[gcc r14-279] c++: remove nsdmi_inst hashtable

[Jason Merrill <jason@gcc.gnu.org>]

https://gcc.gnu.org/g:9b40ca2569d71e54d7dbbdbfd00d733770576f6f

commit r14-279-g9b40ca2569d71e54d7dbbdbfd00d733770576f6f
Author: Jason Merrill <jason@redhat.com>
Date:   Thu Mar 16 17:13:57 2023 -0400

    c++: remove nsdmi_inst hashtable
    
    It occurred to me that we have a perfectly good DECL_INITIAL field to put
    the instantiated DMI into, we don't need a separate hash table.
    
    gcc/cp/ChangeLog:
    
            * init.cc (nsdmi_inst): Remove.
            (maybe_instantiate_nsdmi_init): Use DECL_INITIAL instead.

Diff:
---
 gcc/cp/init.cc | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
index 9571d18170e..1dd24e30d7c 100644
--- a/gcc/cp/init.cc
+++ b/gcc/cp/init.cc
@@ -564,21 +564,19 @@ perform_target_ctor (tree init)
 /* Instantiate the default member initializer of MEMBER, if needed.
    Only get_nsdmi should use the return value of this function.  */
 
-static GTY((cache)) decl_tree_cache_map *nsdmi_inst;
-
 tree
 maybe_instantiate_nsdmi_init (tree member, tsubst_flags_t complain)
 {
   tree init = DECL_INITIAL (member);
-  if (init && DECL_LANG_SPECIFIC (member) && DECL_TEMPLATE_INFO (member))
+
+  /* tsubst_decl uses void_node to indicate an uninstantiated DMI.  */
+  if (init == void_node)
     {
       init = DECL_INITIAL (DECL_TI_TEMPLATE (member));
       location_t expr_loc
 	= cp_expr_loc_or_loc (init, DECL_SOURCE_LOCATION (member));
       if (TREE_CODE (init) == DEFERRED_PARSE)
 	/* Unparsed.  */;
-      else if (tree *slot = hash_map_safe_get (nsdmi_inst, member))
-	init = *slot;
       /* Check recursive instantiation.  */
       else if (DECL_INSTANTIATING_NSDMI_P (member))
 	{
@@ -639,7 +637,7 @@ maybe_instantiate_nsdmi_init (tree member, tsubst_flags_t complain)
 	  DECL_INSTANTIATING_NSDMI_P (member) = 0;
 
 	  if (init != error_mark_node)
-	    hash_map_safe_put<hm_ggc> (nsdmi_inst, member, init);
+	    DECL_INITIAL (member) = init;
 
 	  current_function_decl = cfd;
 	  current_binding_level = cbl;