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Re: Out-of-order update of new_spill_reg_store[]


> gcc/
> 	* reload1.c (reload_regs_reach_end_p): Replace with...
> 	(reload_reg_rtx_reaches_end_p): ...this function.
> 	(new_spill_reg_store): Update commentary.
> 	(emit_input_reload_insns): Don't clear new_spill_reg_store here.
> 	(emit_output_reload_insns): Check reload_reg_rtx_reaches_end_p
> 	before setting new_spill_reg_store.
> 	(emit_reload_insns): Use a separate loop to clear new_spill_reg_store.
> 	Use reload_reg_rtx_reaches_end_p instead of reload_regs_reach_end_p.
> 	Also use reload_reg_rtx_reaches_end_p when recording inheritance
> 	information for non-spill reload registers.

Just an update to say that based on our discussion I think the general
approach is OK, but I'm still trying to figure out what exactly this
piece of code is doing, and whether the changes to it make sense:

> @@ -8329,30 +8329,33 @@ emit_reload_insns (struct insn_chain *ch
>  		 the storing insn so that we may delete this insn with
>  		 delete_output_reload.  */
>  	      src_reg = reload_reg_rtx_for_output[r];
> -
> -	      /* If this is an optional reload, try to find the source reg
> -		 from an input reload.  */
> -	      if (! src_reg)
> +	      if (src_reg
> +		  && reload_reg_rtx_reaches_end_p (src_reg, r))
> +		store_insn = new_spill_reg_store[REGNO (src_reg)];
> +	      else
>  		{
> +		  /* If this is an optional reload, try to find the
> +		     source reg from an input reload.  */
>  		  rtx set = single_set (insn);
>  		  if (set && SET_DEST (set) == rld[r].out)
>  		    {
>  		      int k;
> +		      rtx cand;
>  
>  		      src_reg = SET_SRC (set);
>  		      store_insn = insn;
>  		      for (k = 0; k < n_reloads; k++)
> -			{
> -			  if (rld[k].in == src_reg)
> -			    {
> -			      src_reg = reload_reg_rtx_for_input[k];
> -			      break;
> -			    }
> -			}
> +			if (rld[k].in == src_reg)
> +			  {
> +			    cand = reload_reg_rtx_for_input[k];
> +			    if (reload_reg_rtx_reaches_end_p (cand, k))
> +			      {
> +				src_reg = cand;
> +				break;
> +			      }
> +			  }
>  		    }
>  		}
> -	      else
> -		store_insn = new_spill_reg_store[REGNO (src_reg)];
>  	      if (src_reg && REG_P (src_reg)
>  		  && REGNO (src_reg) < FIRST_PSEUDO_REGISTER)
>  		{


Bernd


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