For PR java/6005 and PR java/7611:

	* fold-const.c (fold_truthop): Use can_use_bit_fields_p.
	(fold): Likewise.
	* langhooks.c (lhd_can_use_bit_fields_p): New function.
	* langhooks-def.h (lhd_can_use_bit_fields_p): Declare.
	(LANG_HOOKS_CAN_USE_BIT_FIELDS_P): New define.
	(LANG_HOOKS_INITIALIZER): Use it.
	* langhooks.h (struct lang_hooks) [can_use_bit_fields_p]: New
	field.

From-SVN: r56498

gcc/ChangeLog

+2002-08-21  Tom Tromey  <tromey@redhat.com>
+
+	For PR java/6005 and PR java/7611:
+	* fold-const.c (fold_truthop): Use can_use_bit_fields_p.
+	(fold): Likewise.
+	* langhooks.c (lhd_can_use_bit_fields_p): New function.
+	* langhooks-def.h (lhd_can_use_bit_fields_p): Declare.
+	(LANG_HOOKS_CAN_USE_BIT_FIELDS_P): New define.
+	(LANG_HOOKS_INITIALIZER): Use it.
+	* langhooks.h (struct lang_hooks) [can_use_bit_fields_p]: New
+	field.
+
 2002-08-21  Stan Shebs  <shebs@apple.com>
 
 	* tree.c (finish_vector_type): Fix a typo in a comment.

gcc/fold-const.c

 /* Fold a constant sub-tree into a single node for C-compiler
-   Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
+   Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 2002,
    1999, 2000, 2001, 2002 Free Software Foundation, Inc.
 
 This file is part of GCC.
@@ -3711,6 +3711,11 @@ fold_truthop (code, truth_type, lhs, rhs)
 	return 0;
     }
 
+  /* After this point all optimizations will generate bit-field
+     references, which we might not want.  */
+  if (! (*lang_hooks.can_use_bit_fields_p) ())
+    return 0;
+
   /* See if we can find a mode that contains both fields being compared on
      the left.  If we can't, fail.  Otherwise, update all constants and masks
      to be relative to a field of that size.  */
@@ -6590,7 +6595,8 @@ fold (expr)
 	}
 
       /* If this is a comparison of a field, we may be able to simplify it.  */
-      if ((TREE_CODE (arg0) == COMPONENT_REF
+      if (((TREE_CODE (arg0) == COMPONENT_REF
+	    && (*lang_hooks.can_use_bit_fields_p) ())
 	   || TREE_CODE (arg0) == BIT_FIELD_REF)
 	  && (code == EQ_EXPR || code == NE_EXPR)
 	  /* Handle the constant case even without -O

gcc/langhooks-def.h

@@ -59,6 +59,7 @@ extern rtx lhd_expand_expr PARAMS ((tree, rtx, enum machine_mode, int));
 extern void lhd_print_error_function PARAMS ((struct diagnostic_context *,
 					      const char *));
 extern void lhd_set_decl_assembler_name PARAMS ((tree));
+extern bool lhd_can_use_bit_fields_p PARAMS ((void));
 extern bool lhd_warn_unused_global_decl PARAMS ((tree));
 extern void lhd_incomplete_type_error PARAMS ((tree, tree));
 extern tree lhd_type_promotes_to PARAMS ((tree));
@@ -102,6 +103,7 @@ tree lhd_tree_inlining_convert_parm_for_inlining PARAMS ((tree, tree, tree));
 #define LANG_HOOKS_UNSAVE_EXPR_NOW	lhd_unsave_expr_now
 #define LANG_HOOKS_MAYBE_BUILD_CLEANUP	lhd_return_null_tree
 #define LANG_HOOKS_SET_DECL_ASSEMBLER_NAME lhd_set_decl_assembler_name
+#define LANG_HOOKS_CAN_USE_BIT_FIELDS_P lhd_can_use_bit_fields_p
 #define LANG_HOOKS_HONOR_READONLY	false
 #define LANG_HOOKS_PRINT_STATISTICS	lhd_do_nothing
 #define LANG_HOOKS_PRINT_XNODE		lhd_print_tree_nothing
@@ -241,6 +243,7 @@ int lhd_tree_dump_type_quals			PARAMS ((tree));
   LANG_HOOKS_UNSAVE_EXPR_NOW, \
   LANG_HOOKS_MAYBE_BUILD_CLEANUP, \
   LANG_HOOKS_SET_DECL_ASSEMBLER_NAME, \
+  LANG_HOOKS_CAN_USE_BIT_FIELDS_P, \
   LANG_HOOKS_HONOR_READONLY, \
   LANG_HOOKS_PRINT_STATISTICS, \
   LANG_HOOKS_PRINT_XNODE, \

gcc/langhooks.c

@@ -175,6 +175,13 @@ lhd_set_decl_assembler_name (decl)
     abort ();
 }
 
+/* By default we always allow bit-field based optimizations.  */
+bool
+lhd_can_use_bit_fields_p ()
+{
+  return true;
+}
+
 /* Provide a default routine to clear the binding stack.  This is used
    by languages that don't need to do anything special.  */
 void

gcc/langhooks.h

@@ -299,6 +299,10 @@ struct lang_hooks
      assembler does not talk about it.  */
   void (*set_decl_assembler_name) PARAMS ((tree));
 
+  /* Return nonzero if fold-const is free to use bit-field
+     optimizations, for instance in fold_truthop().  */
+  bool (*can_use_bit_fields_p) PARAMS ((void));
+
   /* Nonzero if TYPE_READONLY and TREE_READONLY should always be honored.  */
   bool honor_readonly;