re PR tree-optimization/70986 (ICE on valid code at -O3 on x86_64-linux-gnu in combine_blocks, at tree-if-conv.c:2219)

2016-05-12  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/70986
	* cfganal.c: Include cfgloop.h.
	(dfs_find_deadend): Prefer to take edges exiting loops.

	* gcc.dg/torture/pr70986-1.c: New testcase.
	* gcc.dg/torture/pr70986-2.c: Likewise.
	* gcc.dg/torture/pr70986-3.c: Likewise.

From-SVN: r236158

6 files changed, 89 insertions, 1 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 3a81766..da2a10c 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2016-05-12  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/70986
+	* cfganal.c: Include cfgloop.h.
+	(dfs_find_deadend): Prefer to take edges exiting loops.
+
 2016-05-11  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>
 
 	* gcc.target/powerpc/pr70963.c: Require at least power8 at both
diff --git a/gcc/cfganal.c b/gcc/cfganal.c
index 189762c..a4bdef6 100644
--- a/gcc/cfganal.c
+++ b/gcc/cfganal.c
@@ -26,6 +26,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "cfghooks.h"
 #include "timevar.h"
 #include "cfganal.h"
+#include "cfgloop.h"
 
 /* Store the data structures necessary for depth-first search.  */
 struct depth_first_search_ds {
@@ -747,7 +748,21 @@ dfs_find_deadend (basic_block bb)
           return bb;
         }
 
-      bb = EDGE_SUCC (bb, 0)->dest;
+      /* If we are in an analyzed cycle make sure to try exiting it.
+         Note this is a heuristic only and expected to work when loop
+	 fixup is needed as well.  */
+      if (! bb->loop_father
+	  || ! loop_outer (bb->loop_father))
+	bb = EDGE_SUCC (bb, 0)->dest;
+      else
+	{
+	  edge_iterator ei;
+	  edge e;
+	  FOR_EACH_EDGE (e, ei, bb->succs)
+	    if (loop_exit_edge_p (bb->loop_father, e))
+	      break;
+	  bb = e ? e->dest : EDGE_SUCC (bb, 0)->dest;
+	}
     }
 
   gcc_unreachable ();
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index b9c541f..ce5dfea 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2016-05-12  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/70986
+	* gcc.dg/torture/pr70986-1.c: New testcase.
+	* gcc.dg/torture/pr70986-2.c: Likewise.
+	* gcc.dg/torture/pr70986-3.c: Likewise.
+
 2016-05-11  Mikhail Maltsev  <maltsevm@gmail.com>
 
 	PR c/43651
diff --git a/gcc/testsuite/gcc.dg/torture/pr70986-1.c b/gcc/testsuite/gcc.dg/torture/pr70986-1.c
new file mode 100644
index 0000000..4da1f54
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr70986-1.c
@@ -0,0 +1,22 @@
+/* { dg-do compile } */
+
+int a, g;
+char b, c;
+short d, e, f;
+
+char
+fn1 ()
+{
+  return a ? a : 1;
+}
+
+void
+fn2 ()
+{
+  char h;
+  for (; d;)
+    for (; e; e++)
+      c = (fn1 () && h) & !(f |= 9 ^ (b > (g = c)));
+  for (;;)
+    ;
+}
diff --git a/gcc/testsuite/gcc.dg/torture/pr70986-2.c b/gcc/testsuite/gcc.dg/torture/pr70986-2.c
new file mode 100644
index 0000000..2f4d2b6
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr70986-2.c
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+
+int gi, dg;
+
+void
+fe (void)
+{
+  int ka = gi;
+
+  for (;;)
+    {
+      if (ka != 0)
+	{
+	  if (dg != 0)
+	    gi = 0;
+	  ++ka;
+	}
+      ++dg;
+    }
+}
diff --git a/gcc/testsuite/gcc.dg/torture/pr70986-3.c b/gcc/testsuite/gcc.dg/torture/pr70986-3.c
new file mode 100644
index 0000000..5b722d5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr70986-3.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+
+int a, b;
+int
+fn1 (int p1)
+{
+  return p1 < 0 ? p1 : a;
+}
+
+void
+fn2 ()
+{
+lbl_100:
+  b = 1;
+  for (; b != 21; b = fn1 (b))
+    ;
+  goto lbl_100;
+}