[API] Added remove_global_func to the Python API (apache#6787)

This is useful for unregistering functions after a test.

Change-Id: Ic39499aa8f36bfe5470bc1f058ad3b96cf52b49c

include/tvm/runtime/c_runtime_api.h

@@ -366,6 +366,12 @@ TVM_DLL int TVMFuncGetGlobal(const char* name, TVMFunctionHandle* out);
  */
 TVM_DLL int TVMFuncListGlobalNames(int* out_size, const char*** out_array);
 
+/*!
+ * \brief Remove a global function.
+ * \param name The name of the function.
+ */
+TVM_DLL int TVMFuncRemoveGlobal(const char* name);
+
 // Array related apis for quick proptyping
 /*!
  * \brief Allocate a nd-array's memory,

python/tvm/_ffi/registry.py

@@ -262,6 +262,17 @@ def _list(name, func):
     return fdict
 
 
+def remove_global_func(name):
+    """Remove a global function by name
+
+    Parameters
+    ----------
+    name : str
+        The name of the global function
+    """
+    check_call(_LIB.TVMFuncRemoveGlobal(c_str(name)))
+
+
 def _get_api(f):
     flocal = f
     flocal.is_global = True

src/runtime/registry.cc

@@ -146,3 +146,9 @@ int TVMFuncListGlobalNames(int* out_size, const char*** out_array) {
   *out_size = static_cast<int>(ret->ret_vec_str.size());
   API_END();
 }
+
+int TVMFuncRemoveGlobal(const char* name) {
+  API_BEGIN();
+  tvm::runtime::Registry::Remove(name);
+  API_END();
+}