re PR tree-optimization/69740 (gcc ICE at -O2 and above on valid code on x86_64-linux-gnu in "verify_loop_structure")

PR tree-optimization/69740
	* cfghooks.c (remove_edge): Request loop fixups if we delete
	an edge that might turn an irreducible loop into a natural
	loop.

        PR tree-optimization/69740
	* gcc.c-torture/compile/pr69740-1.c: New test.
	* gcc.c-torture/compile/pr69740-2.c: New test.

Co-Authored-By: Jeff Law <law@redhat.com>

From-SVN: r233754

gcc/ChangeLog

@@ -1,3 +1,11 @@
+2016-02-26  Richard Biener  <rguenther@suse.de>
+	    Jeff Law  <law@redhat.com>
+
+	PR tree-optimization/69740
+	* cfghooks.c (remove_edge): Request loop fixups if we delete
+	an edge that might turn an irreducible loop into a natural
+	loop.
+
 2016-02-26  Martin Jambor  <mjambor@suse.cz>
 
 	PR middle-end/69920

gcc/cfghooks.c

@@ -408,7 +408,20 @@ void
 remove_edge (edge e)
 {
   if (current_loops != NULL)
-    rescan_loop_exit (e, false, true);
+    {
+      rescan_loop_exit (e, false, true);
+
+      /* Removal of an edge inside an irreducible region or which leads
+	 to an irreducible region can turn the region into a natural loop.
+	 In that case, ask for the loop structure fixups.
+
+	 FIXME: Note that LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS is not always
+	 set, so always ask for fixups when removing an edge in that case.  */
+      if (!loops_state_satisfies_p (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
+	  || (e->flags & EDGE_IRREDUCIBLE_LOOP)
+	  || (e->dest->flags & BB_IRREDUCIBLE_LOOP))
+	loops_state_set (LOOPS_NEED_FIXUP);
+    }
 
   /* This is probably not needed, but it doesn't hurt.  */
   /* FIXME: This should be called via a remove_edge hook.  */

gcc/testsuite/ChangeLog

@@ -1,3 +1,10 @@
+2016-02-26  Richard Biener  <rguenther@suse.de>
+            Jeff Law  <law@redhat.com>
+
+        PR tree-optimization/69740
+	* gcc.c-torture/compile/pr69740-1.c: New test.
+	* gcc.c-torture/compile/pr69740-2.c: New test.
+
 2016-02-26  Martin Jambor  <mjambor@suse.cz>
 
 	PR middle-end/69920

gcc/testsuite/gcc.c-torture/compile/pr69740-1.c

@@ -0,0 +1,12 @@
+char a;
+short b;
+void fn1() {
+  if (b)
+    ;
+  else {
+    int c[1] = {0};
+  l1:;
+  }
+  if (a)
+    goto l1;
+}

gcc/testsuite/gcc.c-torture/compile/pr69740-2.c

@@ -0,0 +1,19 @@
+inline int foo(int *p1, int p2) {
+  int z = *p1;
+  while (z > p2)
+    p2 = 2;
+  return z;
+}
+int main() {
+  int i;
+  for (;;) {
+    int j, k;
+    i = foo(&k, 7);
+    if (k)
+      j = i;
+    else
+      k = j;
+    if (2 != j)
+      __builtin_abort();
+  }
+}