From: Richard Biener <rguenther@suse.de>
Date: Thu, 3 May 2018 13:20:02 +0000 (+0000)
Subject: re PR tree-optimization/85615 (ICE at -O2 and above on valid code on x86_64-linux... 
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=a378f85c5416aaf7ffea7ee114ee166ff4dd92da;p=gcc.git

re PR tree-optimization/85615 (ICE at -O2 and above on valid code on x86_64-linux-gnu: in dfs_enumerate_from, at cfganal.c:1197)

2018-05-03  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/85615
	* tree-ssa-threadupdate.c (thread_block_1): Only allow exits
	to loops not nested in BBs loop father to avoid creating multi-entry
	loops.

	* gcc.dg/torture/pr85615.c: New testcase.

From-SVN: r259891
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 3ce8273a499..893a459e09a 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2018-05-03  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/85615
+	* tree-ssa-threadupdate.c (thread_block_1): Only allow exits
+	to loops not nested in BBs loop father to avoid creating multi-entry
+	loops.
+
 2018-05-03  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
 	PR tree-optimization/70291
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 3a69665dd69..6d135894c27 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-05-03  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/85615
+	* gcc.dg/torture/pr85615.c: New testcase.
+
 2018-05-03  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
 	PR tree-optimization/70291
diff --git a/gcc/testsuite/gcc.dg/torture/pr85615.c b/gcc/testsuite/gcc.dg/torture/pr85615.c
new file mode 100644
index 00000000000..1695c2e7d1d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr85615.c
@@ -0,0 +1,28 @@
+/* { dg-do compile } */
+
+long a, d;
+int b, c;
+void fn1()
+{
+  int e = -1L, f = 2, g = 8;
+  for (;;)
+    {
+      for (; b; g++)
+	;
+      int i;
+      for (; c;)
+	{
+	  i = 5;
+	  for (; e >= 1; i--)
+	    ;
+	}
+      d = f ?: a;
+      if (d)
+	{
+	  e = 0;
+	  for (; i;)
+	    for (; g < 3; f++)
+	      ;
+	}
+    }
+}
diff --git a/gcc/tree-ssa-threadupdate.c b/gcc/tree-ssa-threadupdate.c
index 9ab9e7d7d93..b6bc5fcf175 100644
--- a/gcc/tree-ssa-threadupdate.c
+++ b/gcc/tree-ssa-threadupdate.c
@@ -1309,7 +1309,9 @@ thread_block_1 (basic_block bb, bool noloop_only, bool joiners)
 	     and thread this elsewhere, so just cancel the jump threading
 	     request by clearing the AUX field now.  */
 	  if (bb->loop_father != e2->src->loop_father
-	      && !loop_exit_edge_p (e2->src->loop_father, e2))
+	      && (!loop_exit_edge_p (e2->src->loop_father, e2)
+		  || flow_loop_nested_p (bb->loop_father,
+					 e2->dest->loop_father)))
 	    {
 	      /* Since this case is not handled by our special code
 		 to thread through a loop header, we must explicitly