Powerpc bootstrap failure due to duplicate case value

Commited as obvious.

	PR target/79098
	* config/rs6000/rs6000.c (rs6000_legitimate_combined_insn): Don't
	use a switch.

On Mon, Jan 16, 2017 at 09:53:17PM +1030, Alan Modra wrote:
> Commited as obvious.
> 
> 	PR target/79098
> 	* config/rs6000/rs6000.c (rs6000_legitimate_combined_insn): Don't
> 	use a switch.

Perhaps it would be useful to write why it can't be written as a switch.
Or, as a switch it could be of the form:
  switch (INSN_CODE (insn))
    {
#ifdef HAVE_ctrsi_internal1
    case CODE_FOR_ctrsi_internal1:
    case CODE_FOR_ctrsi_internal2:
    case CODE_FOR_ctrsi_internal3:
    case CODE_FOR_ctrsi_internal4:
#endif
#ifdef HAVE_ctrdi_internal1
    case CODE_FOR_ctrdi_internal1:
    case CODE_FOR_ctrdi_internal2:
    case CODE_FOR_ctrdi_internal3:
    case CODE_FOR_ctrdi_internal4:
#endif
      return false;
    default:
      break;
    }

> diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
> index 11394b2..f1d5d9d 100644
> --- a/gcc/config/rs6000/rs6000.c
> +++ b/gcc/config/rs6000/rs6000.c
> @@ -9085,40 +9085,41 @@ rs6000_const_not_ok_for_debug_p (rtx x)
>  static bool
>  rs6000_legitimate_combined_insn (rtx_insn *insn)
>  {
> -  switch (INSN_CODE (insn))
> -    {
> -      /* Reject creating doloop insns.  Combine should not be allowed
> -	 to create these for a number of reasons:
> -	 1) In a nested loop, if combine creates one of these in an
> -	 outer loop and the register allocator happens to allocate ctr
> -	 to the outer loop insn, then the inner loop can't use ctr.
> -	 Inner loops ought to be more highly optimized.
> -	 2) Combine often wants to create one of these from what was
> -	 originally a three insn sequence, first combining the three
> -	 insns to two, then to ctrsi/ctrdi.  When ctrsi/ctrdi is not
> -	 allocated ctr, the splitter takes use back to the three insn
> -	 sequence.  It's better to stop combine at the two insn
> -	 sequence.
> -	 3) Faced with not being able to allocate ctr for ctrsi/crtdi
> -	 insns, the register allocator sometimes uses floating point
> -	 or vector registers for the pseudo.  Since ctrsi/ctrdi is a
> -	 jump insn and output reloads are not implemented for jumps,
> -	 the ctrsi/ctrdi splitters need to handle all possible cases.
> -	 That's a pain, and it gets to be seriously difficult when a
> -	 splitter that runs after reload needs memory to transfer from
> -	 a gpr to fpr.  See PR70098 and PR71763 which are not fixed
> -	 for the difficult case.  It's better to not create problems
> -	 in the first place.  */
> -    case CODE_FOR_ctrsi_internal1:
> -    case CODE_FOR_ctrdi_internal1:
> -    case CODE_FOR_ctrsi_internal2:
> -    case CODE_FOR_ctrdi_internal2:
> -    case CODE_FOR_ctrsi_internal3:
> -    case CODE_FOR_ctrdi_internal3:
> -    case CODE_FOR_ctrsi_internal4:
> -    case CODE_FOR_ctrdi_internal4:
> -      return false;
> -    }
> +  int icode = INSN_CODE (insn);
> +
> +  /* Reject creating doloop insns.  Combine should not be allowed
> +     to create these for a number of reasons:
> +     1) In a nested loop, if combine creates one of these in an
> +     outer loop and the register allocator happens to allocate ctr
> +     to the outer loop insn, then the inner loop can't use ctr.
> +     Inner loops ought to be more highly optimized.
> +     2) Combine often wants to create one of these from what was
> +     originally a three insn sequence, first combining the three
> +     insns to two, then to ctrsi/ctrdi.  When ctrsi/ctrdi is not
> +     allocated ctr, the splitter takes use back to the three insn
> +     sequence.  It's better to stop combine at the two insn
> +     sequence.
> +     3) Faced with not being able to allocate ctr for ctrsi/crtdi
> +     insns, the register allocator sometimes uses floating point
> +     or vector registers for the pseudo.  Since ctrsi/ctrdi is a
> +     jump insn and output reloads are not implemented for jumps,
> +     the ctrsi/ctrdi splitters need to handle all possible cases.
> +     That's a pain, and it gets to be seriously difficult when a
> +     splitter that runs after reload needs memory to transfer from
> +     a gpr to fpr.  See PR70098 and PR71763 which are not fixed
> +     for the difficult case.  It's better to not create problems
> +     in the first place.  */
> +  if (icode != CODE_FOR_nothing
> +      && (icode == CODE_FOR_ctrsi_internal1
> +	  || icode == CODE_FOR_ctrdi_internal1
> +	  || icode == CODE_FOR_ctrsi_internal2
> +	  || icode == CODE_FOR_ctrdi_internal2
> +	  || icode == CODE_FOR_ctrsi_internal3
> +	  || icode == CODE_FOR_ctrdi_internal3
> +	  || icode == CODE_FOR_ctrsi_internal4
> +	  || icode == CODE_FOR_ctrdi_internal4))
> +    return false;
> +
>    return true;
>  }
>  
> 
> -- 
> Alan Modra
> Australia Development Lab, IBM

	Jakub

On Mon, Jan 16, 2017 at 12:41:29PM +0100, Jakub Jelinek wrote:
> Or, as a switch it could be of the form:
>   switch (INSN_CODE (insn))
>     {
> #ifdef HAVE_ctrsi_internal1
>     case CODE_FOR_ctrsi_internal1:
>     case CODE_FOR_ctrsi_internal2:
>     case CODE_FOR_ctrsi_internal3:
>     case CODE_FOR_ctrsi_internal4:
> #endif
> #ifdef HAVE_ctrdi_internal1
>     case CODE_FOR_ctrdi_internal1:
>     case CODE_FOR_ctrdi_internal2:
>     case CODE_FOR_ctrdi_internal3:
>     case CODE_FOR_ctrdi_internal4:
> #endif
>       return false;
>     default:
>       break;
>     }

I didn't think of that.  Segher and I discussed the problem on #gcc
and both independently decided an if() was the obvious fix.