re PR tree-optimization/81403 (wrong code at -O3)

2017-11-23  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/81403
	* tree-ssa-pre.c (get_representative_for): Add parameter specifying
	a block we need a leader relative to.
	(phi_translate_1): For nary processing require a leader from
	get_representative_for given we run expression simplification
	using match-and-simplify.  Remove previous fix.

From-SVN: r255092

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 8d5ee90..7cabfd6 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2017-11-23  Richard Biener  <rguenther@suse.de>
+
+       PR tree-optimization/81403
+       * tree-ssa-pre.c (get_representative_for): Add parameter specifying
+       a block we need a leader relative to.
+       (phi_translate_1): For nary processing require a leader from
+       get_representative_for given we run expression simplification
+       using match-and-simplify.  Remove previous fix.
+
 2017-11-22  Jeff Law  <law@redhat.com>
 
        * gimple-ssa-evrp-analyze.c (evrp_range_analyzer::try_find_new_range):

diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c
index 477a41e..a9dcd5e 100644 (file)
--- a/gcc/tree-ssa-pre.c
+++ b/gcc/tree-ssa-pre.c
@@ -1257,7 +1257,7 @@ get_expr_type (const pre_expr e)
   gcc_unreachable ();
 }
 
-/* Get a representative SSA_NAME for a given expression.
+/* Get a representative SSA_NAME for a given expression that is available in B.
    Since all of our sub-expressions are treated as values, we require
    them to be SSA_NAME's for simplicity.
    Prior versions of GVNPRE used to use "value handles" here, so that
@@ -1266,9 +1266,9 @@ get_expr_type (const pre_expr e)
    them to be usable without finding leaders).  */
 
 static tree
-get_representative_for (const pre_expr e)
+get_representative_for (const pre_expr e, basic_block b = NULL)
 {
-  tree name;
+  tree name, valnum = NULL_TREE;
   unsigned int value_id = get_expr_value_id (e);
 
   switch (e->kind)
@@ -1289,7 +1289,18 @@ get_representative_for (const pre_expr e)
          {
            pre_expr rep = expression_for_id (i);
            if (rep->kind == NAME)
-             return VN_INFO (PRE_EXPR_NAME (rep))->valnum;
+             {
+               tree name = PRE_EXPR_NAME (rep);
+               valnum = VN_INFO (name)->valnum;
+               gimple *def = SSA_NAME_DEF_STMT (name);
+               /* We have to return either a new representative or one
+                  that can be used for expression simplification and thus
+                  is available in B.  */
+               if (! b 
+                   || gimple_nop_p (def)
+                   || dominated_by_p (CDI_DOMINATORS, b, gimple_bb (def)))
+                 return name;
+             }
            else if (rep->kind == CONSTANT)
              return PRE_EXPR_CONSTANT (rep);
          }
@@ -1305,7 +1316,7 @@ get_representative_for (const pre_expr e)
      to compute it.  */
   name = make_temp_ssa_name (get_expr_type (e), gimple_build_nop (), "pretmp");
   VN_INFO_GET (name)->value_id = value_id;
-  VN_INFO (name)->valnum = name;
+  VN_INFO (name)->valnum = valnum ? valnum : name;
   /* ???  For now mark this SSA name for release by SCCVN.  */
   VN_INFO (name)->needs_insertion = true;
   add_to_value (value_id, get_or_alloc_expr_for_name (name));
@@ -1356,7 +1367,9 @@ phi_translate_1 (pre_expr expr, bitmap_set_t set1, bitmap_set_t set2,
                leader = find_leader_in_sets (op_val_id, set1, set2);
                 result = phi_translate (leader, set1, set2, pred, phiblock);
                if (result && result != leader)
-                 newnary->op[i] = get_representative_for (result);
+                 /* Force a leader as well as we are simplifying this
+                    expression.  */
+                 newnary->op[i] = get_representative_for (result, pred);
                else if (!result)
                  return NULL;
 
@@ -1398,6 +1411,10 @@ phi_translate_1 (pre_expr expr, bitmap_set_t set1, bitmap_set_t set2,
                  return constant;
              }
 
+           /* vn_nary_* do not valueize operands.  */
+           for (i = 0; i < newnary->length; ++i)
+             if (TREE_CODE (newnary->op[i]) == SSA_NAME)
+               newnary->op[i] = VN_INFO (newnary->op[i])->valnum;
            tree result = vn_nary_op_lookup_pieces (newnary->length,
                                                    newnary->opcode,
                                                    newnary->type,
@@ -1414,45 +1431,6 @@ phi_translate_1 (pre_expr expr, bitmap_set_t set1, bitmap_set_t set2,
                PRE_EXPR_NARY (expr) = nary;
                new_val_id = nary->value_id;
                get_or_alloc_expression_id (expr);
-               /* When we end up re-using a value number make sure that
-                  doesn't have unrelated (which we can't check here)
-                  range or points-to info on it.  */
-               if (result
-                   && INTEGRAL_TYPE_P (TREE_TYPE (result))
-                   && SSA_NAME_RANGE_INFO (result)
-                   && ! SSA_NAME_IS_DEFAULT_DEF (result))
-                 {
-                   if (! VN_INFO (result)->info.range_info)
-                     {
-                       VN_INFO (result)->info.range_info
-                         = SSA_NAME_RANGE_INFO (result);
-                       VN_INFO (result)->range_info_anti_range_p
-                         = SSA_NAME_ANTI_RANGE_P (result);
-                     }
-                   if (dump_file && (dump_flags & TDF_DETAILS))
-                     {
-                       fprintf (dump_file, "clearing range info of ");
-                       print_generic_expr (dump_file, result);
-                       fprintf (dump_file, "\n");
-                     }
-                   SSA_NAME_RANGE_INFO (result) = NULL;
-                 }
-               else if (result
-                        && POINTER_TYPE_P (TREE_TYPE (result))
-                        && SSA_NAME_PTR_INFO (result)
-                        && ! SSA_NAME_IS_DEFAULT_DEF (result))
-                 {
-                   if (! VN_INFO (result)->info.ptr_info)
-                     VN_INFO (result)->info.ptr_info
-                       = SSA_NAME_PTR_INFO (result);
-                   if (dump_file && (dump_flags & TDF_DETAILS))
-                     {
-                       fprintf (dump_file, "clearing points-to info of ");
-                       print_generic_expr (dump_file, result);
-                       fprintf (dump_file, "\n");
-                     }
-                   SSA_NAME_PTR_INFO (result) = NULL;
-                 }
              }
            else
              {