[Bug target/99773] ARM v8.1-m MVE interaction with -mfloat-abi not clear

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99773

--- Comment #3 from Christophe Lyon <clyon at gcc dot gnu.org> ---
I tried changing TARGET_HARD_FLOAT_SUB in arm.h to:
#define TARGET_HARD_FLOAT_SUB   (arm_float_abi != ARM_FLOAT_ABI_SOFT    \
                                 && (bitmap_bit_p (arm_active_target.isa, \
                                                  isa_bit_vfpv2) \
                                    || bitmap_bit_p (arm_active_target.isa, \
                                                     isa_bit_mve))      \
                                 && TARGET_32BIT)

but that has other implications, like enabing VFP patterns: for instance
mulsf3_vfp becomes enabled, leading to a failure when builing libgcc (vmul.f32
is generated for powisf2, but rejected by the assembler)

So maybe we just change the condition to emit the attributes in arm_file_start?

Something like:
      if (! TARGET_SOFT_FLOAT || TARGET_HAVE_MVE)
        {
          if ((TARGET_HARD_FLOAT && TARGET_VFP_SINGLE) || TARGET_HAVE_MVE)
            arm_emit_eabi_attribute ("Tag_ABI_HardFP_use", 27, 1);

          if (TARGET_HARD_FLOAT_ABI || TARGET_HAVE_MVE)
            arm_emit_eabi_attribute ("Tag_ABI_VFP_args", 28, 1);
        }

but that does not look very clean