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target/10404: gcc does not use 0 when using the indexed instructions of altivec like stewx
- From: pinskia at physics dot uc dot edu
- To: gcc-gnats at gcc dot gnu dot org
- Date: 14 Apr 2003 20:48:08 -0000
- Subject: target/10404: gcc does not use 0 when using the indexed instructions of altivec like stewx
- Reply-to: pinskia at physics dot uc dot edu
>Number: 10404
>Category: target
>Synopsis: gcc does not use 0 when using the indexed instructions of altivec like stewx
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Mon Apr 14 20:56:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator: Andrew Pinski
>Release: GNU C version 3.4 20030412 (experimental)
>Organization:
>Environment:
powerpc-apple-darwin6.5
>Description:
compile the follow source with gcc testaltivect1.c -include altivec.h -maltivec -O3 and see that there is `li r2, 0` which is useless.
int f(int a, int *c, vector signed int v1) {
vec_ste(v1, 0, c);
return a;
}
comes out:
_f:
li r5,0
stvewx v2,r5,r4
blr
when it is faster and smaller to do this:
_f:
stvewx v2,0,r4
blr
>How-To-Repeat:
See Description
>Fix:
add or fix the altivec patterns for load/store index so that they allow one register as memory.
>Release-Note:
>Audit-Trail:
>Unformatted: