re PR target/84845 (ICE: in extract_insn, at recog.c:2304: unrecognizable insn at -O2 and above at aarch64)

	PR target/84845
	* config/aarch64/aarch64.md (*aarch64_reg_<mode>3_neg_mask2): Rename
	to ...
	(*aarch64_<optab>_reg_<mode>3_neg_mask2): ... this.  If pseudos can't
	be created, use lowpart_subreg of operands[0] rather than operands[0]
	itself.
	(*aarch64_reg_<mode>3_minus_mask): Rename to ...
	(*aarch64_ashl_reg_<mode>3_minus_mask): ... this.
	(*aarch64_<optab>_reg_di3_mask2): Use const_int_operand predicate
	and n constraint instead of aarch64_shift_imm_di and Usd.
	(*aarch64_reg_<optab>_minus<mode>3): Rename to ...
	(*aarch64_<optab>_reg_minus<mode>3): ... this.

	* gcc.c-torture/compile/pr84845.c: New test.

From-SVN: r258678