OpenE2K
/
gcc
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

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
This commit is contained in:
Jonathan Wakely 2017-01-09 13:05:58 +00:00 committed by Jonathan Wakely
parent f63d601b96
commit cb627cdf5c
2 changed files with 26 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
libstdc++-v3/ChangeLog
View File

@ -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.

26
libstdc++-v3/include/bits/basic_string.tcc
View File

@ -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;
}