[Bug target/99647] New: arm: GCC generates invalid MVE vmov instruction

[acoplan at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99647

            Bug ID: 99647
           Summary: arm: GCC generates invalid MVE vmov instruction
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: acoplan at gcc dot gnu.org
  Target Milestone: ---

We generate invalid assembly for the following testcase:

$ cat test.c
typedef int __attribute((vector_size(16))) V;
V f(void) {
  return (V){ (int)f, (int)f, (int)f, (int)f };
}
$ arm-eabi-gcc -c test.c -O2 -march=armv8.1-m.main+mve -mfloat-abi=hard
/tmp/ccSbIMAM.s: Assembler messages:
/tmp/ccSbIMAM.s:29: Error: expected <Rm> or <Dm> or <Qm> operand -- `vmov.32
q0,#f'

It looks like we're trying to use a label on the RHS of a vmov instruction:

f:
        @ args = 0, pretend = 0, frame = 0
        @ frame_needed = 0, uses_anonymous_args = 0
        @ link register save eliminated.
        vmov.32 q0, #f
        bx      lr

This can also be seen through autovec in the testsuite. In particular
gcc/testsuite/gcc.dg/torture/pr47958-1.c fails at -O3 in the same way:

$ arm-eabi-gcc -c gcc/testsuite/gcc.dg/torture/pr47958-1.c -c -O3
-march=armv8.1-m.main+mve -mfloat-abi=hard
/tmp/cc09hQWF.s: Assembler messages:
/tmp/cc09hQWF.s:42: Error: expected <Rm> or <Dm> or <Qm> operand -- `vmov.32
q3,#bar'

I noticed this while working on PR97252 which is a separate problem with MVE
vector moves.