[PATCH] Emit DW_LANG_C99 for C with -std=c99 (PR debug/38757)

[Jakub Jelinek <jakub at redhat dot com>]

Hi!

Here is updated patch to differentiate C89 and C99 in DWARF3+
DW_TAG_compile_unit.  I've posted it already a year ago and used in Fedora
gcc since then, it hasn't been committed to trunk because of fears of
interaction with LTO, but given that LTO still doesn't have usable
debugging, I think LTO for the time being outputting always DW_LANG_C89
instead of DW_LANG_C99 for -std=c99 when it outputs DW_LANG_C89 instead
of DW_LANG_C_plus_plus etc. for the various languages is the least of
problems LTO debugging currently has.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2010-04-16  Jakub Jelinek  <jakub@redhat.com>

	PR debug/38757
	* langhooks.h (struct lang_hooks): Add source_language langhook.
	* langhooks-def.h (LANG_HOOKS_SOURCE_LANGUAGE): Define to NULL.
	(LANG_HOOKS_INITIALIZER): Add LANG_HOOKS_SOURCE_LANGUAGE.
	* c-lang.c (c_source_language): New function.
	(LANG_HOOKS_SOURCE_LANGUAGE): Define.
	* dwarf2out.c (add_prototyped_attribute): Add DW_AT_prototype
	also for DW_LANG_{C,C99,ObjC}.
	(gen_compile_unit_die): Use lang_hooks.source_language () to
	determine if DW_LANG_C99 or DW_LANG_C89 should be returned.

--- gcc/langhooks-def.h.jj	2010-04-16 14:00:51.000000000 +0200
+++ gcc/langhooks-def.h	2010-04-16 14:03:11.000000000 +0200
@@ -106,6 +106,7 @@ extern void lhd_omp_firstprivatize_type_
 #define LANG_HOOKS_BUILTIN_FUNCTION	lhd_builtin_function
 #define LANG_HOOKS_BUILTIN_FUNCTION_EXT_SCOPE	LANG_HOOKS_BUILTIN_FUNCTION
 #define LANG_HOOKS_EXPR_TO_DECL		lhd_expr_to_decl
+#define LANG_HOOKS_SOURCE_LANGUAGE	NULL
 #define LANG_HOOKS_TO_TARGET_CHARSET	lhd_to_target_charset
 #define LANG_HOOKS_INIT_TS		lhd_do_nothing
 #define LANG_HOOKS_EH_PERSONALITY	lhd_gcc_personality
@@ -298,6 +299,7 @@ extern void lhd_end_section (void);
   LANG_HOOKS_BUILTIN_FUNCTION_EXT_SCOPE, \
   LANG_HOOKS_INIT_TS,          \
   LANG_HOOKS_EXPR_TO_DECL, \
+  LANG_HOOKS_SOURCE_LANGUAGE, \
   LANG_HOOKS_EH_PERSONALITY, \
   LANG_HOOKS_EH_RUNTIME_TYPE, \
   LANG_HOOKS_EH_USE_CXA_END_CLEANUP, \
--- gcc/langhooks.h.jj	2010-04-16 14:00:51.000000000 +0200
+++ gcc/langhooks.h	2010-04-16 14:03:42.000000000 +0200
@@ -443,6 +443,10 @@ struct lang_hooks
      if in the process TREE_CONSTANT or TREE_SIDE_EFFECTS need updating.  */
   tree (*expr_to_decl) (tree expr, bool *tc, bool *se);
 
+  /* Return year of the source language standard version if the FE supports
+     multiple versions of the standard.  */
+  int (*source_language) (void);
+
   /* The EH personality function decl.  */
   tree (*eh_personality) (void);
 
--- gcc/dwarf2out.c.jj	2010-04-16 14:00:51.000000000 +0200
+++ gcc/dwarf2out.c	2010-04-16 14:05:57.000000000 +0200
@@ -16640,9 +16640,18 @@ add_bit_size_attribute (dw_die_ref die, 
 static inline void
 add_prototyped_attribute (dw_die_ref die, tree func_type)
 {
-  if (get_AT_unsigned (comp_unit_die, DW_AT_language) == DW_LANG_C89
-      && TYPE_ARG_TYPES (func_type) != NULL)
-    add_AT_flag (die, DW_AT_prototyped, 1);
+  switch (get_AT_unsigned (comp_unit_die, DW_AT_language))
+    {
+    case DW_LANG_C:
+    case DW_LANG_C89:
+    case DW_LANG_C99:
+    case DW_LANG_ObjC:
+      if (TYPE_ARG_TYPES (func_type) != NULL)
+	add_AT_flag (die, DW_AT_prototyped, 1);
+      break;
+    default:
+      break;
+    }
 }
 
 /* Add an 'abstract_origin' attribute below a given DIE.  The DIE is found
@@ -18711,6 +18720,10 @@ gen_compile_unit_die (const char *filena
 	language = DW_LANG_ObjC;
       else if (strcmp (language_string, "GNU Objective-C++") == 0)
 	language = DW_LANG_ObjC_plus_plus;
+      else if (strcmp (language_string, "GNU C") == 0
+	       && lang_hooks.source_language
+	       && lang_hooks.source_language () >= 1999)
+	language = DW_LANG_C99;
     }
 
   add_AT_unsigned (die, DW_AT_language, language);
--- gcc/c-lang.c.jj	2009-09-03 14:02:04.000000000 +0200
+++ gcc/c-lang.c	2010-04-16 14:01:30.000000000 +0200
@@ -37,6 +37,12 @@ along with GCC; see the file COPYING3.  
 
 enum c_language_kind c_language = clk_c;
 
+static int
+c_source_language (void)
+{
+  return flag_isoc99 ? 1999 : 1989;
+}
+
 /* Lang hooks common to C and ObjC are declared in c-objc-common.h;
    consequently, there should be very few hooks below.  */
 
@@ -44,6 +50,8 @@ enum c_language_kind c_language = clk_c;
 #define LANG_HOOKS_NAME "GNU C"
 #undef LANG_HOOKS_INIT
 #define LANG_HOOKS_INIT c_objc_common_init
+#undef LANG_HOOKS_SOURCE_LANGUAGE
+#define LANG_HOOKS_SOURCE_LANGUAGE c_source_language
 
 /* Each front end provides its own lang hook initializer.  */
 struct lang_hooks lang_hooks = LANG_HOOKS_INITIALIZER;

	Jakub