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[Bug middle-end/24427] missing optimization opportunity with binary operators
- From: "ramana dot radhakrishnan at codito dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 26 Jun 2006 19:13:32 -0000
- Subject: [Bug middle-end/24427] missing optimization opportunity with binary operators
- References: <bug-24427-10957@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #5 from ramana dot radhakrishnan at codito dot com 2006-06-26 19:13 -------
This should be reopened. A related testcase shows a regression from 3.4.6 to
4.1.1 for m68k-elf shows a regression . combine used to take care of this in
3.4.6 . A backport of the patch is ready with me. If its allowed, I'll put it
up .
This is the test case .
#include <stdio.h>
int i;
int main (void)
{
if ( ((i & ~1) | 1) != ( i | 1))
printf ("abc");
}
3.4.6 generated
.file "fail.c"
.text
.align 2
.globl foo
.type foo, @function
foo:
link.w %a6,#0
unlk %a6
rts
.size foo, .-foo
.comm i,4,2
.ident "GCC: (GNU) 3.4.6"
4.1.2 pre-release generates
.file "fail.c"
.section .rodata.str1.1,"aMS",@progbits,1
.LC0:
.string "abc"
.text
.align 2
.globl main
.type main, @function
main:
link.w %fp,#0
move.l %d2,-(%sp)
move.l i,%d1
moveq #-2,%d0
and.l %d1,%d0
moveq #1,%d2
or.l %d2,%d0
or.l %d2,%d1
cmp.l %d0,%d1
jbeq .L5
pea .LC0
jbsr printf
addq.l #4,%sp
.L5:
move.l -4(%fp),%d2
unlk %fp
rts
.size main, .-main
.comm i,4,2
.ident "GCC: (GNU) 4.1.2 20060623 (prerelease)"
--
ramana dot radhakrishnan at codito dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |ramana dot radhakrishnan at
| |codito dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24427