Move constants and helper functions in configdefaults

tests/test_config.py

@@ -242,16 +242,16 @@ def test_no_more_dotting():
 
 def test_mode_apply():
 
-    assert configdefaults.filter_mode("DebugMode") == "DebugMode"
+    assert configdefaults._filter_mode("DebugMode") == "DebugMode"
 
     with pytest.raises(ValueError, match="Expected one of"):
-        configdefaults.filter_mode("not_a_mode")
+        configdefaults._filter_mode("not_a_mode")
 
     # test with theano.Mode instance
     import theano.compile.mode
 
     assert (
-        configdefaults.filter_mode(theano.compile.mode.FAST_COMPILE)
+        configdefaults._filter_mode(theano.compile.mode.FAST_COMPILE)
         == theano.compile.mode.FAST_COMPILE
     )
 

theano/link/c/cmodule.py

@@ -23,13 +23,13 @@ import numpy.distutils
 
 import theano
 from theano import config
-from theano.configdefaults import gcc_version_str, local_bitwidth
+from theano.configdefaults import gcc_version_str
 
 # we will abuse the lockfile mechanism when reading and writing the registry
 from theano.gof import compilelock
 from theano.gof.utils import flatten, hash_from_code
 from theano.link.c.exceptions import MissingGXX
-from theano.utils import output_subprocess_Popen, subprocess_Popen
+from theano.utils import LOCAL_BITWIDTH, output_subprocess_Popen, subprocess_Popen
 
 
 importlib = None
@@ -2308,7 +2308,7 @@ class GCC_compiler(Compiler):
         if not any(["arm" in flag for flag in cxxflags]) and not any(
             arch in platform.machine() for arch in ["arm", "aarch"]
         ):
-            n_bits = local_bitwidth()
+            n_bits = LOCAL_BITWIDTH
             cxxflags.append(f"-m{int(n_bits)}")
             _logger.debug(f"Compiling for {n_bits} bit architecture")
 
@@ -2317,7 +2317,7 @@ class GCC_compiler(Compiler):
             # '-fPIC ignored for target (all code is position independent)'
             cxxflags.append("-fPIC")
 
-        if sys.platform == "win32" and local_bitwidth() == 64:
+        if sys.platform == "win32" and LOCAL_BITWIDTH == 64:
             # Under 64-bit Windows installation, sys.platform is 'win32'.
             # We need to define MS_WIN64 for the preprocessor to be able to
             # link with libpython.

theano/utils.py

@@ -3,6 +3,7 @@
 
 import inspect
 import os
+import struct
 import subprocess
 import sys
 import traceback
@@ -21,12 +22,35 @@ __all__ = [
     "subprocess_Popen",
     "call_subprocess_Popen",
     "output_subprocess_Popen",
+    "LOCAL_BITWIDTH",
+    "PYTHON_INT_BITWIDTH",
 ]
 
 
 __excepthooks = []
 
 
+LOCAL_BITWIDTH = struct.calcsize("P") * 8
+"""
+32 for 32bit arch, 64 for 64bit arch.
+By "architecture", we mean the size of memory pointers (size_t in C),
+*not* the size of long int, as it can be different.
+
+Note that according to Python documentation, `platform.architecture()` is
+not reliable on OS X with universal binaries.
+Also, sys.maxsize does not exist in Python < 2.6.
+'P' denotes a void*, and the size is expressed in bytes.
+"""
+
+PYTHON_INT_BITWIDTH = struct.calcsize("l") * 8
+"""
+The bit width of Python int (C long int).
+
+Note that it can be different from the size of a memory pointer.
+'l' denotes a C long int, and the size is expressed in bytes.
+"""
+
+
 def __call_excepthooks(type, value, trace):
     """
     This function is meant to replace excepthook and do some