arm: Fix MVE predicates synthesis [PR 108443]

This patch fixes the way we synthesize MVE predicate immediates and fixes some
other inconsistencies around predicates. For instance this patch fixes the modes
used in the vctp intrinsics, to couple them with predicate modes with the
appropriate lane numbers. For this V2QI is added to represent a predicate
created by vctp64q. The reason we use V2QI and not for instance a V2BI with
8-bit boolean modes is because we are trying to avoid having two 'INT' modes of
the same size. We make sure we use the V2QI mode instead of HI for any
instruction working on two lanes of 64-bits consuming a predicate.

gcc/ChangeLog:

	PR target/108443
	* config/arm/arm.h (VALID_MVE_PRED_MODE): Add V2QI.
	* config/arm/arm.cc (thumb2_legitimate_address_p): Use HImode for
	addressing MVE predicate modes.
	(mve_bool_vec_to_const): Change to represent correct MVE predicate
	format.
	(arm_hard_regno_mode_ok): Use VALID_MVE_PRED_MODE instead of checking
	modes.
	(arm_vector_mode_supported_p): Likewise.
	(arm_mode_to_pred_mode): Add V2QI.
	* config/arm/arm-builtins.cc (UNOP_PRED_UNONE_QUALIFIERS): New
	qualifier.
	(UNOP_PRED_PRED_QUALIFIERS): New qualifier
	(BINOP_PRED_UNONE_PRED_QUALIFIERS): New qualifier.
	(v2qi_UP): New macro.
	(v4bi_UP): New macro.
	(v8bi_UP): New macro.
	(v16bi_UP): New macro.
	(arm_expand_builtin_args): Make it able to expand the new predicate
	modes.
	* config/arm/arm-modes.def (V2QI): New mode.
	* config/arm/arm-simd-builtin-types.def (Pred1x16_t, Pred2x8_t
	Pred4x4_t): Remove unused predicate builtin types.
	* config/arm/arm_mve.h (__arm_vctp16q, __arm_vctp32q, __arm_vctp64q,
	__arm_vctp8q, __arm_vpnot, __arm_vctp8q_m, __arm_vctp64q_m,
	__arm_vctp32q_m, __arm_vctp16q_m): Use predicate modes.
	* config/arm/arm_mve_builtins.def (vctp16q, vctp32q, vctp64q, vctp8q,
	vpnot, vctp8q_m, vctp16q_m, vctp32q_m, vctp64q_m): Likewise.
	* config/arm/constraints.md (DB): Check for VALID_MVE_PRED_MODE instead
	of MODE_VECTOR_BOOL.
	* config/arm/iterators.md (MVE_7, MVE_7_HI): Add V2QI
	(MVE_VPRED): Likewise.
	(MVE_vpred): Add V2QI and map upper case predicate modes to lower case.
	(MVE_vctp): New mode attribute.
	(mode1): Remove.
	(VCTPQ): Remove.
	(VCTPQ_M): Remove.
	* config/arm/mve.md (mve_vctp<mode1>qhi): Rename this...
	(mve_vctp<MVE_vctp>q<MVE_vpred>): ... to this. And use new mode
	attributes.
	(mve_vpnothi): Rename this...
	(mve_vpnotv16bi): ... to this.
	(mve_vctp<mode1>q_mhi): Rename this...
	(mve_vctp<MVE_vctp>q_m<MVE_vpred>):... to this.
	(mve_vldrdq_gather_base_z_<supf>v2di,
	mve_vldrdq_gather_offset_z_<supf>v2di,
	mve_vldrdq_gather_shifted_offset_z_<supf>v2di,
	mve_vstrdq_scatter_base_p_<supf>v2di,
	mve_vstrdq_scatter_offset_p_<supf>v2di,
	mve_vstrdq_scatter_offset_p_<supf>v2di_insn,
	mve_vstrdq_scatter_shifted_offset_p_<supf>v2di,
	mve_vstrdq_scatter_shifted_offset_p_<supf>v2di_insn,
	mve_vstrdq_scatter_base_wb_p_<supf>v2di,
	mve_vldrdq_gather_base_wb_z_<supf>v2di,
	mve_vldrdq_gather_base_nowb_z_<supf>v2di,
	mve_vldrdq_gather_base_wb_z_<supf>v2di_insn):  Use V2QI insead of HI for
	predicates.
	* config/arm/unspecs.md (VCTP8Q, VCTP16Q, VCTP32Q, VCTP64Q): Replace
	these...
	(VCTP): ... with this.
	(VCTP8Q_M, VCTP16Q_M, VCTP32Q_M, VCTP64Q_M): Replace these...
	(VCTP_M): ... with this.
	* config/arm/vfp.md (*thumb2_movhi_vfp, *thumb2_movhi_fp16): Use
	VALID_MVE_PRED_MODE instead of checking for MODE_VECTOR_BOOL class.

gcc/testsuite/ChangeLog:

	* gcc.target/arm/mve/pr108443-run.c: New test.
	* gcc.target/arm/mve/pr108443.c: New test.