[PATCH] New lang hook

https://gcc.gnu.org/ml/gcc-patches/2017-11/msg01340.html
	PR c++/82836
	PR c++/82737
	* tree.h (COPY_DECL_RTL): Rename parms for clarity.
	(SET_DECL_ASSEMBLER_NAME): Forward to
	overwrite_decl_assembler_name.
	(COPY_DECL_ASSEMBLER_NAME): Rename parms for clarity.
	(overwrite_decl_assembler_name): Declare.
	* tree.c (overwrite_decl_assembler_name): New.
	* langhooks-def.h (lhd_overwrite_decl_assembler_name): Declare.
	(LANG_HOOKS_OVERWRITE_DECL_ASSEMBLER_NAME): Provide default.
	(LANG_HOOKS_INITIALIZER): Add it.
	* langhooks.h (struct lang_hooks): Add overwrite_decl_assembler_name.
	* langhooks.c (lhd_set_decl_assembler_name): Use
	SET_DECL_ASSEMBLER_NAME.
	(lhd_overwrite_decl_assembler_name): Default implementation.

	PR c++/82836
	PR c++/82737
	* cp-objcp-common.h (LANG_HOOKS_OVERWRITE_DECL_ASSEMBLER_NAME):
	Override.
	* cp-tree.h (overwrite_mangling): Declare.
	* decl2.c (struct mangled_decl_hash): Entries are deletable.
	(overwrite_mangling): New.

	PR c++/82836
	PR c++/82737
	* g++.dg/pr82836.C: New.

From-SVN: r254823

gcc/ChangeLog

+2017-11-16  Nathan Sidwell  <nathan@acm.org>
+
+	PR c++/82836
+	PR c++/82737
+	* tree.h (COPY_DECL_RTL): Rename parms for clarity.
+	(SET_DECL_ASSEMBLER_NAME): Forward to
+	overwrite_decl_assembler_name.
+	(COPY_DECL_ASSEMBLER_NAME): Rename parms for clarity.
+	(overwrite_decl_assembler_name): Declare.
+	* tree.c (overwrite_decl_assembler_name): New.
+	* langhooks-def.h (lhd_overwrite_decl_assembler_name): Declare.
+	(LANG_HOOKS_OVERWRITE_DECL_ASSEMBLER_NAME): Provide default.
+	(LANG_HOOKS_INITIALIZER): Add it.
+	* langhooks.h (struct lang_hooks): Add overwrite_decl_assembler_name.
+	* langhooks.c (lhd_set_decl_assembler_name): Use
+	SET_DECL_ASSEMBLER_NAME.
+	(lhd_overwrite_decl_assembler_name): Default implementation.
+
 2017-11-16  Wilco Dijkstra  <wdijkstr@arm.com>
 	    Jackson Woodruff  <jackson.woodruff@arm.com>
 

gcc/cp/ChangeLog

 2017-11-16  Nathan Sidwell  <nathan@acm.org>
 
+	PR c++/82836
+	PR c++/82737
+	* cp-objcp-common.h (LANG_HOOKS_OVERWRITE_DECL_ASSEMBLER_NAME):
+	Override.
+	* cp-tree.h (overwrite_mangling): Declare.
+	* decl2.c (struct mangled_decl_hash): Entries are deletable.
+	(overwrite_mangling): New.
+
 	PR c++/81060
 	* decl.c (xref_tag_1): Push lambda into current scope.
 	* name-lookup.c (do_pushtag): Don't deal with ts_lambda here.

gcc/cp/cp-objcp-common.h

@@ -73,6 +73,8 @@ extern void cp_register_dumps (gcc::dump_manager *);
 #define LANG_HOOKS_DUP_LANG_SPECIFIC_DECL cxx_dup_lang_specific_decl
 #undef LANG_HOOKS_SET_DECL_ASSEMBLER_NAME
 #define LANG_HOOKS_SET_DECL_ASSEMBLER_NAME mangle_decl
+#undef LANG_HOOKS_OVERWRITE_DECL_ASSEMBLER_NAME
+#define LANG_HOOKS_OVERWRITE_DECL_ASSEMBLER_NAME overwrite_mangling
 #undef LANG_HOOKS_PRINT_STATISTICS
 #define LANG_HOOKS_PRINT_STATISTICS cxx_print_statistics
 #undef LANG_HOOKS_PRINT_XNODE

gcc/cp/cp-tree.h

@@ -6187,6 +6187,7 @@ extern tree cxx_maybe_build_cleanup		(tree, tsubst_flags_t);
 
 /* in decl2.c */
 extern void record_mangling			(tree, bool);
+extern void overwrite_mangling			(tree, tree);
 extern void note_mangling_alias			(tree, tree);
 extern void generate_mangling_aliases		(void);
 extern tree build_memfn_type			(tree, tree, cp_cv_quals, cp_ref_qualifier);

gcc/cp/decl2.c

@@ -123,9 +123,14 @@ struct mangled_decl_hash : ggc_remove <tree>
   static inline void mark_empty (value_type &p) {p = NULL_TREE;}
   static inline bool is_empty (value_type p) {return !p;}
 
-  /* Nothing is deletable.  Everything is insertable.  */
-  static bool is_deleted (value_type) { return false; }
-  static void mark_deleted (value_type) { gcc_unreachable (); }
+  static bool is_deleted (value_type e)
+  {
+    return e == reinterpret_cast <value_type> (1);
+  }
+  static void mark_deleted (value_type &e)
+  {
+    e = reinterpret_cast <value_type> (1);
+  }
 };
 
 /* A hash table of decls keyed by mangled name.  Used to figure out if
@@ -4439,6 +4444,33 @@ record_mangling (tree decl, bool need_warning)
     }
 }
 
+/* The mangled name of DECL is being forcibly changed to NAME.  Remove
+   any existing knowledge of DECL's mangled name meaning DECL.  */
+
+void
+overwrite_mangling (tree decl, tree name)
+{
+  if (tree id = DECL_ASSEMBLER_NAME_RAW (decl))
+    if ((TREE_CODE (decl) == VAR_DECL
+	 || TREE_CODE (decl) == FUNCTION_DECL)
+	&& mangled_decls)
+      if (tree *slot
+	  = mangled_decls->find_slot_with_hash (id, IDENTIFIER_HASH_VALUE (id),
+						NO_INSERT))
+	if (*slot == decl)
+	  {
+	    mangled_decls->clear_slot (slot);
+
+	    /* If this is an alias, remove it from the symbol table.  */
+	    if (DECL_ARTIFICIAL (decl) && DECL_IGNORED_P (decl))
+	      if (symtab_node *n = symtab_node::get (decl))
+		if (n->cpp_implicit_alias)
+		  n->remove ();
+	  }
+
+  DECL_ASSEMBLER_NAME_RAW (decl) = name;
+}
+
 /* The entire file is now complete.  If requested, dump everything
    to a file.  */
 

gcc/langhooks-def.h

@@ -51,7 +51,8 @@ extern const char *lhd_dwarf_name (tree, int);
 extern int lhd_types_compatible_p (tree, tree);
 extern void lhd_print_error_function (diagnostic_context *,
 				      const char *, struct diagnostic_info *);
-extern void lhd_set_decl_assembler_name (tree);
+extern void lhd_set_decl_assembler_name (tree decl);
+extern void lhd_overwrite_decl_assembler_name (tree decl, tree name);
 extern bool lhd_warn_unused_global_decl (const_tree);
 extern tree lhd_type_for_size (unsigned precision, int unsignedp);
 extern void lhd_incomplete_type_error (location_t, const_tree, const_tree);
@@ -107,6 +108,7 @@ extern int lhd_type_dwarf_attribute (const_tree, int);
 #define LANG_HOOKS_FINISH_INCOMPLETE_DECL lhd_do_nothing_t
 #define LANG_HOOKS_DUP_LANG_SPECIFIC_DECL lhd_do_nothing_t
 #define LANG_HOOKS_SET_DECL_ASSEMBLER_NAME lhd_set_decl_assembler_name
+#define LANG_HOOKS_OVERWRITE_DECL_ASSEMBLER_NAME lhd_overwrite_decl_assembler_name
 #define LANG_HOOKS_PRINT_STATISTICS	lhd_do_nothing
 #define LANG_HOOKS_PRINT_XNODE		lhd_print_tree_nothing
 #define LANG_HOOKS_PRINT_DECL		lhd_print_tree_nothing
@@ -310,6 +312,7 @@ extern void lhd_end_section (void);
   LANG_HOOKS_FINISH_INCOMPLETE_DECL, \
   LANG_HOOKS_DUP_LANG_SPECIFIC_DECL, \
   LANG_HOOKS_SET_DECL_ASSEMBLER_NAME, \
+  LANG_HOOKS_OVERWRITE_DECL_ASSEMBLER_NAME, \
   LANG_HOOKS_PRINT_STATISTICS, \
   LANG_HOOKS_PRINT_XNODE, \
   LANG_HOOKS_PRINT_DECL, \

gcc/langhooks.c

@@ -171,8 +171,15 @@ lhd_set_decl_assembler_name (tree decl)
       ASM_FORMAT_PRIVATE_NAME (label, name, DECL_UID (decl));
       id = get_identifier (label);
     }
+
   SET_DECL_ASSEMBLER_NAME (decl, id);
+}
 
+/* Forcibly overwrite the DECL_ASSEMBLER_NAME for DECL to NAME.  */
+void
+lhd_overwrite_decl_assembler_name (tree decl, tree name)
+{
+  DECL_ASSEMBLER_NAME_RAW (decl) = name;
 }
 
 /* Type promotion for variable arguments.  */

gcc/langhooks.h

@@ -395,6 +395,10 @@ struct lang_hooks
      assembler does not talk about it.  */
   void (*set_decl_assembler_name) (tree);
 
+  /* Overwrite the DECL_ASSEMBLER_NAME for a node.  The name is being
+     changed (including to or from NULL_TREE).  */
+  void (*overwrite_decl_assembler_name) (tree, tree);
+
   /* The front end can add its own statistics to -fmem-report with
      this hook.  It should output to stderr.  */
   void (*print_statistics) (void);

gcc/testsuite/ChangeLog

 2017-11-16  Nathan Sidwell  <nathan@acm.org>
 
+	PR c++/82836
+	PR c++/82737
+	* g++.dg/pr82836.C: New.
+
 	PR c++81060
 	* g++.dg/cpp0x/lambda/lambda-template13.C: Avoid undefined
 	template using local type error.

gcc/tree.c

@@ -674,6 +674,17 @@ decl_assembler_name (tree decl)
   return DECL_ASSEMBLER_NAME_RAW (decl);
 }
 
+/* The DECL_ASSEMBLER_NAME_RAW of DECL is being explicitly set to NAME
+   (either of which may be NULL).  Inform the FE, if this changes the
+   name.  */
+
+void
+overwrite_decl_assembler_name (tree decl, tree name)
+{
+  if (DECL_ASSEMBLER_NAME_RAW (decl) != name)
+    lang_hooks.overwrite_decl_assembler_name (decl, name);
+}
+
 /* When the target supports COMDAT groups, this indicates which group the
    DECL is associated with.  This can be either an IDENTIFIER_NODE or a
    decl, in which case its DECL_ASSEMBLER_NAME identifies the group.  */

gcc/tree.h

@@ -2528,11 +2528,11 @@ extern void decl_value_expr_insert (tree, tree);
 #define DECL_RTL_SET_P(NODE) \
   (HAS_RTL_P (NODE) && DECL_WRTL_CHECK (NODE)->decl_with_rtl.rtl != NULL)
 
-/* Copy the RTL from NODE1 to NODE2.  If the RTL was not set for
-   NODE1, it will not be set for NODE2; this is a lazy copy.  */
-#define COPY_DECL_RTL(NODE1, NODE2) \
-  (DECL_WRTL_CHECK (NODE2)->decl_with_rtl.rtl \
-   = DECL_WRTL_CHECK (NODE1)->decl_with_rtl.rtl)
+/* Copy the RTL from SRC_DECL to DST_DECL.  If the RTL was not set for
+   SRC_DECL, it will not be set for DST_DECL; this is a lazy copy.  */
+#define COPY_DECL_RTL(SRC_DECL, DST_DECL) \
+  (DECL_WRTL_CHECK (DST_DECL)->decl_with_rtl.rtl \
+   = DECL_WRTL_CHECK (SRC_DECL)->decl_with_rtl.rtl)
 
 /* The DECL_RTL for NODE, if it is set, or NULL, if it is not set.  */
 #define DECL_RTL_IF_SET(NODE) (DECL_RTL_SET_P (NODE) ? DECL_RTL (NODE) : NULL)
@@ -2723,19 +2723,21 @@ extern void decl_value_expr_insert (tree, tree);
 
 /* Set the DECL_ASSEMBLER_NAME for NODE to NAME.  */
 #define SET_DECL_ASSEMBLER_NAME(NODE, NAME) \
-  (DECL_ASSEMBLER_NAME_RAW (NODE) = (NAME))
+  overwrite_decl_assembler_name (NODE, NAME)
 
-/* Copy the DECL_ASSEMBLER_NAME from DECL1 to DECL2.  Note that if DECL1's
-   DECL_ASSEMBLER_NAME has not yet been set, using this macro will not cause
-   the DECL_ASSEMBLER_NAME of either DECL to be set.  In other words, the
-   semantics of using this macro, are different than saying:
+/* Copy the DECL_ASSEMBLER_NAME from SRC_DECL to DST_DECL.  Note that
+   if SRC_DECL's DECL_ASSEMBLER_NAME has not yet been set, using this
+   macro will not cause the DECL_ASSEMBLER_NAME to be set, but will
+   clear DECL_ASSEMBLER_NAME of DST_DECL, if it was already set.  In
+   other words, the semantics of using this macro, are different than
+   saying:
 
-     SET_DECL_ASSEMBLER_NAME(DECL2, DECL_ASSEMBLER_NAME (DECL1))
+     SET_DECL_ASSEMBLER_NAME(DST_DECL, DECL_ASSEMBLER_NAME (SRC_DECL))
 
-   which will try to set the DECL_ASSEMBLER_NAME for DECL1.  */
+   which will try to set the DECL_ASSEMBLER_NAME for SRC_DECL.  */
 
-#define COPY_DECL_ASSEMBLER_NAME(DECL1, DECL2)				\
-  SET_DECL_ASSEMBLER_NAME (DECL2, DECL_ASSEMBLER_NAME_RAW (DECL1))
+#define COPY_DECL_ASSEMBLER_NAME(SRC_DECL, DST_DECL)			\
+  SET_DECL_ASSEMBLER_NAME (DST_DECL, DECL_ASSEMBLER_NAME_RAW (SRC_DECL))
 
 /* Records the section name in a section attribute.  Used to pass
    the name from decl_attributes to make_function_rtl and make_decl_rtl.  */
@@ -3872,6 +3874,7 @@ id_equal (const char *str, const_tree id)
    || ((NODE) && TREE_TYPE ((NODE)) == error_mark_node))
 
 extern tree decl_assembler_name (tree);
+extern void overwrite_decl_assembler_name (tree decl, tree name);
 extern tree decl_comdat_group (const_tree);
 extern tree decl_comdat_group_id (const_tree);
 extern const char *decl_section_name (const_tree);