Don't create superfluous parm in expand_omp_taskreg

2015-08-23  Tom de Vries  <tom@codesourcery.com>

	* omp-low.c (expand_omp_taskreg): If in ssa, set rhs of parcopy stmt to
	parm_decl, rather than generating a dummy default def in cfun.
	* tree-cfg.c (replace_ssa_name): Assume no default defs.  Make sure
	ssa_name from cfun and child_fn do not share a stmt as def stmt.
	(move_stmt_op): Handle PARM_DECl.
	(gather_ssa_name_hash_map_from): New function.
	(move_sese_region_to_fn): Add default defs for function params, and add
	them to vars_map.  Release copied ssa names.
	* tree-cfg.h (gather_ssa_name_hash_map_from): Declare.

From-SVN: r227103

gcc/ChangeLog

@@ -1,3 +1,15 @@
+2015-08-23  Tom de Vries  <tom@codesourcery.com>
+
+	* omp-low.c (expand_omp_taskreg): If in ssa, set rhs of parcopy stmt to
+	parm_decl, rather than generating a dummy default def in cfun.
+	* tree-cfg.c (replace_ssa_name): Assume no default defs.  Make sure
+	ssa_name from cfun and child_fn do not share a stmt as def stmt.
+	(move_stmt_op): Handle PARM_DECl.
+	(gather_ssa_name_hash_map_from): New function.
+	(move_sese_region_to_fn): Add default defs for function params, and add
+	them to vars_map.  Release copied ssa names.
+	* tree-cfg.h (gather_ssa_name_hash_map_from): Declare.
+
 2015-08-23  Tom de Vries  <tom@codesourcery.com>
 
 	* doc/sourcebuild.texi: Rename vect_no_int_max with

gcc/omp-low.c

@@ -5417,7 +5417,7 @@ expand_omp_taskreg (struct omp_region *region)
 	  basic_block entry_succ_bb
 	    = single_succ_p (entry_bb) ? single_succ (entry_bb)
 				       : FALLTHRU_EDGE (entry_bb)->dest;
-	  tree arg, narg;
+	  tree arg;
 	  gimple parcopy_stmt = NULL;
 
 	  for (gsi = gsi_start_bb (entry_succ_bb); ; gsi_next (&gsi))
@@ -5462,15 +5462,15 @@ expand_omp_taskreg (struct omp_region *region)
 	    }
 	  else
 	    {
-	      /* If we are in ssa form, we must load the value from the default
-		 definition of the argument.  That should not be defined now,
-		 since the argument is not used uninitialized.  */
-	      gcc_assert (ssa_default_def (cfun, arg) == NULL);
-	      narg = make_ssa_name (arg, gimple_build_nop ());
-	      set_ssa_default_def (cfun, arg, narg);
-	      /* ?? Is setting the subcode really necessary ??  */
-	      gimple_omp_set_subcode (parcopy_stmt, TREE_CODE (narg));
-	      gimple_assign_set_rhs1 (parcopy_stmt, narg);
+	      tree lhs = gimple_assign_lhs (parcopy_stmt);
+	      gcc_assert (SSA_NAME_VAR (lhs) == arg);
+	      /* We'd like to set the rhs to the default def in the child_fn,
+		 but it's too early to create ssa names in the child_fn.
+		 Instead, we set the rhs to the parm.  In
+		 move_sese_region_to_fn, we introduce a default def for the
+		 parm, map the parm to it's default def, and once we encounter
+		 this stmt, replace the parm with the default def.  */
+	      gimple_assign_set_rhs1 (parcopy_stmt, arg);
 	      update_stmt (parcopy_stmt);
 	    }
 	}

gcc/tree-cfg.c

@@ -6420,17 +6420,19 @@ replace_ssa_name (tree name, hash_map<tree, tree> *vars_map,
       tree decl = SSA_NAME_VAR (name);
       if (decl)
 	{
+	  gcc_assert (!SSA_NAME_IS_DEFAULT_DEF (name));
 	  replace_by_duplicate_decl (&decl, vars_map, to_context);
 	  new_name = make_ssa_name_fn (DECL_STRUCT_FUNCTION (to_context),
 				       decl, SSA_NAME_DEF_STMT (name));
-	  if (SSA_NAME_IS_DEFAULT_DEF (name))
-	    set_ssa_default_def (DECL_STRUCT_FUNCTION (to_context),
-				 decl, new_name);
 	}
       else
 	new_name = copy_ssa_name_fn (DECL_STRUCT_FUNCTION (to_context),
 				     name, SSA_NAME_DEF_STMT (name));
 
+      /* Now that we've used the def stmt to define new_name, make sure it
+	 doesn't define name anymore.  */
+      SSA_NAME_DEF_STMT (name) = NULL;
+
       vars_map->put (name, new_name);
     }
   else
@@ -6482,6 +6484,9 @@ move_stmt_op (tree *tp, int *walk_subtrees, void *data)
     {
       if (TREE_CODE (t) == SSA_NAME)
 	*tp = replace_ssa_name (t, p->vars_map, p->to_context);
+      else if (TREE_CODE (t) == PARM_DECL
+	       && gimple_in_ssa_p (cfun))
+	*tp = *(p->vars_map->get (t));
       else if (TREE_CODE (t) == LABEL_DECL)
 	{
 	  if (p->new_label_map)
@@ -6992,6 +6997,19 @@ verify_sese (basic_block entry, basic_block exit, vec<basic_block> *bbs_p)
   BITMAP_FREE (bbs);
 }
 
+/* If FROM is an SSA_NAME, mark the version in bitmap DATA.  */
+
+bool
+gather_ssa_name_hash_map_from (tree const &from, tree const &, void *data)
+{
+  bitmap release_names = (bitmap)data;
+
+  if (TREE_CODE (from) != SSA_NAME)
+    return true;
+
+  bitmap_set_bit (release_names, SSA_NAME_VERSION (from));
+  return true;
+}
 
 /* Move a single-entry, single-exit region delimited by ENTRY_BB and
    EXIT_BB to function DEST_CFUN.  The whole region is replaced by a
@@ -7189,6 +7207,14 @@ move_sese_region_to_fn (struct function *dest_cfun, basic_block entry_bb,
   d.eh_map = eh_map;
   d.remap_decls_p = true;
 
+  if (gimple_in_ssa_p (cfun))
+    for (tree arg = DECL_ARGUMENTS (d.to_context); arg; arg = DECL_CHAIN (arg))
+      {
+	tree narg = make_ssa_name_fn (dest_cfun, arg, gimple_build_nop ());
+	set_ssa_default_def (dest_cfun, arg, narg);
+	vars_map.put (arg, narg);
+      }
+
   FOR_EACH_VEC_ELT (bbs, i, bb)
     {
       /* No need to update edge counts on the last block.  It has
@@ -7246,6 +7272,19 @@ move_sese_region_to_fn (struct function *dest_cfun, basic_block entry_bb,
   if (eh_map)
     delete eh_map;
 
+  if (gimple_in_ssa_p (cfun))
+    {
+      /* We need to release ssa-names in a defined order, so first find them,
+	 and then iterate in ascending version order.  */
+      bitmap release_names = BITMAP_ALLOC (NULL);
+      vars_map.traverse<void *, gather_ssa_name_hash_map_from> (release_names);
+      bitmap_iterator bi;
+      unsigned i;
+      EXECUTE_IF_SET_IN_BITMAP (release_names, 0, i, bi)
+	release_ssa_name (ssa_name (i));
+      BITMAP_FREE (release_names);
+    }
+
   /* Rewire the entry and exit blocks.  The successor to the entry
      block turns into the successor of DEST_FN's ENTRY_BLOCK_PTR in
      the child function.  Similarly, the predecessor of DEST_FN's

gcc/tree-cfg.h

@@ -75,6 +75,7 @@ extern bool gimple_duplicate_sese_tail (edge, edge, basic_block *, unsigned,
 extern void gather_blocks_in_sese_region (basic_block entry, basic_block exit,
 					  vec<basic_block> *bbs_p);
 extern void verify_sese (basic_block, basic_block, vec<basic_block> *);
+extern bool gather_ssa_name_hash_map_from (tree const &, tree const &, void *);
 extern basic_block move_sese_region_to_fn (struct function *, basic_block,
 				           basic_block, tree);
 extern void dump_function_to_file (tree, FILE *, int);