mojob.py: explicitly select CPU architecture.

mojo/tools/mopy/config.py

Index: mojo/tools/mopy/config.py
diff --git a/mojo/tools/mopy/config.py b/mojo/tools/mopy/config.py
index 448c7192c8dd9c8cf7d698cadb0a686776b1a0dd..7a3ce194847b3778969bf5cf9e63b5002046e9ec 100644
--- a/mojo/tools/mopy/config.py
+++ b/mojo/tools/mopy/config.py
@@ -8,6 +8,7 @@
 
 import json
 import os.path
+import platform
 import sys
 
 
@@ -23,6 +24,11 @@ class Config(object):
   OS_MAC = "mac"
   OS_WINDOWS = "windows"
 
+  # Valid values for target_arch (None is also valid):
+  ARCH_X86 = "x86"
+  ARCH_X64 = "x64"
+  ARCH_ARM = "arm"
+
   # Valid values for sanitizer (None is also valid):
   SANITIZER_ASAN = "asan"
 
@@ -33,13 +39,15 @@ class Config(object):
   TEST_TYPE_PERF = "perf"
   TEST_TYPE_INTEGRATION = "integration"
 
-  def __init__(self, target_os=None, is_debug=True, is_clang=None,
-               sanitizer=None, **kwargs):
+  def __init__(self, target_os=None, target_arch=None, is_debug=True,
+               is_clang=None, sanitizer=None, **kwargs):
     """Constructs a Config with key-value pairs specified via keyword arguments.
     If target_os is not specified, it will be set to the host OS."""
 
     assert target_os in (None, Config.OS_ANDROID, Config.OS_CHROMEOS,
                          Config.OS_LINUX, Config.OS_MAC, Config.OS_WINDOWS)
+    assert target_arch in (None, Config.ARCH_X86, Config.ARCH_X64,
+                           Config.ARCH_ARM)
     assert isinstance(is_debug, bool)
     assert is_clang is None or isinstance(is_clang, bool)
     assert sanitizer in (None, Config.SANITIZER_ASAN)
@@ -49,6 +57,8 @@ class Config(object):
     self.values = {}
     self.values["target_os"] = (self.GetHostOS() if target_os is None else
                                 target_os)
+    self.values["target_arch"] = (self.GetHostCPUArch() if target_arch is None
+                                  else target_arch)
     self.values["is_debug"] = is_debug
     self.values["is_clang"] = is_clang
     self.values["sanitizer"] = sanitizer
@@ -65,6 +75,19 @@ class Config(object):
       return Config.OS_WINDOWS
     raise NotImplementedError("Unsupported host OS")
 
+  @staticmethod
+  def GetHostCPUArch():
+    # Derived from //native_client/pynacl/platform.py
+    machine = platform.machine()
+    if machine in ("x86", "x86-32", "x86_32", "x8632", "i386", "i686", "ia32",
+                   "32"):
+      return Config.ARCH_X86
+    if machine in ("x86-64", "amd64", "x86_64", "x8664", "64"):
+      return Config.ARCH_X64
+    if machine.startswith("arm"):
+      return Config.ARCH_ARM
+    raise Exception("Cannot identify CPU arch: %s" % machine)
+
   # Getters for standard fields ------------------------------------------------
 
   @property
@@ -73,6 +96,11 @@ class Config(object):
     return self.values["target_os"]
 
   @property
+  def target_arch(self):
+    """CPU arch of the build/test target."""
+    return self.values["target_arch"]
+
+  @property
   def is_debug(self):
     """Is Debug build?"""
     return self.values["is_debug"]