Hi:

This patch is about to support Intel Advanced Matrix Extensions (AMX)
which will be enabled in GLC.

AMX is a new 64-bit programming paradigm consisting of two
compo nents: a set of 2-dimensional registers (tiles) representing
sub-arrays from a larger 2-dimensional memory image,
and an accelerator able to operate on tiles

Supported instructions are

AMX-TILE:ldtilecfg/sttilecfg/tileloadd/tileloaddt1/tilezero/tilerelease
AMX-INT8:tdpbssd/tdpbsud/tdpbusd/tdpbuud
AMX-BF16:tdpbf16ps

The intrinsics adopts constant tile register number as its input parameters.

For detailed information, please refer to
https://software.intel.com/content/dam/develop/public/us/en/documents/architecture-instruction-set-extensions-programming-reference.pdf

Bootstrap ok, regression test on i386/x86 backend is ok.

OK for master?

gcc/ChangeLog

    * common/config/i386/i386-common.c (OPTION_MASK_ISA2_AMX_TILE_SET,
    OPTION_MASK_ISA2_AMX_INT8_SET, OPTION_MASK_ISA2_AMX_BF16_SET,
    OPTION_MASK_ISA2_AMX_TILE_UNSET,
    OPTION_MASK_ISA2_AMX_INT8_UNSET, OPTION_MASK_ISA2_AMX_BF16_UNSET):
    New marcos.
    (ix86_handle_option): Hanlde -mamx-tile, -mamx-int8, -mamx-bf16.
    * common/config/i386/i386-cpuinfo.h (processor_types): Add
    FEATURE_AMX_TILE, FEATURE_AMX_INT8, FEATURE_AMX_BF16.
    * common/config/i386/cpuinfo.h (XSTATE_TILECFG,
    XSTATE_TILEDATA, XCR_AMX_ENABLED_MASK): New macro.
    (get_available_features): Enable AMX features only if
    their states are suoorited by OSXSAVE.
    * common/config/i386/i386-isas.h: Add ISA_NAME_TABLE_ENTRY
    for amx-tile, amx-int8, amx-bf16.
    * config.gcc: Add amxtileintrin.h, amxint8intrin.h,
    amxbf16intrin.h to extra headers.
    * config/i386/amxbf16intrin.h: New file.
    * config/i386/amxint8intrin.h: Ditto.
    * config/i386/amxtileintrin.h: Ditto.
    * config/i386/cpuid.h (bit_AMX_BF16, bit_AMX_TILE, bit_AMX_INT8):
    New macro.
    * config/i386/i386-c.c (ix86_target_macros_internal): Define
    __AMX_TILE__, __AMX_INT8__, AMX_BF16__.
    * config/i386/i386-options.c (ix86_target_string): Add
    -mamx-tile, -mamx-int8, -mamx-bf16.
    (ix86_option_override_internal): Handle AMX-TILE,
    AMX-INT8, AMX-BF16.
    * config/i386/i386.h (TARGET_AMX_TILE, TARGET_AMX_TILE_P,
    TARGET_AMX_INT8, TARGET_AMX_INT8_P, TARGET_AMX_BF16_P,
    PTA_AMX_TILE, PTA_AMX_INT8, PTA_AMX_BF16): New macros.
    * config/i386/i386.opt: Add -mamx-tile, -mamx-int8, -mamx-bf16.
    * config/i386/immintrin.h: Include amxtileintrin.h,
    amxint8intrin.h, amxbf16intrin.h.
    * doc/invoke.texi: Document -mamx-tile, -mamx-int8, -mamx-bf16.
    * doc/extend.texi: Document amx-tile, amx-int8, amx-bf16.
    * doc/sourcebuild.texi ((Effective-Target Keywords, Other
    hardware attributes): Document amx_int8, amx_tile, amx_bf16.

gcc/testsuite/ChangeLog

    * lib/target-supports.exp (check_effective_target_amx_tile,
    check_effective_target_amx_int8,
    check_effective_target_amx_bf16): New proc.
    * g++.dg/other/i386-2.C: Add -mamx-tile, -mamx-int8, -mamx-bf16.
    * g++.dg/other/i386-3.C: Ditto.
    * gcc.target/i386/sse-12.c: Ditto.
    * gcc.target/i386/sse-13.c: Ditto.
    * gcc.target/i386/sse-14.c: Ditto.
    * gcc.target/i386/sse-22.c: Ditto.
    * gcc.target/i386/sse-23.c: Ditto.
    * gcc.target/i386/funcspec-56.inc: Add new target attribute.
    * gcc.target/i386/amxbf16-asmatt-1.c: New test.
    * gcc.target/i386/amxint8-asmatt-1.c: Ditto.
    * gcc.target/i386/amxtile-asmatt-1.c: Ditto.
    * gcc.target/i386/amxbf16-asmintel-1.c: Ditto.
    * gcc.target/i386/amxint8-asmintel-1.c: Ditto.
    * gcc.target/i386/amxtile-asmintel-1.c: Ditto.
    * gcc.target/i386/amxbf16-asmatt-2.c: Ditto.
    * gcc.target/i386/amxint8-asmatt-2.c: Ditto.
    * gcc.target/i386/amxtile-asmatt-2.c: Ditto.
    * gcc.target/i386/amxbf16-asmintel-2.c: Ditto.
    * gcc.target/i386/amxint8-asmintel-2.c: Ditto.
    * gcc.target/i386/amxtile-asmintel-2.c: Ditto.