[llvm-commits] [llvm] r168879 - /llvm/trunk/lib/Transforms/Instrumentation/MemorySanitizer.cpp

[Evgeniy Stepanov]

Author: eugenis
Date: Thu Nov 29 07:43:05 2012
New Revision: 168879

URL: http://llvm.org/viewvc/llvm-project?rev=168879&view=rev
Log:
[msan] Optimize getOriginPtr.
    
Rewrite getOriginPtr in a way that lets subsequent optimizations factor out
the common part of Shadow and Origin address calculation. Improves perf by
up to 5%.


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

Modified: llvm/trunk/lib/Transforms/Instrumentation/MemorySanitizer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Instrumentation/MemorySanitizer.cpp?rev=168879&r1=168878&r2=168879&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Instrumentation/MemorySanitizer.cpp (original)
+++ llvm/trunk/lib/Transforms/Instrumentation/MemorySanitizer.cpp Thu Nov 29 07:43:05 2012
@@ -503,15 +503,16 @@
   /// address.
   ///
   /// OriginAddr = (ShadowAddr + OriginOffset) & ~3ULL
-  ///            = Addr & (~ShadowMask & ~3ULL) + OriginOffset
   Value *getOriginPtr(Value *Addr, IRBuilder<> &IRB) {
     Value *ShadowLong =
       IRB.CreateAnd(IRB.CreatePointerCast(Addr, MS.IntptrTy),
-                    ConstantInt::get(MS.IntptrTy, ~MS.ShadowMask & ~3ULL));
+                    ConstantInt::get(MS.IntptrTy, ~MS.ShadowMask));
     Value *Add =
       IRB.CreateAdd(ShadowLong,
                     ConstantInt::get(MS.IntptrTy, MS.OriginOffset));
-    return IRB.CreateIntToPtr(Add, PointerType::get(IRB.getInt32Ty(), 0));
+    Value *SecondAnd =
+      IRB.CreateAnd(Add, ConstantInt::get(MS.IntptrTy, ~3ULL));
+    return IRB.CreateIntToPtr(SecondAnd, PointerType::get(IRB.getInt32Ty(), 0));
   }
 
   /// \brief Compute the shadow address for a given function argument.