* dojump.c (do_jump): If the expression being compared against
	zero, is the subreg of a promoted variable, perform the comparison
	in the promoted mode.
	* simplify-rtx.c (simplify_unary_operation): Optimize sign and
	zero-extensions of subregs of promoted variables where the
	extension is identical to that used to promote the variable.

From-SVN: r74332