Re: Java: Local function pointer aliases for method metadata

[Bryce McKinlay <mckinlay at redhat dot com>]

Richard Henderson wrote:

> On Tue, Aug 17, 2004 at 09:34:48PM -0400, Bryce McKinlay wrote:
>  
>
> > +  const char *alias_id = "LALIAS_";
> > +  int name_len;
> > +  
> > +  /* Make the alias name by prepending alias_id.  */
> > +  name_len = IDENTIFIER_LENGTH (DECL_ASSEMBLER_NAME (method));
> > +  ptr = buf = alloca (strlen (alias_id) + name_len + 1);
> > +  strcpy (ptr, alias_id);
> > +  ptr += strlen (alias_id);
> > +  strcpy (ptr, IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (method)));
> > +  ptr += name_len;
> > +  *ptr = '\0';
> >    
>
> You want to use ASM_GENERATE_INTERNAL_LABEL so that the symbol
> is of a form that is interpreted by the assembler as a temporary.
> This way the symbol isn't retained in the .o file, or copied to
> the executable.
>
> This isn't actively wrong, but you can save a bit o space.
>  

Thanks - is it ok to use the target method's full asm name for the 
"prefix" argument to ASM_GENERATE_INTERNAL_LABEL, or should this really 
be a short prefix? Using the full name makes reading/debugging the asm a 
little easier.

Bryce


2004-08-18  Bryce McKinlay  <mckinlay@redhat.com>

	* class.c (make_local_function_alias): New function. Create local
	alias for public method DECL.
	(make_method_value): Use make_local_function_alias.
	* parse.y (craft_constructor): Don't special-case anonymous classes.
	Always set ctor_name to init_identifier_node.
	(lookup_method_invoke): Call layout_class_method when creating
	anonymous class constructor.

Index: class.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/java/class.c,v
retrieving revision 1.202
diff -u -r1.202 class.c
--- class.c	15 Aug 2004 15:45:29 -0000	1.202
+++ class.c	18 Aug 2004 15:27:50 -0000
@@ -1198,6 +1198,41 @@
   abort ();
 }
 
+static GTY (()) int alias_labelno = 0;
+
+/* Create a private alias for METHOD. Using this alias instead of the method
+decl ensures that ncode entries in the method table point to the real function 
+at runtime, not a PLT entry.  */
+
+static tree
+make_local_function_alias (tree method)
+{
+  tree alias;
+  const char *method_name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (method));
+  char *buf = alloca (strlen (method_name) + 128);
+
+  ASM_GENERATE_INTERNAL_LABEL (buf, method_name, alias_labelno++);  
+  alias = build_decl (FUNCTION_DECL, get_identifier (buf),
+		      TREE_TYPE (method));
+  DECL_CONTEXT (alias) = NULL;
+  TREE_READONLY (alias) = TREE_READONLY (method);
+  TREE_THIS_VOLATILE (alias) = TREE_THIS_VOLATILE (method);
+  TREE_PUBLIC (alias) = 0;
+  DECL_EXTERNAL (alias) = 0;
+  DECL_ARTIFICIAL (alias) = 1;
+  DECL_INLINE (alias) = 0;
+  DECL_INITIAL (alias) = error_mark_node;
+  TREE_ADDRESSABLE (alias) = 1;
+  TREE_USED (alias) = 1;
+  SET_DECL_ASSEMBLER_NAME (alias, DECL_NAME (alias));
+  TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (alias)) = 1;
+  if (!flag_syntax_only)
+    assemble_alias (alias, DECL_ASSEMBLER_NAME (method));
+  return alias;
+}
+
+/** Make reflection data (_Jv_Field) for field FDECL. */
+
 static tree
 make_field_value (tree fdecl)
 {
@@ -1242,6 +1277,8 @@
   return finit;
 }
 
+/** Make reflection data (_Jv_Method) for method MDECL. */
+
 static tree
 make_method_value (tree mdecl)
 {
@@ -1265,7 +1302,8 @@
 
   code = null_pointer_node;
   if (DECL_RTL_SET_P (mdecl))
-    code = build1 (ADDR_EXPR, nativecode_ptr_type_node, mdecl);
+    code = build1 (ADDR_EXPR, nativecode_ptr_type_node, 
+		   make_local_function_alias (mdecl));
   START_RECORD_CONSTRUCTOR (minit, method_type_node);
   PUSH_FIELD_VALUE (minit, "name",
 		    build_utf8_ref (DECL_CONSTRUCTOR_P (mdecl) ?
Index: parse.y
===================================================================
RCS file: /cvs/gcc/gcc/gcc/java/parse.y,v
retrieving revision 1.502
diff -u -r1.502 parse.y
--- parse.y	17 Aug 2004 12:51:01 -0000	1.502
+++ parse.y	18 Aug 2004 15:27:53 -0000
@@ -5422,13 +5422,7 @@
   tree decl, ctor_name;
   char buffer [80];
 
-  /* The constructor name is <init> unless we're dealing with an
-     anonymous class, in which case the name will be fixed after having
-     be expanded. */
-  if (ANONYMOUS_CLASS_P (class_type))
-    ctor_name = DECL_NAME (class_decl);
-  else
-    ctor_name = init_identifier_node;
+  ctor_name = init_identifier_node;
 
   /* If we're dealing with an inner class constructor, we hide the
      this$<n> decl in the name field of its parameter declaration. */
@@ -10930,12 +10924,10 @@
 
   if (lc && ANONYMOUS_CLASS_P (class))
     {
-      tree saved_current_class;
       tree mdecl = craft_constructor (TYPE_NAME (class), atl);
-      saved_current_class = current_class;
-      current_class = class;
-      fix_constructors (mdecl);
-      current_class = saved_current_class;
+      /* The anonymous class may have already been laid out, so make sure
+         the new constructor is laid out here.  */
+      layout_class_method (class, CLASSTYPE_SUPER (class), mdecl, NULL_TREE);
     }
 
   /* Find all candidates and then refine the list, searching for the