[llvm-commits] [llvm] r155701 - /llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp

[Kostya Serebryany]

Author: kcc
Date: Fri Apr 27 05:04:53 2012
New Revision: 155701

URL: http://llvm.org/viewvc/llvm-project?rev=155701&view=rev
Log:
[asan] small optimization: do not emit "x+0" instructions 

Modified:
    llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp

Modified: llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp?rev=155701&r1=155700&r2=155701&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp (original)
+++ llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp Fri Apr 27 05:04:53 2012
@@ -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);