re PR middle-end/52881 (ICE due to null pointer deref in cfgloop.c)

2012-04-11  Richard Guenther  <rguenther@suse.de>

	PR rtl-optimization/52881
	* ifcvt.c (find_if_case_2): Avoid speculating loop latches.

	* gcc.dg/torture/pr52881.c: New testcase.
	* gcc.dg/torture/pr52913.c: Likewise.

From-SVN: r186304

gcc/ChangeLog

@@ -1,3 +1,8 @@
+2012-04-11  Richard Guenther  <rguenther@suse.de>
+
+	PR rtl-optimization/52881
+	* ifcvt.c (find_if_case_2): Avoid speculating loop latches.
+
 2012-04-11  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/52912

gcc/ifcvt.c

@@ -3927,6 +3927,11 @@ find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge)
   edge else_succ;
   int then_prob, else_prob;
 
+  /* We do not want to speculate (empty) loop latches.  */
+  if (current_loops
+      && else_bb->loop_father->latch == else_bb)
+    return FALSE;
+
   /* If we are partitioning hot/cold basic blocks, we don't want to
      mess up unconditional or indirect jumps that cross between hot
      and cold sections.

gcc/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2012-04-11  Richard Guenther  <rguenther@suse.de>
+
+	PR rtl-optimization/52881
+	* gcc.dg/torture/pr52881.c: New testcase.
+	* gcc.dg/torture/pr52913.c: Likewise.
+
 2012-04-11  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/52912

gcc/testsuite/gcc.dg/torture/pr52881.c

@@ -0,0 +1,35 @@
+/* { dg-do compile } */
+
+int a, b, c, d, e, f, h, i, j, k, l, m, n, o;
+static int g;
+int
+fn1 () {
+    for (;; ++f)
+      if (e)
+	break;
+    return 0;
+}
+unsigned char fn2 ();
+void
+fn3 () {
+lbl_220:
+    if (j) {
+lbl_221:
+	l = (g || b) <= fn1 ();
+	for (;;) {
+	    g = 0;
+	    fn2 ();
+	    if (k)
+	      goto lbl_220;
+	    break;
+	}
+	if (l)
+	  goto lbl_221;
+    }
+}
+unsigned char
+fn2 () {
+    o = d ? 0 : c;
+    h = m | a % o != n;
+    return i;
+}

gcc/testsuite/gcc.dg/torture/pr52913.c

@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+
+int a, b, c, d, e;
+void
+fn1 ()
+{
+lbl_101:
+  e = 0;
+lbl_274:
+  for (c = 0; c < 1; c = a)
+    if (d)
+      if (b)
+	goto lbl_101;
+      else
+	break;
+  d = 1;
+  goto lbl_274;
+}