re PR tree-optimization/61221 (ICE on valid code at -O1 and above on x86_64-linux-gnu)

2014-05-19  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/61221
	* tree-ssa-pre.c (eliminate_dom_walker::before_dom_children):
	Do nothing for unreachable blocks.
	* tree-ssa-sccvn.c (cond_dom_walker::before_dom_children):
	Improve unreachability detection.

	* gcc.dg/torture/pr61221.c: New testcase.

From-SVN: r210614

gcc/ChangeLog

 2014-05-19  Richard Biener  <rguenther@suse.de>
 
+	PR tree-optimization/61221
+	* tree-ssa-pre.c (eliminate_dom_walker::before_dom_children):
+	Do nothing for unreachable blocks.
+	* tree-ssa-sccvn.c (cond_dom_walker::before_dom_children):
+	Improve unreachability detection.
+
+2014-05-19  Richard Biener  <rguenther@suse.de>
+
 	PR tree-optimization/61209
 	* tree-ssa-sccvn.c (visit_phi): Avoid setting expr to VN_TOP.
 

gcc/testsuite/ChangeLog

 2014-05-19  Richard Biener  <rguenther@suse.de>
 
+	PR tree-optimization/61221
+	* gcc.dg/torture/pr61221.c: New testcase.
+
+2014-05-19  Richard Biener  <rguenther@suse.de>
+
 	PR tree-optimization/61209
 	* gfortran.dg/pr61209.f90: New testcase.
 

gcc/testsuite/gcc.dg/torture/pr61221.c

+/* { dg-do compile } */
+
+void __assert_fail (void);
+
+int **a, b, c, e, *j;
+short *d, **f;
+
+int *
+foo ()
+{
+  *a = j;
+  if (!(1 & e)) 
+    __assert_fail ();
+  return 0;
+}
+
+void
+bar ()
+{
+  int *g = &b;
+  short **h = &d;
+  if ((f = &d) != h)
+    for (; b;)
+      {
+	int i = 1;
+	if (i)
+	  g = foo ();
+	c = 0;
+      }
+  if (!g)
+    __assert_fail ();
+}

gcc/tree-ssa-pre.c

@@ -4010,6 +4010,15 @@ eliminate_dom_walker::before_dom_children (basic_block b)
   /* Mark new bb.  */
   el_avail_stack.safe_push (NULL_TREE);
 
+  /* If this block is not reachable do nothing.  */
+  edge_iterator ei;
+  edge e;
+  FOR_EACH_EDGE (e, ei, b->preds)
+    if (e->flags & EDGE_EXECUTABLE)
+      break;
+  if (!e)
+    return;
+
   for (gsi = gsi_start_phis (b); !gsi_end_p (gsi);)
     {
       gimple stmt, phi = gsi_stmt (gsi);

gcc/tree-ssa-sccvn.c

@@ -4177,11 +4177,13 @@ cond_dom_walker::before_dom_children (basic_block bb)
   if (fail)
     return;
 
-  /* If any of the predecessor edges are still marked as possibly
-     executable consider this block reachable.  */
+  /* If any of the predecessor edges that do not come from blocks dominated
+     by us are still marked as possibly executable consider this block
+     reachable.  */
   bool reachable = bb == ENTRY_BLOCK_PTR_FOR_FN (cfun);
   FOR_EACH_EDGE (e, ei, bb->preds)
-    reachable |= (e->flags & EDGE_EXECUTABLE);
+    if (!dominated_by_p (CDI_DOMINATORS, e->src, bb))
+      reachable |= (e->flags & EDGE_EXECUTABLE);
 
   /* If the block is not reachable all outgoing edges are not
      executable.  */