[llvm-commits] [llvm] r128319 - in /llvm/trunk: lib/Transforms/Scalar/DeadStoreElimination.cpp test/Transforms/DeadStoreElimination/2011-03-25-DSEMiscompile.ll

[Bill Wendling]

Author: void
Date: Fri Mar 25 20:20:37 2011
New Revision: 128319

URL: http://llvm.org/viewvc/llvm-project?rev=128319&view=rev
Log:
PR9561: A store with a negative offset (via GEP) could erroniously say that it
completely overlaps a previous store, thus mistakenly deleting that store. Check
for this condition.

Added:
    llvm/trunk/test/Transforms/DeadStoreElimination/2011-03-25-DSEMiscompile.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp?rev=128319&r1=128318&r2=128319&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp Fri Mar 25 20:20:37 2011
@@ -354,8 +354,10 @@
   // In this case, we see if the later store completely overlaps all bytes
   // stored by the previous store.
   if (Off1 < Off2 ||                       // Earlier starts before Later.
+      Off2 < 0 ||                          // Later is -.
       Off1+Earlier.Size > Off2+Later.Size) // Earlier goes beyond Later.
     return false;
+
   // Otherwise, we have complete overlap.
   return true;
 }

Added: llvm/trunk/test/Transforms/DeadStoreElimination/2011-03-25-DSEMiscompile.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/DeadStoreElimination/2011-03-25-DSEMiscompile.ll?rev=128319&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/DeadStoreElimination/2011-03-25-DSEMiscompile.ll (added)
+++ llvm/trunk/test/Transforms/DeadStoreElimination/2011-03-25-DSEMiscompile.ll Fri Mar 25 20:20:37 2011
@@ -0,0 +1,22 @@
+; RUN: opt < %s -basicaa -dse -S | FileCheck %s
+; PR9561
+target triple = "i386-apple-darwin9.8"
+
+ at A = external global [0 x i32]
+
+declare cc10 void @Func2(i32*, i32*, i32*, i32)
+
+define cc10 void @Func1(i32* noalias %Arg1, i32* noalias %Arg2, i32* %Arg3, i32 %Arg4) {
+entry:
+  store i32 add (i32 ptrtoint ([0 x i32]* @A to i32), i32 1), i32* %Arg2
+; CHECK: store i32 add (i32 ptrtoint ([0 x i32]* @A to i32), i32 1), i32* %Arg2
+  %ln2gz = getelementptr i32* %Arg1, i32 14
+  %ln2gA = bitcast i32* %ln2gz to double*
+  %ln2gB = load double* %ln2gA
+  %ln2gD = getelementptr i32* %Arg2, i32 -3
+  %ln2gE = bitcast i32* %ln2gD to double*
+  store double %ln2gB, double* %ln2gE
+; CHECK: store double %ln2gB, double* %ln2gE
+  tail call cc10 void @Func2(i32* %Arg1, i32* %Arg2, i32* %Arg3, i32 %Arg4) nounwind
+  ret void
+}