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other/8551: altivec vec_cmplt generates wrong instruction
- From: hartwood at crosslink dot net
- To: gcc-gnats at gcc dot gnu dot org
- Date: 12 Nov 2002 19:21:39 -0000
- Subject: other/8551: altivec vec_cmplt generates wrong instruction
- Reply-to: hartwood at crosslink dot net
>Number: 8551
>Category: other
>Synopsis: altivec vec_cmplt generates wrong instruction
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: wrong-code
>Submitter-Id: net
>Arrival-Date: Tue Nov 12 11:26:17 PST 2002
>Closed-Date:
>Last-Modified:
>Originator: Rick Cellucci
>Release: gcc version 3.3 20021104 (experimental)
>Organization:
>Environment:
Configured with: ../gcc3.3/configure --prefix=/usr/local/darwin --enable-altivec --enable-languages=c --with-cpu=7400 --target=powerpc-apple-darwin6.1
>Description:
Both vec_cmplt and vec_cmpgt generate the same vcmpgtfp instruction. vec_cmplt should generate vcmpgtfp and switch the second and third arguments, which is not happening. Occurs at any optimization level. I assume short and int versions may be broken as well, I only have tested vector floats.
>How-To-Repeat:
void VecCmpltIsBroken (void)
{
vector float zero = (vector float) {0.0, 0.0, 0.0, 0.0};
vector float smaller = (vector float) {1.0, 2.0, 3.0, 4.0};
vector float bigger = (vector float) {5.0, 6.0, 7.0, 8.0};
vector bool int cmp;
cmp = vec_cmplt (bigger, smaller);
bigger = vec_sel (bigger, zero, cmp);
PrintFloatVector (bigger); printf ("\n");
cmp = vec_cmpgt (bigger, smaller);
bigger = vec_sel (bigger, zero, cmp);
PrintFloatVector (bigger); printf ("\n");
}
lvx v31,0,r9
vcmpgtfp v0,v31,v29
vxor v30,v30,v30
vsel v31,v31,v30,v0
vor v2,v31,v31
bl L_PrintFloatVector$stub
li r3,10
bl L_putchar$stub
vcmpgtfp v0,v31,v29
>Fix:
Workaround: Only use vec_cmpgt and switch arguments order in C.
>Release-Note:
>Audit-Trail:
>Unformatted: