Update Colab setup steps and documentation

* Add colab/README.md with "Open in Colab" links for each notebook
* Add notes on installing tf-nightly to getting started docs
* Document using Bazelisk to manage Bazel versions supported by TensorFlow

Relates to #15

Closes #162

COPYBARA_INTEGRATE_REVIEW=#162 from google:scotttodd-colab 95d9917
PiperOrigin-RevId: 282673738

.bazelversion

@@ -0,0 +1 @@
+1.1.0

bindings/python/pyiree/tf_interop/BUILD

@@ -55,6 +55,11 @@ cc_library(
     ],
 )
 
+# Runtime deps needed to compile the tensorflow compiler.
+SAVED_MODEL_TF_RUNTIME_DEPS = [
+    "@org_tensorflow//tensorflow/core:ops",
+]
+
 TF_XLA_PASS_DEPS = [
     "@org_tensorflow//tensorflow/compiler/mlir/xla:xla_legalize_tf",
 ]
@@ -77,7 +82,7 @@ cc_library(
         "@org_tensorflow//tensorflow/compiler/mlir/tensorflow",
         "@org_tensorflow//tensorflow/compiler/mlir/tensorflow:convert_graphdef",
         "//bindings/python/pyiree:base",
-    ] + TF_XLA_PASS_DEPS,
+    ] + SAVED_MODEL_TF_RUNTIME_DEPS + TF_XLA_PASS_DEPS,
 )
 
 cc_library(

build_tools/scripts/start_colab_kernel.py

@@ -30,30 +30,43 @@
 # Setup colab (https://research.google.com/colaboratory/local-runtimes.html)
 #   python3 -m pip install jupyter_http_over_ws
 #   jupyter serverextension enable --py jupyter_http_over_ws
+# If you plan on using TensorFlow, enable the TensorFlow parts of IREE's
+# compiler by adding a define to your user.bazelrc file:
+#   build --define=iree_tensorflow=true
 
 import os
 import subprocess
+import shutil
 import sys
 
 repo_root = None
 bazel_env = dict(os.environ)
 bazel_bin = None
+bazel_exe = None
 
 
 def setup_environment():
   """Sets up some environment globals."""
   global bazel_bin
   global repo_root
+  global bazel_exe
 
   # Determine the repository root (two dir-levels up).
   repo_root = os.path.dirname(
       os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
   print("Repository root: %s" % (repo_root,))
 
+  # Use 'bazelisk' instead of 'bazel' if it exists on the path.
+  # Bazelisk is an optional utility that pick versions of Bazel to use and
+  # passes through all command-line arguments to the real Bazel binary:
+  # https://github.com/bazelbuild/bazelisk
+  bazel_exe = "bazelisk" if shutil.which("bazelisk") else "bazel"
+  print("Using bazel executable: %s" % (bazel_exe))
+
   # Detect python and query bazel for its output.
   print("Setting Bazel PYTHON_BIN=%s" % (sys.executable,))
   bazel_env["PYTHON_BIN"] = sys.executable
-  bazel_bin = subprocess.check_output(["bazel", "info", "bazel-bin"],
+  bazel_bin = subprocess.check_output([bazel_exe, "info", "bazel-bin"],
                                       cwd=repo_root,
                                       env=bazel_env).decode("utf-8")
   bazel_bin = bazel_bin.splitlines()[0]
@@ -69,7 +82,7 @@ def build():
   """Builds the python bundle."""
   print("Building python bindings...")
   subprocess.check_call(
-      ["bazel", "build", "//bindings/python/pyiree:everything_for_colab"],
+      [bazel_exe, "build", "//bindings/python/pyiree:everything_for_colab"],
       cwd=repo_root,
       env=bazel_env)
 

colab/README.md

@@ -0,0 +1,49 @@
+<!--
+  Copyright 2019 Google LLC
+
+  Licensed 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
+
+       https://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.
+-->
+
+# Google Colaboratory (Colab) Notebooks
+
+To run these notebooks with a local runtime, refer to the
+[Using Colab docs](../docs/using_colab.md).
+
+## Notebooks
+
+### [low_level_invoke_function\.ipynb](low_level_invoke_function.ipynb)
+
+Shows off some concepts of the low level IREE python bindings
+
+[![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/google/iree/blob/master/colab/low_level_invoke_function.ipynb)
+
+### [simple_tensorflow_module_import\.ipynb](simple_tensorflow_module_import.ipynb)
+
+Defines a simple TF module, saves it and loads it in IREE
+
+[![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/google/iree/blob/master/colab/simple_tensorflow_module_import.ipynb)
+
+## Working with GitHub
+
+Refer to
+[Colab's GitHub demo](https://colab.research.google.com/github/googlecolab/colabtools/blob/master/notebooks/colab-github-demo.ipynb)
+for general information about using Colab with GitHub.
+
+To make changes to a notebook in this repository, one possible workflow is:
+
+*   Open or create the notebook in Colab
+*   Connect to your local runtime
+*   Make your changes, run the notebook, etc.
+*   Download the modified notebook using `File > Download .ipynb`
+*   Move the downloaded notebook file into a clone of this repository and submit
+    a pull request

docs/getting_started_on_linux.md

@@ -32,6 +32,12 @@ Follow the
 [install instructions](https://docs.bazel.build/versions/master/install-ubuntu.html)
 and verify with: `bazel --version`.
 
+If you are planning on using TensorFlow/Colab, make sure that the Bazel version
+you install is
+[supported by TensorFlow](https://www.tensorflow.org/install/source#install_bazel).
+A .bazelversion file is also provided if you want to use
+[Bazelisk](https://github.com/bazelbuild/bazelisk) to manage Bazel versions.
+
 ### Install clang
 
 ```
@@ -62,6 +68,12 @@ Install packages:
 sudo pip3 install numpy
 ```
 
+If using Colab, you may also want to install TensorFlow:
+
+```shell
+sudo pip3 install tf-nightly
+```
+
 ### Install the Vulkan SDK
 
 Some parts of the project link against the Vulkan SDK and require it be

docs/getting_started_on_windows.md

@@ -86,6 +86,12 @@ scoop install vscode
 
 TODO: Upgrade to head python.
 
+If you are planning on using TensorFlow/Colab, make sure that the Bazel version
+you install is
+[supported by TensorFlow](https://www.tensorflow.org/install/source#install_bazel).
+A .bazelversion file is also provided if you want to use
+[Bazelisk](https://github.com/bazelbuild/bazelisk) to manage Bazel versions.
+
 ## Setup MSYS2
 
 Then run msys2 for the first time for subsequent setup by doing one of:
@@ -280,3 +286,9 @@ python ~/Downloads/get-pip.py
 ```shell
 pip install numpy
 ```
+
+If using Colab, you may also want to install TensorFlow:
+
+```shell
+pip install tf-nightly
+```