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| author | Benjamin Kramer <benny.kra@googlemail.com> | 2010-06-16 10:30:29 +0000 |
|---|---|---|
| committer | Benjamin Kramer <benny.kra@googlemail.com> | 2010-06-16 10:30:29 +0000 |
| commit | ea9ca0236d758967b40d3dd18054e90d65151674 (patch) | |
| tree | 81e28bf6bd992d559b95ca9aea0ed4662c29ef5b | |
| parent | 46df4eb46e784036cf895db271fe29e1cf2a975a (diff) | |
| download | external_llvm-ea9ca0236d758967b40d3dd18054e90d65151674.zip external_llvm-ea9ca0236d758967b40d3dd18054e90d65151674.tar.gz external_llvm-ea9ca0236d758967b40d3dd18054e90d65151674.tar.bz2 | |
simplify-libcalls: fold strncmp(x, y, 1) -> memcmp(x, y, 1)
The memcmp will be optimized further and even the pathological case
'strstr(x, "x") == x' generates optimal code now.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106097 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Transforms/Scalar/SimplifyLibCalls.cpp | 3 | ||||
| -rw-r--r-- | test/Transforms/SimplifyLibCalls/StrNCmp.ll | 7 |
2 files changed, 10 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/lib/Transforms/Scalar/SimplifyLibCalls.cpp index f562a1b..3ae79ee 100644 --- a/lib/Transforms/Scalar/SimplifyLibCalls.cpp +++ b/lib/Transforms/Scalar/SimplifyLibCalls.cpp @@ -342,6 +342,9 @@ struct StrNCmpOpt : public LibCallOptimization { if (Length == 0) // strncmp(x,y,0) -> 0 return ConstantInt::get(CI->getType(), 0); + if (TD && Length == 1) // strncmp(x,y,1) -> memcmp(x,y,1) + return EmitMemCmp(Str1P, Str2P, CI->getOperand(3), B, TD); + std::string Str1, Str2; bool HasStr1 = GetConstantStringInfo(Str1P, Str1); bool HasStr2 = GetConstantStringInfo(Str2P, Str2); diff --git a/test/Transforms/SimplifyLibCalls/StrNCmp.ll b/test/Transforms/SimplifyLibCalls/StrNCmp.ll index ba77385..8b536a5 100644 --- a/test/Transforms/SimplifyLibCalls/StrNCmp.ll +++ b/test/Transforms/SimplifyLibCalls/StrNCmp.ll @@ -2,6 +2,9 @@ ; RUN: opt < %s -simplify-libcalls -S | \ ; RUN: not grep {call.*strncmp} +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-darwin9.0" + @hello = constant [6 x i8] c"hello\00" ; <[6 x i8]*> [#uses=1] @hell = constant [5 x i8] c"hell\00" ; <[5 x i8]*> [#uses=1] @null = constant [1 x i8] zeroinitializer ; <[1 x i8]*> [#uses=1] @@ -26,3 +29,7 @@ define i32 @main() { ret i32 %rslt4 } +define i32 @test1(i8* %P, i8* %Q) { + %cmp = call i32 @strncmp(i8* %P, i8* %Q, i32 1) + ret i32 %cmp +} |