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StringRef: Just forward StringRef::find to libc's memchr.

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Modern libc's have an SSE version of memchr which is a lot faster than our
hand-rolled version. In the past I was reluctant to use it because Darwin's
memchr used a naive ridiculously slow implementation, but that has been fixed
some versions ago.

Should have zero functional impact.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232898 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Benjamin Kramer 2015-03-21 16:42:35 +00:00
parent f85c601683
commit b1c9f1f84e
1 changed files with 6 additions and 3 deletions
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9
include/llvm/ADT/StringRef.h
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@ -238,9 +238,12 @@ namespace llvm {
/// \returns The index of the first occurrence of \p C, or npos if not
/// found.
size_t find(char C, size_t From = 0) const {
for (size_t i = std::min(From, Length), e = Length; i != e; ++i)
if (Data[i] == C)
return i;
size_t FindBegin = std::min(From, Length);
if (FindBegin < Length) { // Avoid calling memchr with nullptr.
// Just forward to memchr, which is faster than a hand-rolled loop.
if (const void *P = ::memchr(Data + FindBegin, C, Length - FindBegin))
return static_cast<const char *>(P) - Data;
}
return npos;
}