From patchwork Tue Jan 29 10:39:15 2013
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Subject: Fix PR55270
Date: Tue, 29 Jan 2013 00:39:15 -0000
From: Richard Guenther <rguenther@suse.de>
X-Patchwork-Id: 216500
Message-Id: <alpine.LNX.2.00.1301291138000.6889@zhemvz.fhfr.qr>
To: gcc-patches@gcc.gnu.org

This fixes PR55270 - we need to fixup loops after phicprop as
that removes edges without doing so.  The following patch makes
us rely on cfgcleanup scheduled after the pass for this.

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.

Richard.

2013-01-29  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/55270
	* tree-ssa-dom.c (eliminate_degenerate_phis): If we changed
	the CFG, schedule loops for fixup.

	* gcc.dg/torture/pr55270.c: New testcase.


Index: gcc/tree-ssa-dom.c
===================================================================
--- gcc/tree-ssa-dom.c	(revision 195530)
+++ gcc/tree-ssa-dom.c	(working copy)
@@ -3006,7 +3006,12 @@ eliminate_degenerate_phis (void)
     }
 
   if (cfg_altered)
-    free_dominance_info (CDI_DOMINATORS);
+    {
+      free_dominance_info (CDI_DOMINATORS);
+      /* If we changed the CFG schedule loops for fixup by cfgcleanup.  */
+      if (current_loops)
+	loops_state_set (LOOPS_NEED_FIXUP);
+    }
 
   /* Propagation of const and copies may make some EH edges dead.  Purge
      such edges from the CFG as needed.  */
Index: gcc/testsuite/gcc.dg/torture/pr55270.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr55270.c	(revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr55270.c	(working copy)
@@ -0,0 +1,22 @@
+/* { dg-do compile } */
+
+unsigned a, b, c;
+
+void f(void)
+{
+  for(; a; a++)
+    {
+      long *p1 = (long *)&b;
+
+      if(*p1)
+	return;
+
+      if(b && (*p1 = b) || c && ++*p1)
+	{
+	  unsigned *p2 = &b;
+
+	  for(*p2 = 0; *p2 < 1;)
+	    for(; b; b++);
+	}
+    }
+}