From dbfa8045afc4dc9166736f0531092580e9e1dfb9 Mon Sep 17 00:00:00 2001
From: Bill Wendling <isanbard@gmail.com>
Date: Wed, 30 Mar 2011 21:44:24 +0000
Subject: [PATCH] Merging r128577

git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_29@128579 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../Scalar/DeadStoreElimination.cpp           |  4 +++-
 .../2011-03-25-DSEMiscompile.ll               | 23 +++++++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 test/Transforms/DeadStoreElimination/2011-03-25-DSEMiscompile.ll

diff --git a/lib/Transforms/Scalar/DeadStoreElimination.cpp b/lib/Transforms/Scalar/DeadStoreElimination.cpp
index b948bed9d44..b2200872031 100644
--- a/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ b/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -361,8 +361,10 @@ static bool isCompleteOverwrite(const AliasAnalysis::Location &Later,
   //
   //        |--earlier--|
   //    |-----  later  ------|
+  //
+  // We have to be careful here as *Off is signed while *.Size is unsigned.
   if (EarlierOff >= LaterOff &&
-      EarlierOff + Earlier.Size <= LaterOff + Later.Size)
+      uint64_t(EarlierOff - LaterOff) + Earlier.Size <= Later.Size)
     return true;
 
   // Otherwise, they don't completely overlap.
diff --git a/test/Transforms/DeadStoreElimination/2011-03-25-DSEMiscompile.ll b/test/Transforms/DeadStoreElimination/2011-03-25-DSEMiscompile.ll
new file mode 100644
index 00000000000..079eec43bf8
--- /dev/null
+++ b/test/Transforms/DeadStoreElimination/2011-03-25-DSEMiscompile.ll
@@ -0,0 +1,23 @@
+; RUN: opt < %s -basicaa -dse -S | FileCheck %s
+; PR9561
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128-n8:16:32"
+target triple = "i386-apple-darwin9.8"
+
+@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
+}