Re: [PATCH] x86: Disallow APX instruction with length > 15 bytes

[Jan Beulich <jbeulich@suse.com>]

On 01.02.2024 23:47, H.J. Lu wrote:
> --- a/gas/config/tc-i386.c
> +++ b/gas/config/tc-i386.c
> @@ -11772,8 +11772,14 @@ output_insn (const struct last_insn *last_insn)
>  	{
>  	  j = encoding_length (insn_start_frag, insn_start_off, frag_more (0));
>  	  if (j > 15)
> -	    as_warn (_("instruction length of %u bytes exceeds the limit of 15"),
> -		     j);
> +	    {
> +	      if (i.tm.cpu.bitfield.cpuapx_f)
> +		as_bad (_("instruction length of %u bytes exceeds the limit of 15"),
> +			j);
> +	      else
> +		as_warn (_("instruction length of %u bytes exceeds the limit of 15"),
> +			 j);
> +	    }

Why would APX insns be different from others? IOW I continue to think that
having a warning here is good enough, uniformly. And it's quite sad that
with introducing APX the limit isn't raised, to accommodate all valid insn
forms (not considering ones with redundant prefixes, of course). _That_
would then permit special casing APX here, in _not_ warning anymore.

Jan