* bitmap.h (nBITMAP_WORD_BITS): Remove.
(BITMAP_WORD_BITS): Force unsigned by use of 1u.
(BITMAP_ELEMENT_WORDS, BITMAP_ELEMENT_ALL_BITS): Remove
unnecessary casts.
(bitmap_first_set_bit): Return unsigned, use ctzl.
(bitmap_last_set_bit): Remove.
* bitmap.c (bitmap_element_zerop, bitmap_copy): Make iterator
unsigned.
(bitmap_first_set_bit): Return unsigned, require non-empty bitmap,
remove special case code for two word elements.
(bitmap_last_set_bit): Remove.
* ra-build.c (livethrough_conflicts_bb): Replace unnecessary use of
bitmap_first_set_bit with bitmap_empty_p.
* tree-outof-ssa.c (analyze_edges_for_bb): Likewise.
* tree-ssa-pre.c (bitmap_print_value): Use simple flag rather than
bitmap_last_bit_set.