https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103798
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|libstdc++ |tree-optimization
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
Severity|normal |enhancement
Summary|Missed optimization: |memchr with a (small)
|char_traits<char>::find |constant string should be
|(and thus |expanded inline.
|string_view::find_first_of) |
|is slow when invoked with |
|short strings |
Last reconfirmed| |2021-12-22
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Really the issue is:
_8 = __builtin_memchr ("eE", _7, 2);
if (_8 != 0B)
Should just be expanded to _7 == 'e' || _7 == 'E' .
That is:
int f(char a)
{
return __builtin_memchr ("e", a, 1) != 0;
}
int f1(char a)
{
return a == 'e';
}
int g(char a)
{
return __builtin_memchr ("eE", a, 2) != 0;
}
int g1(char a)
{
return a == 'e' || a == 'E';
}
f and f1 should produce the same assembly
and g and g1 should produce the same (similar) assembly.
