aarch64: Convert SVE gather patterns to compact syntax

aarch64: Convert SVE gather patterns to compact syntax

This patch converts the SVE load gather patterns to the new compact syntax
that Tamar introduced. This allows for a future patch I want to contribute
to add more alternatives that are better viewed in the more compact form.

The lines in some patterns are >80 long now, but I think that's unavoidable
and those patterns already had overly long constraint strings.

No functional change intended.
Bootstrapped and tested on aarch64-none-linux-gnu.

gcc/ChangeLog:

	* config/aarch64/aarch64-sve.md (mask_gather_load<mode><v_int_container>):
	Convert to compact alternatives syntax.
	(mask_gather_load<mode><v_int_container>): Likewise.
	(*mask_gather_load<mode><v_int_container>_<su>xtw_unpacked): Likewise.
	(*mask_gather_load<mode><v_int_container>_sxtw): Likewise.
	(*mask_gather_load<mode><v_int_container>_uxtw): Likewise.
	(@aarch64_gather_load_<ANY_EXTEND:optab><SVE_4HSI:mode><SVE_4BHI:mode>):
	Likewise.
	(@aarch64_gather_load_<ANY_EXTEND:optab><SVE_2HSDI:mode><SVE_2BHSI:mode>):
	Likewise.
	(*aarch64_gather_load_<ANY_EXTEND:optab><SVE_2HSDI:mode>
	<SVE_2BHSI:mode>_<ANY_EXTEND2:su>xtw_unpacked): Likewise.
	(*aarch64_gather_load_<ANY_EXTEND:optab><SVE_2HSDI:mode>
	<SVE_2BHSI:mode>_sxtw): Likewise.
	(*aarch64_gather_load_<ANY_EXTEND:optab><SVE_2HSDI:mode>
	<SVE_2BHSI:mode>_uxtw): Likewise.
	(@aarch64_ldff1_gather<mode>): Likewise.
	(@aarch64_ldff1_gather<mode>): Likewise.
	(*aarch64_ldff1_gather<mode>_sxtw): Likewise.
	(*aarch64_ldff1_gather<mode>_uxtw): Likewise.
	(@aarch64_ldff1_gather_<ANY_EXTEND:optab><VNx4_WIDE:mode>
	<VNx4_NARROW:mode>): Likewise.
	(@aarch64_ldff1_gather_<ANY_EXTEND:optab><VNx2_WIDE:mode>
	<VNx2_NARROW:mode>): Likewise.
	(*aarch64_ldff1_gather_<ANY_EXTEND:optab><VNx2_WIDE:mode>
	<VNx2_NARROW:mode>_sxtw): Likewise.
	(*aarch64_ldff1_gather_<ANY_EXTEND:optab><VNx2_WIDE:mode>
	<VNx2_NARROW:mode>_uxtw): Likewise.
	* config/aarch64/aarch64-sve2.md (@aarch64_gather_ldnt<mode>): Likewise.
	(@aarch64_gather_ldnt_<ANY_EXTEND:optab><SVE_FULL_SDI:mode>
	<SVE_PARTIAL_I:mode>): Likewise.