* gcse.c (try_replace_reg): Do replacements in REG_EQUAL/REG_EQUIV

	notes too, create one when replacement failed, attempt to simplify
	resulting notes.
	(cprop_insn): Propagate even to registers mentioned only in REG_EQUAL
	or REG_EQUIV notes.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@30992 138bc75d-0d04-0410-961f-82ee72b054a4