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[asan] use ADD instead of OR when applying shadow offset of PowerPC. See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55975 for details

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173258 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Kostya Serebryany 2013-01-23 12:54:55 +00:00
parent 70465616c2
commit 48a615fee7
1 changed files with 15 additions and 4 deletions
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19
lib/Transforms/Instrumentation/AddressSanitizer.cpp
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@ -53,6 +53,7 @@ using namespace llvm;
static const uint64_t kDefaultShadowScale = 3;
static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
static const size_t kMaxStackMallocSize = 1 << 16; // 64K
static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
@ -186,21 +187,29 @@ class SetOfDynamicallyInitializedGlobals {
};
/// This struct defines the shadow mapping using the rule:
/// shadow = (mem >> Scale) + Offset.
/// shadow = (mem >> Scale) ADD-or-OR Offset.
struct ShadowMapping {
int Scale;
uint64_t Offset;
bool OrShadowOffset;
};
static ShadowMapping getShadowMapping(const Module &M, int LongSize,
bool ZeroBaseShadow) {
llvm::Triple TargetTriple(M.getTargetTriple());
bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64;
ShadowMapping Mapping;
// OR-ing shadow offset if more efficient (at least on x86),
// but on ppc64 we have to use add since the shadow offset is not neccesary
// 1/8-th of the address space.
Mapping.OrShadowOffset = !IsPPC64;
Mapping.Offset = (IsAndroid || ZeroBaseShadow) ? 0 :
(LongSize == 32 ? kDefaultShadowOffset32 : kDefaultShadowOffset64);
(LongSize == 32 ? kDefaultShadowOffset32 :
IsPPC64 ? kPPC64_ShadowOffset64 : kDefaultShadowOffset64);
if (ClMappingOffsetLog >= 0) {
// Zero offset log is the special case.
Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog;
@ -520,8 +529,10 @@ Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
if (Mapping.Offset == 0)
return Shadow;
// (Shadow >> scale) | offset
return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy,
Mapping.Offset));
if (Mapping.OrShadowOffset)
return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
else
return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
}
void AddressSanitizer::instrumentMemIntrinsicParam(