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Re: [PATCH] Fix PR70484, RTL DSE using wrong dependence check

From: Bernd Schmidt <bschmidt at redhat dot com>
To: Richard Biener <rguenther at suse dot de>, gcc-patches at gcc dot gnu dot org
Date: Fri, 1 Apr 2016 17:26:21 +0200
Subject: Re: [PATCH] Fix PR70484, RTL DSE using wrong dependence check
Authentication-results: sourceware.org; auth=none
References: <alpine dot LSU dot 2 dot 11 dot 1604011106140 dot 13384 at t29 dot fhfr dot qr>

On 04/01/2016 11:08 AM, Richard Biener wrote:

   	{
! 	  if (canon_true_dependence (s_info->mem,
! 				     GET_MODE (s_info->mem),
! 				     s_info->mem_addr,
! 				     mem, mem_addr))
   	    {
   	      s_info->rhs = NULL;
   	      s_info->const_rhs = NULL;
--- 1609,1617 ----
   	   the value of store_info.  If it is, set the rhs to NULL to
   	   keep it from being used to remove a load.  */
   	{
! 	  if (canon_output_dependence (s_info->mem, true,
! 				       mem, GET_MODE (mem),
! 				       mem_addr))
   	    {
   	      s_info->rhs = NULL;
   	      s_info->const_rhs = NULL;

I think the patch is ok, but there is a comment in that function whichreferences canon_true_dependence; that should also be fixed up.

Isn't the testcase invalid though? I thought accesses through char *pointers bypass aliasing rules, but accessing a char array through int *and long * pointers doesn't?



Bernd

Follow-Ups:
- Re: [PATCH] Fix PR70484, RTL DSE using wrong dependence check
  - From: Richard Biener
- Re: [PATCH] Fix PR70484, RTL DSE using wrong dependence check
  - From: Richard Biener

References:
- [PATCH] Fix PR70484, RTL DSE using wrong dependence check
  - From: Richard Biener

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