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From: "tobi at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/30398] memmove for string operations Date: Fri, 13 Apr 2007 15:27:00 -0000 [thread overview] Message-ID: <20070413152736.24267.qmail@sourceware.org> (raw) In-Reply-To: <bug-30398-10391@http.gcc.gnu.org/bugzilla/> ------- Comment #3 from tobi at gcc dot gnu dot org 2007-04-13 16:27 ------- With FX' patch to inline REPEAT (see PR31304), we are left with this as final dump after a -O compilation: ;; Function MAIN__ (MAIN__) MAIN__ () { char[1:] * pstr.1; char s[1:1]; char c[1:2]; void * D.1004; <bb 2>: _gfortran_set_std (68, 127, 0, 0, 0); s[1]{lb: 1 sz: 1} = 97; D.1004 = _gfortran_internal_malloc (2); pstr.1 = (char[1:] *) D.1004; __builtin_memcpy ((char *) pstr.1, &s, 1); __builtin_memcpy (pstr.1 + 1B, &s, 1); __builtin_memmove (&c, pstr.1, 2); _gfortran_internal_free (pstr.1); return; } The call to memmove makes it way into the assembly, even though pstr and c can't alias. This is now an optimizer issue, moving to component tree-optimization, as the tree-ssa optimizers should be able to eliminate the memmove in favor of a memcpy. Or even better, get rid of the whole copying business and predict the correct results. If that's possible it would be great to have a way to get rid of the then unnecessary temporary allocation. -- tobi at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |tobi at gcc dot gnu dot org, | |fxcoudert at gcc dot gnu dot | |org Component|fortran |tree-optimization http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30398
next prev parent reply other threads:[~2007-04-13 15:27 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2007-01-06 22:05 [Bug fortran/30398] New: " tkoenig at gcc dot gnu dot org 2007-01-06 22:07 ` [Bug fortran/30398] " tkoenig at gcc dot gnu dot org 2007-01-22 10:03 ` fxcoudert at gcc dot gnu dot org 2007-04-13 15:27 ` tobi at gcc dot gnu dot org [this message] [not found] <bug-30398-4@http.gcc.gnu.org/bugzilla/> 2020-11-11 9:31 ` [Bug tree-optimization/30398] " tkoenig at gcc dot gnu.org
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