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From: "matz at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/57569] [4.8/4.9 Regression] wrong code for struct copy at -O3 on x86_64-linux
Date: Tue, 11 Jun 2013 14:18:00 -0000	[thread overview]
Message-ID: <bug-57569-4-0bH32BHGfM@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-57569-4@http.gcc.gnu.org/bugzilla/>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57569

--- Comment #3 from Michael Matz <matz at gcc dot gnu.org> ---
It's cse, and it's because it indeed uses the wrong dependence test.
The CSE tables holds values read from memory which are supposed to be
clobbered by following writes, i.e. write-after-read, which has to use
anti_dependence.  This fixes the testcase:

Index: cse.c
===================================================================
--- cse.c       (revision 199694)
+++ cse.c       (working copy)
@@ -1837,7 +1837,7 @@ check_dependence (rtx *x, void *data)
 {
   struct check_dependence_data *d = (struct check_dependence_data *) data;
   if (*x && MEM_P (*x))
-    return canon_true_dependence (d->exp, d->mode, d->addr, *x, NULL_RTX);
+    return anti_dependence (*x, d->exp);
   else
     return 0;
 }


  parent reply	other threads:[~2013-06-11 14:18 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-06-08 19:25 [Bug rtl-optimization/57569] New: " dhazeghi at yahoo dot com
2013-06-08 20:11 ` [Bug rtl-optimization/57569] [4.8/4.9 Regression] " jakub at gcc dot gnu.org
2013-06-10 15:22 ` matz at gcc dot gnu.org
2013-06-11 14:18 ` matz at gcc dot gnu.org [this message]
2013-06-16 13:38 ` amylaar at gcc dot gnu.org
2013-10-16  9:50 ` jakub at gcc dot gnu.org
2013-10-30 12:56 ` [Bug rtl-optimization/57569] [4.8 " rguenth at gcc dot gnu.org
2014-03-17 15:32 ` wschmidt at gcc dot gnu.org
2014-05-22  9:02 ` rguenth at gcc dot gnu.org
2014-12-19 13:40 ` jakub at gcc dot gnu.org
2014-12-20 13:51 ` mikpelinux at gmail dot com
2014-12-20 15:54 ` jakub at gcc dot gnu.org

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