[gcc r11-5669] c++: RTTI accessors for modules

[gcc r11-5669] c++: RTTI accessors for modules

[Nathan Sidwell]

https://gcc.gnu.org/g:af4180513836806e2b351d516af55f6664c8821a

commit r11-5669-gaf4180513836806e2b351d516af55f6664c8821a
Author: Nathan Sidwell <nathan@acm.org>
Date:   Wed Dec 2 08:27:53 2020 -0800

    c++: RTTI accessors for modules
    
    The module machinery needs to serialize tinfo types and vars by
    meaning, not literally.  This adds the necessary pieces to rtti.
    
            gcc/cp/
            * cp-tree.h (DECL_TINFO_P): Also for TYPE_DECLs.
            (get_tinfo_decl_direct): Declare.
            (get_pseudo_tinfo_index, get_pseudo_tinfo_type): Declare.
            * rtti.c (get_tinfo_decl_direct): Externalize.
            (get_tinfo_desc): Set DECL_TINFO_P on the typedef.
            (get_pseudo_tinfo_index, get_pseudo_tinfo_type): New.

Diff:
---
 gcc/cp/cp-tree.h |  8 ++++++--
 gcc/cp/rtti.c    | 34 ++++++++++++++++++++++++++++++++--
 2 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 4eaa10bc7fd..d69110f7ab6 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -494,7 +494,7 @@ extern GTY(()) tree cp_global_trees[CPTI_MAX];
    4: IDENTIFIER_MARKED (IDENTIFIER_NODEs)
       TREE_HAS_CONSTRUCTOR (in INDIRECT_REF, SAVE_EXPR, CONSTRUCTOR,
 	  CALL_EXPR, or FIELD_DECL).
-      DECL_TINFO_P (in VAR_DECL)
+      DECL_TINFO_P (in VAR_DECL, TYPE_DECL)
       FUNCTION_REF_QUALIFIED (in FUNCTION_TYPE, METHOD_TYPE)
       OVL_LOOKUP_P (in OVERLOAD)
       LOOKUP_FOUND_P (in RECORD_TYPE, UNION_TYPE, ENUMERAL_TYPE, NAMESPACE_DECL)
@@ -3350,7 +3350,8 @@ struct GTY(()) lang_decl {
 
 /* 1 iff VAR_DECL node NODE is a type-info decl.  This flag is set for
    both the primary typeinfo object and the associated NTBS name.  */
-#define DECL_TINFO_P(NODE) TREE_LANG_FLAG_4 (VAR_DECL_CHECK (NODE))
+#define DECL_TINFO_P(NODE)			\
+  TREE_LANG_FLAG_4 (TREE_CHECK2 (NODE,VAR_DECL,TYPE_DECL))
 
 /* 1 iff VAR_DECL node NODE is virtual table or VTT.  We forward to
    DECL_VIRTUAL_P from the common code, as that has the semantics we
@@ -7025,6 +7026,7 @@ extern GTY(()) vec<tree, va_gc> *unemitted_tinfo_decls;
 
 extern void init_rtti_processing		(void);
 extern tree build_typeid			(tree, tsubst_flags_t);
+extern tree get_tinfo_decl_direct	        (tree, tree, int);
 extern tree get_tinfo_decl			(tree);
 extern tree get_typeid				(tree, tsubst_flags_t);
 extern tree build_headof			(tree);
@@ -7032,6 +7034,8 @@ extern tree build_dynamic_cast			(location_t, tree, tree,
 						 tsubst_flags_t);
 extern void emit_support_tinfos			(void);
 extern bool emit_tinfo_decl			(tree);
+extern unsigned get_pseudo_tinfo_index		(tree);
+extern tree get_pseudo_tinfo_type		(unsigned);
 
 /* in search.c */
 extern bool accessible_base_p			(tree, tree, bool);
diff --git a/gcc/cp/rtti.c b/gcc/cp/rtti.c
index 887aae31bf6..d6288622246 100644
--- a/gcc/cp/rtti.c
+++ b/gcc/cp/rtti.c
@@ -123,7 +123,6 @@ 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);
@@ -431,7 +430,7 @@ get_tinfo_decl (tree type)
 /* 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
+tree
 get_tinfo_decl_direct (tree type, tree name, int pseudo_ix)
 {
   /* For a class type, the variable is cached in the type node
@@ -1479,6 +1478,7 @@ get_tinfo_desc (unsigned ix)
   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);
+  DECL_TINFO_P (TYPE_NAME (pseudo_type)) = true;
   xref_basetypes (pseudo_type, /*bases=*/NULL_TREE);
 
   res->type = cp_build_qualified_type (pseudo_type, TYPE_QUAL_CONST);
@@ -1491,6 +1491,36 @@ get_tinfo_desc (unsigned ix)
   return res;
 }
 
+/* Return an identifying index for the pseudo type_info TYPE.
+   We wrote the index at the end of the name, so just scan it from
+   there.  This isn't critical, as it's only on the first use of this
+   type during module stream out.  */
+
+unsigned
+get_pseudo_tinfo_index (tree type)
+{
+  tree name = DECL_NAME (TYPE_NAME (type));
+  unsigned ix = 0, scale = 1;
+  size_t len = IDENTIFIER_LENGTH (name);
+  const char *ptr = IDENTIFIER_POINTER (name) + len;
+
+  for (; *--ptr != '_'; scale *= 10)
+    {
+      len--;
+      gcc_checking_assert (len && ISDIGIT (*ptr));
+      ix += (*ptr - '0') * scale;
+    }
+
+  gcc_assert (len != IDENTIFIER_LENGTH (name));
+  return ix;
+}
+
+tree
+get_pseudo_tinfo_type (unsigned ix)
+{
+  return get_tinfo_desc (ix)->type;
+}
+
 /* We lazily create the type info types.  */
 
 static void