fix PR4284, a bug in simplifylibcalls handling memcmp. Patch by

Benjamin Kramer!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72625 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
index 8c41c728c06a466a0b8346be2a62d9f1b6b6b08f..4b0064090cf33b5cb0363e5f05259aad418f7ba8 100644 (file)
--- a/lib/Transforms/Scalar/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
@@ -878,7 +878,7 @@ struct VISIBILITY_HIDDEN MemCmpOpt : public LibCallOptimization {
     if (Len == 1) { // memcmp(S1,S2,1) -> *LHS - *RHS
       Value *LHSV = B.CreateLoad(CastToCStr(LHS, B), "lhsv");
       Value *RHSV = B.CreateLoad(CastToCStr(RHS, B), "rhsv");
-      return B.CreateZExt(B.CreateSub(LHSV, RHSV, "chardiff"), CI->getType());
+      return B.CreateSExt(B.CreateSub(LHSV, RHSV, "chardiff"), CI->getType());
     }
 
     // memcmp(S1,S2,2) != 0 -> (*(short*)LHS ^ *(short*)RHS)  != 0

diff --git a/test/Transforms/SimplifyLibCalls/2009-05-30-memcmp-byte.ll b/test/Transforms/SimplifyLibCalls/2009-05-30-memcmp-byte.ll
new file mode 100644 (file)
index 0000000..f720993
--- /dev/null
+++ b/test/Transforms/SimplifyLibCalls/2009-05-30-memcmp-byte.ll
@@ -0,0 +1,14 @@
+; RUN: llvm-as < %s | opt -simplify-libcalls -instcombine | llvm-dis | grep {ret i32 -65}
+; PR4284
+
+define i32 @test() nounwind {
+entry:
+       %c0 = alloca i8, align 1                ; <i8*> [#uses=2]
+       %c2 = alloca i8, align 1                ; <i8*> [#uses=2]
+       store i8 64, i8* %c0
+       store i8 -127, i8* %c2
+       %call = call i32 @memcmp(i8* %c0, i8* %c2, i32 1)               ; <i32> [#uses=1]
+       ret i32 %call
+}
+
+declare i32 @memcmp(i8*, i8*, i32)