[Bug target/107515] New: MVE: Generic functions do not accept _Float16 scalars

["kevin.bracey at alifsemi dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107515

            Bug ID: 107515
           Summary: MVE: Generic functions do not accept _Float16 scalars
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kevin.bracey at alifsemi dot com
  Target Milestone: ---

Compiling C code, generic functions taking floating point scalars in arm_mve.h
do not accept `_Float16` values.

// Using gcc -mcpu=cortex-m55 -O2
// Uploaded at https://godbolt.org/z/7jrqWWroY

#include <arm_mve.h>

void test(void)
{
    float16x8_t x;

    x = vmulq(x, 0.5); // ok
    x = vmulq(x, 0.5f); // ok
    x = vmulq(x, (__fp16) 0.5); // ok
    x = vmulq(x, 0.15f16); // rejected
    x = vmulq(x, (_Float16) 0.15); // rejected
}

Output:

<source>:10:9: error: '_Generic' selector of type 'int (*)[4][39]' is not
compatible with any association
   10 |     x = vmulq(x, 0.15f16); // rejected
      |         ^~~~~
<source>:11:9: error: '_Generic' selector of type 'int (*)[4][39]' is not
compatible with any association
   11 |     x = vmulq(x, (_Float16) 0.15); // rejected
      |         ^~~~~