[AArch64] Add support for SVE [SU]{MAX,MIN} immediate

[AArch64] Add support for SVE [SU]{MAX,MIN} immediate

This patch adds support for the immediate forms of SVE SMAX, SMIN, UMAX
and UMIN.  SMAX and SMIN take the same range as MUL, so the patch
basically just moves and generalises the existing MUL patterns.

2019-08-14  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* config/aarch64/constraints.md (vsb): New constraint.
	(vsm): Generalize description.
	* config/aarch64/iterators.md (SVE_INT_BINARY_IMM): New code
	iterator.
	(sve_imm_con): Handle smax, smin, umax and umin.
	(sve_imm_prefix): New code attribute.
	* config/aarch64/predicates.md (aarch64_sve_vsb_immediate)
	(aarch64_sve_vsb_operand): New predicates.
	(aarch64_sve_mul_immediate): Rename to...
	(aarch64_sve_vsm_immediate): ...this.
	(aarch64_sve_mul_operand): Rename to...
	(aarch64_sve_vsm_operand): ...this.
	* config/aarch64/aarch64-sve.md (mul<mode>3): Generalize to...
	(<SVE_INT_BINARY_IMM:optab><SVE_I:mode>3): ...this.
	(*mul<mode>3, *post_ra_mul<mode>3): Generalize to...
	(*<SVE_INT_BINARY_IMM:optab><SVE_I:mode>3)
	(*post_ra_<SVE_INT_BINARY_IMM:optab><SVE_I:mode>3): ...these and
	add movprfx support for the immediate alternatives.
	(<su><maxmin><mode>3, *<su><maxmin><mode>3): Delete in favor
	of the above.
	(*<SVE_INT_BINARY_SD:optab><SVE_SDI:mode>3): Fix incorrect predicate
	for operand 3.

gcc/testsuite/
	* gcc.target/aarch64/sve/smax_1.c: New test.
	* gcc.target/aarch64/sve/smin_1.c: Likewise.
	* gcc.target/aarch64/sve/umax_1.c: Likewise.
	* gcc.target/aarch64/sve/umin_1.c: Likewise.

From-SVN: r274439