[PATCH] microMIPS/GAS: Correct the handling of hazard clearance NOPs

[Maciej W. Rozycki]

On Sat, 6 Aug 2011, Richard Sandiford wrote:

> These sorts of test are becoming a maintenance and readability problem,
> so it seemed like a good time to abstract them away.  Perhaps the only
> noteworthy part is that the microMIPS relaxation code tested:
> 
> 	       || (pinfo2 & ~INSN2_ALIAS) == INSN2_UNCOND_BRANCH
> 
> instead of plain:
> 
> 	       || (pinfo2 & INSN2_UNCOND_BRANCH)
> 
> The first form excludes JRC and JRADDIUSP, which should of course not be
> relaxed.  But those instructions wouldn't have address expressions or
> fixups anyway, so both conditions ought to be equivalent.

 Yes, fair enough as it stands, but things may change and then someone 
will scratch their head ten years on or suchlike -- as we do about 1990s 
stuff these days sometimes.

 How about adding a comment to the effect of your explanation above where 
you've removed the ~INSN2_ALIAS mask -- ...

> @@ -4198,16 +4224,12 @@ append_insn (struct mips_cl_insn *ip, ex
>  	   && address_expr
>  	   && ((relax32 && *reloc_type == BFD_RELOC_16_PCREL_S2)
>  	       || *reloc_type > BFD_RELOC_UNUSED)
> -	   && (pinfo & INSN_UNCOND_BRANCH_DELAY
> -	       || pinfo & INSN_COND_BRANCH_DELAY
> -	       || (pinfo2 & ~INSN2_ALIAS) == INSN2_UNCOND_BRANCH
> -	       || pinfo2 & INSN2_COND_BRANCH))
> +	   && (delayed_branch_p (ip) || compact_branch_p (ip)))
>      {
>        bfd_boolean relax16 = *reloc_type > BFD_RELOC_UNUSED;
>        int type = relax16 ? *reloc_type - BFD_RELOC_UNUSED : 0;

 ... specifically here?

  Maciej