ if (CS.onlyReadsMemory(ArgNo)) {
+ R = AliasAnalysis::Ref;
+ continue;
}
+ return AliasAnalysis::ModRef;
}
- return AliasAnalysis::NoModRef;
+ return R;
}
// AliasAnalysis destructor: DO NOT move this to the header file for
/// AliasAnalysis interface before any other methods are called.
///
void AliasAnalysis::InitializeAliasAnalysis(Pass *P) {
- TD = P->getAnalysisIfAvailable<DataLayout>();
+ DataLayoutPass *DLP = P->getAnalysisIfAvailable<DataLayoutPass>();
+ DL = DLP ? &DLP->getDataLayout() : nullptr;
TLI = P->getAnalysisIfAvailable<TargetLibraryInfo>();
AA = &P->getAnalysis<AliasAnalysis>();
}
/// if known, or a conservative value otherwise.
///
uint64_t AliasAnalysis::getTypeStoreSize(Type *Ty) {
- return TD ? TD->getTypeStoreSize(Ty) : UnknownSize;
+ return DL ? DL->getTypeStoreSize(Ty) : UnknownSize;
}
/// canBasicBlockModify - Return true if it is possible for execution of the
return A->hasNoAliasAttr() || A->hasByValAttr();
return false;
}
+
+/// isIdentifiedFunctionLocal - Return true if V is umabigously identified
+/// at the function-level. Different IdentifiedFunctionLocals can't alias.
+/// Further, an IdentifiedFunctionLocal can not alias with any function
+/// arguments other than itself, which is not necessarily true for
+/// IdentifiedObjects.
+bool llvm::isIdentifiedFunctionLocal(const Value *V)
+{
+ return isa<AllocaInst>(V) || isNoAliasCall(V) || isNoAliasArgument(V);
+}
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