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From: "pinskia at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/19988] [4.0 Regression] pessimizes fp multiply-add/subtract combo Date: Wed, 16 Feb 2005 19:01:00 -0000 [thread overview] Message-ID: <20050216145106.21322.qmail@sourceware.org> (raw) In-Reply-To: <20050215225352.19988.stevenj@fftw.org> ------- Additional Comments From pinskia at gcc dot gnu dot org 2005-02-16 14:51 ------- Ok, this is the patch which caused this code generation regression: 2004-02-07 Roger Sayle <roger@eyesopen.com> * fold-const.c (negate_expr_p, negate_expr): Optimize -(A+B) into either (-A)-B or (-B)-A, if A or B is easily negated respectively. (fold) <MINUS_EXPR>: Optimize (A*C) - (B*C) -> (A-B)*C for both integer types and floating point with unsafe_math_optimizations. Add similar optimization for (A*C1) - (A*C2) -> A*(C1-C2). Optimize A - B as A + (-B), if B is easily negated. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19988
next prev parent reply other threads:[~2005-02-16 14:51 UTC|newest] Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top 2005-02-16 4:49 [Bug c/19988] New: " gcc-bugzilla at gcc dot gnu dot org 2005-02-16 5:15 ` [Bug middle-end/19988] " pinskia at gcc dot gnu dot org 2005-02-16 6:33 ` pinskia at gcc dot gnu dot org 2005-02-16 19:00 ` pinskia at gcc dot gnu dot org 2005-02-16 19:01 ` pinskia at gcc dot gnu dot org [this message] 2005-02-16 23:47 ` roger at eyesopen dot com 2005-02-17 3:35 ` athena at fftw dot org 2005-02-17 3:38 ` athena at fftw dot org 2005-02-19 16:58 ` roger at eyesopen dot com 2005-04-21 5:03 ` [Bug middle-end/19988] [4.0/4.1 " mmitchel at gcc dot gnu dot org 2005-07-08 1:42 ` mmitchel at gcc dot gnu dot org 2005-08-17 12:45 ` pinskia at gcc dot gnu dot org 2005-09-27 16:23 ` mmitchel at gcc dot gnu dot org
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