[asan] small optimization: do not emit "x+0" instructions
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155701 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 33b56d5..b01cdbf 100644
--- a/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -363,11 +363,12 @@
size_t Granularity = 1 << MappingScale;
if (TypeSize < 8 * Granularity) {
// Addr & (Granularity - 1)
- Value *Lower3Bits = IRB2.CreateAnd(
+ Value *LastAccessedByte = IRB2.CreateAnd(
AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
// (Addr & (Granularity - 1)) + size - 1
- Value *LastAccessedByte = IRB2.CreateAdd(
- Lower3Bits, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
+ if (TypeSize / 8 > 1)
+ LastAccessedByte = IRB2.CreateAdd(
+ LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
// (uint8_t) ((Addr & (Granularity-1)) + size - 1)
LastAccessedByte = IRB2.CreateIntCast(
LastAccessedByte, IRB.getInt8Ty(), false);