c-family, c++: Look up built-in traits via identifier node

Since RID_MAX soon reaches 255 and all built-in traits are used
approximately once in a C++ translation unit, this patch removes
all RID values for built-in traits and uses the identifier node to
look up the specific trait.  Rather than holding traits as keywords,
we set all trait identifiers as cik_trait, which is a new
cp_identifier_kind.  As cik_reserved_for_udlit was unused and
cp_identifier_kind is 3 bits, we replaced the unused field with the new
cik_trait.  Also, the later patch handles a subsequent token to the
built-in identifier so that we accept the use of non-function-like
built-in trait identifiers.

gcc/c-family/ChangeLog:

	* c-common.cc (c_common_reswords): Remove all mappings of
	built-in traits.
	* c-common.h (enum rid): Remove all RID values for built-in
	traits.

gcc/cp/ChangeLog:

	* cp-objcp-common.cc (names_builtin_p): Remove all RID value
	cases for built-in traits.  Check for built-in traits via
	the new cik_trait kind.
	* cp-tree.h (enum cp_trait_kind): Set its underlying type to
	addr_space_t.
	(struct cp_trait): New struct to hold trait information.
	(cp_traits): New array to hold a mapping to all traits.
	(cik_reserved_for_udlit): Rename to ...
	(cik_trait): ... this.
	(IDENTIFIER_ANY_OP_P): Exclude cik_trait.
	(IDENTIFIER_TRAIT_P): New macro to detect cik_trait.
	* lex.cc (cp_traits): Define its values, declared in cp-tree.h.
	(init_cp_traits): New function to set cik_trait and
	IDENTIFIER_CP_INDEX for all built-in trait identifiers.
	(cxx_init): Call init_cp_traits function.
	* parser.cc (cp_lexer_lookup_trait): New function to look up a
	built-in trait by IDENTIFIER_CP_INDEX.
	(cp_lexer_lookup_trait_expr): Likewise, look up an
	expression-yielding built-in trait.
	(cp_lexer_lookup_trait_type): Likewise, look up a type-yielding
	built-in trait.
	(cp_keyword_starts_decl_specifier_p): Remove all RID value cases
	for built-in traits.
	(cp_lexer_next_token_is_decl_specifier_keyword): Handle
	type-yielding built-in traits.
	(cp_parser_primary_expression): Remove all RID value cases for
	built-in traits.  Handle expression-yielding built-in traits.
	(cp_parser_trait): Handle cp_trait instead of enum rid.
	(cp_parser_simple_type_specifier): Remove all RID value cases
	for built-in traits.  Handle type-yielding built-in traits.

Co-authored-by: Patrick Palka <ppalka@redhat.com>
Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>

1 files changed, 34 insertions, 0 deletions

diff --git a/gcc/cp/lex.cc b/gcc/cp/lex.cc
index 64bcfb1..a939e2e 100644
--- a/gcc/cp/lex.cc
+++ b/gcc/cp/lex.cc
@@ -35,6 +35,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "langhooks.h"
 
 static int interface_strcmp (const char *);
+static void init_cp_traits (void);
 static void init_cp_pragma (void);
 
 static tree parse_strconst_pragma (const char *, int);
@@ -97,6 +98,19 @@ ovl_op_info_t ovl_op_info[2][OVL_OP_MAX] =
 unsigned char ovl_op_mapping[MAX_TREE_CODES];
 unsigned char ovl_op_alternate[OVL_OP_MAX];
 
+/* The trait table, declared in cp-tree.h.  */
+const cp_trait cp_traits[] =
+{
+#define DEFTRAIT(TCC, CODE, NAME, ARITY) \
+  { NAME, CPTK_##CODE, ARITY, (TCC == tcc_type) },
+#include "cp-trait.def"
+#undef DEFTRAIT
+};
+/* The trait table cannot have more than 255 (addr_space_t) entries since
+   the index is retrieved through IDENTIFIER_CP_INDEX.  */
+static_assert(ARRAY_SIZE (cp_traits) <= 255,
+	      "cp_traits array cannot have more than 255 entries");
+
 /* Get the name of the kind of identifier T.  */
 
 const char *
@@ -283,6 +297,25 @@ init_reswords (void)
     }
 }
 
+/* Initialize the C++ traits.  */
+static void
+init_cp_traits (void)
+{
+  tree id;
+
+  for (unsigned int i = 0; i < ARRAY_SIZE (cp_traits); ++i)
+    {
+      id = get_identifier (cp_traits[i].name);
+      IDENTIFIER_CP_INDEX (id) = cp_traits[i].kind;
+      set_identifier_kind (id, cik_trait);
+    }
+
+  /* An alias for __is_same.  */
+  id = get_identifier ("__is_same_as");
+  IDENTIFIER_CP_INDEX (id) = CPTK_IS_SAME;
+  set_identifier_kind (id, cik_trait);
+}
+
 static void
 init_cp_pragma (void)
 {
@@ -324,6 +357,7 @@ cxx_init (void)
   input_location = BUILTINS_LOCATION;
 
   init_reswords ();
+  init_cp_traits ();
   init_tree ();
   init_cp_semantics ();
   init_operators ();