[AArch64] Enable CLI for Armv8.6-a: armv8.6-a, i8mm and bf16

[AArch64] Enable CLI for Armv8.6-a: armv8.6-a, i8mm and bf16

2019-12-13  Dennis Zhang  <dennis.zhang@arm.com>

gcc/
	* config/aarch64/aarch64-arches.def (armv8.6-a): New.
	* config/aarch64/aarch64-c.c (aarch64_update_cpp_builtins): Define
	__ARM_FEATURE_MATMUL_INT8, __ARM_FEATURE_BF16_VECTOR_ARITHMETIC and
	__ARM_FEATURE_BF16_SCALAR_ARITHMETIC when enabled.
	* config/aarch64/aarch64-option-extensions.def (i8mm, bf16): New.
	(fp): Disabling fp also disables i8mm and bf16.
	(simd): Disabling simd also disables i8mm.
	* config/aarch64/aarch64.h (AARCH64_FL_V8_6): New macro.
	(AARCH64_FL_I8MM, AARCH64_FL_BF16, AARCH64_FL_FOR_ARCH8_6): Likewise.
	(AARCH64_ISA_V8_6, AARCH64_ISA_I8MM, AARCH64_ISA_BF16): Likewise.
	(TARGET_I8MM, TARGET_BF16_FP, TARGET_BF16_SIMD): Likewise.
	* doc/invoke.texi (armv8.6-a, i8mm, bf16): Document new options
	and add a new table to list permissible values for ARCH.

gcc/testsuite/
	* gcc.target/aarch64/pragma_cpp_predefs_2.c: Add tests for i8mm
	and bf16 features.

From-SVN: r279370