[gcse] PR rtl-optimization/69886: Check target mode in can_assign_to_reg_without_clob...

[gcse] PR rtl-optimization/69886: Check target mode in can_assign_to_reg_without_clobbers_p

	PR rtl-optimization/69886
	* gcse.c (can_assign_to_reg_without_clobbers_p): Accept mode
	argument.  Use it when checking validity of set instructions.
	(want_to_gcse_p): Pass mode to can_assign_to_reg_without_clobbers_p.
	(compute_ld_motion_mems): Update can_assign_to_reg_without_clobbers_p
	callsite.
	* rtl.h (can_assign_to_reg_without_clobbers_p): Update prototype.
	* store-motion.c (find_moveable_store): Update
	can_assign_to_reg_without_clobbers_p callsite.

	* gcc.dg/torture/pr69886.c: New test.

From-SVN: r233662