combine: Another hard register problem (PR85805)

combine: Another hard register problem (PR85805)

The current code in reg_nonzero_bits_for_combine allows using the
reg_stat info when last_set_mode is a different integer mode.  This is
completely wrong for non-pseudos.  For example, as in the PR, a value
in a DImode hard register is set by eight writes to its constituent
QImode parts.  The value written to the DImode is not the same as that
written to the lowest-numbered QImode!

	PR rtl-optimization/85805
	* combine.c (reg_nonzero_bits_for_combine): Only use the last set
	value for hard registers if that was written in the same mode.

From-SVN: r262994