Update copyright years.

[thirdparty/gcc.git] / gcc / tree-ssa-pre.c

diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c
index d1fe72cca3f699402fc4e70c435ae692e47f462c..681c412d130e6c03106b0f88b7d69ea453a7f218 100644 (file)
--- a/gcc/tree-ssa-pre.c
+++ b/gcc/tree-ssa-pre.c
@@ -1,5 +1,5 @@
 /* Full and partial redundancy elimination and code hoisting on SSA GIMPLE.
-   Copyright (C) 2001-2016 Free Software Foundation, Inc.
+   Copyright (C) 2001-2017 Free Software Foundation, Inc.
    Contributed by Daniel Berlin <dan@dberlin.org> and Steven Bosscher
    <stevenb@suse.de>
 
@@ -2025,9 +2025,17 @@ prune_clobbered_mems (bitmap_set_t set, basic_block block)
 {
   bitmap_iterator bi;
   unsigned i;
+  pre_expr to_remove = NULL;
 
   FOR_EACH_EXPR_ID_IN_SET (set, i, bi)
     {
+      /* Remove queued expr.  */
+      if (to_remove)
+       {
+         bitmap_remove_from_set (set, to_remove);
+         to_remove = NULL;
+       }
+
       pre_expr expr = expression_for_id (i);
       if (expr->kind == REFERENCE)
        {
@@ -2041,7 +2049,7 @@ prune_clobbered_mems (bitmap_set_t set, basic_block block)
                                           block, gimple_bb (def_stmt)))
                      || (gimple_bb (def_stmt) == block
                          && value_dies_in_block_x (expr, block))))
-               bitmap_remove_from_set (set, expr);
+               to_remove = expr;
            }
        }
       else if (expr->kind == NARY)
@@ -2053,9 +2061,13 @@ prune_clobbered_mems (bitmap_set_t set, basic_block block)
             as the available expression might be after the exit point.  */
          if (BB_MAY_NOTRETURN (block)
              && vn_nary_may_trap (nary))
-           bitmap_remove_from_set (set, expr);
+           to_remove = expr;
        }
     }
+
+  /* Remove queued expr.  */
+  if (to_remove)
+    bitmap_remove_from_set (set, to_remove);
 }
 
 static sbitmap has_abnormal_preds;
@@ -2881,13 +2893,16 @@ create_expression_by_pieces (basic_block block, pre_expr expr,
     }
   /* Likewise if we simplified to sth not queued for insertion.  */
   bool found = false;
-  gsi = gsi_start (forced_stmts);
-  for (; !gsi_end_p (gsi); gsi_next (&gsi))
+  gsi = gsi_last (forced_stmts);
+  for (; !gsi_end_p (gsi); gsi_prev (&gsi))
     {
       gimple *stmt = gsi_stmt (gsi);
       tree forcedname = gimple_get_lhs (stmt);
       if (forcedname == folded)
-       found = true;
+       {
+         found = true;
+         break;
+       }
     }
   if (! found)
     {
@@ -4428,26 +4443,36 @@ eliminate_dom_walker::before_dom_children (basic_block b)
          && !is_gimple_reg (gimple_assign_lhs (stmt))
          && (TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME
              || is_gimple_min_invariant (gimple_assign_rhs1 (stmt))))
-        {
-          tree val;
+       {
+         tree val;
          tree rhs = gimple_assign_rhs1 (stmt);
-          val = vn_reference_lookup (gimple_assign_lhs (stmt),
-                                     gimple_vuse (stmt), VN_WALK, NULL, false);
-          if (TREE_CODE (rhs) == SSA_NAME)
-            rhs = VN_INFO (rhs)->valnum;
-          if (val
-              && operand_equal_p (val, rhs, 0))
-            {
-              if (dump_file && (dump_flags & TDF_DETAILS))
-                {
-                  fprintf (dump_file, "Deleted redundant store ");
-                  print_gimple_stmt (dump_file, stmt, 0, 0);
-                }
+         vn_reference_t vnresult;
+         val = vn_reference_lookup (lhs, gimple_vuse (stmt), VN_WALKREWRITE,
+                                    &vnresult, false);
+         if (TREE_CODE (rhs) == SSA_NAME)
+           rhs = VN_INFO (rhs)->valnum;
+         if (val
+             && operand_equal_p (val, rhs, 0))
+           {
+             /* We can only remove the later store if the former aliases
+                at least all accesses the later one does or if the store
+                was to readonly memory storing the same value.  */
+             alias_set_type set = get_alias_set (lhs);
+             if (! vnresult
+                 || vnresult->set == set
+                 || alias_set_subset_of (set, vnresult->set))
+               {
+                 if (dump_file && (dump_flags & TDF_DETAILS))
+                   {
+                     fprintf (dump_file, "Deleted redundant store ");
+                     print_gimple_stmt (dump_file, stmt, 0, 0);
+                   }
 
-              /* Queue stmt for removal.  */
-              el_to_remove.safe_push (stmt);
-             continue;
-            }
+                 /* Queue stmt for removal.  */
+                 el_to_remove.safe_push (stmt);
+                 continue;
+               }
+           }
        }
 
       /* If this is a control statement value numbering left edges