aarch64: Add LS64 extension and intrinsics

This patch is adding support for LS64 (Armv8.7-A Load/Store 64 Byte extension)
which is part of Armv8.7-A architecture. Changes include missing plumbing for
TARGET_LS64, LS64 data structure and intrinsics defined in ACLE. Machine
description of intrinsics is using new V8DI mode added in a separate patch.
__ARM_FEATURE_LS64 is defined if the Armv8.7-A LS64 instructions for atomic
64-byte access to device memory are supported.

New compiler internal type is added wrapping ACLE struct data512_t:

typedef struct {
  uint64_t val[8];
} __arm_data512_t;

gcc/ChangeLog:

	* config/aarch64/aarch64-builtins.c (enum aarch64_builtins):
	Define AARCH64_LS64_BUILTIN_LD64B, AARCH64_LS64_BUILTIN_ST64B,
	AARCH64_LS64_BUILTIN_ST64BV, AARCH64_LS64_BUILTIN_ST64BV0.
	(aarch64_init_ls64_builtin_decl): Helper function.
	(aarch64_init_ls64_builtins): Helper function.
	(aarch64_init_ls64_builtins_types): Helper function.
	(aarch64_general_init_builtins): Init LS64 intrisics for
	TARGET_LS64.
	(aarch64_expand_builtin_ls64): LS64 intrinsics expander.
	(aarch64_general_expand_builtin): Handle aarch64_expand_builtin_ls64.
	(ls64_builtins_data): New helper struct.
	(v8di_UP): New define.
	* config/aarch64/aarch64-c.c (aarch64_update_cpp_builtins): Define
	__ARM_FEATURE_LS64.
	* config/aarch64/aarch64.c (aarch64_classify_address): Enforce the
	V8DI range (7-bit signed scaled) for both ends of the range.
	* config/aarch64/aarch64-simd.md (movv8di): New pattern.
	(aarch64_movv8di): New pattern.
	* config/aarch64/aarch64.h (AARCH64_ISA_LS64): New define.
	(TARGET_LS64): New define.
	* config/aarch64/aarch64.md: Add UNSPEC_LD64B, UNSPEC_ST64B,
	UNSPEC_ST64BV and UNSPEC_ST64BV0.
	(ld64b): New define_insn.
	(st64b): New define_insn.
	(st64bv): New define_insn.
	(st64bv0): New define_insn.
	* config/aarch64/arm_acle.h (data512_t): New type derived from
	__arm_data512_t.
	(__arm_data512_t): New internal type.
	(__arm_ld64b): New intrinsic.
	(__arm_st64b): New intrinsic.
	(__arm_st64bv): New intrinsic.
	(__arm_st64bv0): New intrinsic.
	* config/arm/types.md: Add new type ls64.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/acle/ls64_asm.c: New test.
	* gcc.target/aarch64/acle/ls64_ld64b.c: New test.
	* gcc.target/aarch64/acle/ls64_ld64b-2.c: New test.
	* gcc.target/aarch64/acle/ls64_ld64b-3.c: New test.
	* gcc.target/aarch64/acle/ls64_st64b.c: New test.
	* gcc.target/aarch64/acle/ls64_ld_st_o0.c: New test.
	* gcc.target/aarch64/acle/ls64_st64b-2.c: New test.
	* gcc.target/aarch64/acle/ls64_st64bv.c: New test.
	* gcc.target/aarch64/acle/ls64_st64bv-2.c: New test.
	* gcc.target/aarch64/acle/ls64_st64bv-3.c: New test.
	* gcc.target/aarch64/acle/ls64_st64bv0.c: New test.
	* gcc.target/aarch64/acle/ls64_st64bv0-2.c: New test.
	* gcc.target/aarch64/acle/ls64_st64bv0-3.c: New test.
	* gcc.target/aarch64/pragma_cpp_predefs_2.c: Add checks
	for __ARM_FEATURE_LS64.