re PR tree-optimization/67121 (wrong code at -O3 on x86_64-linux-gnu)

2015-08-05  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/67121
	* tree-if-conv.c (combine_blocks): Clear range-info produced
	by stmts no longer executed conditionally.

	* gcc.dg/torture/pr67121.c: New testcase.

From-SVN: r226630

gcc/ChangeLog

+2015-08-05  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/67121
+	* tree-if-conv.c (combine_blocks): Clear range-info produced
+	by stmts no longer executed conditionally.
+
 2015-08-05  Nick Clifton  <nickc@redhat.com>
 
 	* config/rl78/rl78.c (rl78_force_nonfar_3): Remove optimization

gcc/testsuite/ChangeLog

+2015-08-05  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/67121
+	* gcc.dg/torture/pr67121.c: New testcase.
+
 2015-08-05  Nick Clifton  <nickc@redhat.com>
 
 	* gcc.target/rl78: New directory.

gcc/testsuite/gcc.dg/torture/pr67121.c

+/* { dg-do run } */
+
+int a[6], b, c = 226, d, e, f;
+signed char g;
+
+void
+fn1 (int p1)
+{
+  b = a[p1];
+}
+
+int
+main ()
+{
+  a[0] = 1;
+  for (f = 0; f < 9; f++)
+    {
+      signed char h = c;
+      int i = 1;
+      g = h < 0 ? h : h >> i;
+      e = g;
+      for (d = 1; d; d = 0)
+	;
+    }
+  fn1 (g >> 8 & 1);
+
+  if (b != 0) 
+    __builtin_abort (); 
+
+  return 0;
+}

gcc/tree-if-conv.c

@@ -2199,9 +2199,11 @@ combine_blocks (struct loop *loop, bool any_mask_load_store)
   /* Merge basic blocks: first remove all the edges in the loop,
      except for those from the exit block.  */
   exit_bb = NULL;
+  bool *predicated = XNEWVEC (bool, orig_loop_num_nodes);
   for (i = 0; i < orig_loop_num_nodes; i++)
     {
       bb = ifc_bbs[i];
+      predicated[i] = !is_true_predicate (bb_predicate (bb));
       free_bb_predicate (bb);
       if (bb_with_exit_edge_p (loop, bb))
 	{
@@ -2259,9 +2261,21 @@ combine_blocks (struct loop *loop, bool any_mask_load_store)
       if (bb == exit_bb || bb == loop->latch)
 	continue;
 
-      /* Make stmts member of loop->header.  */
+      /* Make stmts member of loop->header and clear range info from all stmts
+	 in BB which is now no longer executed conditional on a predicate we
+	 could have derived it from.  */
       for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
-	gimple_set_bb (gsi_stmt (gsi), merge_target_bb);
+	{
+	  gimple stmt = gsi_stmt (gsi);
+	  gimple_set_bb (stmt, merge_target_bb);
+	  if (predicated[i])
+	    {
+	      ssa_op_iter i;
+	      tree op;
+	      FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_DEF)
+		reset_flow_sensitive_info (op);
+	    }
+	}
 
       /* Update stmt list.  */
       last = gsi_last_bb (merge_target_bb);
@@ -2281,6 +2295,7 @@ combine_blocks (struct loop *loop, bool any_mask_load_store)
 
   free (ifc_bbs);
   ifc_bbs = NULL;
+  free (predicated);
 }
 
 /* Version LOOP before if-converting it; the original loop