re PR tree-optimization/67470 (ICE at -O3 on x86_64-linux-gnu in…

re PR tree-optimization/67470 (ICE at -O3 on x86_64-linux-gnu in compute_live_loop_exits, at tree-ssa-loop-manip.c:235)

2015-09-15  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/67470
	* tree-ssa-loop-im.c (execute_sm_if_changed): Preserve PHI
	structure for PHI hoisting by inserting a forwarder block
	if appropriate.

	* gcc.dg/torture/pr67470.c: New testcase.

From-SVN: r227797

gcc/ChangeLog

+2015-09-15  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/67470
+	* tree-ssa-loop-im.c (execute_sm_if_changed): Preserve PHI
+	structure for PHI hoisting by inserting a forwarder block
+	if appropriate.
+
 2015-09-15  Christian Bruel  <christian.bruel@st.com>
 
 	* config/arm/arm.c (TARGET_OPTION_PRINT): Define.

gcc/testsuite/ChangeLog

+2015-09-15  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/67470
+	* gcc.dg/torture/pr67470.c: New testcase.
+
 2015-09-15  Alan Lawrence  <alan.lawrence@arm.com>
 
 	* gcc.target/aarch64/vect_int32x2x4_1.c: New.

gcc/testsuite/gcc.dg/torture/pr67470.c

+/* { dg-do run } */
+
+int a, b, *c, d, e;
+
+void abort (void);
+
+int
+main ()
+{
+  int f, *g, **h = &g;
+  for (; b;)
+    {
+      c = &a;
+      for (e = 0; e < 1; e++)
+	*h = 0;
+      for (; d; d++)
+	if (f)
+	  *c = 0;
+	else
+	  {
+	    *c = e = 0;
+	    *h = &a;
+	  }
+
+      if (a && !g)
+	abort ();
+
+    }
+  return 0;
+}

gcc/tree-ssa-loop-im.c

@@ -1839,6 +1839,23 @@ execute_sm_if_changed (edge ex, tree mem, tree tmp_var, tree flag)
 
   if (loop_has_only_one_exit)
     ex = split_block_after_labels (ex->dest);
+  else
+    {
+      for (gphi_iterator gpi = gsi_start_phis (ex->dest);
+	   !gsi_end_p (gpi); gsi_next (&gpi))
+	{
+	  gphi *phi = gpi.phi ();
+	  if (virtual_operand_p (gimple_phi_result (phi)))
+	    continue;
+
+	  /* When the destination has a non-virtual PHI node with multiple
+	     predecessors make sure we preserve the PHI structure by
+	     forcing a forwarder block so that hoisting of that PHI will
+	     still work.  */
+	  split_edge (ex);
+	  break;
+	}
+    }
 
   old_dest = ex->dest;
   new_bb = split_edge (ex);