Fix crtstuff.c wrt used/unused attrs

[Jan Hubicka <hubicka at ucw dot cz>]

Hi,
my unused variable/function removal patch cause us to remove unused vars with
-fno-toplevel-reorder.  I am not sure if we want to do this (i.e. we can just
disable the feature for toplevel-reorder), but it is valid optimization.

This breaks bootstrap because crtstuff is decorating constructor arrays as
unused rather than used (because it was written before used attribute was
introduced for variables).  I think this should be fixed in any case.  We can
decide on -fno-toplevel-reorder behaviour later based on if glibc/kernel breaks
with removal too or not.

Bootstrapped/regtested x86_64-linux, OK?

Honza

	* crtstuff.c (force_to_data, __do_global_dtors_aux_fini_array_entry,
	__frame_dummy_init_array_entry, force_to_data): Attribute as used
	rather than unused.
Index: crtstuff.c
===================================================================
--- crtstuff.c	(revision 159199)
+++ crtstuff.c	(working copy)
@@ -187,14 +187,14 @@ CTOR_LIST_BEGIN;
 #elif defined(CTORS_SECTION_ASM_OP)
 /* Hack: force cc1 to switch to .data section early, so that assembling
    __CTOR_LIST__ does not undo our behind-the-back change to .ctors.  */
-static func_ptr force_to_data[1] __attribute__ ((__unused__)) = { };
+static func_ptr force_to_data[1] __attribute__ ((__used__)) = { };
 asm (CTORS_SECTION_ASM_OP);
 STATIC func_ptr __CTOR_LIST__[1]
-  __attribute__ ((__unused__, aligned(sizeof(func_ptr))))
+  __attribute__ ((__used__, aligned(sizeof(func_ptr))))
   = { (func_ptr) (-1) };
 #else
 STATIC func_ptr __CTOR_LIST__[1]
-  __attribute__ ((__unused__, section(".ctors"), aligned(sizeof(func_ptr))))
+  __attribute__ ((__used__, section(".ctors"), aligned(sizeof(func_ptr))))
   = { (func_ptr) (-1) };
 #endif /* __CTOR_LIST__ alternatives */
 
@@ -336,7 +336,7 @@ __do_global_dtors_aux (void)
 CRT_CALL_STATIC_FUNCTION (FINI_SECTION_ASM_OP, __do_global_dtors_aux)
 #elif defined (FINI_ARRAY_SECTION_ASM_OP)
 static func_ptr __do_global_dtors_aux_fini_array_entry[]
-  __attribute__ ((__unused__, section(".fini_array")))
+  __attribute__ ((__used__, section(".fini_array")))
   = { __do_global_dtors_aux };
 #else /* !FINI_SECTION_ASM_OP && !FINI_ARRAY_SECTION_ASM_OP */
 static void __attribute__((used))
@@ -383,7 +383,7 @@ frame_dummy (void)
 CRT_CALL_STATIC_FUNCTION (INIT_SECTION_ASM_OP, frame_dummy)
 #else /* defined(INIT_SECTION_ASM_OP) */
 static func_ptr __frame_dummy_init_array_entry[]
-  __attribute__ ((__unused__, section(".init_array")))
+  __attribute__ ((__used__, section(".init_array")))
   = { frame_dummy };
 #endif /* !defined(INIT_SECTION_ASM_OP) */
 #endif /* USE_EH_FRAME_REGISTRY || JCR_SECTION_NAME */
@@ -491,7 +491,7 @@ CTOR_LIST_END;
 #elif defined(CTORS_SECTION_ASM_OP)
 /* Hack: force cc1 to switch to .data section early, so that assembling
    __CTOR_LIST__ does not undo our behind-the-back change to .ctors.  */
-static func_ptr force_to_data[1] __attribute__ ((__unused__)) = { };
+static func_ptr force_to_data[1] __attribute__ ((__used__)) = { };
 asm (CTORS_SECTION_ASM_OP);
 STATIC func_ptr __CTOR_END__[1]
   __attribute__((aligned(sizeof(func_ptr))))