250 lines
8.5 KiB
Python
250 lines
8.5 KiB
Python
# Copyright 2019 The JAX Authors.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# https://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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r"""Tool to convert a JAX function to serialized representations.
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This script is meant to be used as part of a genrule that converts a JAX program
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into an IR that can be consumed by another system (e.g. a compiler).
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Convert to HLO
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==============
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For example, you can generate an HLO proto for the XLA compiler. The HLO proto
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represents an XLA program, and can be run from e.g. a C++ program, without
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involving any Python.
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This lets you use JAX as a convenient frontend for writing "XLA programs". From
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another perspective, this script lets you make JAX into an ahead-of-time JAX ->
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XLA compiler, although when you run the XLA program, it will still be compiled
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just-in-time.
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See tensorflow/compiler/xla/service/hlo_runner.h.
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Usage:
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$ cat prog.py
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import jax.numpy as jnp
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def fn(x, y, z):
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return jnp.dot(x, y) / z
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$ python jax_to_ir.py \
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--fn prog.fn \
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--input_shapes '[("y", "f32[128,32]"), ("x", "f32[8,128]")]' \
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--constants '{"z": 3.14159}' \
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--ir_format HLO \
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--ir_human_dest /tmp/fn_hlo.txt \
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--ir_dest /tmp/fn_hlo.pb
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Alternatively, you can use this script via a genrule. This way bazel will
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generate the hlo text/proto as part of compilation, and then e.g. a C++ program
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can depend on this. See jax_to_hlo macro in build_defs.bzl.
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The order of elements in input_shapes determines the order of parameters in the
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resulting HLO program.
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Values of `constants` which are lists are converted to Numpy arrays using
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jnp.asarray. In addition, you can specify constants using the flag
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--evaled_constants; values there that are strings are first evaluated using
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ast.literal_eval. --evaled_constants is primarily useful for genrules; Skylark
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doesn't support floating-point types, so genrules need to deal in strings.
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Note that XLA's backwards-compatibility guarantees for saved HLO are currently
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(2019-06-13) best-effort. It will mostly work, but it will occasionally break,
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and the XLA team won't (and in fact will be unable to) help. One way to be sure
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it won't break is to use the same version of XLA to build the HLO as you use to
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run it. The genrule above makes this easy.
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"""
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from ast import literal_eval
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import importlib
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import functools
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import re
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from absl import app
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from absl import flags
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import jax
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import jax.numpy as jnp
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try:
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from jax.experimental import jax2tf
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except ImportError:
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jax2tf = None # type: ignore[assignment]
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try:
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import tensorflow as tf
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except ImportError:
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tf = None # type: ignore
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FLAGS = flags.FLAGS
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def jax_to_ir(fn, input_shapes, *, constants=None, format):
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"""Converts a JAX function to a serialized ir and a debug txt dump.
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Args:
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fn: Function to convert.
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input_shapes: List of tuples (arg name, jax.core.ShapedArray),
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indicating the shapes of the arguments to fn. The order of parameters in
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the resulting XLA program will match the order in this list.
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constants: Dict mapping function argument name to a Python value. Specified
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arguments these values as compile-time constants.
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format: Which IR format to use. Supported values are 'HLO' and 'TF'.
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Returns:
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A tuple of (compiler_suitable_ir, human_readable_ir).
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"""
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if not constants:
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constants = {}
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overlapping_args = {arg_name for arg_name, _ in input_shapes} & set(
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constants.keys())
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if overlapping_args:
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raise ValueError(
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'Arguments appear in both `input_shapes` and `constants`: %s' %
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', '.join(sorted(overlapping_args)))
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# TODO(tomhennigan): Ideally we could avoid creating actual values here.
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args = [jnp.zeros(s.shape, s.dtype) for _, s in input_shapes]
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# Curry `constants` into the function.
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fn_curried = functools.partial(fn, **constants)
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# Wrapper that takes in args in the order of `input_shapes` and converts them
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# to kwargs for calling `fn`.
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def ordered_wrapper(*args):
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arg_names = [arg_name for arg_name, _ in input_shapes]
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return fn_curried(**dict(zip(arg_names, args)))
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if format == 'HLO':
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comp = jax.xla_computation(ordered_wrapper)(*args)
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serialized_proto = comp.as_serialized_hlo_module_proto()
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debug_txt = comp.as_hlo_text()
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else:
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assert format == 'TF'
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if tf is None:
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raise ValueError(
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'Conversion to TF graph requires TensorFlow to be installed.')
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f = jax2tf.convert(ordered_wrapper, native_serialization=False)
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f = tf_wrap_with_input_names(f, input_shapes)
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f = tf.function(f, autograph=False)
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g = f.get_concrete_function(*args).graph.as_graph_def()
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serialized_proto = g.SerializeToString()
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debug_txt = str(g)
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return serialized_proto, debug_txt
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def tf_wrap_with_input_names(f, input_shapes):
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def wrapper(*args):
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args = tuple(
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tf.identity(a, name=name) for a, (name, _) in zip(args, input_shapes))
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# NOTE: Output names already set via `jax2tf.convert(..)`.
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return f(*args)
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return wrapper
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jax_to_hlo = functools.partial(jax_to_ir, format='HLO')
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jax_to_tf = functools.partial(jax_to_ir, format='TF')
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def main(argv):
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if len(argv) != 1:
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raise app.UsageError('No positional arguments are accepted.')
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if not FLAGS.ir_dest and not FLAGS.ir_human_dest:
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raise app.Error('At least one of --ir_dest and '
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'--ir_human_dest is required.')
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module_name, fn_name = FLAGS.fn.rsplit('.', 1)
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module = importlib.import_module(module_name)
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fn = getattr(module, fn_name)
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input_shapes = [(name, parse_shape_str(shape_str))
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for name, shape_str in literal_eval(FLAGS.input_shapes)]
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# Parse --constants and --evaled_constants.
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constants = {}
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for k, v in literal_eval(FLAGS.constants).items():
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if isinstance(v, list):
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v = jnp.asarray(v)
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constants[k] = v
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for k, v in literal_eval(FLAGS.evaled_constants).items():
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if isinstance(v, str):
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v = literal_eval(v)
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if isinstance(v, list):
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v = jnp.asarray(v)
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if k in constants:
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raise ValueError(
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'Argument appears in both --constants and --evaled_constants: %s' % k)
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constants[k] = v
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ir, debug_ir = jax_to_ir(fn, input_shapes, constants=constants,
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format=FLAGS.ir_format)
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if FLAGS.ir_dest:
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with open(FLAGS.ir_dest, 'wb') as f:
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f.write(ir)
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if FLAGS.ir_human_dest:
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with open(FLAGS.ir_human_dest, 'w') as f:
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f.write(debug_ir)
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def parse_shape_str(s):
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match = _SHAPE_RE.match(s)
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if not match:
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raise ValueError(f'Invalid shape {s}. Valid example: "f32[1,2,3]".'
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f'Note that dtype must be one of {list(_DT)}')
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dtype = _DT[match.group(1)]
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if match.group(2):
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shape = tuple(int(d.strip()) for d in match.group(2).split(","))
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else:
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shape = ()
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return jax.core.ShapedArray(shape, dtype)
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_DT = {'pred': jnp.bool_,
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'u8': jnp.uint8, 'u16': jnp.uint16, 'u32': jnp.uint32, 'u64': jnp.uint64,
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's8': jnp.int8, 's16': jnp.int16, 's32': jnp.int32, 's64': jnp.int64,
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'bf16': jnp.bfloat16,
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'f16': jnp.float16, 'f32': jnp.float32, 'f64': jnp.float64,
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'c64': jnp.complex64, 'c128': jnp.complex128}
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_SHAPE_RE = re.compile(f"^({'|'.join(_DT)})\\[\\s*(\\d*[\\s*,\\d+]*)\\s*\\]$")
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def set_up_flags():
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flags.DEFINE_string(
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'fn', None,
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"Fully-qualified name of function that we're going to convert")
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flags.DEFINE_string('input_shapes', None,
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'Python dict indicating XLA shapes of params')
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flags.DEFINE_string('constants', '{}',
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'Python dict giving constant values for some params')
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flags.DEFINE_string('evaled_constants', '{}',
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'Python dict giving constant values for some params. '
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'Values in this dict that are of type str are evaluated '
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'using ast.literal_eval.')
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flags.DEFINE_enum('ir_format', 'HLO', ('HLO', 'TF'), 'Output format.')
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flags.DEFINE_string('ir_dest', None, 'File to write IR to')
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flags.DEFINE_string('ir_human_dest', None,
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'File to write human readable debug output')
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flags.mark_flag_as_required('fn')
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flags.mark_flag_as_required('input_shapes')
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if __name__ == '__main__':
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set_up_flags()
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app.run(main)
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