PATCH for debug/23336 - enums types missing from debug info

[Daniel Jacobowitz <drow at false dot org>]

This patch extends Aldy's fix, which caused (foo *) casts to emit the foo
type in debug information, to make enumerator usage emit the containing
enumeral type.

We already set TREE_USED on the enumerator; I could have checked for any
used member of an enum before skipping it in dwarf2out and that would also
have fixed the PR.  But it would bloat debug information.  As I noted in
c++/26965, this is a general problem with the compiler right now: TREE_USED
is often set for types during parsing, but we don't know until late whether
we're going to emit them.  I know we used to have a problem where this:

enum foo {
  bar = 1,
  zed = bar
};

would always cause enum foo to be emitted, because it was self-referential.
I don't see any way to fix this sort of thing without keeping explicit debug
type dependencies associated with objects at the level we can usefully
garbage collect: functions, initializers for statics, types.  Obviously this
is much more information than the single TREE_USED bit, and I don't know if
it's enough more to be fatally flawed.

Anyway, in the mean time, let's at least fix enums!

I would appreciate a C++ maintainer looking at this; I'm not sure if I put
it in the right place.  It's remarkably annoying that there's a second copy
of this entire layer of the C++ frontend for template instantiation.

Bootstrapped and tested on x86_64-pc-linux-gnu.   OK?

-- 
Daniel Jacobowitz
CodeSourcery

2006-07-22  Daniel Jacobowitz  <dan@codesourcery.com>

	PR debug/23336
	* c-typeck.c (build_external_type): Mark used enum types.
	* dwarf2out.c (dwarf2out_abstract_function): Save and restore
	cfun also.
	(gen_subprogram_die): Whitespace fix.

2006-07-22  Daniel Jacobowitz  <dan@codesourcery.com>

	PR debug/23336
	* pt.c (tsubst_copy_and_build): Mark used enum types.
	* semantics.c (finish_id_expression): Likewise.

2006-07-22  Daniel Jacobowitz  <dan@codesourcery.com>

	PR debug/23336
	* lib/gcc-dg.exp (gcc-dg-debug-runtest): Suppress new tests
	at -g1.
	* gcc.dg/debug/enum-1.c, g++.dg/debug/enum-1.C,
	g++.dg/debug/enum-2.C: New.

Index: testsuite/lib/gcc-dg.exp
===================================================================
--- testsuite/lib/gcc-dg.exp	(revision 115676)
+++ testsuite/lib/gcc-dg.exp	(working copy)
@@ -292,7 +292,12 @@ proc gcc-dg-debug-runtest { target_compi
 
 	foreach flags $DEBUG_TORTURE_OPTIONS {
 	    set doit 1
-	    if { [string match {*/debug-[126].c} "$nshort"] \
+
+	    # These tests check for information which may be deliberately
+	    # suppressed at -g1.
+	    if { ([string match {*/debug-[126].c} "$nshort"] \
+		   || [string match {*/enum-1.c} "$nshort"] \
+		   || [string match {*/enum-[12].C} "$nshort"]) \
 		    && [string match "*1" [lindex "$flags" 0] ] } {
 		set doit 0
 	    }
Index: cp/pt.c
===================================================================
--- cp/pt.c	(revision 115676)
+++ cp/pt.c	(working copy)
@@ -9182,7 +9182,10 @@ tsubst_copy_and_build (tree t,
       /* As in finish_id_expression, we resolve enumeration constants
 	 to their underlying values.  */
       if (TREE_CODE (t) == CONST_DECL)
-	return DECL_INITIAL (t);
+	{
+	  used_types_insert (TREE_TYPE (t));
+	  return DECL_INITIAL (t);
+	}
       return t;
 
     default:
Index: cp/semantics.c
===================================================================
--- cp/semantics.c	(revision 115676)
+++ cp/semantics.c	(working copy)
@@ -2589,7 +2589,10 @@ finish_id_expression (tree id_expression
     {
       *idk = CP_ID_KIND_NONE;
       if (!processing_template_decl)
-	return DECL_INITIAL (decl);
+	{
+	  used_types_insert (TREE_TYPE (decl));
+	  return DECL_INITIAL (decl);
+	}
       return decl;
     }
   else
Index: c-typeck.c
===================================================================
--- c-typeck.c	(revision 115676)
+++ c-typeck.c	(working copy)
@@ -2067,6 +2067,7 @@ build_external_ref (tree id, int fun, lo
 
   if (TREE_CODE (ref) == CONST_DECL)
     {
+      used_types_insert (TREE_TYPE (ref));
       ref = DECL_INITIAL (ref);
       TREE_CONSTANT (ref) = 1;
       TREE_INVARIANT (ref) = 1;
--- /dev/null	2006-07-20 04:40:48.651748895 -0400
+++ testsuite/gcc.dg/debug/enum-1.c	2006-07-22 14:47:18.000000000 -0400
@@ -0,0 +1,16 @@
+/* Verify that used enums are output.  */
+/* { dg-do compile } */
+/* { dg-final { scan-assembler "JTI_MAX" } } */
+
+int var;
+
+enum java_tree_index
+{
+  JTI_MAX
+};
+
+void function (void)
+{
+  var = JTI_MAX;
+}
+ 
--- /dev/null	2006-07-20 04:40:48.651748895 -0400
+++ testsuite/g++.dg/debug/enum-1.C	2006-07-22 14:49:53.000000000 -0400
@@ -0,0 +1,16 @@
+/* Verify that used enums are output.  */
+/* { dg-do compile } */
+/* { dg-final { scan-assembler "JTI_MAX" } } */
+
+int var;
+
+enum java_tree_index
+{
+  JTI_MAX
+};
+
+void function (void)
+{
+  var = JTI_MAX;
+}
+ 
--- /dev/null	2006-07-20 04:40:48.651748895 -0400
+++ testsuite/g++.dg/debug/enum-2.C	2006-07-22 15:07:34.000000000 -0400
@@ -0,0 +1,22 @@
+/* Verify that used enums are output.  */
+/* { dg-do compile } */
+/* { dg-final { scan-assembler "JTI_MAX" } } */
+
+int var;
+
+enum java_tree_index
+{
+  JTI_MAX
+};
+
+template<int X>
+void tmpl (void)
+{
+  var = JTI_MAX + X;
+}
+ 
+void
+function (void)
+{
+  tmpl<2>();
+}
Index: dwarf2out.c
===================================================================
--- dwarf2out.c	(revision 115676)
+++ dwarf2out.c	(working copy)
@@ -11457,6 +11457,7 @@ dwarf2out_abstract_function (tree decl)
 {
   dw_die_ref old_die;
   tree save_fn;
+  struct function *save_cfun;
   tree context;
   int was_abstract = DECL_ABSTRACT (decl);
 
@@ -11480,7 +11481,9 @@ dwarf2out_abstract_function (tree decl)
 
   /* Pretend we've just finished compiling this function.  */
   save_fn = current_function_decl;
+  save_cfun = cfun;
   current_function_decl = decl;
+  cfun = DECL_STRUCT_FUNCTION (decl);
 
   set_decl_abstract_flags (decl, 1);
   dwarf2out_decl (decl);
@@ -11488,6 +11491,7 @@ dwarf2out_abstract_function (tree decl)
     set_decl_abstract_flags (decl, 0);
 
   current_function_decl = save_fn;
+  cfun = save_cfun;
 }
 
 /* Helper function of premark_used_types() which gets called through
@@ -11531,7 +11535,7 @@ gen_subprogram_die (tree decl, dw_die_re
   int declaration = (current_function_decl != decl
 		     || class_or_namespace_scope_p (context_die));
 
-  premark_used_types();
+  premark_used_types ();
 
   /* It is possible to have both DECL_ABSTRACT and DECLARATION be true if we
      started to generate the abstract instance of an inline, decided to output