buildman: Allow architecture to alias to multiple toolchains

Some archs have need than one alias, so support a list of alises in the
..buildman file.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/buildman/README

@@ -701,8 +701,9 @@ a set of (tag, value) pairs.
 
     This converts toolchain architecture names to U-Boot names. For example,
     if an x86 toolchains is called i386-linux-gcc it will not normally be
-    used for architecture 'x86'. Adding 'x86: i386' to this section will
-    tell buildman that the i386 toolchain can be used for x86.
+    used for architecture 'x86'. Adding 'x86: i386 x86_64' to this section
+    will tell buildman that the i386 and x86_64 toolchains can be used for
+    the x86 architecture.
 
 '[make-flags]' section
 

tools/buildman/test.py

@@ -394,5 +394,20 @@ class TestBuild(unittest.TestCase):
         build.commit_count = 0
         self.CheckDirs(build, '')
 
+    def testToolchainAliases(self):
+        self.assertTrue(self.toolchains.Select('arm') != None)
+        with self.assertRaises(ValueError):
+            self.toolchains.Select('no-arch')
+        with self.assertRaises(ValueError):
+            self.toolchains.Select('x86')
+
+        self.toolchains = toolchain.Toolchains()
+        self.toolchains.Add('x86_64-linux-gcc', test=False)
+        self.assertTrue(self.toolchains.Select('x86') != None)
+
+        self.toolchains = toolchain.Toolchains()
+        self.toolchains.Add('i386-linux-gcc', test=False)
+        self.assertTrue(self.toolchains.Select('x86') != None)
+
 if __name__ == "__main__":
     unittest.main()

tools/buildman/toolchain.py

@@ -185,9 +185,11 @@ class Toolchains:
         returns:
             toolchain object, or None if none found
         """
-        for name, value in bsettings.GetItems('toolchain-alias'):
-            if arch == name:
-                arch = value
+        for tag, value in bsettings.GetItems('toolchain-alias'):
+            if arch == tag:
+                for alias in value.split():
+                    if alias in self.toolchains:
+                        return self.toolchains[alias]
 
         if not arch in self.toolchains:
             raise ValueError, ("No tool chain found for arch '%s'" % arch)