[PATCH] eliminate calls to build_constructor_from_list in Fortran FE

[Nathan Froyd <froydnj at codesourcery dot com>]

The patch below eliminates calls to build_constructor_from_list from the
Fortran FE.  The benefit is less consing during compilation and one less
obstacle to getting rid of TREE_LIST.

Tested on x86_64-unknown-linux-gnu.  OK?

-Nathan

	* trans-array.c (gfc_trans_array_constructor_value): Use
	build_constructor instead of build_constructor_from_list.
	(gfc_build_constant_array_constructor): Likewise.
	* trans-decl.c (create_main_function): Likewise.
	* trans-stmt.c (gfc_trans_character_select): Likewise.

diff --git a/gcc/fortran/trans-array.c b/gcc/fortran/trans-array.c
index 8ece643..a94c8d2 100644
--- a/gcc/fortran/trans-array.c
+++ b/gcc/fortran/trans-array.c
@@ -1308,14 +1308,13 @@ gfc_trans_array_constructor_value (stmtblock_t * pblock, tree type,
 	  else
 	    {
 	      /* Collect multiple scalar constants into a constructor.  */
-	      tree list;
+	      VEC(constructor_elt,gc) *v = NULL;
 	      tree init;
 	      tree bound;
 	      tree tmptype;
 	      HOST_WIDE_INT idx = 0;
 
 	      p = c;
-	      list = NULL_TREE;
               /* Count the number of consecutive scalar constants.  */
 	      while (p && !(p->iterator
 			    || p->expr->expr_type != EXPR_CONSTANT))
@@ -1332,8 +1331,10 @@ gfc_trans_array_constructor_value (stmtblock_t * pblock, tree type,
 				(gfc_get_pchar_type (p->expr->ts.kind),
 				 se.expr);
 
-		  list = tree_cons (build_int_cst (gfc_array_index_type,
-						   idx++), se.expr, list);
+                  CONSTRUCTOR_APPEND_ELT (v,
+                                          build_int_cst (gfc_array_index_type,
+                                                         idx++),
+                                          se.expr);
 		  c = p;
 		  p = gfc_constructor_next (p);
 		}
@@ -1344,7 +1345,7 @@ gfc_trans_array_constructor_value (stmtblock_t * pblock, tree type,
 					  gfc_index_zero_node, bound);
 	      tmptype = build_array_type (type, tmptype);
 
-	      init = build_constructor_from_list (tmptype, nreverse (list));
+	      init = build_constructor (tmptype, v);
 	      TREE_CONSTANT (init) = 1;
 	      TREE_STATIC (init) = 1;
 	      /* Create a static variable to hold the data.  */
@@ -1671,17 +1672,17 @@ gfc_constant_array_constructor_p (gfc_constructor_base base)
 tree
 gfc_build_constant_array_constructor (gfc_expr * expr, tree type)
 {
-  tree tmptype, list, init, tmp;
+  tree tmptype, init, tmp;
   HOST_WIDE_INT nelem;
   gfc_constructor *c;
   gfc_array_spec as;
   gfc_se se;
   int i;
+  VEC(constructor_elt,gc) *v = NULL;
 
   /* First traverse the constructor list, converting the constants
      to tree to build an initializer.  */
   nelem = 0;
-  list = NULL_TREE;
   c = gfc_constructor_first (expr->value.constructor);
   while (c)
     {
@@ -1692,8 +1693,8 @@ gfc_build_constant_array_constructor (gfc_expr * expr, tree type)
       else if (POINTER_TYPE_P (type))
 	se.expr = gfc_build_addr_expr (gfc_get_pchar_type (c->expr->ts.kind),
 				       se.expr);
-      list = tree_cons (build_int_cst (gfc_array_index_type, nelem),
-			se.expr, list);
+      CONSTRUCTOR_APPEND_ELT (v, build_int_cst (gfc_array_index_type, nelem),
+                              se.expr);
       c = gfc_constructor_next (c);
       nelem++;
     }
@@ -1723,7 +1724,7 @@ gfc_build_constant_array_constructor (gfc_expr * expr, tree type)
 
   tmptype = gfc_get_nodesc_array_type (type, &as, PACKED_STATIC, true);
 
-  init = build_constructor_from_list (tmptype, nreverse (list));
+  init = build_constructor (tmptype, v);
 
   TREE_CONSTANT (init) = 1;
   TREE_STATIC (init) = 1;
diff --git a/gcc/fortran/trans-decl.c b/gcc/fortran/trans-decl.c
index 64d87ca..65e7741 100644
--- a/gcc/fortran/trans-decl.c
+++ b/gcc/fortran/trans-decl.c
@@ -4196,6 +4196,7 @@ create_main_function (tree fndecl)
      language standard parameters.  */
   {
     tree array_type, array, var;
+    VEC(constructor_elt,gc) *v = NULL;
 
     /* Passing a new option to the library requires four modifications:
      + add it to the tree_cons list below
@@ -4204,28 +4205,34 @@ create_main_function (tree fndecl)
             gfor_fndecl_set_options
           + modify the library (runtime/compile_options.c)!  */
 
-    array = tree_cons (NULL_TREE, build_int_cst (integer_type_node,
-		       gfc_option.warn_std), NULL_TREE);
-    array = tree_cons (NULL_TREE, build_int_cst (integer_type_node,
-		       gfc_option.allow_std), array);
-    array = tree_cons (NULL_TREE, build_int_cst (integer_type_node, pedantic),
-		       array);
-    array = tree_cons (NULL_TREE, build_int_cst (integer_type_node,
-		       gfc_option.flag_dump_core), array);
-    array = tree_cons (NULL_TREE, build_int_cst (integer_type_node,
-		       gfc_option.flag_backtrace), array);
-    array = tree_cons (NULL_TREE, build_int_cst (integer_type_node,
-		       gfc_option.flag_sign_zero), array);
-
-    array = tree_cons (NULL_TREE, build_int_cst (integer_type_node,
-		       (gfc_option.rtcheck & GFC_RTCHECK_BOUNDS)), array);
-
-    array = tree_cons (NULL_TREE, build_int_cst (integer_type_node,
-		       gfc_option.flag_range_check), array);
+    CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
+                            build_int_cst (integer_type_node,
+                                           gfc_option.warn_std));
+    CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
+                            build_int_cst (integer_type_node,
+                                           gfc_option.allow_std));
+    CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
+                            build_int_cst (integer_type_node, pedantic));
+    CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
+                            build_int_cst (integer_type_node,
+                                           gfc_option.flag_dump_core));
+    CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
+                            build_int_cst (integer_type_node,
+                                           gfc_option.flag_backtrace));
+    CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
+                            build_int_cst (integer_type_node,
+                                           gfc_option.flag_sign_zero));
+    CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
+                            build_int_cst (integer_type_node,
+                                           (gfc_option.rtcheck
+                                            & GFC_RTCHECK_BOUNDS)));
+    CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
+                            build_int_cst (integer_type_node,
+                                           gfc_option.flag_range_check));
 
     array_type = build_array_type (integer_type_node,
 		       build_index_type (build_int_cst (NULL_TREE, 7)));
-    array = build_constructor_from_list (array_type, nreverse (array));
+    array = build_constructor (array_type, v);
     TREE_CONSTANT (array) = 1;
     TREE_STATIC (array) = 1;
 
diff --git a/gcc/fortran/trans-stmt.c b/gcc/fortran/trans-stmt.c
index 0a2ad53..f618f02 100644
--- a/gcc/fortran/trans-stmt.c
+++ b/gcc/fortran/trans-stmt.c
@@ -1593,12 +1593,13 @@ gfc_trans_logical_select (gfc_code * code)
 static tree
 gfc_trans_character_select (gfc_code *code)
 {
-  tree init, node, end_label, tmp, type, case_num, label, fndecl;
+  tree init, end_label, tmp, type, case_num, label, fndecl;
   stmtblock_t block, body;
   gfc_case *cp, *d;
   gfc_code *c;
   gfc_se se;
   int n, k;
+  VEC(constructor_elt,gc) *inits = NULL;
 
   /* The jump table types are stored in static variables to avoid
      constructing them from scratch every single time.  */
@@ -1678,52 +1679,50 @@ gfc_trans_character_select (gfc_code *code)
     }
 
   /* Generate the structure describing the branches */
-  init = NULL_TREE;
-
   for(d = cp; d; d = d->right)
     {
-      node = NULL_TREE;
+      VEC(constructor_elt,gc) *node = NULL;
 
       gfc_init_se (&se, NULL);
 
       if (d->low == NULL)
         {
-          node = tree_cons (ss_string1[k], null_pointer_node, node);
-          node = tree_cons (ss_string1_len[k], integer_zero_node, node);
+          CONSTRUCTOR_APPEND_ELT (node, ss_string1[k], null_pointer_node);
+          CONSTRUCTOR_APPEND_ELT (node, ss_string1_len[k], integer_zero_node);
         }
       else
         {
           gfc_conv_expr_reference (&se, d->low);
 
-          node = tree_cons (ss_string1[k], se.expr, node);
-          node = tree_cons (ss_string1_len[k], se.string_length, node);
+          CONSTRUCTOR_APPEND_ELT (node, ss_string1[k], se.expr);
+          CONSTRUCTOR_APPEND_ELT (node, ss_string1_len[k], se.string_length);
         }
 
       if (d->high == NULL)
         {
-          node = tree_cons (ss_string2[k], null_pointer_node, node);
-          node = tree_cons (ss_string2_len[k], integer_zero_node, node);
+          CONSTRUCTOR_APPEND_ELT (node, ss_string2[k], null_pointer_node);
+          CONSTRUCTOR_APPEND_ELT (node, ss_string2_len[k], integer_zero_node);
         }
       else
         {
           gfc_init_se (&se, NULL);
           gfc_conv_expr_reference (&se, d->high);
 
-          node = tree_cons (ss_string2[k], se.expr, node);
-          node = tree_cons (ss_string2_len[k], se.string_length, node);
+          CONSTRUCTOR_APPEND_ELT (node, ss_string2[k], se.expr);
+          CONSTRUCTOR_APPEND_ELT (node, ss_string2_len[k], se.string_length);
         }
 
-      node = tree_cons (ss_target[k], build_int_cst (integer_type_node, d->n),
-			node);
+      CONSTRUCTOR_APPEND_ELT (node, ss_target[k],
+                              build_int_cst (integer_type_node, d->n));
 
-      tmp = build_constructor_from_list (select_struct[k], nreverse (node));
-      init = tree_cons (NULL_TREE, tmp, init);
+      tmp = build_constructor (select_struct[k], node);
+      CONSTRUCTOR_APPEND_ELT (inits, NULL_TREE, tmp);
     }
 
   type = build_array_type (select_struct[k],
 			   build_index_type (build_int_cst (NULL_TREE, n-1)));
 
-  init = build_constructor_from_list (type, nreverse(init));
+  init = build_constructor (type, inits);
   TREE_CONSTANT (init) = 1;
   TREE_STATIC (init) = 1;
   /* Create a static variable to hold the jump table.  */