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[asan] implement --asan-always-slow-path, which is a part of the improvement to handle unaligned partially OOB accesses. See http://code.google.com/p/address-sanitizer/issues/detail?id=100

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llvm-svn: 161937
This commit is contained in:
Kostya Serebryany 2012-08-15 08:58:58 +00:00
parent 3b09e94409
commit 8af4402528
1 changed files with 5 additions and 2 deletions
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7
lib/Transforms/Instrumentation/AddressSanitizer.cpp
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@ -86,6 +86,9 @@ static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
cl::Hidden, cl::init(true));
static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
cl::desc("use instrumentation with slow path for all accesses"),
cl::Hidden, cl::init(false));
// This flag limits the number of instructions to be instrumented
// in any given BB. Normally, this should be set to unlimited (INT_MAX),
// but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
@ -416,7 +419,7 @@ Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
// (uint8_t) ((Addr & (Granularity-1)) + size - 1)
LastAccessedByte = IRB.CreateIntCast(
LastAccessedByte, IRB.getInt8Ty(), false);
LastAccessedByte, ShadowValue->getType(), false);
// ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
}
@ -440,7 +443,7 @@ void AddressSanitizer::instrumentAddress(AsanFunctionContext &AFC,
size_t Granularity = 1 << MappingScale;
TerminatorInst *CrashTerm = 0;
if (TypeSize < 8 * Granularity) {
if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
TerminatorInst *CheckTerm = splitBlockAndInsertIfThen(Cmp, false);
assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
BasicBlock *NextBB = CheckTerm->getSuccessor(0);