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

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Benjamin Kramer!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72625 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2009-05-30 18:43:04 +00:00
parent 1e8c7a687d
commit 0e98e4d299
2 changed files with 15 additions and 1 deletions
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2
lib/Transforms/Scalar/SimplifyLibCalls.cpp
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@ -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

14
test/Transforms/SimplifyLibCalls/2009-05-30-memcmp-byte.ll Normal file
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@ -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)