ping^3 [PATCH] Fix reloads_unique_chain_p() missing a conflict

[Rask Ingemann Lambertsen <rask@sygehus.dk>]

On Mon, Jul 30, 2007 at 04:37:45PM +0200, Rask Ingemann Lambertsen wrote:
>    As discussed starting with this message
> <URL:http://gcc.gnu.org/ml/gcc-patches/2007-07/msg01343.html>, it is
> possible for reloads_unique_chain() to miss a reload conflict. It happens
> when two reloads are in a different other than expected. Reloads are sorted
> using target specific information and besides, the sorting is performed by
> qsort() which isn't guaranteed to be stable. The fix here is to check both
> reloads passed to reloads_unique_chain_p().
> 
>    This and the other two reload patches in this patch set were bootstrapped
> and tested together on x86_64-unknown-linux-gnu with no new failures. I also
> built and tested cross compilers for arm-unknown-elf, cris-axis-elf,
> m32c-unknown-elf, mipsisa64-unknown-elf, sh-unknown-elf and v850-unknown-elf
> with no new failures.
> 
>    Ok for trunk?
> 
> 2007-07-30  Rask Ingemann Lambertsen  <rask@sygehus.dk>
> 
> 	* reload1.c (reloads_unique_chain_p): Check both reloads.
> 
> Index: gcc/reload1.c
> ===================================================================
> --- gcc/reload1.c	(revision 126653)
> +++ gcc/reload1.c	(working copy)
> @@ -4960,7 +4976,8 @@ reloads_unique_chain_p (int r1, int r2)
>      if (i != r1 && i != r2 && rld[i].in)
>        {
>  	/* If our reload is mentioned at all, it isn't a simple chain.  */
> -	if (reg_mentioned_p (rld[r1].in, rld[i].in))
> +	if (reg_mentioned_p (rld[r1].in, rld[i].in)
> +	    || reg_mentioned_p (rld[r2].in, rld[i].in))
>  	  return false;
>        }
>    return true;
> 
> -- 
> Rask Ingemann Lambertsen