From 28537a45de776c6d4eb4a21447374e27acc4573d Mon Sep 17 00:00:00 2001
From: Richard Biener <rguenther@suse.de>
Date: Thu, 23 Jul 2015 07:23:23 +0000
Subject: [PATCH] re PR middle-end/66945 (ICE in generic_simplify
 (generic-match.c:24790))

2015-07-23  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/66945
	* tree-ssa-propagate.c (substitute_and_fold_dom_walker
	::before_dom_children): Force the propagators idea of
	non-executable edges to materialize, not what the folder
	chooses.

	* gcc.dg/torture/pr66945.c: New testcase.

From-SVN: r226088
---
 gcc/ChangeLog                          |  8 ++++++++
 gcc/testsuite/ChangeLog                |  5 +++++
 gcc/testsuite/gcc.dg/torture/pr66945.c | 12 ++++++++++++
 gcc/tree-ssa-propagate.c               | 26 +++++++++++++++++++++++---
 4 files changed, 48 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/torture/pr66945.c

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 7cd07f9d7d6..e89f685cb8c 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2015-07-23  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/66945
+	* tree-ssa-propagate.c (substitute_and_fold_dom_walker
+	::before_dom_children): Force the propagators idea of
+	non-executable edges to materialize, not what the folder
+	chooses.
+
 2015-07-23  Richard Biener  <rguenther@suse.de>
 
 	* gimple.h (gimple_cond_make_false): Use 0 != 0.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index f457b27fe6a..20fad268d2d 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2015-07-23  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/66945
+	* gcc.dg/torture/pr66945.c: New testcase.
+
 2015-07-22  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR target/66954
diff --git a/gcc/testsuite/gcc.dg/torture/pr66945.c b/gcc/testsuite/gcc.dg/torture/pr66945.c
new file mode 100644
index 00000000000..53ac2302657
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr66945.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+
+unsigned b;
+void f()
+{
+  for(;;)
+    if(!b?:(b=0))
+      ;
+    else if(b%0<b?:b) /* { dg-warning "division by zero" } */
+      for(;;)
+	;
+}
diff --git a/gcc/tree-ssa-propagate.c b/gcc/tree-ssa-propagate.c
index 3f3a694702e..b7684e07905 100644
--- a/gcc/tree-ssa-propagate.c
+++ b/gcc/tree-ssa-propagate.c
@@ -1236,13 +1236,33 @@ substitute_and_fold_dom_walker::before_dom_children (basic_block bb)
 
       /* If we made a replacement, fold the statement.  */
       if (did_replace)
-	fold_stmt (&i, follow_single_use_edges);
+	{
+	  fold_stmt (&i, follow_single_use_edges);
+	  stmt = gsi_stmt (i);
+	}
+
+      /* If this is a control statement the propagator left edges
+         unexecuted on force the condition in a way consistent with
+	 that.  See PR66945 for cases where the propagator can end
+	 up with a different idea of a taken edge than folding
+	 (once undefined behavior is involved).  */
+      if (gimple_code (stmt) == GIMPLE_COND)
+	{
+	  if ((EDGE_SUCC (bb, 0)->flags & EDGE_EXECUTABLE)
+	      ^ (EDGE_SUCC (bb, 1)->flags & EDGE_EXECUTABLE))
+	    {
+	      if (((EDGE_SUCC (bb, 0)->flags & EDGE_TRUE_VALUE) != 0)
+		  == ((EDGE_SUCC (bb, 0)->flags & EDGE_EXECUTABLE) != 0))
+		gimple_cond_make_true (as_a <gcond *> (stmt));
+	      else
+		gimple_cond_make_false (as_a <gcond *> (stmt));
+	      did_replace = true;
+	    }
+	}
 
       /* Now cleanup.  */
       if (did_replace)
 	{
-	  stmt = gsi_stmt (i);
-
 	  /* If we cleaned up EH information from the statement,
 	     remove EH edges.  */
 	  if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt))
-- 
2.30.2