build(codegen): suppress noise in console output (#2742)

build(codegen): suppress noise in console output

Redirect output from the code_generator binary so that when it's
used within the build system, it doesn't print unexpected,
distracting noise to the console. Generally, compiler or
generator commands don't print output unless there's an error.

This reverts "build(codegen): suppress noise in console output
(#2708)", commit d249577, which attempted to fix the same
problem by adding a --quiet flag. A subsequent upgrade to the
Tensorflow Python package caused new noise that wasn't possible
to suppress with the flag.

BUG=description

Author: rkuester

codegen/build_def.bzl

@@ -18,10 +18,24 @@ def tflm_inference_library(
     native.genrule(
         name = generated_target,
         srcs = [tflite_model],
-        outs = [name + ".h", name + ".cc"],
+        outs = [
+            name + ".h",
+            name + ".cc",
+            name + ".log",
+        ],
         tools = ["//codegen:code_generator"],
-        cmd = "$(location //codegen:code_generator) --quiet " +
-              "--model=$< --output_dir=$(RULEDIR) --output_name=%s" % name,
+        cmd = """
+            # code_generator (partially because it uses Tensorflow) outputs
+            # much noise to the console. Intead, write output to a logfile to
+            # prevent noise in the error-free bazel output.
+            NAME=%s
+            LOGFILE=$(RULEDIR)/$$NAME.log
+            $(location //codegen:code_generator) \
+                    --model=$< \
+                    --output_dir=$(RULEDIR) \
+                    --output_name=$$NAME \
+                    >$$LOGFILE 2>&1
+        """ % name,
         visibility = ["//visibility:private"],
     )
 

codegen/code_generator.py

@@ -15,14 +15,14 @@
 """ Generates C/C++ source code capable of performing inference for a model. """
 
 import os
-import pathlib
 
 from absl import app
 from absl import flags
 from collections.abc import Sequence
 
 from tflite_micro.codegen import inference_generator
 from tflite_micro.codegen import graph
+from tflite_micro.tensorflow.lite.tools import flatbuffer_utils
 
 # Usage information:
 # Default:
@@ -48,33 +48,15 @@
           "'model' basename."),
     required=False)
 
-_QUIET = flags.DEFINE_bool(
-    name="quiet",
-    default=False,
-    help="Suppress informational output (e.g., for use in for build system)",
-    required=False)
-
 
 def main(argv: Sequence[str]) -> None:
-  if _QUIET.value:
-    restore = os.environ.get("TF_CPP_MIN_LOG_LEVEL", "0")
-    os.environ["TF_CPP_MIN_LOG_LEVEL"] = "3"
-    from tflite_micro.tensorflow.lite.tools import flatbuffer_utils
-    os.environ["TF_CPP_MIN_LOG_LEVEL"] = restore
-  else:
-    from tflite_micro.tensorflow.lite.tools import flatbuffer_utils
-
   output_dir = _OUTPUT_DIR.value or os.path.dirname(_MODEL_PATH.value)
   output_name = _OUTPUT_NAME.value or os.path.splitext(
       os.path.basename(_MODEL_PATH.value))[0]
 
   model = flatbuffer_utils.read_model(_MODEL_PATH.value)
 
-  if not _QUIET.value:
-    print("Generating inference code for model: {}".format(_MODEL_PATH.value))
-    output_path = pathlib.Path(output_dir) / output_name
-    print(f"Generating {output_path}.h")
-    print(f"Generating {output_path}.cc")
+  print("Generating inference code for model: {}".format(_MODEL_PATH.value))
 
   inference_generator.generate(output_dir, output_name,
                                graph.OpCodeTable([model]), graph.Graph(model))

codegen/inference_generator.py

@@ -35,6 +35,7 @@ class ModelData(TypedDict):
 
 def _render(output_file: pathlib.Path, template_file: pathlib.Path,
             model_data: ModelData) -> None:
+  print("Generating {}".format(output_file))
   t = template.Template(filename=str(template_file))
   with output_file.open('w+') as file:
     file.write(t.render(**model_data))