combine.c (struct reg_stat): Add new fields truncation_label and truncated_to_mode.

combine.c (struct reg_stat): Add new fields truncation_label and truncated_to_mode.

	* combine.c (struct reg_stat): Add new fields truncation_label and
	truncated_to_mode.
	(record_value_for_reg): Reset truncated_to_mode.
	(record_truncated_value): New function.
	(check_promoted_subreg): Call it.  Rename to check_conversions.
	(combine_instructions): Rename check_promoted_subreg to
	check_conversions.
	(reg_truncated_to_mode): New function.
	(make_extraction): Use it.  Check TRULY_NOOP_TRUNCATION.
	(gen_lowpart_or_truncate): New function.
	(force_to_mode): Use it instead of gen_lowpart.

From-SVN: r109679