ccompiler_opt.py

"""Provides the `CCompilerOpt` class, used for handling the CPU/hardware
optimization, starting from parsing the command arguments, to managing the
relation between the CPU baseline and dispatch-able features,
also generating the required C headers and ending with compiling
the sources with proper compiler's flags.

`CCompilerOpt` doesn't provide runtime detection for the CPU features,
instead only focuses on the compiler side, but it creates abstract C headers
that can be used later for the final runtime dispatching process."""

import atexit
import inspect
import os
import pprint
import re
import subprocess
import textwrap

class _Config:
    """An abstract class holds all configurable attributes of `CCompilerOpt`,
    these class attributes can be used to change the default behavior
    of `CCompilerOpt` in order to fit other requirements.

    Attributes
    ----------
    conf_nocache : bool
        Set True to disable memory and file cache.
        Default is False.

    conf_noopt : bool
        Set True to forces the optimization to be disabled,
        in this case `CCompilerOpt` tends to generate all
        expected headers in order to 'not' break the build.
        Default is False.

    conf_cache_factors : list
        Add extra factors to the primary caching factors. The caching factors
        are utilized to determine if there are changes had happened that
        requires to discard the cache and re-updating it. The primary factors
        are the arguments of `CCompilerOpt` and `CCompiler`'s properties(type, flags, etc).
        Default is list of two items, containing the time of last modification
        of `ccompiler_opt` and value of attribute "conf_noopt"

    conf_tmp_path : str,
        The path of temporary directory. Default is auto-created
        temporary directory via ``tempfile.mkdtemp()``.

    conf_check_path : str
        The path of testing files. Each added CPU feature must have a
        **C** source file contains at least one intrinsic or instruction that
        related to this feature, so it can be tested against the compiler.
        Default is ``./distutils/checks``.

    conf_target_groups : dict
        Extra tokens that can be reached from dispatch-able sources through
        the special mark ``@targets``. Default is an empty dictionary.

        **Notes**:
            - case-insensitive for tokens and group names
            - sign '#' must stick in the begin of group name and only within ``@targets``

        **Example**:
            .. code-block:: console

                $ "@targets #avx_group other_tokens" > group_inside.c

            >>> CCompilerOpt.conf_target_groups["avx_group"] = \\
            "$werror $maxopt avx2 avx512f avx512_skx"
            >>> cco = CCompilerOpt(cc_instance)
            >>> cco.try_dispatch(["group_inside.c"])

    conf_c_prefix : str
        The prefix of public C definitions. Default is ``"NPY_"``.

    conf_c_prefix_ : str
        The prefix of internal C definitions. Default is ``"NPY__"``.

    conf_cc_flags : dict
        Nested dictionaries defining several compiler flags
        that linked to some major functions, the main key
        represent the compiler name and sub-keys represent
        flags names. Default is already covers all supported
        **C** compilers.

        Sub-keys explained as follows:

        "native": str or None
            used by argument option `native`, to detect the current
            machine support via the compiler.
        "werror": str or None
            utilized to treat warning as errors during testing CPU features
            against the compiler and also for target's policy `$werror`
            via dispatch-able sources.
        "maxopt": str or None
            utilized for target's policy '$maxopt' and the value should
            contains the maximum acceptable optimization by the compiler.
            e.g. in gcc `'-O3'`

        **Notes**:
            * case-sensitive for compiler names and flags
            * use space to separate multiple flags
            * any flag will tested against the compiler and it will skipped
              if it's not applicable.

    conf_min_features : dict
        A dictionary defines the used CPU features for
        argument option `'min'`, the key represent the CPU architecture
        name e.g. `'x86'`. Default values provide the best effort
        on wide range of users platforms.

        **Note**: case-sensitive for architecture names.

    conf_features : dict
        Nested dictionaries used for identifying the CPU features.
        the primary key is represented as a feature name or group name
        that gathers several features. Default values covers all
        supported features but without the major options like "flags",
        these undefined options handle it by method `conf_features_partial()`.
        Default value is covers almost all CPU features for *X86*, *IBM/Power64*
        and *ARM 7/8*.

        Sub-keys explained as follows:

        "implies" : str or list, optional,
            List of CPU feature names to be implied by it,
            the feature name must be defined within `conf_features`.
            Default is None.

        "flags": str or list, optional
            List of compiler flags. Default is None.

        "detect": str or list, optional
            List of CPU feature names that required to be detected
            in runtime. By default, its the feature name or features
            in "group" if its specified.

        "implies_detect": bool, optional
            If True, all "detect" of implied features will be combined.
            Default is True. see `feature_detect()`.

        "group": str or list, optional
            Same as "implies" but doesn't require the feature name to be
            defined within `conf_features`.

        "interest": int, required
            a key for sorting CPU features

        "headers": str or list, optional
            intrinsics C header file

        "disable": str, optional
            force disable feature, the string value should contains the
            reason of disabling.

        "autovec": bool or None, optional
            True or False to declare that CPU feature can be auto-vectorized
            by the compiler.
            By default(None), treated as True if the feature contains at
            least one applicable flag. see `feature_can_autovec()`

        "extra_checks": str or list, optional
            Extra test case names for the CPU feature that need to be tested
            against the compiler.

            Each test case must have a C file named ``extra_xxxx.c``, where
            ``xxxx`` is the case name in lower case, under 'conf_check_path'.
            It should contain at least one intrinsic or function related to the test case.

            If the compiler able to successfully compile the C file then `CCompilerOpt`
            will add a C ``#define`` for it into the main dispatch header, e.g.
            ``#define {conf_c_prefix}_XXXX`` where ``XXXX`` is the case name in upper case.

        **NOTES**:
            * space can be used as separator with options that supports "str or list"
            * case-sensitive for all values and feature name must be in upper-case.
            * if flags aren't applicable, its will skipped rather than disable the
              CPU feature
            * the CPU feature will disabled if the compiler fail to compile
              the test file
    """
    conf_nocache = False
    conf_noopt = False
    conf_cache_factors = None
    conf_tmp_path = None
    conf_check_path = os.path.join(
        os.path.dirname(os.path.realpath(__file__)), "checks"
    )
    conf_target_groups = {}
    conf_c_prefix = 'NPY_'
    conf_c_prefix_ = 'NPY__'
    conf_cc_flags = dict(
        gcc = dict(
            # native should always fail on arm and ppc64,
            # native usually works only with x86
            native = '-march=native',
            opt = '-O3',
            werror = '-Werror',
        ),
        clang = dict(
            native = '-march=native',
            opt = "-O3",
            # One of the following flags needs to be applicable for Clang to
            # guarantee the sanity of the testing process, however in certain
            # cases `-Werror` gets skipped during the availability test due to
            # "unused arguments" warnings.
            # see https://github.com/numpy/numpy/issues/19624
            werror = '-Werror=switch -Werror',
        ),
        icc = dict(
            native = '-xHost',
            opt = '-O3',
            werror = '-Werror',
        ),
        iccw = dict(
            native = '/QxHost',
            opt = '/O3',
            werror = '/Werror',
        ),
        msvc = dict(
            native = None,
            opt = '/O2',
            werror = '/WX',
        ),
        fcc = dict(
            native = '-mcpu=a64fx',
            opt = None,
            werror = None,
        )
    )
    conf_min_features = dict(
        x86 = "SSE SSE2",
        x64 = "SSE SSE2 SSE3",
        ppc64 = '', # play it safe
        ppc64le = "VSX VSX2",
        s390x = '',
        armhf = '', # play it safe
        aarch64 = "NEON NEON_FP16 NEON_VFPV4 ASIMD"
    )
    conf_features = dict(
        # X86
        SSE = dict(
            interest=1, headers="xmmintrin.h",
            # enabling SSE without SSE2 is useless also
            # it's non-optional for x86_64
            implies="SSE2"
        ),
        SSE2   = dict(interest=2, implies="SSE", headers="emmintrin.h"),
        SSE3   = dict(interest=3, implies="SSE2", headers="pmmintrin.h"),
        SSSE3  = dict(interest=4, implies="SSE3", headers="tmmintrin.h"),
        SSE41  = dict(interest=5, implies="SSSE3", headers="smmintrin.h"),
        POPCNT = dict(interest=6, implies="SSE41", headers="popcntintrin.h"),
        SSE42  = dict(interest=7, implies="POPCNT"),
        AVX    = dict(
            interest=8, implies="SSE42", headers="immintrin.h",
            implies_detect=False
        ),
        XOP    = dict(interest=9, implies="AVX", headers="x86intrin.h"),
        FMA4   = dict(interest=10, implies="AVX", headers="x86intrin.h"),
        F16C   = dict(interest=11, implies="AVX"),
        FMA3   = dict(interest=12, implies="F16C"),
        AVX2   = dict(interest=13, implies="F16C"),
        AVX512F = dict(
            interest=20, implies="FMA3 AVX2", implies_detect=False,
            extra_checks="AVX512F_REDUCE"
        ),
        AVX512CD = dict(interest=21, implies="AVX512F"),
        AVX512_KNL = dict(
            interest=40, implies="AVX512CD", group="AVX512ER AVX512PF",
            detect="AVX512_KNL", implies_detect=False
        ),
        AVX512_KNM = dict(
            interest=41, implies="AVX512_KNL",
            group="AVX5124FMAPS AVX5124VNNIW AVX512VPOPCNTDQ",
            detect="AVX512_KNM", implies_detect=False
        ),
        AVX512_SKX = dict(
            interest=42, implies="AVX512CD", group="AVX512VL AVX512BW AVX512DQ",
            detect="AVX512_SKX", implies_detect=False,
            extra_checks="AVX512BW_MASK AVX512DQ_MASK"
        ),
        AVX512_CLX = dict(
            interest=43, implies="AVX512_SKX", group="AVX512VNNI",
            detect="AVX512_CLX"
        ),
        AVX512_CNL = dict(
            interest=44, implies="AVX512_SKX", group="AVX512IFMA AVX512VBMI",
            detect="AVX512_CNL", implies_detect=False
        ),
        AVX512_ICL = dict(
            interest=45, implies="AVX512_CLX AVX512_CNL",
            group="AVX512VBMI2 AVX512BITALG AVX512VPOPCNTDQ",
            detect="AVX512_ICL", implies_detect=False
        ),
        AVX512_SPR = dict(
            interest=46, implies="AVX512_ICL", group="AVX512FP16",
            detect="AVX512_SPR", implies_detect=False
        ),
        # IBM/Power
        ## Power7/ISA 2.06
        VSX = dict(interest=1, headers="altivec.h", extra_checks="VSX_ASM"),
        ## Power8/ISA 2.07
        VSX2 = dict(interest=2, implies="VSX", implies_detect=False),
        ## Power9/ISA 3.00
        VSX3 = dict(interest=3, implies="VSX2", implies_detect=False),
        ## Power10/ISA 3.1
        VSX4 = dict(interest=4, implies="VSX3", implies_detect=False,
                    extra_checks="VSX4_MMA"),
        # IBM/Z
        ## VX(z13) support
        VX = dict(interest=1, headers="vecintrin.h"),
        ## Vector-Enhancements Facility
        VXE = dict(interest=2, implies="VX", implies_detect=False),
        ## Vector-Enhancements Facility 2
        VXE2 = dict(interest=3, implies="VXE", implies_detect=False),
        # ARM
        NEON  = dict(interest=1, headers="arm_neon.h"),
        NEON_FP16 = dict(interest=2, implies="NEON"),
        ## FMA
        NEON_VFPV4 = dict(interest=3, implies="NEON_FP16"),
        ## Advanced SIMD
        ASIMD = dict(interest=4, implies="NEON_FP16 NEON_VFPV4", implies_detect=False),
        ## ARMv8.2 half-precision & vector arithm
        ASIMDHP = dict(interest=5, implies="ASIMD"),
        ## ARMv8.2 dot product
        ASIMDDP = dict(interest=6, implies="ASIMD"),
        ## ARMv8.2 Single & half-precision Multiply
        ASIMDFHM = dict(interest=7, implies="ASIMDHP"),
    )
    def conf_features_partial(self):
        """Return a dictionary of supported CPU features by the platform,
        and accumulate the rest of undefined options in `conf_features`,
        the returned dict has same rules and notes in
        class attribute `conf_features`, also its override
        any options that been set in 'conf_features'.
        """
        if self.cc_noopt:
            # optimization is disabled
            return {}

        on_x86 = self.cc_on_x86 or self.cc_on_x64
        is_unix = self.cc_is_gcc or self.cc_is_clang or self.cc_is_fcc

        if on_x86 and is_unix: return dict(
            SSE    = dict(flags="-msse"),
            SSE2   = dict(flags="-msse2"),
            SSE3   = dict(flags="-msse3"),
            SSSE3  = dict(flags="-mssse3"),
            SSE41  = dict(flags="-msse4.1"),
            POPCNT = dict(flags="-mpopcnt"),
            SSE42  = dict(flags="-msse4.2"),
            AVX    = dict(flags="-mavx"),
            F16C   = dict(flags="-mf16c"),
            XOP    = dict(flags="-mxop"),
            FMA4   = dict(flags="-mfma4"),
            FMA3   = dict(flags="-mfma"),
            AVX2   = dict(flags="-mavx2"),
            AVX512F = dict(flags="-mavx512f -mno-mmx"),
            AVX512CD = dict(flags="-mavx512cd"),
            AVX512_KNL = dict(flags="-mavx512er -mavx512pf"),
            AVX512_KNM = dict(
                flags="-mavx5124fmaps -mavx5124vnniw -mavx512vpopcntdq"
            ),
            AVX512_SKX = dict(flags="-mavx512vl -mavx512bw -mavx512dq"),
            AVX512_CLX = dict(flags="-mavx512vnni"),
            AVX512_CNL = dict(flags="-mavx512ifma -mavx512vbmi"),
            AVX512_ICL = dict(
                flags="-mavx512vbmi2 -mavx512bitalg -mavx512vpopcntdq"
            ),
            AVX512_SPR = dict(flags="-mavx512fp16"),
        )
        if on_x86 and self.cc_is_icc: return dict(
            SSE    = dict(flags="-msse"),
            SSE2   = dict(flags="-msse2"),
            SSE3   = dict(flags="-msse3"),
            SSSE3  = dict(flags="-mssse3"),
            SSE41  = dict(flags="-msse4.1"),
            POPCNT = {},
            SSE42  = dict(flags="-msse4.2"),
            AVX    = dict(flags="-mavx"),
            F16C   = {},
            XOP    = dict(disable="Intel Compiler doesn't support it"),
            FMA4   = dict(disable="Intel Compiler doesn't support it"),
            # Intel Compiler doesn't support AVX2 or FMA3 independently
            FMA3 = dict(
                implies="F16C AVX2", flags="-march=core-avx2"
            ),
            AVX2 = dict(implies="FMA3", flags="-march=core-avx2"),
            # Intel Compiler doesn't support AVX512F or AVX512CD independently
            AVX512F = dict(
                implies="AVX2 AVX512CD", flags="-march=common-avx512"
            ),
            AVX512CD = dict(
                implies="AVX2 AVX512F", flags="-march=common-avx512"
            ),
            AVX512_KNL = dict(flags="-xKNL"),
            AVX512_KNM = dict(flags="-xKNM"),
            AVX512_SKX = dict(flags="-xSKYLAKE-AVX512"),
            AVX512_CLX = dict(flags="-xCASCADELAKE"),
            AVX512_CNL = dict(flags="-xCANNONLAKE"),
            AVX512_ICL = dict(flags="-xICELAKE-CLIENT"),
            AVX512_SPR = dict(disable="Not supported yet")
        )
        if on_x86 and self.cc_is_iccw: return dict(
            SSE    = dict(flags="/arch:SSE"),
            SSE2   = dict(flags="/arch:SSE2"),
            SSE3   = dict(flags="/arch:SSE3"),
            SSSE3  = dict(flags="/arch:SSSE3"),
            SSE41  = dict(flags="/arch:SSE4.1"),
            POPCNT = {},
            SSE42  = dict(flags="/arch:SSE4.2"),
            AVX    = dict(flags="/arch:AVX"),
            F16C   = {},
            XOP    = dict(disable="Intel Compiler doesn't support it"),
            FMA4   = dict(disable="Intel Compiler doesn't support it"),
            # Intel Compiler doesn't support FMA3 or AVX2 independently
            FMA3 = dict(
                implies="F16C AVX2", flags="/arch:CORE-AVX2"
            ),
            AVX2 = dict(
                implies="FMA3", flags="/arch:CORE-AVX2"
            ),
            # Intel Compiler doesn't support AVX512F or AVX512CD independently
            AVX512F = dict(
                implies="AVX2 AVX512CD", flags="/Qx:COMMON-AVX512"
            ),
            AVX512CD = dict(
                implies="AVX2 AVX512F", flags="/Qx:COMMON-AVX512"
            ),
            AVX512_KNL = dict(flags="/Qx:KNL"),
            AVX512_KNM = dict(flags="/Qx:KNM"),
            AVX512_SKX = dict(flags="/Qx:SKYLAKE-AVX512"),
            AVX512_CLX = dict(flags="/Qx:CASCADELAKE"),
            AVX512_CNL = dict(flags="/Qx:CANNONLAKE"),
            AVX512_ICL = dict(flags="/Qx:ICELAKE-CLIENT"),
            AVX512_SPR = dict(disable="Not supported yet")
        )
        if on_x86 and self.cc_is_msvc: return dict(
            SSE = dict(flags="/arch:SSE") if self.cc_on_x86 else {},
            SSE2 = dict(flags="/arch:SSE2") if self.cc_on_x86 else {},
            SSE3   = {},
            SSSE3  = {},
            SSE41  = {},
            POPCNT = dict(headers="nmmintrin.h"),
            SSE42  = {},
            AVX    = dict(flags="/arch:AVX"),
            F16C   = {},
            XOP    = dict(headers="ammintrin.h"),
            FMA4   = dict(headers="ammintrin.h"),
            # MSVC doesn't support FMA3 or AVX2 independently
            FMA3 = dict(
                implies="F16C AVX2", flags="/arch:AVX2"
            ),
            AVX2 = dict(
                implies="F16C FMA3", flags="/arch:AVX2"
            ),
            # MSVC doesn't support AVX512F or AVX512CD independently,
            # always generate instructions belong to (VL/VW/DQ)
            AVX512F = dict(
                implies="AVX2 AVX512CD AVX512_SKX", flags="/arch:AVX512"
            ),
            AVX512CD = dict(
                implies="AVX512F AVX512_SKX", flags="/arch:AVX512"
            ),
            AVX512_KNL = dict(
                disable="MSVC compiler doesn't support it"
            ),
            AVX512_KNM = dict(
                disable="MSVC compiler doesn't support it"
            ),
            AVX512_SKX = dict(flags="/arch:AVX512"),
            AVX512_CLX = {},
            AVX512_CNL = {},
            AVX512_ICL = {},
            AVX512_SPR= dict(
                disable="MSVC compiler doesn't support it"
            )
        )

        on_power = self.cc_on_ppc64le or self.cc_on_ppc64
        if on_power:
            partial = dict(
                VSX = dict(
                    implies=("VSX2" if self.cc_on_ppc64le else ""),
                    flags="-mvsx"
                ),
                VSX2 = dict(
                    flags="-mcpu=power8", implies_detect=False
                ),
                VSX3 = dict(
                    flags="-mcpu=power9 -mtune=power9", implies_detect=False
                ),
                VSX4 = dict(
                    flags="-mcpu=power10 -mtune=power10", implies_detect=False
                )
            )
            if self.cc_is_clang:
                partial["VSX"]["flags"]  = "-maltivec -mvsx"
                partial["VSX2"]["flags"] = "-mcpu=power8"
                partial["VSX3"]["flags"] = "-mcpu=power9"
                partial["VSX4"]["flags"] = "-mcpu=power10"

            return partial

        on_zarch = self.cc_on_s390x
        if on_zarch:
            partial = dict(
                VX = dict(
                    flags="-march=arch11 -mzvector"
                ),
                VXE = dict(
                    flags="-march=arch12", implies_detect=False
                ),
                VXE2 = dict(
                    flags="-march=arch13", implies_detect=False
                )
            )

            return partial


        if self.cc_on_aarch64 and is_unix: return dict(
            NEON = dict(
                implies="NEON_FP16 NEON_VFPV4 ASIMD", autovec=True
            ),
            NEON_FP16 = dict(
                implies="NEON NEON_VFPV4 ASIMD", autovec=True
            ),
            NEON_VFPV4 = dict(
                implies="NEON NEON_FP16 ASIMD", autovec=True
            ),
            ASIMD = dict(
                implies="NEON NEON_FP16 NEON_VFPV4", autovec=True
            ),
            ASIMDHP = dict(
                flags="-march=armv8.2-a+fp16"
            ),
            ASIMDDP = dict(
                flags="-march=armv8.2-a+dotprod"
            ),
            ASIMDFHM = dict(
                flags="-march=armv8.2-a+fp16fml"
            ),
        )
        if self.cc_on_armhf and is_unix: return dict(
            NEON = dict(
                flags="-mfpu=neon"
            ),
            NEON_FP16 = dict(
                flags="-mfpu=neon-fp16 -mfp16-format=ieee"
            ),
            NEON_VFPV4 = dict(
                flags="-mfpu=neon-vfpv4",
            ),
            ASIMD = dict(
                flags="-mfpu=neon-fp-armv8 -march=armv8-a+simd",
            ),
            ASIMDHP = dict(
                flags="-march=armv8.2-a+fp16"
            ),
            ASIMDDP = dict(
                flags="-march=armv8.2-a+dotprod",
            ),
            ASIMDFHM = dict(
                flags="-march=armv8.2-a+fp16fml"
            )
        )
        # TODO: ARM MSVC
        return {}

    def __init__(self):
        if self.conf_tmp_path is None:
            import shutil
            import tempfile
            tmp = tempfile.mkdtemp()
            def rm_temp():
                try:
                    shutil.rmtree(tmp)
                except OSError:
                    pass
            atexit.register(rm_temp)
            self.conf_tmp_path = tmp

        if self.conf_cache_factors is None:
            self.conf_cache_factors = [
                os.path.getmtime(__file__),
                self.conf_nocache
            ]

class _Distutils:
    """A helper class that provides a collection of fundamental methods
    implemented in a top of Python and NumPy Distutils.

    The idea behind this class is to gather all methods that it may
    need to override in case of reuse 'CCompilerOpt' in environment
    different than of what NumPy has.

    Parameters
    ----------
    ccompiler : `CCompiler`
        The generate instance that returned from `distutils.ccompiler.new_compiler()`.
    """
    def __init__(self, ccompiler):
        self._ccompiler = ccompiler

    def dist_compile(self, sources, flags, ccompiler=None, **kwargs):
        """Wrap CCompiler.compile()"""
        assert(isinstance(sources, list))
        assert(isinstance(flags, list))
        flags = kwargs.pop("extra_postargs", []) + flags
        if not ccompiler:
            ccompiler = self._ccompiler

        return ccompiler.compile(sources, extra_postargs=flags, **kwargs)

    def dist_test(self, source, flags, macros=[]):
        """Return True if 'CCompiler.compile()' able to compile
        a source file with certain flags.
        """
        assert(isinstance(source, str))
        from distutils.errors import CompileError
        cc = self._ccompiler;
        bk_spawn = getattr(cc, 'spawn', None)
        if bk_spawn:
            cc_type = getattr(self._ccompiler, "compiler_type", "")
            if cc_type in ("msvc",):
                setattr(cc, 'spawn', self._dist_test_spawn_paths)
            else:
                setattr(cc, 'spawn', self._dist_test_spawn)
        test = False
        try:
            self.dist_compile(
                [source], flags, macros=macros, output_dir=self.conf_tmp_path
            )
            test = True
        except CompileError as e:
            self.dist_log(str(e), stderr=True)
        if bk_spawn:
            setattr(cc, 'spawn', bk_spawn)
        return test

    def dist_info(self):
        """
        Return a tuple containing info about (platform, compiler, extra_args),
        required by the abstract class '_CCompiler' for discovering the
        platform environment. This is also used as a cache factor in order
        to detect any changes happening from outside.
        """
        if hasattr(self, "_dist_info"):
            return self._dist_info

        cc_type = getattr(self._ccompiler, "compiler_type", '')
        if cc_type in ("intelem", "intelemw"):
            platform = "x86_64"
        elif cc_type in ("intel", "intelw", "intele"):
            platform = "x86"
        else:
            from distutils.util import get_platform
            platform = get_platform()

        cc_info = getattr(self._ccompiler, "compiler", getattr(self._ccompiler, "compiler_so", ''))
        if not cc_type or cc_type == "unix":
            if hasattr(cc_info, "__iter__"):
                compiler = cc_info[0]
            else:
                compiler = str(cc_info)
        else:
            compiler = cc_type

        if hasattr(cc_info, "__iter__") and len(cc_info) > 1:
            extra_args = ' '.join(cc_info[1:])
        else:
            extra_args  = os.environ.get("CFLAGS", "")
            extra_args += os.environ.get("CPPFLAGS", "")

        self._dist_info = (platform, compiler, extra_args)
        return self._dist_info

    @staticmethod
    def dist_error(*args):
        """Raise a compiler error"""
        from distutils.errors import CompileError
        raise CompileError(_Distutils._dist_str(*args))

    @staticmethod
    def dist_fatal(*args):
        """Raise a distutils error"""
        from distutils.errors import DistutilsError
        raise DistutilsError(_Distutils._dist_str(*args))

    @staticmethod
    def dist_log(*args, stderr=False):
        """Print a console message"""
        from numpy.distutils import log
        out = _Distutils._dist_str(*args)
        if stderr:
            log.warn(out)
        else:
            log.info(out)

    @staticmethod
    def dist_load_module(name, path):
        """Load a module from file, required by the abstract class '_Cache'."""
        from .misc_util import exec_mod_from_location
        try:
            return exec_mod_from_location(name, path)
        except Exception as e:
            _Distutils.dist_log(e, stderr=True)
        return None

    @staticmethod
    def _dist_str(*args):
        """Return a string to print by log and errors."""
        def to_str(arg):
            if not isinstance(arg, str) and hasattr(arg, '__iter__'):
                ret = []
                for a in arg:
                    ret.append(to_str(a))
                return '('+ ' '.join(ret) + ')'
            return str(arg)

        stack = inspect.stack()[2]
        start = "CCompilerOpt.%s[%d] : " % (stack.function, stack.lineno)
        out = ' '.join([
            to_str(a)
            for a in (*args,)
        ])
        return start + out

    def _dist_test_spawn_paths(self, cmd, display=None):
        """
        Fix msvc SDK ENV path same as distutils do
        without it we get c1: fatal error C1356: unable to find mspdbcore.dll
        """
        if not hasattr(self._ccompiler, "_paths"):
            self._dist_test_spawn(cmd)
            return
        old_path = os.getenv("path")
        try:
            os.environ["path"] = self._ccompiler._paths
            self._dist_test_spawn(cmd)
        finally:
            os.environ["path"] = old_path

    _dist_warn_regex = re.compile(
        # intel and msvc compilers don't raise
        # fatal errors when flags are wrong or unsupported
        ".*("
        "warning D9002|"  # msvc, it should be work with any language.
        "invalid argument for option" # intel
        ").*"
    )
    @staticmethod
    def _dist_test_spawn(cmd, display=None):
        try:
            o = subprocess.check_output(cmd, stderr=subprocess.STDOUT,
                                        text=True)
            if o and re.match(_Distutils._dist_warn_regex, o):
                _Distutils.dist_error(
                    "Flags in command", cmd ,"aren't supported by the compiler"
                    ", output -> \n%s" % o
                )
        except subprocess.CalledProcessError as exc:
            o = exc.output
            s = exc.returncode
        except OSError as e:
            o = e
            s = 127
        else:
            return None
        _Distutils.dist_error(
            "Command", cmd, "failed with exit status %d output -> \n%s" % (
            s, o
        ))

_share_cache = {}
class _Cache:
    """An abstract class handles caching functionality, provides two
    levels of caching, in-memory by share instances attributes among
    each other and by store attributes into files.

    **Note**:
        any attributes that start with ``_`` or ``conf_`` will be ignored.

    Parameters
    ----------
    cache_path : str or None
        The path of cache file, if None then cache in file will disabled.

    *factors :
        The caching factors that need to utilize next to `conf_cache_factors`.

    Attributes
    ----------
    cache_private : set
        Hold the attributes that need be skipped from "in-memory cache".

    cache_infile : bool
        Utilized during initializing this class, to determine if the cache was able
        to loaded from the specified cache path in 'cache_path'.
    """

    # skip attributes from cache
    _cache_ignore = re.compile("^(_|conf_)")

    def __init__(self, cache_path=None, *factors):
        self.cache_me = {}
        self.cache_private = set()
        self.cache_infile = False
        self._cache_path = None

        if self.conf_nocache:
            self.dist_log("cache is disabled by `Config`")
            return

        self._cache_hash = self.cache_hash(*factors, *self.conf_cache_factors)
        self._cache_path = cache_path
        if cache_path:
            if os.path.exists(cache_path):
                self.dist_log("load cache from file ->", cache_path)
                cache_mod = self.dist_load_module("cache", cache_path)
                if not cache_mod:
                    self.dist_log(
                        "unable to load the cache file as a module",
                        stderr=True
                    )
                elif not hasattr(cache_mod, "hash") or \
                     not hasattr(cache_mod, "data"):
                    self.dist_log("invalid cache file", stderr=True)
                elif self._cache_hash == cache_mod.hash:
                    self.dist_log("hit the file cache")
                    for attr, val in cache_mod.data.items():
                        setattr(self, attr, val)
                    self.cache_infile = True
                else:
                    self.dist_log("miss the file cache")

        if not self.cache_infile:
            other_cache = _share_cache.get(self._cache_hash)
            if other_cache:
                self.dist_log("hit the memory cache")
                for attr, val in other_cache.__dict__.items():
                    if attr in other_cache.cache_private or \
                               re.match(self._cache_ignore, attr):
                        continue
                    setattr(self, attr, val)

        _share_cache[self._cache_hash] = self
        atexit.register(self.cache_flush)

    def __del__(self):
        for h, o in _share_cache.items():
            if o == self:
                _share_cache.pop(h)
                break

    def cache_flush(self):
        """
        Force update the cache.
        """
        if not self._cache_path:
            return
        # TODO: don't write if the cache doesn't change
        self.dist_log("write cache to path ->", self._cache_path)
        cdict = self.__dict__.copy()
        for attr in self.__dict__.keys():
            if re.match(self._cache_ignore, attr):
                cdict.pop(attr)

        d = os.path.dirname(self._cache_path)
        if not os.path.exists(d):
            os.makedirs(d)

        repr_dict = pprint.pformat(cdict, compact=True)
        with open(self._cache_path, "w") as f:
            f.write(textwrap.dedent("""\
            # AUTOGENERATED DON'T EDIT
            # Please make changes to the code generator \
            (distutils/ccompiler_opt.py)
            hash = {}
            data = \\
            """).format(self._cache_hash))
            f.write(repr_dict)

    def cache_hash(self, *factors):
        # is there a built-in non-crypto hash?
        # sdbm
        chash = 0
        for f in factors:
            for char in str(f):
                chash  = ord(char) + (chash << 6) + (chash << 16) - chash
                chash &= 0xFFFFFFFF
        return chash

    @staticmethod
    def me(cb):
        """
        A static method that can be treated as a decorator to
        dynamically cache certain methods.
        """
        def cache_wrap_me(self, *args, **kwargs):
            # good for normal args
            cache_key = str((
                cb.__name__, *args, *kwargs.keys(), *kwargs.values()
            ))
            if cache_key in self.cache_me:
                return self.cache_me[cache_key]
            ccb = cb(self, *args, **kwargs)
            self.cache_me[cache_key] = ccb
            return ccb
        return cache_wrap_me

class _CCompiler:
    """A helper class for `CCompilerOpt` containing all utilities that
    related to the fundamental compiler's functions.

    Attributes
    ----------
    cc_on_x86 : bool
        True when the target architecture is 32-bit x86
    cc_on_x64 : bool
        True when the target architecture is 64-bit x86
    cc_on_ppc64 : bool
        True when the target architecture is 64-bit big-endian powerpc
    cc_on_ppc64le : bool
        True when the target architecture is 64-bit litle-endian powerpc
    cc_on_s390x : bool
        True when the target architecture is IBM/ZARCH on linux
    cc_on_armhf : bool
        True when the target architecture is 32-bit ARMv7+
    cc_on_aarch64 : bool
        True when the target architecture is 64-bit Armv8-a+
    cc_on_noarch : bool
        True when the target architecture is unknown or not supported
    cc_is_gcc : bool
        True if the compiler is GNU or
        if the compiler is unknown
    cc_is_clang : bool
        True if the compiler is Clang
    cc_is_icc : bool
        True if the compiler is Intel compiler (unix like)
    cc_is_iccw : bool
        True if the compiler is Intel compiler (msvc like)
    cc_is_nocc : bool
        True if the compiler isn't supported directly,
        Note: that cause a fail-back to gcc
    cc_has_debug : bool
        True if the compiler has debug flags
    cc_has_native : bool
        True if the compiler has native flags
    cc_noopt : bool
        True if the compiler has definition 'DISABLE_OPT*',
        or 'cc_on_noarch' is True
    cc_march : str
        The target architecture name, or "unknown" if
        the architecture isn't supported
    cc_name : str
        The compiler name, or "unknown" if the compiler isn't supported
    cc_flags : dict
        Dictionary containing the initialized flags of `_Config.conf_cc_flags`
    """
    def __init__(self):
        if hasattr(self, "cc_is_cached"):
            return
        #      attr            regex        compiler-expression
        detect_arch = (
            ("cc_on_x64",      ".*(x|x86_|amd)64.*", ""),
            ("cc_on_x86",      ".*(win32|x86|i386|i686).*", ""),
            ("cc_on_ppc64le",  ".*(powerpc|ppc)64(el|le).*|.*powerpc.*",
                                          "defined(__powerpc64__) && "
                                          "defined(__LITTLE_ENDIAN__)"),
            ("cc_on_ppc64",    ".*(powerpc|ppc).*|.*powerpc.*",
                                          "defined(__powerpc64__) && "
                                          "defined(__BIG_ENDIAN__)"),
            ("cc_on_aarch64",  ".*(aarch64|arm64).*", ""),
            ("cc_on_armhf",    ".*arm.*", "defined(__ARM_ARCH_7__) || "
                                          "defined(__ARM_ARCH_7A__)"),
            ("cc_on_s390x",    ".*s390x.*", ""),
            # undefined platform
            ("cc_on_noarch",   "", ""),
        )
        detect_compiler = (
            ("cc_is_gcc",     r".*(gcc|gnu\-g).*", ""),
            ("cc_is_clang",    ".*clang.*", ""),
            # intel msvc like
            ("cc_is_iccw",     ".*(intelw|intelemw|iccw).*", ""),
            ("cc_is_icc",      ".*(intel|icc).*", ""),  # intel unix like
            ("cc_is_msvc",     ".*msvc.*", ""),
            ("cc_is_fcc",     ".*fcc.*", ""),
            # undefined compiler will be treat it as gcc
            ("cc_is_nocc",     "", ""),
        )
        detect_args = (
           ("cc_has_debug",  ".*(O0|Od|ggdb|coverage|debug:full).*", ""),
           ("cc_has_native",
                ".*(-march=native|-xHost|/QxHost|-mcpu=a64fx).*", ""),
           # in case if the class run with -DNPY_DISABLE_OPTIMIZATION
           ("cc_noopt", ".*DISABLE_OPT.*", ""),
        )

        dist_info = self.dist_info()
        platform, compiler_info, extra_args = dist_info
        # set False to all attrs
        for section in (detect_arch, detect_compiler, detect_args):
            for attr, rgex, cexpr in section:
                setattr(self, attr, False)

        for detect, searchin in ((detect_arch, platform), (detect_compiler, compiler_info)):
            for attr, rgex, cexpr in detect:
                if rgex and not re.match(rgex, searchin, re.IGNORECASE):
                    continue
                if cexpr and not self.cc_test_cexpr(cexpr):
                    continue
                setattr(self, attr, True)
                break

        for attr, rgex, cexpr in detect_args:
            if rgex and not re.match(rgex, extra_args, re.IGNORECASE):
                continue
            if cexpr and not self.cc_test_cexpr(cexpr):
                continue
            setattr(self, attr, True)

        if self.cc_on_noarch:
            self.dist_log(
                "unable to detect CPU architecture which lead to disable the optimization. "
                f"check dist_info:<<\n{dist_info}\n>>",
                stderr=True
            )
            self.cc_noopt = True

        if self.conf_noopt:
            self.dist_log("Optimization is disabled by the Config", stderr=True)
            self.cc_noopt = True

        if self.cc_is_nocc:
            """
            mingw can be treated as a gcc, and also xlc even if it based on clang,
            but still has the same gcc optimization flags.
            """
            self.dist_log(
                "unable to detect compiler type which leads to treating it as GCC. "
                "this is a normal behavior if you're using gcc-like compiler such as MinGW or IBM/XLC."
                f"check dist_info:<<\n{dist_info}\n>>",
                stderr=True
            )
            self.cc_is_gcc = True

        self.cc_march = "unknown"
        for arch in ("x86", "x64", "ppc64", "ppc64le",
                     "armhf", "aarch64", "s390x"):
            if getattr(self, "cc_on_" + arch):
                self.cc_march = arch
                break

        self.cc_name = "unknown"
        for name in ("gcc", "clang", "iccw", "icc", "msvc", "fcc"):
            if getattr(self, "cc_is_" + name):
                self.cc_name = name
                break

        self.cc_flags = {}
        compiler_flags = self.conf_cc_flags.get(self.cc_name)
        if compiler_flags is None:
            self.dist_fatal(
                "undefined flag for compiler '%s', "
                "leave an empty dict instead" % self.cc_name
            )
        for name, flags in compiler_flags.items():
            self.cc_flags[name] = nflags = []
            if flags:
                assert(isinstance(flags, str))
                flags = flags.split()
                for f in flags:
                    if self.cc_test_flags([f]):
                        nflags.append(f)

        self.cc_is_cached = True

    @_Cache.me
    def cc_test_flags(self, flags):
        """
        Returns True if the compiler supports 'flags'.
        """
        assert(isinstance(flags, list))
        self.dist_log("testing flags", flags)
        test_path = os.path.join(self.conf_check_path, "test_flags.c")
        test = self.dist_test(test_path, flags)
        if not test:
            self.dist_log("testing failed", stderr=True)
        return test

    @_Cache.me
    def cc_test_cexpr(self, cexpr, flags=[]):
        """
        Same as the above but supports compile-time expressions.
        """
        self.dist_log("testing compiler expression", cexpr)
        test_path = os.path.join(self.conf_tmp_path, "npy_dist_test_cexpr.c")
        with open(test_path, "w") as fd:
            fd.write(textwrap.dedent(f"""\
               #if !({cexpr})
                   #error "unsupported expression"
               #endif
               int dummy;
            """))
        test = self.dist_test(test_path, flags)
        if not test:
            self.dist_log("testing failed", stderr=True)
        return test

    def cc_normalize_flags(self, flags):
        """
        Remove the conflicts that caused due gathering implied features flags.

        Parameters
        ----------
        'flags' list, compiler flags
            flags should be sorted from the lowest to the highest interest.

        Returns
        -------
        list, filtered from any conflicts.

        Examples
        --------
        >>> self.cc_normalize_flags(['-march=armv8.2-a+fp16', '-march=armv8.2-a+dotprod'])
        ['armv8.2-a+fp16+dotprod']

        >>> self.cc_normalize_flags(
            ['-msse', '-msse2', '-msse3', '-mssse3', '-msse4.1', '-msse4.2', '-mavx', '-march=core-avx2']
        )
        ['-march=core-avx2']
        """
        assert(isinstance(flags, list))
        if self.cc_is_gcc or self.cc_is_clang or self.cc_is_icc:
            return self._cc_normalize_unix(flags)

        if self.cc_is_msvc or self.cc_is_iccw:
            return self._cc_normalize_win(flags)
        return flags

    _cc_normalize_unix_mrgx = re.compile(
        # 1- to check the highest of
        r"^(-mcpu=|-march=|-x[A-Z0-9\-])"
    )
    _cc_normalize_unix_frgx = re.compile(
        # 2- to remove any flags starts with
        # -march, -mcpu, -x(INTEL) and '-m' without '='
        r"^(?!(-mcpu=|-march=|-x[A-Z0-9\-]|-m[a-z0-9\-\.]*.$))|"
        # exclude:
        r"(?:-mzvector)"
    )
    _cc_normalize_unix_krgx = re.compile(
        # 3- keep only the highest of
        r"^(-mfpu|-mtune)"
    )
    _cc_normalize_arch_ver = re.compile(
        r"[0-9.]"
    )
    def _cc_normalize_unix(self, flags):
        def ver_flags(f):
            #        arch ver  subflag
            # -march=armv8.2-a+fp16fml
            tokens = f.split('+')
            ver = float('0' + ''.join(
                re.findall(self._cc_normalize_arch_ver, tokens[0])
            ))
            return ver, tokens[0], tokens[1:]

        if len(flags) <= 1:
            return flags
        # get the highest matched flag
        for i, cur_flag in enumerate(reversed(flags)):
            if not re.match(self._cc_normalize_unix_mrgx, cur_flag):
                continue
            lower_flags = flags[:-(i+1)]
            upper_flags = flags[-i:]
            filtered = list(filter(
                self._cc_normalize_unix_frgx.search, lower_flags
            ))
            # gather subflags
            ver, arch, subflags = ver_flags(cur_flag)
            if ver > 0 and len(subflags) > 0:
                for xflag in lower_flags:
                    xver, _, xsubflags = ver_flags(xflag)
                    if ver == xver:
                        subflags = xsubflags + subflags
                cur_flag = arch + '+' + '+'.join(subflags)

            flags = filtered + [cur_flag]
            if i > 0:
                flags += upper_flags
            break

        # to remove overridable flags
        final_flags = []
        matched = set()
        for f in reversed(flags):
            match = re.match(self._cc_normalize_unix_krgx, f)
            if not match:
                pass
            elif match[0] in matched:
                continue
            else:
                matched.add(match[0])
            final_flags.insert(0, f)
        return final_flags

    _cc_normalize_win_frgx = re.compile(
        r"^(?!(/arch\:|/Qx\:))"
    )
    _cc_normalize_win_mrgx = re.compile(
        r"^(/arch|/Qx:)"
    )
    def _cc_normalize_win(self, flags):
        for i, f in enumerate(reversed(flags)):
            if not re.match(self._cc_normalize_win_mrgx, f):
                continue
            i += 1
            return list(filter(
                self._cc_normalize_win_frgx.search, flags[:-i]
            )) + flags[-i:]
        return flags

class _Feature:
    """A helper class for `CCompilerOpt` that managing CPU features.

    Attributes
    ----------
    feature_supported : dict
        Dictionary containing all CPU features that supported
        by the platform, according to the specified values in attribute
        `_Config.conf_features` and `_Config.conf_features_partial()`

    feature_min : set
        The minimum support of CPU features, according to
        the specified values in attribute `_Config.conf_min_features`.
    """
    def __init__(self):
        if hasattr(self, "feature_is_cached"):
            return
        self.feature_supported = pfeatures = self.conf_features_partial()
        for feature_name in list(pfeatures.keys()):
            feature  = pfeatures[feature_name]
            cfeature = self.conf_features[feature_name]
            feature.update({
                k:v for k,v in cfeature.items() if k not in feature
            })
            disabled = feature.get("disable")
            if disabled is not None:
                pfeatures.pop(feature_name)
                self.dist_log(
                    "feature '%s' is disabled," % feature_name,
                    disabled, stderr=True
                )
                continue
            # list is used internally for these options
            for option in (
                "implies", "group", "detect", "headers", "flags", "extra_checks"
            ) :
                oval = feature.get(option)
                if isinstance(oval, str):
                    feature[option] = oval.split()

        self.feature_min = set()
        min_f = self.conf_min_features.get(self.cc_march, "")
        for F in min_f.upper().split():
            if F in self.feature_supported:
                self.feature_min.add(F)

        self.feature_is_cached = True

    def feature_names(self, names=None, force_flags=None, macros=[]):
        """
        Returns a set of CPU feature names that supported by platform and the **C** compiler.

        Parameters
        ----------
        names : sequence or None, optional
            Specify certain CPU features to test it against the **C** compiler.
            if None(default), it will test all current supported features.
            **Note**: feature names must be in upper-case.

        force_flags : list or None, optional
            If None(default), default compiler flags for every CPU feature will
            be used during the test.

        macros : list of tuples, optional
            A list of C macro definitions.
        """
        assert(
            names is None or (
                not isinstance(names, str) and
                hasattr(names, "__iter__")
            )
        )
        assert(force_flags is None or isinstance(force_flags, list))
        if names is None:
            names = self.feature_supported.keys()
        supported_names = set()
        for f in names:
            if self.feature_is_supported(
                f, force_flags=force_flags, macros=macros
            ):
                supported_names.add(f)
        return supported_names

    def feature_is_exist(self, name):
        """
        Returns True if a certain feature is exist and covered within
        `_Config.conf_features`.

        Parameters
        ----------
        'name': str
            feature name in uppercase.
        """
        assert(name.isupper())
        return name in self.conf_features

    def feature_sorted(self, names, reverse=False):
        """
        Sort a list of CPU features ordered by the lowest interest.

        Parameters
        ----------
        'names': sequence
            sequence of supported feature names in uppercase.
        'reverse': bool, optional
            If true, the sorted features is reversed. (highest interest)

        Returns
        -------
        list, sorted CPU features
        """
        def sort_cb(k):
            if isinstance(k, str):
                return self.feature_supported[k]["interest"]
            # multiple features
            rank = max([self.feature_supported[f]["interest"] for f in k])
            # FIXME: that's not a safe way to increase the rank for
            # multi targets
            rank += len(k) -1
            return rank
        return sorted(names, reverse=reverse, key=sort_cb)

    def feature_implies(self, names, keep_origins=False):
        """
        Return a set of CPU features that implied by 'names'

        Parameters
        ----------
        names : str or sequence of str
            CPU feature name(s) in uppercase.

        keep_origins : bool
            if False(default) then the returned set will not contain any
            features from 'names'. This case happens only when two features
            imply each other.

        Examples
        --------
        >>> self.feature_implies("SSE3")
        {'SSE', 'SSE2'}
        >>> self.feature_implies("SSE2")
        {'SSE'}
        >>> self.feature_implies("SSE2", keep_origins=True)
        # 'SSE2' found here since 'SSE' and 'SSE2' imply each other
        {'SSE', 'SSE2'}
        """
        def get_implies(name, _caller=set()):
            implies = set()
            d = self.feature_supported[name]
            for i in d.get("implies", []):
                implies.add(i)
                if i in _caller:
                    # infinity recursive guard since
                    # features can imply each other
                    continue
                _caller.add(name)
                implies = implies.union(get_implies(i, _caller))
            return implies

        if isinstance(names, str):
            implies = get_implies(names)
            names = [names]
        else:
            assert(hasattr(names, "__iter__"))
            implies = set()
            for n in names:
                implies = implies.union(get_implies(n))
        if not keep_origins:
            implies.difference_update(names)
        return implies

    def feature_implies_c(self, names):
        """same as feature_implies() but combining 'names'"""
        if isinstance(names, str):
            names = set((names,))
        else:
            names = set(names)
        return names.union(self.feature_implies(names))

    def feature_ahead(self, names):
        """
        Return list of features in 'names' after remove any
        implied features and keep the origins.

        Parameters
        ----------
        'names': sequence
            sequence of CPU feature names in uppercase.

        Returns
        -------
        list of CPU features sorted as-is 'names'

        Examples
        --------
        >>> self.feature_ahead(["SSE2", "SSE3", "SSE41"])
        ["SSE41"]
        # assume AVX2 and FMA3 implies each other and AVX2
        # is the highest interest
        >>> self.feature_ahead(["SSE2", "SSE3", "SSE41", "AVX2", "FMA3"])
        ["AVX2"]
        # assume AVX2 and FMA3 don't implies each other
        >>> self.feature_ahead(["SSE2", "SSE3", "SSE41", "AVX2", "FMA3"])
        ["AVX2", "FMA3"]
        """
        assert(
            not isinstance(names, str)
            and hasattr(names, '__iter__')
        )
        implies = self.feature_implies(names, keep_origins=True)
        ahead = [n for n in names if n not in implies]
        if len(ahead) == 0:
            # return the highest interested feature
            # if all features imply each other
            ahead = self.feature_sorted(names, reverse=True)[:1]
        return ahead

    def feature_untied(self, names):
        """
        same as 'feature_ahead()' but if both features implied each other
        and keep the highest interest.

        Parameters
        ----------
        'names': sequence
            sequence of CPU feature names in uppercase.

        Returns
        -------
        list of CPU features sorted as-is 'names'

        Examples
        --------
        >>> self.feature_untied(["SSE2", "SSE3", "SSE41"])
        ["SSE2", "SSE3", "SSE41"]
        # assume AVX2 and FMA3 implies each other
        >>> self.feature_untied(["SSE2", "SSE3", "SSE41", "FMA3", "AVX2"])
        ["SSE2", "SSE3", "SSE41", "AVX2"]
        """
        assert(
            not isinstance(names, str)
            and hasattr(names, '__iter__')
        )
        final = []
        for n in names:
            implies = self.feature_implies(n)
            tied = [
                nn for nn in final
                if nn in implies and n in self.feature_implies(nn)
            ]
            if tied:
                tied = self.feature_sorted(tied + [n])
                if n not in tied[1:]:
                    continue
                final.remove(tied[:1][0])
            final.append(n)
        return final

    def feature_get_til(self, names, keyisfalse):
        """
        same as `feature_implies_c()` but stop collecting implied
        features when feature's option that provided through
        parameter 'keyisfalse' is False, also sorting the returned
        features.
        """
        def til(tnames):
            # sort from highest to lowest interest then cut if "key" is False
            tnames = self.feature_implies_c(tnames)
            tnames = self.feature_sorted(tnames, reverse=True)
            for i, n in enumerate(tnames):
                if not self.feature_supported[n].get(keyisfalse, True):
                    tnames = tnames[:i+1]
                    break
            return tnames

        if isinstance(names, str) or len(names) <= 1:
            names = til(names)
            # normalize the sort
            names.reverse()
            return names

        names = self.feature_ahead(names)
        names = {t for n in names for t in til(n)}
        return self.feature_sorted(names)

    def feature_detect(self, names):
        """
        Return a list of CPU features that required to be detected
        sorted from the lowest to highest interest.
        """
        names = self.feature_get_til(names, "implies_detect")
        detect = []
        for n in names:
            d = self.feature_supported[n]
            detect += d.get("detect", d.get("group", [n]))
        return detect

    @_Cache.me
    def feature_flags(self, names):
        """
        Return a list of CPU features flags sorted from the lowest
        to highest interest.
        """
        names = self.feature_sorted(self.feature_implies_c(names))
        flags = []
        for n in names:
            d = self.feature_supported[n]
            f = d.get("flags", [])
            if not f or not self.cc_test_flags(f):
                continue
            flags += f
        return self.cc_normalize_flags(flags)

    @_Cache.me
    def feature_test(self, name, force_flags=None, macros=[]):
        """
        Test a certain CPU feature against the compiler through its own
        check file.

        Parameters
        ----------
        name : str
            Supported CPU feature name.

        force_flags : list or None, optional
            If None(default), the returned flags from `feature_flags()`
            will be used.

        macros : list of tuples, optional
            A list of C macro definitions.
        """
        if force_flags is None:
            force_flags = self.feature_flags(name)

        self.dist_log(
            "testing feature '%s' with flags (%s)" % (
            name, ' '.join(force_flags)
        ))
        # Each CPU feature must have C source code contains at
        # least one intrinsic or instruction related to this feature.
        test_path = os.path.join(
            self.conf_check_path, "cpu_%s.c" % name.lower()
        )
        if not os.path.exists(test_path):
            self.dist_fatal("feature test file is not exist", test_path)

        test = self.dist_test(
            test_path, force_flags + self.cc_flags["werror"], macros=macros
        )
        if not test:
            self.dist_log("testing failed", stderr=True)
        return test

    @_Cache.me
    def feature_is_supported(self, name, force_flags=None, macros=[]):
        """
        Check if a certain CPU feature is supported by the platform and compiler.

        Parameters
        ----------
        name : str
            CPU feature name in uppercase.

        force_flags : list or None, optional
            If None(default), default compiler flags for every CPU feature will
            be used during test.

        macros : list of tuples, optional
            A list of C macro definitions.
        """
        assert(name.isupper())
        assert(force_flags is None or isinstance(force_flags, list))

        supported = name in self.feature_supported
        if supported:
            for impl in self.feature_implies(name):
                if not self.feature_test(impl, force_flags, macros=macros):
                    return False
            if not self.feature_test(name, force_flags, macros=macros):
                return False
        return supported

    @_Cache.me
    def feature_can_autovec(self, name):
        """
        check if the feature can be auto-vectorized by the compiler
        """
        assert(isinstance(name, str))
        d = self.feature_supported[name]
        can = d.get("autovec", None)
        if can is None:
            valid_flags = [
                self.cc_test_flags([f]) for f in d.get("flags", [])
            ]
            can = valid_flags and any(valid_flags)
        return can

    @_Cache.me
    def feature_extra_checks(self, name):
        """
        Return a list of supported extra checks after testing them against
        the compiler.

        Parameters
        ----------
        names : str
            CPU feature name in uppercase.
        """
        assert isinstance(name, str)
        d = self.feature_supported[name]
        extra_checks = d.get("extra_checks", [])
        if not extra_checks:
            return []

        self.dist_log("Testing extra checks for feature '%s'" % name, extra_checks)
        flags = self.feature_flags(name)
        available = []
        not_available = []
        for chk in extra_checks:
            test_path = os.path.join(
                self.conf_check_path, "extra_%s.c" % chk.lower()
            )
            if not os.path.exists(test_path):
                self.dist_fatal("extra check file does not exist", test_path)

            is_supported = self.dist_test(test_path, flags + self.cc_flags["werror"])
            if is_supported:
                available.append(chk)
            else:
                not_available.append(chk)

        if not_available:
            self.dist_log("testing failed for checks", not_available, stderr=True)
        return available


    def feature_c_preprocessor(self, feature_name, tabs=0):
        """
        Generate C preprocessor definitions and include headers of a CPU feature.

        Parameters
        ----------
        'feature_name': str
            CPU feature name in uppercase.
        'tabs': int
            if > 0, align the generated strings to the right depend on number of tabs.

        Returns
        -------
        str, generated C preprocessor

        Examples
        --------
        >>> self.feature_c_preprocessor("SSE3")
        /** SSE3 **/
        #define NPY_HAVE_SSE3 1
        #include <pmmintrin.h>
        """
        assert(feature_name.isupper())
        feature = self.feature_supported.get(feature_name)
        assert(feature is not None)

        prepr = [
            "/** %s **/" % feature_name,
            "#define %sHAVE_%s 1" % (self.conf_c_prefix, feature_name)
        ]
        prepr += [
            "#include <%s>" % h for h in feature.get("headers", [])
        ]

        extra_defs = feature.get("group", [])
        extra_defs += self.feature_extra_checks(feature_name)
        for edef in extra_defs:
            # Guard extra definitions in case of duplicate with
            # another feature
            prepr += [
                "#ifndef %sHAVE_%s" % (self.conf_c_prefix, edef),
                "\t#define %sHAVE_%s 1" % (self.conf_c_prefix, edef),
                "#endif",
            ]

        if tabs > 0:
            prepr = [('\t'*tabs) + l for l in prepr]
        return '\n'.join(prepr)

class _Parse:
    """A helper class that parsing main arguments of `CCompilerOpt`,
    also parsing configuration statements in dispatch-able sources.

    Parameters
    ----------
    cpu_baseline : str or None
        minimal set of required CPU features or special options.

    cpu_dispatch : str or None
        dispatched set of additional CPU features or special options.

    Special options can be:
        - **MIN**: Enables the minimum CPU features that utilized via `_Config.conf_min_features`
        - **MAX**: Enables all supported CPU features by the Compiler and platform.
        - **NATIVE**: Enables all CPU features that supported by the current machine.
        - **NONE**: Enables nothing
        - **Operand +/-**: remove or add features, useful with options **MAX**, **MIN** and **NATIVE**.
            NOTE: operand + is only added for nominal reason.

    NOTES:
        - Case-insensitive among all CPU features and special options.
        - Comma or space can be used as a separator.
        - If the CPU feature is not supported by the user platform or compiler,
          it will be skipped rather than raising a fatal error.
        - Any specified CPU features to 'cpu_dispatch' will be skipped if its part of CPU baseline features
        - 'cpu_baseline' force enables implied features.

    Attributes
    ----------
    parse_baseline_names : list
        Final CPU baseline's feature names(sorted from low to high)
    parse_baseline_flags : list
        Compiler flags of baseline features
    parse_dispatch_names : list
        Final CPU dispatch-able feature names(sorted from low to high)
    parse_target_groups : dict
        Dictionary containing initialized target groups that configured
        through class attribute `conf_target_groups`.

        The key is represent the group name and value is a tuple
        contains three items :
            - bool, True if group has the 'baseline' option.
            - list, list of CPU features.
            - list, list of extra compiler flags.

    """
    def __init__(self, cpu_baseline, cpu_dispatch):
        self._parse_policies = dict(
            # POLICY NAME, (HAVE, NOT HAVE, [DEB])
            KEEP_BASELINE = (
                None, self._parse_policy_not_keepbase,
                []
            ),
            KEEP_SORT = (
                self._parse_policy_keepsort,
                self._parse_policy_not_keepsort,
                []
            ),
            MAXOPT = (
                self._parse_policy_maxopt, None,
                []
            ),
            WERROR = (
                self._parse_policy_werror, None,
                []
            ),
            AUTOVEC = (
                self._parse_policy_autovec, None,
                ["MAXOPT"]
            )
        )
        if hasattr(self, "parse_is_cached"):
            return

        self.parse_baseline_names = []
        self.parse_baseline_flags = []
        self.parse_dispatch_names = []
        self.parse_target_groups = {}

        if self.cc_noopt:
            # skip parsing baseline and dispatch args and keep parsing target groups
            cpu_baseline = cpu_dispatch = None

        self.dist_log("check requested baseline")
        if cpu_baseline is not None:
            cpu_baseline = self._parse_arg_features("cpu_baseline", cpu_baseline)
            baseline_names = self.feature_names(cpu_baseline)
            self.parse_baseline_flags = self.feature_flags(baseline_names)
            self.parse_baseline_names = self.feature_sorted(
                self.feature_implies_c(baseline_names)
            )

        self.dist_log("check requested dispatch-able features")
        if cpu_dispatch is not None:
            cpu_dispatch_ = self._parse_arg_features("cpu_dispatch", cpu_dispatch)
            cpu_dispatch = {
                f for f in cpu_dispatch_
                if f not in self.parse_baseline_names
            }
            conflict_baseline = cpu_dispatch_.difference(cpu_dispatch)
            self.parse_dispatch_names = self.feature_sorted(
                self.feature_names(cpu_dispatch)
            )
            if len(conflict_baseline) > 0:
                self.dist_log(
                    "skip features", conflict_baseline, "since its part of baseline"
                )

        self.dist_log("initialize targets groups")
        for group_name, tokens in self.conf_target_groups.items():
            self.dist_log("parse target group", group_name)
            GROUP_NAME = group_name.upper()
            if not tokens or not tokens.strip():
                # allow empty groups, useful in case if there's a need
                # to disable certain group since '_parse_target_tokens()'
                # requires at least one valid target
                self.parse_target_groups[GROUP_NAME] = (
                    False, [], []
                )
                continue
            has_baseline, features, extra_flags = \
                self._parse_target_tokens(tokens)
            self.parse_target_groups[GROUP_NAME] = (
                has_baseline, features, extra_flags
            )

        self.parse_is_cached = True

    def parse_targets(self, source):
        """
        Fetch and parse configuration statements that required for
        defining the targeted CPU features, statements should be declared
        in the top of source in between **C** comment and start
        with a special mark **@targets**.

        Configuration statements are sort of keywords representing
        CPU features names, group of statements and policies, combined
        together to determine the required optimization.

        Parameters
        ----------
        source : str
            the path of **C** source file.

        Returns
        -------
        - bool, True if group has the 'baseline' option
        - list, list of CPU features
        - list, list of extra compiler flags
        """
        self.dist_log("looking for '@targets' inside -> ", source)
        # get lines between /*@targets and */
        with open(source) as fd:
            tokens = ""
            max_to_reach = 1000 # good enough, isn't?
            start_with = "@targets"
            start_pos = -1
            end_with = "*/"
            end_pos = -1
            for current_line, line in enumerate(fd):
                if current_line == max_to_reach:
                    self.dist_fatal("reached the max of lines")
                    break
                if start_pos == -1:
                    start_pos = line.find(start_with)
                    if start_pos == -1:
                        continue
                    start_pos += len(start_with)
                tokens += line
                end_pos = line.find(end_with)
                if end_pos != -1:
                    end_pos += len(tokens) - len(line)
                    break

        if start_pos == -1:
            self.dist_fatal("expected to find '%s' within a C comment" % start_with)
        if end_pos == -1:
            self.dist_fatal("expected to end with '%s'" % end_with)

        tokens = tokens[start_pos:end_pos]
        return self._parse_target_tokens(tokens)

    _parse_regex_arg = re.compile(r'\s|,|([+-])')
    def _parse_arg_features(self, arg_name, req_features):
        if not isinstance(req_features, str):
            self.dist_fatal("expected a string in '%s'" % arg_name)

        final_features = set()
        # space and comma can be used as a separator
        tokens = list(filter(None, re.split(self._parse_regex_arg, req_features)))
        append = True # append is the default
        for tok in tokens:
            if tok[0] in ("#", "$"):
                self.dist_fatal(
                    arg_name, "target groups and policies "
                    "aren't allowed from arguments, "
                    "only from dispatch-able sources"
                )
            if tok == '+':
                append = True
                continue
            if tok == '-':
                append = False
                continue

            TOK = tok.upper() # we use upper-case internally
            features_to = set()
            if TOK == "NONE":
                pass
            elif TOK == "NATIVE":
                native = self.cc_flags["native"]
                if not native:
                    self.dist_fatal(arg_name,
                        "native option isn't supported by the compiler"
                    )
                features_to = self.feature_names(
                    force_flags=native, macros=[("DETECT_FEATURES", 1)]
                )
            elif TOK == "MAX":
                features_to = self.feature_supported.keys()
            elif TOK == "MIN":
                features_to = self.feature_min
            else:
                if TOK in self.feature_supported:
                    features_to.add(TOK)
                else:
                    if not self.feature_is_exist(TOK):
                        self.dist_fatal(arg_name,
                            ", '%s' isn't a known feature or option" % tok
                        )
            if append:
                final_features = final_features.union(features_to)
            else:
                final_features = final_features.difference(features_to)

            append = True # back to default

        return final_features

    _parse_regex_target = re.compile(r'\s|[*,/]|([()])')
    def _parse_target_tokens(self, tokens):
        assert(isinstance(tokens, str))
        final_targets = [] # to keep it sorted as specified
        extra_flags = []
        has_baseline = False

        skipped  = set()
        policies = set()
        multi_target = None

        tokens = list(filter(None, re.split(self._parse_regex_target, tokens)))
        if not tokens:
            self.dist_fatal("expected one token at least")

        for tok in tokens:
            TOK = tok.upper()
            ch = tok[0]
            if ch in ('+', '-'):
                self.dist_fatal(
                    "+/- are 'not' allowed from target's groups or @targets, "
                    "only from cpu_baseline and cpu_dispatch parms"
                )
            elif ch == '$':
                if multi_target is not None:
                    self.dist_fatal(
                        "policies aren't allowed inside multi-target '()'"
                        ", only CPU features"
                    )
                policies.add(self._parse_token_policy(TOK))
            elif ch == '#':
                if multi_target is not None:
                    self.dist_fatal(
                        "target groups aren't allowed inside multi-target '()'"
                        ", only CPU features"
                    )
                has_baseline, final_targets, extra_flags = \
                self._parse_token_group(TOK, has_baseline, final_targets, extra_flags)
            elif ch == '(':
                if multi_target is not None:
                    self.dist_fatal("unclosed multi-target, missing ')'")
                multi_target = set()
            elif ch == ')':
                if multi_target is None:
                    self.dist_fatal("multi-target opener '(' wasn't found")
                targets = self._parse_multi_target(multi_target)
                if targets is None:
                    skipped.add(tuple(multi_target))
                else:
                    if len(targets) == 1:
                        targets = targets[0]
                    if targets and targets not in final_targets:
                        final_targets.append(targets)
                multi_target = None # back to default
            else:
                if TOK == "BASELINE":
                    if multi_target is not None:
                        self.dist_fatal("baseline isn't allowed inside multi-target '()'")
                    has_baseline = True
                    continue

                if multi_target is not None:
                    multi_target.add(TOK)
                    continue

                if not self.feature_is_exist(TOK):
                    self.dist_fatal("invalid target name '%s'" % TOK)

                is_enabled = (
                    TOK in self.parse_baseline_names or
                    TOK in self.parse_dispatch_names
                )
                if  is_enabled:
                    if TOK not in final_targets:
                        final_targets.append(TOK)
                    continue

                skipped.add(TOK)

        if multi_target is not None:
            self.dist_fatal("unclosed multi-target, missing ')'")
        if skipped:
            self.dist_log(
                "skip targets", skipped,
                "not part of baseline or dispatch-able features"
            )

        final_targets = self.feature_untied(final_targets)

        # add polices dependencies
        for p in list(policies):
            _, _, deps = self._parse_policies[p]
            for d in deps:
                if d in policies:
                    continue
                self.dist_log(
                    "policy '%s' force enables '%s'" % (
                    p, d
                ))
                policies.add(d)

        # release policies filtrations
        for p, (have, nhave, _) in self._parse_policies.items():
            func = None
            if p in policies:
                func = have
                self.dist_log("policy '%s' is ON" % p)
            else:
                func = nhave
            if not func:
                continue
            has_baseline, final_targets, extra_flags = func(
                has_baseline, final_targets, extra_flags
            )

        return has_baseline, final_targets, extra_flags

    def _parse_token_policy(self, token):
        """validate policy token"""
        if len(token) <= 1 or token[-1:] == token[0]:
            self.dist_fatal("'$' must stuck in the begin of policy name")
        token = token[1:]
        if token not in self._parse_policies:
            self.dist_fatal(
                "'%s' is an invalid policy name, available policies are" % token,
                self._parse_policies.keys()
            )
        return token

    def _parse_token_group(self, token, has_baseline, final_targets, extra_flags):
        """validate group token"""
        if len(token) <= 1 or token[-1:] == token[0]:
            self.dist_fatal("'#' must stuck in the begin of group name")

        token = token[1:]
        ghas_baseline, gtargets, gextra_flags = self.parse_target_groups.get(
            token, (False, None, [])
        )
        if gtargets is None:
            self.dist_fatal(
                "'%s' is an invalid target group name, " % token + \
                "available target groups are",
                self.parse_target_groups.keys()
            )
        if ghas_baseline:
            has_baseline = True
        # always keep sorting as specified
        final_targets += [f for f in gtargets if f not in final_targets]
        extra_flags += [f for f in gextra_flags if f not in extra_flags]
        return has_baseline, final_targets, extra_flags

    def _parse_multi_target(self, targets):
        """validate multi targets that defined between parentheses()"""
        # remove any implied features and keep the origins
        if not targets:
            self.dist_fatal("empty multi-target '()'")
        if not all([
            self.feature_is_exist(tar) for tar in targets
        ]) :
            self.dist_fatal("invalid target name in multi-target", targets)
        if not all([
            (
                tar in self.parse_baseline_names or
                tar in self.parse_dispatch_names
            )
            for tar in targets
        ]) :
            return None
        targets = self.feature_ahead(targets)
        if not targets:
            return None
        # force sort multi targets, so it can be comparable
        targets = self.feature_sorted(targets)
        targets = tuple(targets) # hashable
        return targets

    def _parse_policy_not_keepbase(self, has_baseline, final_targets, extra_flags):
        """skip all baseline features"""
        skipped = []
        for tar in final_targets[:]:
            is_base = False
            if isinstance(tar, str):
                is_base = tar in self.parse_baseline_names
            else:
                # multi targets
                is_base = all([
                    f in self.parse_baseline_names
                    for f in tar
                ])
            if is_base:
                skipped.append(tar)
                final_targets.remove(tar)

        if skipped:
            self.dist_log("skip baseline features", skipped)

        return has_baseline, final_targets, extra_flags

    def _parse_policy_keepsort(self, has_baseline, final_targets, extra_flags):
        """leave a notice that $keep_sort is on"""
        self.dist_log(
            "policy 'keep_sort' is on, dispatch-able targets", final_targets, "\n"
            "are 'not' sorted depend on the highest interest but"
            "as specified in the dispatch-able source or the extra group"
        )
        return has_baseline, final_targets, extra_flags

    def _parse_policy_not_keepsort(self, has_baseline, final_targets, extra_flags):
        """sorted depend on the highest interest"""
        final_targets = self.feature_sorted(final_targets, reverse=True)
        return has_baseline, final_targets, extra_flags

    def _parse_policy_maxopt(self, has_baseline, final_targets, extra_flags):
        """append the compiler optimization flags"""
        if self.cc_has_debug:
            self.dist_log("debug mode is detected, policy 'maxopt' is skipped.")
        elif self.cc_noopt:
            self.dist_log("optimization is disabled, policy 'maxopt' is skipped.")
        else:
            flags = self.cc_flags["opt"]
            if not flags:
                self.dist_log(
                    "current compiler doesn't support optimization flags, "
                    "policy 'maxopt' is skipped", stderr=True
                )
            else:
                extra_flags += flags
        return has_baseline, final_targets, extra_flags

    def _parse_policy_werror(self, has_baseline, final_targets, extra_flags):
        """force warnings to treated as errors"""
        flags = self.cc_flags["werror"]
        if not flags:
            self.dist_log(
                "current compiler doesn't support werror flags, "
                "warnings will 'not' treated as errors", stderr=True
            )
        else:
            self.dist_log("compiler warnings are treated as errors")
            extra_flags += flags
        return has_baseline, final_targets, extra_flags

    def _parse_policy_autovec(self, has_baseline, final_targets, extra_flags):
        """skip features that has no auto-vectorized support by compiler"""
        skipped = []
        for tar in final_targets[:]:
            if isinstance(tar, str):
                can = self.feature_can_autovec(tar)
            else: # multiple target
                can = all([
                    self.feature_can_autovec(t)
                    for t in tar
                ])
            if not can:
                final_targets.remove(tar)
                skipped.append(tar)

        if skipped:
            self.dist_log("skip non auto-vectorized features", skipped)

        return has_baseline, final_targets, extra_flags

class CCompilerOpt(_Config, _Distutils, _Cache, _CCompiler, _Feature, _Parse):
    """
    A helper class for `CCompiler` aims to provide extra build options
    to effectively control of compiler optimizations that are directly
    related to CPU features.
    """
    def __init__(self, ccompiler, cpu_baseline="min", cpu_dispatch="max", cache_path=None):
        _Config.__init__(self)
        _Distutils.__init__(self, ccompiler)
        _Cache.__init__(self, cache_path, self.dist_info(), cpu_baseline, cpu_dispatch)
        _CCompiler.__init__(self)
        _Feature.__init__(self)
        if not self.cc_noopt and self.cc_has_native:
            self.dist_log(
                "native flag is specified through environment variables. "
                "force cpu-baseline='native'"
            )
            cpu_baseline = "native"
        _Parse.__init__(self, cpu_baseline, cpu_dispatch)
        # keep the requested features untouched, need it later for report
        # and trace purposes
        self._requested_baseline = cpu_baseline
        self._requested_dispatch = cpu_dispatch
        # key is the dispatch-able source and value is a tuple
        # contains two items (has_baseline[boolean], dispatched-features[list])
        self.sources_status = getattr(self, "sources_status", {})
        # every instance should has a separate one
        self.cache_private.add("sources_status")
        # set it at the end to make sure the cache writing was done after init
        # this class
        self.hit_cache = hasattr(self, "hit_cache")

    def is_cached(self):
        """
        Returns True if the class loaded from the cache file
        """
        return self.cache_infile and self.hit_cache

    def cpu_baseline_flags(self):
        """
        Returns a list of final CPU baseline compiler flags
        """
        return self.parse_baseline_flags

    def cpu_baseline_names(self):
        """
        return a list of final CPU baseline feature names
        """
        return self.parse_baseline_names

    def cpu_dispatch_names(self):
        """
        return a list of final CPU dispatch feature names
        """
        return self.parse_dispatch_names

    def try_dispatch(self, sources, src_dir=None, ccompiler=None, **kwargs):
        """
        Compile one or more dispatch-able sources and generates object files,
        also generates abstract C config headers and macros that
        used later for the final runtime dispatching process.

        The mechanism behind it is to takes each source file that specified
        in 'sources' and branching it into several files depend on
        special configuration statements that must be declared in the
        top of each source which contains targeted CPU features,
        then it compiles every branched source with the proper compiler flags.

        Parameters
        ----------
        sources : list
            Must be a list of dispatch-able sources file paths,
            and configuration statements must be declared inside
            each file.

        src_dir : str
            Path of parent directory for the generated headers and wrapped sources.
            If None(default) the files will generated in-place.

        ccompiler : CCompiler
            Distutils `CCompiler` instance to be used for compilation.
            If None (default), the provided instance during the initialization
            will be used instead.

        **kwargs : any
            Arguments to pass on to the `CCompiler.compile()`

        Returns
        -------
        list : generated object files

        Raises
        ------
        CompileError
            Raises by `CCompiler.compile()` on compiling failure.
        DistutilsError
            Some errors during checking the sanity of configuration statements.

        See Also
        --------
        parse_targets :
            Parsing the configuration statements of dispatch-able sources.
        """
        to_compile = {}
        baseline_flags = self.cpu_baseline_flags()
        include_dirs = kwargs.setdefault("include_dirs", [])

        for src in sources:
            output_dir = os.path.dirname(src)
            if src_dir:
                if not output_dir.startswith(src_dir):
                    output_dir = os.path.join(src_dir, output_dir)
                if output_dir not in include_dirs:
                    # To allow including the generated config header(*.dispatch.h)
                    # by the dispatch-able sources
                    include_dirs.append(output_dir)

            has_baseline, targets, extra_flags = self.parse_targets(src)
            nochange = self._generate_config(output_dir, src, targets, has_baseline)
            for tar in targets:
                tar_src = self._wrap_target(output_dir, src, tar, nochange=nochange)
                flags = tuple(extra_flags + self.feature_flags(tar))
                to_compile.setdefault(flags, []).append(tar_src)

            if has_baseline:
                flags = tuple(extra_flags + baseline_flags)
                to_compile.setdefault(flags, []).append(src)

            self.sources_status[src] = (has_baseline, targets)

        # For these reasons, the sources are compiled in a separate loop:
        # - Gathering all sources with the same flags to benefit from
        #   the parallel compiling as much as possible.
        # - To generate all config headers of the dispatchable sources,
        #   before the compilation in case if there are dependency relationships
        #   among them.
        objects = []
        for flags, srcs in to_compile.items():
            objects += self.dist_compile(
                srcs, list(flags), ccompiler=ccompiler, **kwargs
            )
        return objects

    def generate_dispatch_header(self, header_path):
        """
        Generate the dispatch header which contains the #definitions and headers
        for platform-specific instruction-sets for the enabled CPU baseline and
        dispatch-able features.

        Its highly recommended to take a look at the generated header
        also the generated source files via `try_dispatch()`
        in order to get the full picture.
        """
        self.dist_log("generate CPU dispatch header: (%s)" % header_path)

        baseline_names = self.cpu_baseline_names()
        dispatch_names = self.cpu_dispatch_names()
        baseline_len = len(baseline_names)
        dispatch_len = len(dispatch_names)

        header_dir = os.path.dirname(header_path)
        if not os.path.exists(header_dir):
            self.dist_log(
                f"dispatch header dir {header_dir} does not exist, creating it",
                stderr=True
            )
            os.makedirs(header_dir)

        with open(header_path, 'w') as f:
            baseline_calls = ' \\\n'.join([
                (
                    "\t%sWITH_CPU_EXPAND_(MACRO_TO_CALL(%s, __VA_ARGS__))"
                ) % (self.conf_c_prefix, f)
                for f in baseline_names
            ])
            dispatch_calls = ' \\\n'.join([
                (
                    "\t%sWITH_CPU_EXPAND_(MACRO_TO_CALL(%s, __VA_ARGS__))"
                ) % (self.conf_c_prefix, f)
                for f in dispatch_names
            ])
            f.write(textwrap.dedent("""\
                /*
                 * AUTOGENERATED DON'T EDIT
                 * Please make changes to the code generator (distutils/ccompiler_opt.py)
                */
                #define {pfx}WITH_CPU_BASELINE  "{baseline_str}"
                #define {pfx}WITH_CPU_DISPATCH  "{dispatch_str}"
                #define {pfx}WITH_CPU_BASELINE_N {baseline_len}
                #define {pfx}WITH_CPU_DISPATCH_N {dispatch_len}
                #define {pfx}WITH_CPU_EXPAND_(X) X
                #define {pfx}WITH_CPU_BASELINE_CALL(MACRO_TO_CALL, ...) \\
                {baseline_calls}
                #define {pfx}WITH_CPU_DISPATCH_CALL(MACRO_TO_CALL, ...) \\
                {dispatch_calls}
            """).format(
                pfx=self.conf_c_prefix, baseline_str=" ".join(baseline_names),
                dispatch_str=" ".join(dispatch_names), baseline_len=baseline_len,
                dispatch_len=dispatch_len, baseline_calls=baseline_calls,
                dispatch_calls=dispatch_calls
            ))
            baseline_pre = ''
            for name in baseline_names:
                baseline_pre += self.feature_c_preprocessor(name, tabs=1) + '\n'

            dispatch_pre = ''
            for name in dispatch_names:
                dispatch_pre += textwrap.dedent("""\
                #ifdef {pfx}CPU_TARGET_{name}
                {pre}
                #endif /*{pfx}CPU_TARGET_{name}*/
                """).format(
                    pfx=self.conf_c_prefix_, name=name, pre=self.feature_c_preprocessor(
                    name, tabs=1
                ))

            f.write(textwrap.dedent("""\
            /******* baseline features *******/
            {baseline_pre}
            /******* dispatch features *******/
            {dispatch_pre}
            """).format(
                pfx=self.conf_c_prefix_, baseline_pre=baseline_pre,
                dispatch_pre=dispatch_pre
            ))

    def report(self, full=False):
        report = []
        platform_rows = []
        baseline_rows = []
        dispatch_rows = []
        report.append(("Platform", platform_rows))
        report.append(("", ""))
        report.append(("CPU baseline", baseline_rows))
        report.append(("", ""))
        report.append(("CPU dispatch", dispatch_rows))

        ########## platform ##########
        platform_rows.append(("Architecture", (
            "unsupported" if self.cc_on_noarch else self.cc_march)
        ))
        platform_rows.append(("Compiler", (
            "unix-like"   if self.cc_is_nocc   else self.cc_name)
        ))
        ########## baseline ##########
        if self.cc_noopt:
            baseline_rows.append(("Requested", "optimization disabled"))
        else:
            baseline_rows.append(("Requested", repr(self._requested_baseline)))

        baseline_names = self.cpu_baseline_names()
        baseline_rows.append((
            "Enabled", (' '.join(baseline_names) if baseline_names else "none")
        ))
        baseline_flags = self.cpu_baseline_flags()
        baseline_rows.append((
            "Flags", (' '.join(baseline_flags) if baseline_flags else "none")
        ))
        extra_checks = []
        for name in baseline_names:
            extra_checks += self.feature_extra_checks(name)
        baseline_rows.append((
            "Extra checks", (' '.join(extra_checks) if extra_checks else "none")
        ))

        ########## dispatch ##########
        if self.cc_noopt:
            baseline_rows.append(("Requested", "optimization disabled"))
        else:
            dispatch_rows.append(("Requested", repr(self._requested_dispatch)))

        dispatch_names = self.cpu_dispatch_names()
        dispatch_rows.append((
            "Enabled", (' '.join(dispatch_names) if dispatch_names else "none")
        ))
        ########## Generated ##########
        # TODO:
        # - collect object names from 'try_dispatch()'
        #   then get size of each object and printed
        # - give more details about the features that not
        #   generated due compiler support
        # - find a better output's design.
        #
        target_sources = {}
        for source, (_, targets) in self.sources_status.items():
            for tar in targets:
                target_sources.setdefault(tar, []).append(source)

        if not full or not target_sources:
            generated = ""
            for tar in self.feature_sorted(target_sources):
                sources = target_sources[tar]
                name = tar if isinstance(tar, str) else '(%s)' % ' '.join(tar)
                generated += name + "[%d] " % len(sources)
            dispatch_rows.append(("Generated", generated[:-1] if generated else "none"))
        else:
            dispatch_rows.append(("Generated", ''))
            for tar in self.feature_sorted(target_sources):
                sources = target_sources[tar]
                pretty_name = tar if isinstance(tar, str) else '(%s)' % ' '.join(tar)
                flags = ' '.join(self.feature_flags(tar))
                implies = ' '.join(self.feature_sorted(self.feature_implies(tar)))
                detect = ' '.join(self.feature_detect(tar))
                extra_checks = []
                for name in ((tar,) if isinstance(tar, str) else tar):
                    extra_checks += self.feature_extra_checks(name)
                extra_checks = (' '.join(extra_checks) if extra_checks else "none")

                dispatch_rows.append(('', ''))
                dispatch_rows.append((pretty_name, implies))
                dispatch_rows.append(("Flags", flags))
                dispatch_rows.append(("Extra checks", extra_checks))
                dispatch_rows.append(("Detect", detect))
                for src in sources:
                    dispatch_rows.append(("", src))

        ###############################
        # TODO: add support for 'markdown' format
        text = []
        secs_len = [len(secs) for secs, _ in report]
        cols_len = [len(col) for _, rows in report for col, _ in rows]
        tab = ' ' * 2
        pad =  max(max(secs_len), max(cols_len))
        for sec, rows in report:
            if not sec:
                text.append("") # empty line
                continue
            sec += ' ' * (pad - len(sec))
            text.append(sec + tab + ': ')
            for col, val in rows:
                col += ' ' * (pad - len(col))
                text.append(tab + col + ': ' + val)

        return '\n'.join(text)

    def _wrap_target(self, output_dir, dispatch_src, target, nochange=False):
        assert(isinstance(target, (str, tuple)))
        if isinstance(target, str):
            ext_name = target_name = target
        else:
            # multi-target
            ext_name = '.'.join(target)
            target_name = '__'.join(target)

        wrap_path = os.path.join(output_dir, os.path.basename(dispatch_src))
        wrap_path = "{0}.{2}{1}".format(*os.path.splitext(wrap_path), ext_name.lower())
        if nochange and os.path.exists(wrap_path):
            return wrap_path

        self.dist_log("wrap dispatch-able target -> ", wrap_path)
        # sorting for readability
        features = self.feature_sorted(self.feature_implies_c(target))
        target_join = "#define %sCPU_TARGET_" % self.conf_c_prefix_
        target_defs = [target_join + f for f in features]
        target_defs = '\n'.join(target_defs)

        with open(wrap_path, "w") as fd:
            fd.write(textwrap.dedent("""\
            /**
             * AUTOGENERATED DON'T EDIT
             * Please make changes to the code generator \
             (distutils/ccompiler_opt.py)
             */
            #define {pfx}CPU_TARGET_MODE
            #define {pfx}CPU_TARGET_CURRENT {target_name}
            {target_defs}
            #include "{path}"
            """).format(
                pfx=self.conf_c_prefix_, target_name=target_name,
                path=os.path.abspath(dispatch_src), target_defs=target_defs
            ))
        return wrap_path

    def _generate_config(self, output_dir, dispatch_src, targets, has_baseline=False):
        config_path = os.path.basename(dispatch_src)
        config_path = os.path.splitext(config_path)[0] + '.h'
        config_path = os.path.join(output_dir, config_path)
        # check if targets didn't change to avoid recompiling
        cache_hash = self.cache_hash(targets, has_baseline)
        try:
            with open(config_path) as f:
                last_hash = f.readline().split("cache_hash:")
                if len(last_hash) == 2 and int(last_hash[1]) == cache_hash:
                    return True
        except OSError:
            pass

        os.makedirs(os.path.dirname(config_path), exist_ok=True)

        self.dist_log("generate dispatched config -> ", config_path)
        dispatch_calls = []
        for tar in targets:
            if isinstance(tar, str):
                target_name = tar
            else: # multi target
                target_name = '__'.join([t for t in tar])
            req_detect = self.feature_detect(tar)
            req_detect = '&&'.join([
                "CHK(%s)" % f for f in req_detect
            ])
            dispatch_calls.append(
                "\t%sCPU_DISPATCH_EXPAND_(CB((%s), %s, __VA_ARGS__))" % (
                self.conf_c_prefix_, req_detect, target_name
            ))
        dispatch_calls = ' \\\n'.join(dispatch_calls)

        if has_baseline:
            baseline_calls = (
                "\t%sCPU_DISPATCH_EXPAND_(CB(__VA_ARGS__))"
            ) % self.conf_c_prefix_
        else:
            baseline_calls = ''

        with open(config_path, "w") as fd:
            fd.write(textwrap.dedent("""\
            // cache_hash:{cache_hash}
            /**
             * AUTOGENERATED DON'T EDIT
             * Please make changes to the code generator (distutils/ccompiler_opt.py)
             */
            #ifndef {pfx}CPU_DISPATCH_EXPAND_
                #define {pfx}CPU_DISPATCH_EXPAND_(X) X
            #endif
            #undef {pfx}CPU_DISPATCH_BASELINE_CALL
            #undef {pfx}CPU_DISPATCH_CALL
            #define {pfx}CPU_DISPATCH_BASELINE_CALL(CB, ...) \\
            {baseline_calls}
            #define {pfx}CPU_DISPATCH_CALL(CHK, CB, ...) \\
            {dispatch_calls}
            """).format(
                pfx=self.conf_c_prefix_, baseline_calls=baseline_calls,
                dispatch_calls=dispatch_calls, cache_hash=cache_hash
            ))
        return False

def new_ccompiler_opt(compiler, dispatch_hpath, **kwargs):
    """
    Create a new instance of 'CCompilerOpt' and generate the dispatch header
    which contains the #definitions and headers of platform-specific instruction-sets for
    the enabled CPU baseline and dispatch-able features.

    Parameters
    ----------
    compiler : CCompiler instance
    dispatch_hpath : str
        path of the dispatch header

    **kwargs: passed as-is to `CCompilerOpt(...)`
    Returns
    -------
    new instance of CCompilerOpt
    """
    opt = CCompilerOpt(compiler, **kwargs)
    if not os.path.exists(dispatch_hpath) or not opt.is_cached():
        opt.generate_dispatch_header(dispatch_hpath)
    return opt