ENH: [3/7] enable multi-platform SIMD compiler optimizations

  - Put `CCompilerOpt` in action through add two command line
    arguments that passed directly to `CCompilerOpt`'s
    parameters which explained as follows:

    * `--cpu-baseline` minimal set of required optimizations,
      default is 'min' which provides the minimum CPU features
      that can safely run on a wide range of users platforms.

    * `--cpu-dispatch` dispatched set of additional optimizations,
      default is 'max-xop-fma4' which enables all CPU features,
      except for AMD legacy features.

    the new arguments can be reached from `build`, `build_clib`,
    `build_ext`, if `build_clib` or `build_ext` are not specified
    by the user the arguments of `build` will be used, which also
    hold the default values.

  - Activate the new compiler dispatcher that comes with `CCompilerOpt`,
    through adding a hock inside `build_clib` and `build_ext`
    that works as a filter taking any C source files ends with
    `.dispatch.c` and pass it directly to `CCompilerOpt` and
    then take returned objects and linked to the final C lib.

  - Add a third command-line argument `--disable-optimization` which
    explicitly disable the whole new infrastructure, also
    It adds a new compiler definition called `NPY_DISABLE_OPTIMIZATION`.

    when `--disable-optimization` is enabled the dispatch-able sources
    that end with `.dispatch.c` will be treated as a normal
    C sources, also due to this disabling any C headers that
    generated by `CCompilerOpt` must guard it with `NPY_DISABLE_OPTIMIZATION`,
    otherwise, it will definitely break the build.

  - New auto-generated C header located at `core/include/numpy/_cpu_dispatch.h`,
    the new header contains all definitions and headers of CPU features that
    enabled according to specified configuration in `--cpu-baseline`
    and `--cpu-dispatch`.

1 files changed, 9 insertions, 0 deletions

diff --git a/numpy/distutils/command/build.py b/numpy/distutils/command/build.py
index a156a7c6e..60ba4c917 100644
--- a/numpy/distutils/command/build.py
+++ b/numpy/distutils/command/build.py
@@ -16,6 +16,12 @@ class build(old_build):
          "specify the Fortran compiler type"),
         ('warn-error', None,
          "turn all warnings into errors (-Werror)"),
+        ('cpu-baseline=', None,
+         "specify a list of enabled baseline CPU optimizations"),
+        ('cpu-dispatch=', None,
+         "specify a list of dispatched CPU optimizations"),
+        ('disable-optimization', None,
+         "disable CPU optimized code(dispatch,simd,fast...)"),
         ]
 
     help_options = old_build.help_options + [
@@ -27,6 +33,9 @@ class build(old_build):
         old_build.initialize_options(self)
         self.fcompiler = None
         self.warn_error = False
+        self.cpu_baseline = "min"
+        self.cpu_dispatch = "max -xop -fma4" # drop AMD legacy features by default
+        self.disable_optimization = False
 
     def finalize_options(self):
         build_scripts = self.build_scripts