This patch supports following MVE ACLE intrinsics with writeback.

vldrdq_gather_base_wb_s64, vldrdq_gather_base_wb_u64, vldrdq_gather_base_wb_z_s64,
vldrdq_gather_base_wb_z_u64, vldrwq_gather_base_wb_f32, vldrwq_gather_base_wb_s32,
vldrwq_gather_base_wb_u32, vldrwq_gather_base_wb_z_f32, vldrwq_gather_base_wb_z_s32,
vldrwq_gather_base_wb_z_u32, vstrdq_scatter_base_wb_p_s64, vstrdq_scatter_base_wb_p_u64,
vstrdq_scatter_base_wb_s64, vstrdq_scatter_base_wb_u64, vstrwq_scatter_base_wb_p_s32,
vstrwq_scatter_base_wb_p_f32, vstrwq_scatter_base_wb_p_u32, vstrwq_scatter_base_wb_s32,
vstrwq_scatter_base_wb_u32, vstrwq_scatter_base_wb_f32.

Please refer to M-profile Vector Extension (MVE) intrinsics [1]  for more details.
[1] https://developer.arm.com/architectures/instruction-sets/simd-isas/helium/mve-intrinsics

2020-03-20  Srinath Parvathaneni  <srinath.parvathaneni@arm.com>
            Andre Vieira  <andre.simoesdiasvieira@arm.com>
            Mihail Ionescu  <mihail.ionescu@arm.com>

	* config/arm/arm-builtins.c (LDRGBWBS_QUALIFIERS): Define builtin
	qualifier.
	(LDRGBWBU_QUALIFIERS): Likewise.
	(LDRGBWBS_Z_QUALIFIERS): Likewise.
	(LDRGBWBU_Z_QUALIFIERS): Likewise.
	(STRSBWBS_QUALIFIERS): Likewise.
	(STRSBWBU_QUALIFIERS): Likewise.
	(STRSBWBS_P_QUALIFIERS): Likewise.
	(STRSBWBU_P_QUALIFIERS): Likewise.
	* config/arm/arm_mve.h (vldrdq_gather_base_wb_s64): Define macro.
	(vldrdq_gather_base_wb_u64): Likewise.
	(vldrdq_gather_base_wb_z_s64): Likewise.
	(vldrdq_gather_base_wb_z_u64): Likewise.
	(vldrwq_gather_base_wb_f32): Likewise.
	(vldrwq_gather_base_wb_s32): Likewise.
	(vldrwq_gather_base_wb_u32): Likewise.
	(vldrwq_gather_base_wb_z_f32): Likewise.
	(vldrwq_gather_base_wb_z_s32): Likewise.
	(vldrwq_gather_base_wb_z_u32): Likewise.
	(vstrdq_scatter_base_wb_p_s64): Likewise.
	(vstrdq_scatter_base_wb_p_u64): Likewise.
	(vstrdq_scatter_base_wb_s64): Likewise.
	(vstrdq_scatter_base_wb_u64): Likewise.
	(vstrwq_scatter_base_wb_p_s32): Likewise.
	(vstrwq_scatter_base_wb_p_f32): Likewise.
	(vstrwq_scatter_base_wb_p_u32): Likewise.
	(vstrwq_scatter_base_wb_s32): Likewise.
	(vstrwq_scatter_base_wb_u32): Likewise.
	(vstrwq_scatter_base_wb_f32): Likewise.
	(__arm_vldrdq_gather_base_wb_s64): Define intrinsic.
	(__arm_vldrdq_gather_base_wb_u64): Likewise.
	(__arm_vldrdq_gather_base_wb_z_s64): Likewise.
	(__arm_vldrdq_gather_base_wb_z_u64): Likewise.
	(__arm_vldrwq_gather_base_wb_s32): Likewise.
	(__arm_vldrwq_gather_base_wb_u32): Likewise.
	(__arm_vldrwq_gather_base_wb_z_s32): Likewise.
	(__arm_vldrwq_gather_base_wb_z_u32): Likewise.
	(__arm_vstrdq_scatter_base_wb_s64): Likewise.
	(__arm_vstrdq_scatter_base_wb_u64): Likewise.
	(__arm_vstrdq_scatter_base_wb_p_s64): Likewise.
	(__arm_vstrdq_scatter_base_wb_p_u64): Likewise.
	(__arm_vstrwq_scatter_base_wb_p_s32): Likewise.
	(__arm_vstrwq_scatter_base_wb_p_u32): Likewise.
	(__arm_vstrwq_scatter_base_wb_s32): Likewise.
	(__arm_vstrwq_scatter_base_wb_u32): Likewise.
	(__arm_vldrwq_gather_base_wb_f32): Likewise.
	(__arm_vldrwq_gather_base_wb_z_f32): Likewise.
	(__arm_vstrwq_scatter_base_wb_f32): Likewise.
	(__arm_vstrwq_scatter_base_wb_p_f32): Likewise.
	(vstrwq_scatter_base_wb): Define polymorphic variant.
	(vstrwq_scatter_base_wb_p): Likewise.
	(vstrdq_scatter_base_wb_p): Likewise.
	(vstrdq_scatter_base_wb): Likewise.
	* config/arm/arm_mve_builtins.def (LDRGBWBS_QUALIFIERS): Use builtin
	qualifier.
	* config/arm/mve.md (mve_vstrwq_scatter_base_wb_<supf>v4si): Define RTL
	pattern.
	(mve_vstrwq_scatter_base_wb_add_<supf>v4si): Likewise.
	(mve_vstrwq_scatter_base_wb_<supf>v4si_insn): Likewise.
	(mve_vstrwq_scatter_base_wb_p_<supf>v4si): Likewise.
	(mve_vstrwq_scatter_base_wb_p_add_<supf>v4si): Likewise.
	(mve_vstrwq_scatter_base_wb_p_<supf>v4si_insn): Likewise.
	(mve_vstrwq_scatter_base_wb_fv4sf): Likewise.
	(mve_vstrwq_scatter_base_wb_add_fv4sf): Likewise.
	(mve_vstrwq_scatter_base_wb_fv4sf_insn): Likewise.
	(mve_vstrwq_scatter_base_wb_p_fv4sf): Likewise.
	(mve_vstrwq_scatter_base_wb_p_add_fv4sf): Likewise.
	(mve_vstrwq_scatter_base_wb_p_fv4sf_insn): Likewise.
	(mve_vstrdq_scatter_base_wb_<supf>v2di): Likewise.
	(mve_vstrdq_scatter_base_wb_add_<supf>v2di): Likewise.
	(mve_vstrdq_scatter_base_wb_<supf>v2di_insn): Likewise.
	(mve_vstrdq_scatter_base_wb_p_<supf>v2di): Likewise.
	(mve_vstrdq_scatter_base_wb_p_add_<supf>v2di): Likewise.
	(mve_vstrdq_scatter_base_wb_p_<supf>v2di_insn): Likewise.
	(mve_vldrwq_gather_base_wb_<supf>v4si): Likewise.
	(mve_vldrwq_gather_base_wb_<supf>v4si_insn): Likewise.
	(mve_vldrwq_gather_base_wb_z_<supf>v4si): Likewise.
	(mve_vldrwq_gather_base_wb_z_<supf>v4si_insn): Likewise.
	(mve_vldrwq_gather_base_wb_fv4sf): Likewise.
	(mve_vldrwq_gather_base_wb_fv4sf_insn): Likewise.
	(mve_vldrwq_gather_base_wb_z_fv4sf): Likewise.
	(mve_vldrwq_gather_base_wb_z_fv4sf_insn): Likewise.
	(mve_vldrdq_gather_base_wb_<supf>v2di): Likewise.
	(mve_vldrdq_gather_base_wb_<supf>v2di_insn): Likewise.
	(mve_vldrdq_gather_base_wb_z_<supf>v2di): Likewise.
	(mve_vldrdq_gather_base_wb_z_<supf>v2di_insn): Likewise.

gcc/testsuite/ChangeLog:

2020-03-20  Srinath Parvathaneni  <srinath.parvathaneni@arm.com>
            Andre Vieira  <andre.simoesdiasvieira@arm.com>
            Mihail Ionescu  <mihail.ionescu@arm.com>

	* gcc.target/arm/mve/intrinsics/vldrdq_gather_base_wb_s64.c: New test.
	* gcc.target/arm/mve/intrinsics/vldrdq_gather_base_wb_u64.c: Likewise.
	* gcc.target/arm/mve/intrinsics/vldrdq_gather_base_wb_z_s64.c: Likewise.
	* gcc.target/arm/mve/intrinsics/vldrdq_gather_base_wb_z_u64.c: Likewise.
	* gcc.target/arm/mve/intrinsics/vldrwq_gather_base_wb_f32.c: Likewise.
	* gcc.target/arm/mve/intrinsics/vldrwq_gather_base_wb_s32.c: Likewise.
	* gcc.target/arm/mve/intrinsics/vldrwq_gather_base_wb_u32.c: Likewise.
	* gcc.target/arm/mve/intrinsics/vldrwq_gather_base_wb_z_f32.c: Likewise.
	* gcc.target/arm/mve/intrinsics/vldrwq_gather_base_wb_z_s32.c: Likewise.
	* gcc.target/arm/mve/intrinsics/vldrwq_gather_base_wb_z_u32.c: Likewise.
	* gcc.target/arm/mve/intrinsics/vstrdq_scatter_base_wb_p_s64.c:
	Likewise.
	* gcc.target/arm/mve/intrinsics/vstrdq_scatter_base_wb_p_u64.c:
	Likewise.
	* gcc.target/arm/mve/intrinsics/vstrdq_scatter_base_wb_s64.c: Likewise.
	* gcc.target/arm/mve/intrinsics/vstrdq_scatter_base_wb_u64.c: Likewise.
	* gcc.target/arm/mve/intrinsics/vstrwq_scatter_base_wb_f32.c: Likewise.
	* gcc.target/arm/mve/intrinsics/vstrwq_scatter_base_wb_p_f32.c:
	Likewise.
	* gcc.target/arm/mve/intrinsics/vstrwq_scatter_base_wb_p_s32.c:
	Likewise.
	* gcc.target/arm/mve/intrinsics/vstrwq_scatter_base_wb_p_u32.c:
	Likewise.
	* gcc.target/arm/mve/intrinsics/vstrwq_scatter_base_wb_s32.c: Likewise.
	* gcc.target/arm/mve/intrinsics/vstrwq_scatter_base_wb_u32.c: Likewise.