[Bug target/91047] New: PowerPC: inline assembly doesn't know the difference between altivec and vsx registers

[shawn at git dot icu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91047

            Bug ID: 91047
           Summary: PowerPC: inline assembly doesn't know the difference
                    between altivec and vsx registers
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: shawn at git dot icu
  Target Milestone: ---

AltiVec registers are differn't registers from VSX registers, and even when the
VSX register class ("wa"[1]) is specified to an inline assembly, gcc doesn't
put the variable in the right register

#include <altivec.h>
#include <stdint.h>
void store_unaligned(vector unsigned char vec, unsigned char *dest) {
uintptr_t zero = 0;

    __asm__ volatile ("stxvb16x %0, %1, %2\n\t"
      :
      : "wa" (vec), "r" (zero), "r" ((uintptr_t)dest));
}

compiled with gcc -mvsx unaligned.c --save-temps -c -O3

store_unaligned:
.LFB0:
        .cfi_startproc
        li 9,0
#APP
 # 6 "unaligned.c" 1
        stxvb16x 2, 9, 5 <=== gcc needs to move it from vr3 to vs2, but didn't