[Bug target/121749] New: [14/15/16 Regression] aarch64: Invalid assembly with vqshrn intrinsic since r14-1886-gd20b2ad845876e

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121749

            Bug ID: 121749
           Summary: [14/15/16 Regression] aarch64: Invalid assembly with
                    vqshrn intrinsic since r14-1886-gd20b2ad845876e
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: acoplan at gcc dot gnu.org
  Target Milestone: ---

The following fails:

$ cat t.c
#include <arm_neon.h>
uint32_t foo(uint64_t v0) {
  return vqshrnd_n_u64(vshrd_n_u64(v0, 26), 7);
}
$ gcc/xgcc -B gcc -c t.c -O2
/tmp/ccGC4KcV.s: Assembler messages:
/tmp/ccGC4KcV.s:12: Error: immediate value out of range 1 to 32 at operand 3 --
`uqshrn s31,d31,33'

the assembler correctly rejects GCC's output, which is:

foo:
        fmov    d31, x0
        uqshrn  s31, d31, 33
        fmov    w0, s31
        ret

this started with r14-1886-gd20b2ad845876eec0ee80a3933ad49f9f6c4ee30, before
which we used to generate (in GCC 13):

foo:
        fmov    d0, x0
        ushr    d0, d0, 26
        uqshrn  s0, d0, 7
        fmov    w0, s0
        ret