aarch64: Add support for unpacked SVE FP conditional binary arithmetic

aarch64: Add support for unpacked SVE FP conditional binary arithmetic

This patch extends the expander for conditional smax, smin, add, sub, mul,
min, max, and div to support partial SVE FP modes.

If exceptions from undefined vector elements must be suppressed, this
expansion converts the container-level predicate to an element-level one, and
ensures that these elements are inactive for the operation.  In practice, this
is a predicate AND with the existing mask and a container-size PTRUE.

gcc/ChangeLog:

	* config/aarch64/aarch64-protos.h (aarch64_sve_emit_masked_fp_pred):
	Declare.
	* config/aarch64/aarch64-sve.md (and<mode>3):  Change this to...
	(@and<mode>3): ...this, so that we can use gen_and3.
	(@cond_<optab><mode>): Extend from SVE_FULL_F_B16B16 to SVE_F_B16B16,
	use aarch64_predicate_operand.
	(*cond_<optab><mode>_2_strict): Likewise.
	(*cond_<optab><mode>_3_strict): Likewise.
	(*cond_<optab><mode>_any_strict): Likwise.
	(*cond_<optab><mode>_2_const_strict): Extend from SVE_FULL_F to SVE_F,
	use aarch64_predicate_operand.
	(*cond_<optab><mode>_any_const_strict): Likewise.
	(*cond_sub<mode>_3_const_strict): Likwise.
	(*cond_sub<mode>_const_strict): Likewise.
	(*vcond_mask_<mode><vpred>): Use aarch64_predicate_operand, and update
	the comment here.
	* config/aarch64/aarch64.cc (aarch64_sve_emit_masked_fp_pred): New
	function.  Helper to mask the predicate in conditional expanders.

gcc/testsuite/ChangeLog:

	* g++.target/aarch64/sve/unpacked_cond_binary_bf16_2.C: New test.
	* gcc.target/aarch64/sve/unpacked_cond_builtin_fmax_2.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_cond_builtin_fmin_2.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_cond_fadd_2.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_cond_fdiv_2.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_cond_fmaxnm_2.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_cond_fminnm_2.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_cond_fmul_2.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_cond_fsubr_2.c: Likewise.