jump.c (delete_prior_computation): New function, broken out of delete_computation.

jump.c (delete_prior_computation): New function, broken out of delete_computation.

	* jump.c (delete_prior_computation): New function, broken
	out of delete_computation.  Check for side effects with
	side_effects_p instead of FIND_REG_INC_NOTE.  Handle
	multi-word hard registers.
	(delete_computation): Use it.  Check for side effects with
	side_effects_p instead of FIND_REG_INC_NOTE.  Synthesize a
	missing REG_DEAD note for a register which is both set and
	used by an insn.

From-SVN: r28558