[PATCH v2] x86: Disallow instructions with length > 15 bytes

[Jan Beulich]

On 02.02.2024 12:33, H.J. Lu wrote:
> --- a/gas/config/tc-i386.c
> +++ b/gas/config/tc-i386.c
> @@ -11780,8 +11780,8 @@ 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);
> +	    as_bad (_("instruction length of %u bytes exceeds the limit of 15"),
> +		    j);

When taking purely a gas perspective, this may be okay. But I'd like
to retain the ability to generate overlong insns (without resorting
to .byte), so there wants to be a way to downgrade the error to a
warning. This is useful in particular when trying to make testcases
for disassemblers or other software decoding insns.

Jan