add option to override march=native

README.md

@@ -43,12 +43,27 @@ Or if that fails:
 pip install --no-use-pep517 hpfrec
 ```
 
+** *
 **Note for macOS users:** on macOS, the Python version of this package might compile **without** multi-threading capabilities. In order to enable multi-threading support, first install OpenMP:
 ```
 brew install libomp
 ```
 And then reinstall this package: `pip install --force-reinstall hpfrec`.
 
+** *
+**IMPORTANT:** the setup script will try to add compilation flag `-march=native`. This instructs the compiler to tune the package for the CPU in which it is being installed, but the result might not be usable in other computers. If building a binary wheel of this package or putting it into a docker image which will be used in different machines, this can be overriden by manually supplying compilation `CFLAGS` as an environment variable with something related to architecture. For maximum compatibility (but slowest speed), assuming `x86-64` computers, it's possible to do something like this:
+
+```
+export CFLAGS="-msse2"
+pip install ctpfrec
+```
+
+or for creating wheels:
+```
+export CFLAGS="-msse2"
+python setup.py bwheel
+```
+** *
 
 As it contains Cython code, it requires a C compiler. In Windows, this usually means it requires a Visual Studio Build Tools installation (with MSVC140 component for `conda`) (or MinGW + GCC), and if using Anaconda, might also require configuring it to use said Visual Studio instead of MinGW, otherwise the installation from `pip` might fail. For more details see this guide:
 [Cython Extensions On Windows](https://github.com/cython/cython/wiki/CythonExtensionsOnWindows)

setup.py

@@ -21,7 +21,8 @@ def build_extensions(self):
 			for e in self.extensions:
 				e.extra_compile_args += ['/openmp', '/O2', '/fp:fast']
 		else:
-			self.add_march_native()
+			if not self.check_cflags_contain_arch():
+				self.add_march_native()
 			self.add_openmp_linkage()
 			self.add_no_math_errno()
 			self.add_no_trapping_math()
@@ -34,6 +35,14 @@ def build_extensions(self):
 
 		build_ext.build_extensions(self)
 
+	def check_cflags_contain_arch(self):
+		if "CFLAGS" in os.environ:
+			arch_list = ["-march", "-mcpu", "-mtune", "-msse", "-msse2", "-msse3", "-mssse3", "-msse4", "-msse4a", "-msse4.1", "-msse4.2", "-mavx", "-mavx2"]
+			for flag in arch_list:
+				if flag in os.environ["CFLAGS"]:
+					return True
+		return False
+
 	def add_march_native(self):
 		arg_march_native = "-march=native"
 		arg_mcpu_native = "-mcpu=native"
@@ -123,7 +132,7 @@ def test_supports_compile_arg(self, comm):
 	 'scipy',
 	 'cython'
 ],
-	version = '0.2.5-3',
+	version = '0.2.5-4',
 	description = 'Hierarchical Poisson matrix factorization for recommender systems',
 	author = 'David Cortes',
 	author_email = 'david.cortes.rivera@gmail.com',