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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 /lib/Transforms | |
| parent | 46df4eb46e784036cf895db271fe29e1cf2a975a (diff) | |
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
Diffstat (limited to 'lib/Transforms')
| -rw-r--r-- | lib/Transforms/Scalar/SimplifyLibCalls.cpp | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/lib/Transforms/Scalar/SimplifyLibCalls.cpp index f562a1b8fe..3ae79eeca4 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); |