c++: Improve cp_parser_objc_messsage_args compile time

On Tue, Jan 21, 2025 at 06:47:53PM +0100, Jakub Jelinek wrote:
> Indeed, I've just used what it was doing without thinking too much about it,
> sorry.
> addl_args = tree_cons (NULL_TREE, arg, addl_args);
> with addl_args = nreverse (addl_args); after the loop might be better,
> can test that incrementally.  sel_args is handled the same and should have
> the same treatment.

Here is incremental patch to do that.

Verified also on the 2 va-meth*.mm testcases (one without CPP_EMBED, one
with) that -fdump-tree-gimple is the same before/after the patch.

2025-01-22  Jakub Jelinek  <jakub@redhat.com>

	* parser.cc (cp_parser_objc_message_args): Use tree_cons with
	nreverse at the end for both sel_args and addl_args, instead of
	chainon with build_tree_list second argument.

diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index a9eddd1a6da580c0588f4ae5072cc81c28c4b549..e1fa7e5ee2214e514a6ad604cf6bcd97dfa0e45a 100644 (file)
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -36721,9 +36721,7 @@ cp_parser_objc_message_args (cp_parser* parser)
       cp_parser_require (parser, CPP_COLON, RT_COLON);
       arg = cp_parser_assignment_expression (parser);
 
-      sel_args
-       = chainon (sel_args,
-                  build_tree_list (selector, arg));
+      sel_args = tree_cons (selector, arg, sel_args);
 
       token = cp_lexer_peek_token (parser->lexer);
     }
@@ -36738,14 +36736,12 @@ cp_parser_objc_message_args (cp_parser* parser)
          tree raw_data = cp_lexer_peek_token (parser->lexer)->u.value;
          cp_lexer_consume_token (parser->lexer);
          for (tree argument : raw_data_range (raw_data))
-           addl_args = chainon (addl_args,
-                                build_tree_list (NULL_TREE, argument));
+           addl_args = tree_cons (NULL_TREE, argument, addl_args);
        }
       else
        {
          tree arg = cp_parser_assignment_expression (parser);
-         addl_args = chainon (addl_args,
-                              build_tree_list (NULL_TREE, arg));
+         addl_args = tree_cons (NULL_TREE, arg, addl_args);
        }
 
       token = cp_lexer_peek_token (parser->lexer);
@@ -36757,7 +36753,7 @@ cp_parser_objc_message_args (cp_parser* parser)
       return build_tree_list (error_mark_node, error_mark_node);
     }
 
-  return build_tree_list (sel_args, addl_args);
+  return build_tree_list (nreverse (sel_args), nreverse (addl_args));
 }
 
 /* Parse an Objective-C encode expression.