* regcprop.c (maybe_mode_change): Avoid creating copies of the
	stack pointer.

	Revert:
	2017-04-13  Jeff Law  <law@redhat.com>
	* config/mips.mips.md (zero_extendsidi2): Do not allow SP to appear
	in operands[1] if it is a MEM and TARGET_MIPS16 is active.

From-SVN: r246970