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[Bug tree-optimization/16962] loop unrolling with x86-64 asm not efficient
- From: "falk at debian dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 10 Aug 2004 14:55:20 -0000
- Subject: [Bug tree-optimization/16962] loop unrolling with x86-64 asm not efficient
- References: <20040810134244.16962.tomstdenis@iahu.ca>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From falk at debian dot org 2004-08-10 14:55 -------
Well, the fundamental problem is independent of assembly. Here's a much simpler
example:
void f(int *p, int l) {
int i;
for (i = 0; i < l; ++i)
p[i] = 0;
}
With 3.4 and also with an oldish lno, on Alpha I get
$L36:
stq $31,0($3)
lda $5,1($5)
lda $3,8($3)
$L35:
stq $31,0($3)
lda $5,1($5)
lda $3,8($3)
...
while the offsets could easily be constant folded if there were no jumps into
the loop.
--
What |Removed |Added
----------------------------------------------------------------------------
Status|RESOLVED |UNCONFIRMED
Resolution|INVALID |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16962