* ggc-callbacks.c (lang_mark_tree, lang_mark_false_label_stack):
Mark with ATTRIBUTE_NORETURN.
* hash.c (hash_newfunc): Mark parameter with ATTRIBUTE_UNUSED.
* local-alloc.c (no_conflict_p): Likewise.
* loop.c (insert_bct): Hide definitions of variables with hidden
usage.
(note_reg_stored): Mark parameter with ATTRIBUTE_UNUSED.
* regclass.c (memory_move_secondary_cost): Mark variable `mem'
with ATTRIBUTE_UNUSED.
(record_reg_classes): Mark parameter with ATTRIBUTE_UNUSED.
(reg_scan): Likewise.