https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102976
Bug ID: 102976
Summary: MMA test case emits wrong code when building a vector
pair
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: bergner at gcc dot gnu.org
Target Milestone: ---
The following test case generates wrong code using trunk and GCC11:
[bergner@pike debug]$ cat bug.c
#include <altivec.h>
void
bug (__vector_pair *dst)
{
register vector unsigned char vec0 asm ("vs44");
register vector unsigned char vec1 asm ("vs32");
__builtin_vsx_build_pair (dst, vec0, vec1);
}
[bergner@pike debug]$ gcc -S -O2 -mcpu=power10 bug.c
[bergner@pike debug]$ cat bug.s
bug:
xxlor 0,32,32
xxlor 1,32,32
stxvp 0,0(3)
blr
The above only copies one of the inputs into the output pair, when it should
copy both r44 and r32, like so:
bug:
xxlor 0,44,44
xxlor 1,32,32
stxvp 0,0(3)
blr
This is due to a missing early clobber in the MMA patterns. I have a fix I'm
testing.
