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tsan: properly instrument unaligned accesses

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If a memory access is unaligned, emit __tsan_unaligned_read/write
callbacks instead of __tsan_read/write.
Required to change semantics of __tsan_unaligned_read/write to not do the user memory.
But since they were unused (other than through __sanitizer_unaligned_load/store) this is fine.
Fixes long standing issue 17:
https://code.google.com/p/thread-sanitizer/issues/detail?id=17



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227231 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dmitry Vyukov
2015-01-27 20:19:17 +00:00
parent e67f5de1f7
commit a18b3e06fc
2 changed files with 165 additions and 1 deletions
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lib/Transforms/Instrumentation/ThreadSanitizer.cpp
+22 -1
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@@ -99,6 +99,8 @@ struct ThreadSanitizer : public FunctionPass {
static const size_t kNumberOfAccessSizes = 5;
Function *TsanRead[kNumberOfAccessSizes];
Function *TsanWrite[kNumberOfAccessSizes];
Function *TsanUnalignedRead[kNumberOfAccessSizes];
Function *TsanUnalignedWrite[kNumberOfAccessSizes];
Function *TsanAtomicLoad[kNumberOfAccessSizes];
Function *TsanAtomicStore[kNumberOfAccessSizes];
Function *TsanAtomicRMW[AtomicRMWInst::LAST_BINOP + 1][kNumberOfAccessSizes];
@@ -150,6 +152,16 @@ void ThreadSanitizer::initializeCallbacks(Module &M) {
TsanWrite[i] = checkInterfaceFunction(M.getOrInsertFunction(
WriteName, IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
SmallString<64> UnalignedReadName("__tsan_unaligned_read" +
itostr(ByteSize));
TsanUnalignedRead[i] = checkInterfaceFunction(M.getOrInsertFunction(
UnalignedReadName, IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
SmallString<64> UnalignedWriteName("__tsan_unaligned_write" +
itostr(ByteSize));
TsanUnalignedWrite[i] = checkInterfaceFunction(M.getOrInsertFunction(
UnalignedWriteName, IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
Type *Ty = Type::getIntNTy(M.getContext(), BitSize);
Type *PtrTy = Ty->getPointerTo();
SmallString<32> AtomicLoadName("__tsan_atomic" + itostr(BitSize) +
@@ -412,7 +424,16 @@ bool ThreadSanitizer::instrumentLoadOrStore(Instruction *I) {
NumInstrumentedVtableReads++;
return true;
}
Value *OnAccessFunc = IsWrite ? TsanWrite[Idx] : TsanRead[Idx];
const unsigned Alignment = IsWrite
? cast<StoreInst>(I)->getAlignment()
: cast<LoadInst>(I)->getAlignment();
Type *OrigTy = cast<PointerType>(Addr->getType())->getElementType();
const uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy);
Value *OnAccessFunc = nullptr;
if (Alignment == 0 || Alignment >= 8 || (Alignment % (TypeSize / 8)) == 0)
OnAccessFunc = IsWrite ? TsanWrite[Idx] : TsanRead[Idx];
else
OnAccessFunc = IsWrite ? TsanUnalignedWrite[Idx] : TsanUnalignedRead[Idx];
IRB.CreateCall(OnAccessFunc, IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
if (IsWrite) NumInstrumentedWrites++;
else NumInstrumentedReads++;