make it easier to set flags needed to run native python

CMakeLists.txt

@@ -462,6 +462,7 @@ if (FF_USE_PYTHON)
     WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/deps/legion/bindings/python
   )
   # create flexflow_python interpreter. When building from pip, we install the FF_HOME/python/flexflow_python script instead.
+  # create set_python_envs.sh script to set up the environment variables to run flexflow_python
   if (NOT FF_BUILD_FROM_PYPI)
     add_custom_command(TARGET flexflow
       PRE_BUILD	

INSTALL.md

@@ -85,10 +85,11 @@ export FF_HOME=/path/to/FlexFlow
 ### Run FlexFlow Python examples
 The Python examples are in the [examples/python](https://github.com/flexflow/FlexFlow/tree/master/examples/python). The native, Keras integration and PyTorch integration examples are listed in `native`, `keras` and `pytorch` respectively.
 
-To run the Python examples, you have two options: you can use the `flexflow_python` interpreter, available in the `build` folder, or you can use the native Python interpreter. If you choose to use the native Python interpreter, you should either install FlexFlow, or, if you prefer to build without installing, export the following flags:
+To run the Python examples, you have two options: you can use the `flexflow_python` interpreter, available in the `build` folder, or you can use the native Python interpreter. If you choose to use the native Python interpreter, you should either install FlexFlow, or, if you prefer to build without installing, export the required environment flags by running the following command (edit the path if your build folder is not named `build`):
 
-* `export PYTHONPATH="${FF_HOME}/python:${FF_HOME}/build/deps/legion/bindings/python:${PYTHONPATH}"`
-* `export LD_LIBRARY_PATH="${FF_HOME}/build:${FF_HOME}/build/deps/legion/lib:${LD_LIBRARY_PATH}"`
+```
+source ./build/set_python_envs.sh
+```
 
 **We recommend that you run the** `mnist_mlp` **test under** `native` **using the following cmd to check if FlexFlow has been installed correctly:**
 

python/flexflow_python_build.py

@@ -29,14 +29,15 @@
     sys.exit(1)
 build_dir = os.path.abspath(build_dir)
 script_dir = os.path.abspath(os.path.dirname(__file__))
-script_path = os.path.join(build_dir, "flexflow_python")
 if not os.path.isdir(build_dir):
     print(f"Folder {build_dir} does not exist")
     sys.exit(1)
 if not os.path.isdir(script_dir):
     print(f"Folder {script_dir} does not exist")
     sys.exit(1)
-script_path = os.path.abspath(script_path)
+# Build flexflow_python script
+flexflow_python_path = os.path.join(build_dir, "flexflow_python")
+flexflow_python_path = os.path.abspath(flexflow_python_path)
 lines = [
     '#! /usr/bin/env bash',
     f'BUILD_FOLDER="{build_dir}"',
@@ -52,10 +53,26 @@
     '\tlegion_python "$@"',
     'fi'
 ]
-
-with open(script_path, "w+") as script_file:
+with open(flexflow_python_path, "w+") as flexflow_python_file:
     for line in lines:
-        script_file.write(line + "\n")
+        flexflow_python_file.write(line + "\n")
+cur_stat = os.stat(flexflow_python_path)
+os.chmod(flexflow_python_path, cur_stat.st_mode | stat.S_IEXEC)
 
-cur_stat = os.stat(script_path)
-os.chmod(script_path, cur_stat.st_mode | stat.S_IEXEC)
+# Build set_python_envs.sh
+python_envs_path = os.path.join(build_dir, "set_python_envs.sh")
+python_envs_path = os.path.abspath(python_envs_path)
+lines = [
+    '#! /usr/bin/env bash',
+    f'BUILD_FOLDER="{build_dir}"',
+    f'PYTHON_FOLDER="{script_dir}"',
+    'PYLIB_PATH="$("$PYTHON_FOLDER"/flexflow/findpylib.py)"',
+    'PYLIB_DIR="$(dirname "$PYLIB_PATH")"',
+    'export LD_LIBRARY_PATH="$BUILD_FOLDER:$BUILD_FOLDER/deps/legion/lib:$PYLIB_DIR:$LD_LIBRARY_PATH"',
+    'export PYTHONPATH="$PYTHON_FOLDER:$BUILD_FOLDER/deps/legion/bindings/python:$PYTHONPATH"',
+]
+with open(python_envs_path, "w+") as python_envs_file:
+    for line in lines:
+        python_envs_file.write(line + "\n")
+cur_stat = os.stat(python_envs_path)
+os.chmod(python_envs_path, cur_stat.st_mode | stat.S_IEXEC)