[Relay][Transform] Support Dumping IR to help debugging

include/tvm/relay/transform.h

@@ -540,6 +540,13 @@ TVM_DLL Pass CanonicalizeCast();
  */
 TVM_DLL Pass EtaExpand();
 
+/*!
+ * \brief Print the IR for a module to help debugging.
+ *
+ * \return the pass.
+ */
+TVM_DLL Pass PrintIR();
+
 }  // namespace transform
 
 /*!

python/tvm/relay/transform.py

@@ -529,6 +529,18 @@ def CanonicalizeCast():
     return _transform.CanonicalizeCast()
 
 
+def PrintIR():
+    """
+    Print the IR for a module to help debugging.
+
+    Returns
+    -------
+    ret : tvm.relay.Pass
+        The registered pass that prints the module IR.
+    """
+    return _transform.PrintIR()
+
+
 def gradient(expr, mod=None, mode='higher_order'):
     """
     Transform the input function,

src/relay/pass/print_ir.cc

@@ -0,0 +1,50 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+/*!
+ * Copyright (c) 2019 by Contributors
+ *
+ * \file src/relay/pass/print_ir.cc
+ *
+ * \brief Print the module IR to help debugging.
+ */
+#include <tvm/relay/expr.h>
+#include <tvm/relay/transform.h>
+
+namespace tvm {
+namespace relay {
+
+namespace transform {
+
+Pass PrintIR() {
+  runtime::TypedPackedFunc<Module(Module, PassContext)> pass_func =
+    [=](Module m, PassContext pc) {
+      LOG(INFO) << "Dumping the module IR: " << std::endl << AsText(m);
+      return m;
+  };
+  return CreateModulePass(pass_func, 0, "PrintIR", {});
+}
+
+TVM_REGISTER_API("relay._transform.PrintIR")
+.set_body_typed(PrintIR);
+
+}  // namespace transform
+
+}  // namespace relay
+}  // namespace tvm

tests/python/relay/test_pass_manager.py

@@ -504,6 +504,62 @@ def expected():
     assert analysis.alpha_equal(zz, zexpected)
 
 
+def test_print_ir():
+    shape = (1, 2, 3)
+    tp = relay.TensorType(shape, "float32")
+    x = relay.var("x", tp)
+    y = relay.add(x, x)
+    y = relay.multiply(y, relay.const(2, "float32"))
+    func = relay.Function([x], y)
+
+    seq = _transform.Sequential([
+        relay.transform.InferType(),
+        relay.transform.FoldConstant(),
+        relay.transform.PrintIR(),
+        relay.transform.DeadCodeElimination()
+    ])
+
+    def redirect_output(call):
+        """Redirect the C++ logging info."""
+        import sys
+        import os
+        import threading
+        stderr_fileno = sys.stderr.fileno()
+        stderr_save = os.dup(stderr_fileno)
+        stderr_pipe = os.pipe()
+        os.dup2(stderr_pipe[1], stderr_fileno)
+        os.close(stderr_pipe[1])
+        output = ''
+
+        def record():
+            nonlocal output
+            while True:
+                data = os.read(stderr_pipe[0], 1024)
+                if not data:
+                    break
+                output += data.decode("utf-8")
+
+        t = threading.Thread(target=record)
+        t.start()
+        call()
+        os.close(stderr_fileno)
+        t.join()
+        os.close(stderr_pipe[0])
+        os.dup2(stderr_save, stderr_fileno)
+        os.close(stderr_save)
+
+        return output
+
+    def run_pass():
+        mod = relay.Module({"main": func})
+        with relay.build_config(opt_level=3):
+            mod = seq(mod)
+
+    out = redirect_output(run_pass)
+    assert "Dumping the module IR" in out
+    assert "multiply" in out
+
+
 if __name__ == "__main__":
     test_function_class_pass()
     test_module_class_pass()
@@ -512,3 +568,4 @@ def expected():
     test_sequential_pass()
     test_sequential_with_scoping()
     test_pass_info()
+    test_print_ir()