[gcc r14-3709] c++: more dummy non_constant_p arg avoidance

[gcc r14-3709] c++: more dummy non_constant_p arg avoidance

[Patrick Palka]

https://gcc.gnu.org/g:9922bfa59c6bd881c997cf9a0d070fd62f2940c9

commit r14-3709-g9922bfa59c6bd881c997cf9a0d070fd62f2940c9
Author: Patrick Palka <ppalka@redhat.com>
Date:   Tue Sep 5 10:20:51 2023 -0400

    c++: more dummy non_constant_p arg avoidance
    
    As a follow-up to Marek's r14-3088-ga263152643bbec, this patch makes
    us avoid passing an effectively dummy non_constant_p argument in two
    more spots in the parser so that we further avoid unnecessary
    constantness checks from cp_parser_constant_expression.
    
    gcc/cp/ChangeLog:
    
            * parser.cc (cp_parser_parenthesized_expression_list_elt): Pass
            nullptr as non_constant_p to cp_parser_braced_list if our
            non_constant_p is null.
            (cp_parser_initializer_list): Likewise to
            cp_parser_initializer_clause.  Avoid inspecting
            clause_non_constant_p if it's uninitialized.

Diff:
---
 gcc/cp/parser.cc | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index 7811d582b072..ed0675c95992 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -8160,7 +8160,10 @@ cp_parser_parenthesized_expression_list_elt (cp_parser *parser, bool cast_p,
       /* A braced-init-list.  */
       cp_lexer_set_source_position (parser->lexer);
       maybe_warn_cpp0x (CPP0X_INITIALIZER_LISTS);
-      expr = cp_parser_braced_list (parser, &expr_non_constant_p);
+      expr = cp_parser_braced_list (parser,
+				    (non_constant_p != nullptr
+				    ? &expr_non_constant_p
+				    : nullptr));
       if (non_constant_p && expr_non_constant_p)
 	*non_constant_p = true;
     }
@@ -25986,9 +25989,11 @@ cp_parser_initializer_list (cp_parser* parser, bool* non_constant_p,
 
       /* Parse the initializer.  */
       initializer = cp_parser_initializer_clause (parser,
-						  &clause_non_constant_p);
+						  (non_constant_p != nullptr
+						   ? &clause_non_constant_p
+						   : nullptr));
       /* If any clause is non-constant, so is the entire initializer.  */
-      if (clause_non_constant_p && non_constant_p)
+      if (non_constant_p && clause_non_constant_p)
 	*non_constant_p = true;
 
       if (TREE_CODE (initializer) == CONSTRUCTOR)