[AutoScheduler] Add custom build function

python/tvm/auto_scheduler/measure.py

@@ -64,6 +64,18 @@
 MAX_FLOAT = 1e10
 
 
+class BuildFunc:
+    """store build_func name and callable to class variable.
+    name: str = "default"
+        The name of registered build function.
+    build_func: callable = tar.tar
+        The callable of registered build function.
+    """
+
+    name = "default"
+    build_func = tar.tar
+
+
 @tvm._ffi.register_object("auto_scheduler.MeasureCallback")
 class MeasureCallback(Object):
     """ The base class of measurement callback functions. """
@@ -303,12 +315,28 @@ class LocalBuilder(ProgramBuilder):
         This is used in a wrapper of the multiprocessing.Process.join().
     n_parallel : int = multiprocessing.cpu_count()
         Number of threads used to build in parallel.
-    build_func : str = 'default'
-        The name of registered build function.
+    build_func: callable or str = "default"
+        If is 'default', use default build function
+        If is 'ndk', use function for android ndk
+        If is callable, use it as custom build function, expect lib_format field.
     """
 
     def __init__(self, timeout=15, n_parallel=multiprocessing.cpu_count(), build_func="default"):
-        self.__init_handle_by_constructor__(_ffi_api.LocalBuilder, timeout, n_parallel, build_func)
+        if build_func == "default":
+            BuildFunc.name = "default"
+            BuildFunc.build_func = tar.tar
+        elif build_func == "ndk":
+            BuildFunc.name = "ndk"
+            BuildFunc.build_func = ndk.create_shared
+        elif not isinstance(build_func, str):
+            BuildFunc.name = "custom"
+            BuildFunc.build_func = build_func
+        else:
+            raise ValueError("Invalid build_func" + build_func)
+
+        self.__init_handle_by_constructor__(
+            _ffi_api.LocalBuilder, timeout, n_parallel, BuildFunc.name
+        )
 
 
 @tvm._ffi.register_object("auto_scheduler.LocalRunner")
@@ -624,12 +652,10 @@ def local_build_worker(args):
         The build result of this Builder thread.
     """
     inp, build_func, timeout, verbose = args
-    if build_func == "default":
-        build_func = tar.tar
-    elif build_func == "ndk":
-        build_func = ndk.create_shared
-    else:
-        raise ValueError("Invalid build_func" + build_func)
+    assert build_func == BuildFunc.name, (
+        "BuildFunc.name: " + BuildFunc.name + ", but args is: " + build_func
+    )
+    build_func = BuildFunc.build_func
 
     res = call_func_with_timeout(timeout, _timed_func, args=(inp, build_func, verbose))
     if isinstance(res, TimeoutError):