[Bug target/102868] New: Missed optimization with __builtin_shuffle and zero vector on ppc

[luoxhu at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102868

            Bug ID: 102868
           Summary: Missed optimization with __builtin_shuffle and zero
                    vector on ppc
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: luoxhu at gcc dot gnu.org
  Target Milestone: ---

Similar to PR94680 and PR100165, PPC currently generates inefficient
instructions for below case:

typedef float V __attribute__((vector_size(16)));
typedef int VI __attribute__((vector_size(16)));
V foo (V x)
{
return __builtin_shuffle (x, (V) { 0, 0, 0, 0 }, (VI) {0, 1, 4, 5});
}


foo:
.LFB0:
        .cfi_startproc
.LCF0:
0:      addis 2,12,.TOC.-.LCF0@ha
        addi 2,2,.TOC.-.LCF0@l
        .localentry     foo,.-foo
        addis %r9,%r2,.LC0@toc@ha
        xxspltib %vs32,0
        addi %r9,%r9,.LC0@toc@l
        lxv %vs33,0(%r9)
        xxperm %vs34,%vs32,%vs33
        blr



It will be better to produce:

foo:
.LFB0:
        .cfi_startproc
        vspltisw %v0,0
        xxpermdi %vs34,%vs32,%vs34,3