[gcc r11-4656] c++: rtti cleanups

[gcc r11-4656] c++: rtti cleanups

[Nathan Sidwell]

https://gcc.gnu.org/g:fbc3f847438f2297c31d9eaaec5e662192acb779

commit r11-4656-gfbc3f847438f2297c31d9eaaec5e662192acb779
Author: Nathan Sidwell <nathan@acm.org>
Date:   Tue Nov 3 05:08:18 2020 -0800

    c++: rtti cleanups
    
    Here are a few cleanups from the modules branch.  Generally some RAII,
    and a bit of lazy namespace pushing.
    
            gcc/cp/
            * rtti.c (init_rtti_processing): Move var decl to its init.
            (get_tinfo_decl): Likewise.  Break out creation to called helper
            ...
            (get_tinfo_decl_direct): ... here.
            (build_dynamic_cast_1): Move var decls to their initializers.
            (tinfo_base_init): Set decl's location to BUILTINS_LOCATION.
            (get_tinfo_desc): Only push ABI namespace when needed.  Set type's
            context.

Diff:
---
 gcc/cp/rtti.c | 88 ++++++++++++++++++++++++++++++++---------------------------
 1 file changed, 48 insertions(+), 40 deletions(-)

diff --git a/gcc/cp/rtti.c b/gcc/cp/rtti.c
index 7c4bff76e8c..887aae31bf6 100644
--- a/gcc/cp/rtti.c
+++ b/gcc/cp/rtti.c
@@ -123,6 +123,7 @@ static GTY (()) vec<tinfo_s, va_gc> *tinfo_descs;
 
 static tree ifnonnull (tree, tree, tsubst_flags_t);
 static tree tinfo_name (tree, bool);
+static tree get_tinfo_decl_direct (tree type, tree name, int pseudo_ix);
 static tree build_dynamic_cast_1 (location_t, tree, tree, tsubst_flags_t);
 static tree throw_bad_cast (void);
 static tree throw_bad_typeid (void);
@@ -166,10 +167,8 @@ pop_abi_namespace (void)
 void
 init_rtti_processing (void)
 {
-  tree type_info_type;
-
   push_nested_namespace (std_node);
-  type_info_type = xref_tag (class_type, get_identifier ("type_info"));
+  tree type_info_type = xref_tag (class_type, get_identifier ("type_info"));
   pop_nested_namespace (std_node);
   const_type_info_type_node
     = cp_build_qualified_type (type_info_type, TYPE_QUAL_CONST);
@@ -414,9 +413,6 @@ tinfo_name (tree type, bool mark_private)
 tree
 get_tinfo_decl (tree type)
 {
-  tree name;
-  tree d;
-
   if (variably_modified_type_p (type, /*fn=*/NULL_TREE))
     {
       error ("cannot create type information for type %qT because "
@@ -429,25 +425,41 @@ get_tinfo_decl (tree type)
     type = build_function_type (TREE_TYPE (type),
 				TREE_CHAIN (TYPE_ARG_TYPES (type)));
 
-  type = complete_type (type);
+  return get_tinfo_decl_direct (type, NULL, -1);
+}
 
+/* Get or create a tinfo VAR_DECL directly from the provided information.
+   The caller must have already checked it is valid to do so.  */
+
+static tree
+get_tinfo_decl_direct (tree type, tree name, int pseudo_ix)
+{
   /* For a class type, the variable is cached in the type node
      itself.  */
+  tree d = NULL_TREE;
+
+  gcc_checking_assert (TREE_CODE (type) != METHOD_TYPE);
+
+  if (pseudo_ix < 0)
+    type = complete_type (type);
+
   if (CLASS_TYPE_P (type))
-    {
-      d = CLASSTYPE_TYPEINFO_VAR (TYPE_MAIN_VARIANT (type));
-      if (d)
-	return d;
-    }
+    d = CLASSTYPE_TYPEINFO_VAR (TYPE_MAIN_VARIANT (type));
+
+  if (!name)
+    name = mangle_typeinfo_for_type (type);
 
-  name = mangle_typeinfo_for_type (type);
+  if (!CLASS_TYPE_P (type))
+    d = get_global_binding (name);
 
-  d = get_global_binding (name);
   if (!d)
     {
-      int ix = get_pseudo_ti_index (type);
-      const tinfo_s *ti = get_tinfo_desc (ix);
-      
+      /* Create it.  */
+      if (pseudo_ix < 0)
+	pseudo_ix = get_pseudo_ti_index (type);
+
+      const tinfo_s *ti = get_tinfo_desc (pseudo_ix);
+
       d = build_lang_decl (VAR_DECL, name, ti->type);
       SET_DECL_ASSEMBLER_NAME (d, name);
       /* Remember the type it is for.  */
@@ -754,23 +766,21 @@ build_dynamic_cast_1 (location_t loc, tree type, tree expr,
 	  dcast_fn = dynamic_cast_node;
 	  if (!dcast_fn)
 	    {
-	      tree tmp;
-	      tree tinfo_ptr;
-	      const char *name;
-
 	      push_abi_namespace ();
-	      tinfo_ptr = xref_tag (class_type,
-				    get_identifier ("__class_type_info"));
-	      tinfo_ptr = build_pointer_type
-		(cp_build_qualified_type
-		 (tinfo_ptr, TYPE_QUAL_CONST));
-	      name = "__dynamic_cast";
-	      tmp = build_function_type_list (ptr_type_node,
-					      const_ptr_type_node,
-					      tinfo_ptr, tinfo_ptr,
-					      ptrdiff_type_node, NULL_TREE);
-	      dcast_fn = build_library_fn_ptr (name, tmp,
-					       ECF_LEAF | ECF_PURE | ECF_NOTHROW);
+	      tree tinfo_ptr = xref_tag (class_type,
+					 get_identifier ("__class_type_info"));
+	      tinfo_ptr = cp_build_qualified_type (tinfo_ptr, TYPE_QUAL_CONST);
+	      tinfo_ptr = build_pointer_type (tinfo_ptr);
+
+	      const char *fn_name = "__dynamic_cast";
+	      /* void *() (void const *, __class_type_info const *,
+		           __class_type_info const *, ptrdiff_t)  */
+	      tree fn_type = (build_function_type_list
+			      (ptr_type_node, const_ptr_type_node,
+			       tinfo_ptr, tinfo_ptr, ptrdiff_type_node,
+			       NULL_TREE));
+	      dcast_fn = (build_library_fn_ptr
+			  (fn_name, fn_type, ECF_LEAF | ECF_PURE | ECF_NOTHROW));
 	      pop_abi_namespace ();
 	      dynamic_cast_node = dcast_fn;
 	    }
@@ -947,6 +957,8 @@ tinfo_base_init (tinfo_s *ti, tree target)
     {
       push_abi_namespace ();
       tree real_type = xref_tag (class_type, ti->name);
+      tree real_decl = TYPE_NAME (real_type);
+      DECL_SOURCE_LOCATION (real_decl) = BUILTINS_LOCATION;
       pop_abi_namespace ();
 
       if (!COMPLETE_TYPE_P (real_type))
@@ -1450,8 +1462,6 @@ get_tinfo_desc (unsigned ix)
       }
     }
 
-  push_abi_namespace ();
-
   /* Generate the pseudo type name.  */
   const char *real_name = tinfo_names[ix < TK_VMI_CLASS_TYPES
 				      ? ix : unsigned (TK_VMI_CLASS_TYPES)];
@@ -1468,6 +1478,7 @@ get_tinfo_desc (unsigned ix)
   /* Pass the fields chained in reverse.  */
   finish_builtin_struct (pseudo_type, pseudo_name, fields, NULL_TREE);
   CLASSTYPE_AS_BASE (pseudo_type) = pseudo_type;
+  DECL_CONTEXT (TYPE_NAME (pseudo_type)) = FROB_CONTEXT (global_namespace);
   xref_basetypes (pseudo_type, /*bases=*/NULL_TREE);
 
   res->type = cp_build_qualified_type (pseudo_type, TYPE_QUAL_CONST);
@@ -1477,7 +1488,6 @@ get_tinfo_desc (unsigned ix)
      internal linkage.  */
   TREE_PUBLIC (TYPE_MAIN_DECL (res->type)) = 1;
 
-  pop_abi_namespace ();
   return res;
 }
 
@@ -1608,12 +1618,10 @@ emit_support_tinfos (void)
 bool
 emit_tinfo_decl (tree decl)
 {
-  tree type = TREE_TYPE (DECL_NAME (decl));
-  int in_library = typeinfo_in_lib_p (type);
-
   gcc_assert (DECL_TINFO_P (decl));
 
-  if (in_library)
+  tree type = TREE_TYPE (DECL_NAME (decl));
+  if (typeinfo_in_lib_p (type))
     {
       if (doing_runtime)
 	DECL_EXTERNAL (decl) = 0;