[Bug tree-optimization/62156] memcmp doesn't see through memcpy at compile-time

2014-08-19 Thread rguenther at suse dot de
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62156 --- Comment #6 from rguenther at suse dot de --- On Tue, 19 Aug 2014, glisse at gcc dot gnu.org wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62156 > > --- Comment #5 from Marc Glisse --- > (In reply to rguent...@suse.de from comment #

[Bug tree-optimization/62156] memcmp doesn't see through memcpy at compile-time

2014-08-19 Thread glisse at gcc dot gnu.org
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62156 --- Comment #5 from Marc Glisse --- (In reply to rguent...@suse.de from comment #4) > Eventually worth "fixing" the libstdc++ side to generate better > initial code? Replacing memcpy(,,3)+assign(,'\0') with memcpy(,,4) can indeed be done at the

[Bug tree-optimization/62156] memcmp doesn't see through memcpy at compile-time

2014-08-19 Thread rguenther at suse dot de
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62156 --- Comment #4 from rguenther at suse dot de --- On Mon, 18 Aug 2014, glisse at gcc dot gnu.org wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62156 > > --- Comment #2 from Marc Glisse --- > (In reply to Richard Biener from comment #1)

[Bug tree-optimization/62156] memcmp doesn't see through memcpy at compile-time

2014-08-18 Thread glisse at gcc dot gnu.org
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62156 --- Comment #3 from Marc Glisse --- Not much difference using __gnu_cxx::__vstring (no reference counting, small string optimization): __builtin_memcpy (&MEM[(struct __sso_string_base *)&D.28720].D.23707._M_local_data, "foo", 3); MEM[(size_type

[Bug tree-optimization/62156] memcmp doesn't see through memcpy at compile-time

2014-08-18 Thread glisse at gcc dot gnu.org
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62156 --- Comment #2 from Marc Glisse --- (In reply to Richard Biener from comment #1) > What kind of std::string code is this? That is, can we expect > memcmp and memcpy to be adjacent (without intermediate memory operations?) I don't remember the e

[Bug tree-optimization/62156] memcmp doesn't see through memcpy at compile-time

2014-08-18 Thread rguenth at gcc dot gnu.org
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62156 Richard Biener changed: What|Removed |Added Status|UNCONFIRMED |NEW Last reconfirmed|