[asan] adaptive redzones for globals (the larger the global the larger is the redzone)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173335 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index f4715f5..477cb1a 100644
--- a/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -875,12 +875,22 @@
Value *FirstDynamic = 0, *LastDynamic = 0;
for (size_t i = 0; i < n; i++) {
+ static const size_t kMaxGlobalRedzone = 1 << 18;
GlobalVariable *G = GlobalsToChange[i];
PointerType *PtrTy = cast<PointerType>(G->getType());
Type *Ty = PtrTy->getElementType();
uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
- size_t RZ = RedzoneSize();
- uint64_t RightRedzoneSize = RZ + (RZ - (SizeInBytes % RZ));
+ size_t MinRZ = RedzoneSize();
+ // MinRZ <= RZ <= kMaxGlobalRedzone
+ // and trying to make RZ to be ~ 1/4 of SizeInBytes.
+ size_t RZ = std::max(MinRZ,
+ std::min(kMaxGlobalRedzone,
+ (SizeInBytes / MinRZ / 4) * MinRZ));
+ uint64_t RightRedzoneSize = RZ;
+ // Round up to MinRZ
+ if (SizeInBytes % MinRZ)
+ RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
+ assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
// Determine whether this global should be poisoned in initialization.
bool GlobalHasDynamicInitializer =
@@ -904,7 +914,7 @@
M, NewTy, G->isConstant(), G->getLinkage(),
NewInitializer, "", G, G->getThreadLocalMode());
NewGlobal->copyAttributesFrom(G);
- NewGlobal->setAlignment(RZ);
+ NewGlobal->setAlignment(MinRZ);
Value *Indices2[2];
Indices2[0] = IRB.getInt32(0);