Support Intel AVX-IFMA

x86: Support Intel AVX-IFMA

Intel AVX IFMA instructions are marked with CpuVEX_PREFIX, which is
cleared by default.  Without {vex} pseudo prefix, Intel IFMA instructions
are encoded with EVEX prefix.  {vex} pseudo prefix will turn on VEX
encoding for Intel IFMA instructions.

gas/

	* NEWS: Support Intel AVX-IFMA.
	* config/tc-i386.c (cpu_arch): Add avx_ifma.
	* doc/c-i386.texi: Document .avx_ifma.
	* testsuite/gas/i386/avx-ifma.d: New file.
	* testsuite/gas/i386/avx-ifma-intel.d: Likewise.
	* testsuite/gas/i386/avx-ifma.s: Likewise.
	* testsuite/gas/i386/x86-64-avx-ifma.d: Likewise.
	* testsuite/gas/i386/x86-64-avx-ifma-intel.d: Likewise.
	* testsuite/gas/i386/x86-64-avx-ifma.s: Likewise.
	* testsuite/gas/i386/i386.exp: Run AVX IFMA tests.

opcodes/

	* i386-dis.c (PREFIX_VEX_0F38B4): New.
	(PREFIX_VEX_0F38B5): Likewise.
	(VEX_W_0F38B4_P_2): Likewise.
	(VEX_W_0F38B5_P_2): Likewise.
	(prefix_table): Add PREFIX_VEX_0F38B4 and PREFIX_VEX_0F38B5.
	(vex_table): Add VEX_W_0F38B4_P_2 and VEX_W_0F38B5_P_2.
	* i386-dis-evex.h: Fold AVX512IFMA entries to AVX-IFMA.
	* i386-gen.c (cpu_flag_init): Clear the CpuAVX_IFMA bit in
	CPU_UNKNOWN_FLAGS. Add CPU_AVX_IFMA_FLGAS and
	CPU_ANY_AVX_IFMA_FLAGS. Add CpuAVX_IFMA to CPU_AVX2_FLAGS.
	(cpu_flags): Add CpuAVX_IFMA.
	* i386-opc.h (CpuAVX_IFMA): New.
	(i386_cpu_flags): Add cpuavx_ifma.
	* i386-opc.tbl: Add Intel AVX IFMA instructions.
	* i386-init.h: Regenerated.
	* i386-tbl.h: Likewise.

Co-authored-by: Haochen Jiang <haochen.jiang@intel.com>