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[asan] inline the calls to __asan_stack_free_* with small sizes. Yet another 10%-20% speedup for use-after-return 

llvm-svn: 190863
This commit is contained in:
Kostya Serebryany 2013-09-17 12:14:50 +00:00
parent 830c27ab2d
commit bc86efb89d
1 changed files with 48 additions and 3 deletions
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51
llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
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@ -88,10 +88,12 @@ static const char *const kAsanPoisonStackMemoryName =
static const char *const kAsanUnpoisonStackMemoryName =
"__asan_unpoison_stack_memory";
// These constants must match the definitions in the run-time library.
static const int kAsanStackLeftRedzoneMagic = 0xf1;
static const int kAsanStackMidRedzoneMagic = 0xf2;
static const int kAsanStackRightRedzoneMagic = 0xf3;
static const int kAsanStackPartialRedzoneMagic = 0xf4;
static const int kAsanStackAfterReturnMagic = 0xf5;
// Accesses sizes are powers of two: 1, 2, 4, 8, 16.
static const size_t kNumberOfAccessSizes = 5;
@ -519,6 +521,9 @@ struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
void poisonRedZones(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> &IRB,
Value *ShadowBase, bool DoPoison);
void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
int Size);
};
} // namespace
@ -1362,6 +1367,22 @@ static int StackMallocSizeClass(uint64_t LocalStackSize) {
llvm_unreachable("impossible LocalStackSize");
}
// Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
// We can not use MemSet intrinsic because it may end up calling the actual
// memset. Size is a multiple of 8.
// Currently this generates 8-byte stores on x86_64; it may be better to
// generate wider stores.
void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
IRBuilder<> &IRB, Value *ShadowBase, int Size) {
assert(!(Size % 8));
assert(kAsanStackAfterReturnMagic == 0xf5);
for (int i = 0; i < Size; i += 8) {
Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
}
}
void FunctionStackPoisoner::poisonStack() {
uint64_t LocalStackSize = TotalStackSize +
(AllocaVec.size() + 1) * RedzoneSize();
@ -1465,9 +1486,33 @@ void FunctionStackPoisoner::poisonStack() {
if (DoStackMalloc) {
assert(StackMallocIdx >= 0);
// In use-after-return mode, mark the whole stack frame unaddressable.
IRBRet.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
ConstantInt::get(IntptrTy, LocalStackSize),
OrigStackBase);
if (StackMallocIdx <= 4) {
// For small sizes inline the whole thing:
// if LocalStackBase != OrigStackBase:
// memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
// **SavedFlagPtr(LocalStackBase) = 0
// FIXME: if LocalStackBase != OrigStackBase don't call poisonRedZones.
Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
TerminatorInst *PoisonTerm =
SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
IRBuilder<> IRBPoison(PoisonTerm);
int ClassSize = kMinStackMallocSize << StackMallocIdx;
SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
ClassSize >> Mapping.Scale);
Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
LocalStackBase,
ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
Value *SavedFlagPtr = IRBPoison.CreateLoad(
IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
IRBPoison.CreateStore(
Constant::getNullValue(IRBPoison.getInt8Ty()),
IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
} else {
// For larger frames call __asan_stack_free_*.
IRBRet.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
ConstantInt::get(IntptrTy, LocalStackSize),
OrigStackBase);
}
} else if (HavePoisonedAllocas) {
// If we poisoned some allocas in llvm.lifetime analysis,
// unpoison whole stack frame now.