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| author | Jonathan Wakely <jwakely@redhat.com> | 2017-01-09 13:05:58 +0000 |
|---|---|---|
| committer | Jonathan Wakely <redi@gcc.gnu.org> | 2017-01-09 13:05:58 +0000 |
| commit | cb627cdf5c0761f9e1be587a1416db9446a4801b (patch) | |
| tree | 46f37e5514f528ae92eb070447b2bf14ee402a03 | |
| parent | f63d601b9629ffbf756c97dac2d4241ed43d9e4e (diff) | |
| download | gcc-cb627cdf5c0761f9e1be587a1416db9446a4801b.zip gcc-cb627cdf5c0761f9e1be587a1416db9446a4801b.tar.gz gcc-cb627cdf5c0761f9e1be587a1416db9446a4801b.tar.bz2 | |
PR66414 optimize std::string::find
2017-01-09 Jonathan Wakely <jwakely@redhat.com>
Aditya Kumar <hiraditya@msn.com>
PR libstdc++/66414
* include/bits/basic_string.tcc
(basic_string::find(const CharT*, size_type, size_type)): Optimize.
Co-Authored-By: Aditya Kumar <hiraditya@msn.com>
From-SVN: r244225
| -rw-r--r-- | libstdc++-v3/ChangeLog | 7 | ||||
| -rw-r--r-- | libstdc++-v3/include/bits/basic_string.tcc | 26 |
2 files changed, 26 insertions, 7 deletions
diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index cab1848..79b12cc 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,3 +1,10 @@ +2017-01-09 Jonathan Wakely <jwakely@redhat.com> + Aditya Kumar <hiraditya@msn.com> + + PR libstdc++/66414 + * include/bits/basic_string.tcc + (basic_string::find(const CharT*, size_type, size_type)): Optimize. + 2017-01-06 Jonathan Wakely <jwakely@redhat.com> * testsuite/21_strings/basic_string/operations/find/char/6.cc: New. diff --git a/libstdc++-v3/include/bits/basic_string.tcc b/libstdc++-v3/include/bits/basic_string.tcc index 8b2895b..41b7fa1 100644 --- a/libstdc++-v3/include/bits/basic_string.tcc +++ b/libstdc++-v3/include/bits/basic_string.tcc @@ -1190,18 +1190,30 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { __glibcxx_requires_string_len(__s, __n); const size_type __size = this->size(); - const _CharT* __data = _M_data(); if (__n == 0) return __pos <= __size ? __pos : npos; + if (__pos >= __size) + return npos; - if (__n <= __size) + const _CharT __elem0 = __s[0]; + const _CharT* const __data = data(); + const _CharT* __first = __data + __pos; + const _CharT* const __last = __data + __size; + size_type __len = __size - __pos; + + while (__len >= __n) { - for (; __pos <= __size - __n; ++__pos) - if (traits_type::eq(__data[__pos], __s[0]) - && traits_type::compare(__data + __pos + 1, - __s + 1, __n - 1) == 0) - return __pos; + // Find the first occurrence of __elem0: + __first = traits_type::find(__first, __len - __n + 1, __elem0); + if (!__first) + return npos; + // Compare the full strings from the first occurrence of __elem0. + // We already know that __first[0] == __s[0] but compare them again + // anyway because __s is probably aligned, which helps memcmp. + if (traits_type::compare(__first, __s, __n) == 0) + return __first - __data; + __len = __last - ++__first; } return npos; } |