re PR rtl-optimization/4330 (Optimizer generates illegal assembly code)

        PR opt/4330
        * langhooks.h (lang_hooks.decls.warn_unused_global): New.
        * toplev.c (check_global_declarations): Use it.
        * langhooks-def.h (lhd_warn_unused_global_decl): Declare.
        (LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL): New.
        (LANG_HOOKS_DECLS): Add it.
        * langhooks.c (lhd_warn_unused_global_decl): New.
        * c-decl.c (LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL): New.
        * c-objc-common.c (c_warn_unused_global_decl): New.
        * c-tree.h (c_warn_unused_global_decl): Declare.
        * objc/objc-lang.c (LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL): New.

        * cp-lang.c (cxx_warn_unused_global_decl): New.
        (LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL): New.

	* g++.dg/warn/Wunused-2.C: New.
	* gcc.dg/unused-4.c: New.

From-SVN: r51818

2 files changed, 67 insertions, 41 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index a7ffd32..50dfde8 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+2002-04-03  Richard Henderson  <rth@redhat.com>
+
+	* cp-lang.c (cxx_warn_unused_global_decl): New.
+	(LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL): New.
+
 2002-04-03  Neil Booth  <neil@daikokuya.demon.co.uk>
 
 	* cp-lang.c (LANG_HOOKS_SET_DECL_ASSEMBLER_NAME): Redefine.
diff --git a/gcc/cp/cp-lang.c b/gcc/cp/cp-lang.c
index b7d129a..3c086ca 100644
--- a/gcc/cp/cp-lang.c
+++ b/gcc/cp/cp-lang.c
@@ -30,6 +30,7 @@ Boston, MA 02111-1307, USA.  */
 
 static HOST_WIDE_INT cxx_get_alias_set PARAMS ((tree));
 static bool ok_to_generate_alias_set_for_type PARAMS ((tree));
+static bool cxx_warn_unused_global_decl PARAMS ((tree));
 
 #undef LANG_HOOKS_NAME
 #define LANG_HOOKS_NAME "GNU C++"
@@ -87,6 +88,8 @@ static bool ok_to_generate_alias_set_for_type PARAMS ((tree));
 #define LANG_HOOKS_PRINT_ERROR_FUNCTION	cxx_print_error_function
 #undef LANG_HOOKS_SET_YYDEBUG
 #define LANG_HOOKS_SET_YYDEBUG cxx_set_yydebug
+#undef LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL
+#define LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL cxx_warn_unused_global_decl
 
 #undef LANG_HOOKS_TREE_INLINING_WALK_SUBTREES
 #define LANG_HOOKS_TREE_INLINING_WALK_SUBTREES \
@@ -133,6 +136,47 @@ static bool ok_to_generate_alias_set_for_type PARAMS ((tree));
 /* Each front end provides its own hooks, for toplev.c.  */
 const struct lang_hooks lang_hooks = LANG_HOOKS_INITIALIZER;
 
+/* Tree code classes. */
+
+#define DEFTREECODE(SYM, NAME, TYPE, LENGTH) TYPE,
+
+const char tree_code_type[] = {
+#include "tree.def"
+  'x',
+#include "c-common.def"
+  'x',
+#include "cp-tree.def"
+};
+#undef DEFTREECODE
+
+/* Table indexed by tree code giving number of expression
+   operands beyond the fixed part of the node structure.
+   Not used for types or decls.  */
+
+#define DEFTREECODE(SYM, NAME, TYPE, LENGTH) LENGTH,
+
+const unsigned char tree_code_length[] = {
+#include "tree.def"
+  0,
+#include "c-common.def"
+  0,
+#include "cp-tree.def"
+};
+#undef DEFTREECODE
+
+/* Names of tree components.
+   Used for printing out the tree and error messages.  */
+#define DEFTREECODE(SYM, NAME, TYPE, LEN) NAME,
+
+const char *const tree_code_name[] = {
+#include "tree.def"
+  "@@dummy",
+#include "c-common.def"
+  "@@dummy",
+#include "cp-tree.def"
+};
+#undef DEFTREECODE
+
 /* Check if a C++ type is safe for aliasing.
    Return TRUE if T safe for aliasing FALSE otherwise.  */
 
@@ -185,47 +229,6 @@ ok_to_generate_alias_set_for_type (t)
     return true;
 }
 
-/* Tree code classes. */
-
-#define DEFTREECODE(SYM, NAME, TYPE, LENGTH) TYPE,
-
-const char tree_code_type[] = {
-#include "tree.def"
-  'x',
-#include "c-common.def"
-  'x',
-#include "cp-tree.def"
-};
-#undef DEFTREECODE
-
-/* Table indexed by tree code giving number of expression
-   operands beyond the fixed part of the node structure.
-   Not used for types or decls.  */
-
-#define DEFTREECODE(SYM, NAME, TYPE, LENGTH) LENGTH,
-
-const unsigned char tree_code_length[] = {
-#include "tree.def"
-  0,
-#include "c-common.def"
-  0,
-#include "cp-tree.def"
-};
-#undef DEFTREECODE
-
-/* Names of tree components.
-   Used for printing out the tree and error messages.  */
-#define DEFTREECODE(SYM, NAME, TYPE, LEN) NAME,
-
-const char *const tree_code_name[] = {
-#include "tree.def"
-  "@@dummy",
-#include "c-common.def"
-  "@@dummy",
-#include "cp-tree.def"
-};
-#undef DEFTREECODE
-
 /* Special routine to get the alias set for C++.  */
 
 static HOST_WIDE_INT
@@ -238,3 +241,21 @@ cxx_get_alias_set (t)
 
   return c_common_get_alias_set (t);
 }
+
+/* Called from check_global_declarations.  */
+
+static bool
+cxx_warn_unused_global_decl (decl)
+     tree decl;
+{
+  if (TREE_CODE (decl) == FUNCTION_DECL && DECL_DECLARED_INLINE_P (decl))
+    return false;
+  if (DECL_IN_SYSTEM_HEADER (decl))
+    return false;
+
+  /* Const variables take the place of #defines in C++.  */
+  if (TREE_CODE (decl) == VAR_DECL && TREE_READONLY (decl))
+    return false;
+
+  return true;
+}