re PR tree-optimization/47365 (wrong code with -O -ftree-pre)

2011-01-21  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/47365
	* tree-ssa-sccvn.h (vn_lookup_kind): Declare.
	(vn_reference_lookup_pieces): Adjust.
	(vn_reference_lookup): Likewise.
	* tree-ssa-sccvn.c (vn_walk_kind): New static global.
	(vn_reference_lookup_3): Only look through kills if in
	VN_WALKREWRITE mode.
	(vn_reference_lookup_pieces): Adjust.
	(vn_reference_lookup): Likewise.
	(visit_reference_op_load): Likewise.
	(visit_reference_op_store): Likewise.
	* tree-ssa-pre.c (phi_translate_1): Use VN_WALK mode.
	(compute_avail): Likewise.
	(eliminate): Likewise.

	* gcc.dg/torture/pr47365.c: New testcase.
	* gcc.dg/tree-ssa/pr47392.c: Likewise.

From-SVN: r169089

gcc/ChangeLog

+2011-01-21  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/47365
+	* tree-ssa-sccvn.h (vn_lookup_kind): Declare.
+	(vn_reference_lookup_pieces): Adjust.
+	(vn_reference_lookup): Likewise.
+	* tree-ssa-sccvn.c (vn_walk_kind): New static global.
+	(vn_reference_lookup_3): Only look through kills if in
+	VN_WALKREWRITE mode.
+	(vn_reference_lookup_pieces): Adjust.
+	(vn_reference_lookup): Likewise.
+	(visit_reference_op_load): Likewise.
+	(visit_reference_op_store): Likewise.
+	* tree-ssa-pre.c (phi_translate_1): Use VN_WALK mode.
+	(compute_avail): Likewise.
+	(eliminate): Likewise.
+
 2011-01-21  Jakub Jelinek  <jakub@redhat.com>
 
 	* tree-ssa-live.c (remove_unused_scope_block_p): Don't remove

gcc/testsuite/ChangeLog

+2011-01-21  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/47365
+	* gcc.dg/torture/pr47365.c: New testcase.
+	* gcc.dg/tree-ssa/pr47392.c: Likewise.
+
 2011-01-21  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
 
 	* g++.dg/other/anon5.C: Skip on mips-sgi-irix*.

gcc/testsuite/gcc.dg/torture/pr47365.c

+/* { dg-do run } */
+
+struct A
+{
+  int i;
+};
+
+struct B
+{
+  struct A a[2];
+};
+
+int i = 1;
+struct B b = { 0, 3 };
+
+static void
+test ()
+{
+  if (b.a[0].i != i)
+    {
+      int t = b.a[0].i;
+      b.a[0] = b.a[1];
+      b.a[1].i = t;
+    }
+
+  if (b.a[1].i == i)
+    __builtin_abort ();
+
+  if (b.a[0].i == 0)
+    __builtin_abort ();
+}
+
+int
+main ()
+{
+  test ();
+  return 0;
+}
+

gcc/testsuite/gcc.dg/tree-ssa/pr47392.c

+/* { dg-do run } */
+/* { dg-options "-O2 -fdump-tree-pre-stats" } */
+
+struct A
+{
+  int i;
+};
+
+struct B
+{
+  struct A a[2];
+};
+
+int i = 1;
+struct B b = { 0, 3 };
+
+static void
+test ()
+{
+  if (b.a[0].i != i)
+    {
+      int t = b.a[0].i;
+      b.a[0] = b.a[1];
+      b.a[1].i = t;
+    }
+
+  if (b.a[1].i == i)
+    __builtin_abort ();
+
+  if (b.a[0].i == 0)
+    __builtin_abort ();
+}
+
+int __attribute__((hot))
+main ()
+{
+  test ();
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump "Eliminated: 1" "pre" } } */
+/* { dg-final { cleanup-tree-dump "pre" } } */

gcc/tree-ssa-pre.c

@@ -1681,7 +1681,7 @@ phi_translate_1 (pre_expr expr, bitmap_set_t set1, bitmap_set_t set2,
 	    tree result = vn_reference_lookup_pieces (newvuse, ref->set,
 						      ref->type,
 						      newoperands,
-						      &newref, true);
+						      &newref, VN_WALK);
 	    if (result)
 	      VEC_free (vn_reference_op_s, heap, newoperands);
 
@@ -2594,6 +2594,10 @@ compute_antic (void)
     {
       if (dump_file && (dump_flags & TDF_DETAILS))
 	fprintf (dump_file, "Starting iteration %d\n", num_iterations);
+      /* ???  We need to clear our PHI translation cache here as the
+         ANTIC sets shrink and we restrict valid translations to
+	 those having operands with leaders in ANTIC.  Same below
+	 for PA ANTIC computation.  */
       num_iterations++;
       changed = false;
       for (i = n_basic_blocks - NUM_FIXED_BLOCKS - 1; i >= 0; i--)
@@ -3607,10 +3611,22 @@ do_regular_insertion (basic_block block, basic_block dom)
 	     already existing along every predecessor, and
 	     it's defined by some predecessor, it is
 	     partially redundant.  */
-	  if (!cant_insert && !all_same && by_some && do_insertion
-	      && dbg_cnt (treepre_insert))
+	  if (!cant_insert && !all_same && by_some)
 	    {
-	      if (insert_into_preds_of_block (block, get_expression_id (expr),
+	      if (!do_insertion)
+		{
+		  if (dump_file && (dump_flags & TDF_DETAILS))
+		    {
+		      fprintf (dump_file, "Skipping partial redundancy for "
+			       "expression ");
+		      print_pre_expr (dump_file, expr);
+		      fprintf (dump_file, " (%04d), no redundancy on to be "
+			       "optimized for speed edge\n", val);
+		    }
+		}
+	      else if (dbg_cnt (treepre_insert)
+		       && insert_into_preds_of_block (block,
+						      get_expression_id (expr),
 						      avail))
 		new_stuff = true;
 	    }
@@ -3999,7 +4015,7 @@ compute_avail (void)
 		copy_reference_ops_from_call (stmt, &ops);
 		vn_reference_lookup_pieces (gimple_vuse (stmt), 0,
 					    gimple_expr_type (stmt),
-					    ops, &ref, false);
+					    ops, &ref, VN_NOWALK);
 		VEC_free (vn_reference_op_s, heap, ops);
 		if (!ref)
 		  continue;
@@ -4069,7 +4085,7 @@ compute_avail (void)
 
 		      vn_reference_lookup (gimple_assign_rhs1 (stmt),
 					   gimple_vuse (stmt),
-					   true, &ref);
+					   VN_WALK, &ref);
 		      if (!ref)
 			continue;
 
@@ -4313,7 +4329,7 @@ eliminate (void)
 	      tree rhs = gimple_assign_rhs1 (stmt);
 	      tree val;
 	      val = vn_reference_lookup (gimple_assign_lhs (stmt),
-					 gimple_vuse (stmt), true, NULL);
+					 gimple_vuse (stmt), VN_WALK, NULL);
 	      if (TREE_CODE (rhs) == SSA_NAME)
 		rhs = VN_INFO (rhs)->valnum;
 	      if (val

gcc/tree-ssa-sccvn.c

@@ -1243,6 +1243,7 @@ vn_reference_lookup_1 (vn_reference_t vr, vn_reference_t *vnresult)
 }
 
 static tree *last_vuse_ptr;
+static vn_lookup_kind vn_walk_kind;
 
 /* Callback for walk_non_aliased_vuses.  Adjusts the vn_reference_t VR_
    with the current VUSE and performs the expression lookup.  */
@@ -1379,7 +1380,8 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *vr_)
 
   /* For aggregate copies translate the reference through them if
      the copy kills ref.  */
-  else if (gimple_assign_single_p (def_stmt)
+  else if (vn_walk_kind == VN_WALKREWRITE
+	   && gimple_assign_single_p (def_stmt)
 	   && (DECL_P (gimple_assign_rhs1 (def_stmt))
 	       || TREE_CODE (gimple_assign_rhs1 (def_stmt)) == MEM_REF
 	       || handled_component_p (gimple_assign_rhs1 (def_stmt))))
@@ -1473,7 +1475,7 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *vr_)
 tree
 vn_reference_lookup_pieces (tree vuse, alias_set_type set, tree type,
 			    VEC (vn_reference_op_s, heap) *operands,
-			    vn_reference_t *vnresult, bool maywalk)
+			    vn_reference_t *vnresult, vn_lookup_kind kind)
 {
   struct vn_reference_s vr1;
   vn_reference_t tmp;
@@ -1501,10 +1503,11 @@ vn_reference_lookup_pieces (tree vuse, alias_set_type set, tree type,
 
   vn_reference_lookup_1 (&vr1, vnresult);
   if (!*vnresult
-      && maywalk
+      && kind != VN_NOWALK
       && vr1.vuse)
     {
       ao_ref r;
+      vn_walk_kind = kind;
       if (ao_ref_init_from_vn_reference (&r, set, type, vr1.operands))
 	*vnresult =
 	  (vn_reference_t)walk_non_aliased_vuses (&r, vr1.vuse,
@@ -1527,7 +1530,7 @@ vn_reference_lookup_pieces (tree vuse, alias_set_type set, tree type,
    stored in the hashtable if one exists.  */
 
 tree
-vn_reference_lookup (tree op, tree vuse, bool maywalk,
+vn_reference_lookup (tree op, tree vuse, vn_lookup_kind kind,
 		     vn_reference_t *vnresult)
 {
   VEC (vn_reference_op_s, heap) *operands;
@@ -1545,12 +1548,13 @@ vn_reference_lookup (tree op, tree vuse, bool maywalk,
   if ((cst = fully_constant_vn_reference_p (&vr1)))
     return cst;
 
-  if (maywalk
+  if (kind != VN_NOWALK
       && vr1.vuse)
     {
       vn_reference_t wvnresult;
       ao_ref r;
       ao_ref_init (&r, op);
+      vn_walk_kind = kind;
       wvnresult =
 	(vn_reference_t)walk_non_aliased_vuses (&r, vr1.vuse,
 						vn_reference_lookup_2,
@@ -2257,14 +2261,14 @@ visit_reference_op_load (tree lhs, tree op, gimple stmt)
 
   last_vuse = gimple_vuse (stmt);
   last_vuse_ptr = &last_vuse;
-  result = vn_reference_lookup (op, gimple_vuse (stmt), true, NULL);
+  result = vn_reference_lookup (op, gimple_vuse (stmt), VN_WALKREWRITE, NULL);
   last_vuse_ptr = NULL;
 
   /* If we have a VCE, try looking up its operand as it might be stored in
      a different type.  */
   if (!result && TREE_CODE (op) == VIEW_CONVERT_EXPR)
     result = vn_reference_lookup (TREE_OPERAND (op, 0), gimple_vuse (stmt),
-    				  true, NULL);
+    				  VN_WALKREWRITE, NULL);
 
   /* We handle type-punning through unions by value-numbering based
      on offset and size of the access.  Be prepared to handle a
@@ -2375,7 +2379,7 @@ visit_reference_op_store (tree lhs, tree op, gimple stmt)
      Otherwise, the vdefs for the store are used when inserting into
      the table, since the store generates a new memory state.  */
 
-  result = vn_reference_lookup (lhs, gimple_vuse (stmt), false, NULL);
+  result = vn_reference_lookup (lhs, gimple_vuse (stmt), VN_NOWALK, NULL);
 
   if (result)
     {

gcc/tree-ssa-sccvn.h

@@ -187,10 +187,11 @@ void copy_reference_ops_from_ref (tree, VEC(vn_reference_op_s, heap) **);
 void copy_reference_ops_from_call (gimple, VEC(vn_reference_op_s, heap) **);
 bool ao_ref_init_from_vn_reference (ao_ref *, alias_set_type, tree,
 				    VEC (vn_reference_op_s, heap) *);
+typedef enum { VN_NOWALK, VN_WALK, VN_WALKREWRITE } vn_lookup_kind;
 tree vn_reference_lookup_pieces (tree, alias_set_type, tree,
 				 VEC (vn_reference_op_s, heap) *,
-				 vn_reference_t *, bool);
-tree vn_reference_lookup (tree, tree, bool, vn_reference_t *);
+				 vn_reference_t *, vn_lookup_kind);
+tree vn_reference_lookup (tree, tree, vn_lookup_kind, vn_reference_t *);
 vn_reference_t vn_reference_insert (tree, tree, tree);
 vn_reference_t vn_reference_insert_pieces (tree, alias_set_type, tree,
 					   VEC (vn_reference_op_s, heap) *,