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[Bug optimization/3507] appalling optimisation with sub/cmp on i386
- From: "pinskia at physics dot uc dot edu" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 3 Aug 2003 17:59:19 -0000
- Subject: [Bug optimization/3507] appalling optimisation with sub/cmp on i386
- References: <20010701091600.3507.75773-quiet@bugs.debian.org>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=3507
pinskia at physics dot uc dot edu changed:
What |Removed |Added
----------------------------------------------------------------------------
GCC target triplet|i386-linux |i386-linux, powerpc-*-*
Last reconfirmed|0000-00-00 00:00:00 |2003-08-03 17:59:19
date| |
------- Additional Comments From pinskia at physics dot uc dot edu 2003-08-03 17:59 -------
It also happens on powerpc-apple-darwin6.6
Currently GCC produces:
_foo:
cmplw cr0,r3,r4
subf r3,r4,r3
bgelr- cr0
addi r3,r3,100
blr
But GCC should be able to produce:
_foo:
subf. r3,r4,r3
bgelr- cr0
addi r3,r3,100
blr
Which is smaller (and faster on every thing except maybe 970 and Power4).