* expr.c (store_constructor): When initializing a field that is smaller
	than a word, at the start of a word, try to widen it to a full word.
	* cse.c (cse_insn): When we are about to change a register,
	remove any invalid references to it.
	(remove_invalid_subreg_refs): New function.
	(mention_regs): Special treatment for SUBREGs.
	(insert_regs): Don't strip SUBREG for call to mention_regs.
	Check if reg_tick needs to be bumped up before that call.
	(lookup_as_function): Try to match known word_mode constants when
	looking for a norrower constant.
	(canon_hash): Special treatment for SUBREGs.

From-SVN: r22567