mirror of https://github.com/llvm/torch-mlir
126 lines
5.0 KiB
Python
126 lines
5.0 KiB
Python
# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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# See https://llvm.org/LICENSE.txt for license information.
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# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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import os
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import torch
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from mlir.ir import *
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from mlir.passmanager import *
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from npcomp.compiler.utils import logging
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__all__ = [
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"lower_object_graph",
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"lower_module",
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]
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# The set of passes that lowers from a TorchScript object graph representation
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# to a module semantics where symbols correspond to dotted paths into the
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# module.
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OBJECT_GRAPH_LOWERING_PASSES = (
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# When we import TorchScript IR, we import their entire "compilation unit",
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# which can contain numerous functions unrelated to the current program,
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# which breaks torch-globalization-pipeline; for example, there can be
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# random functions referencing types that haven't been imported
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# as part of the root `torch.nn.Module` we imported. Those will
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# be unreferenced private functions which symbol-dce will clean up nicely.
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"symbol-dce",
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# Globalize the program. The rest of the compiler assumes a globalized
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# program, which makes all analyses and transforms significantly easier
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# to write.
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"torch-globalize-pipeline",
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# "lower" `torch.global_slot` ops by deleting them if unused, which we
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# currently require because we don't have a lowering path for backends to
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# handle them.
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# Torch usually inserts a few unused global slots so this ends up hitting
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# every single module even if it doesn't have any explicit slots.
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# TODO: Support global slots in backends.
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"symbol-dce",
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# Currently, our shape inference is not powerful enough to deal with
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# calls, so inline everything.
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# TODO: Improve shape inference.
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"inline",
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# Incorporate user annotations and remove signature Python-isms.
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"torch-adjust-calling-conventions",
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)
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TORCH_TO_TCP_PASSES = (
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# Recognize ATen kernels.
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"func(aten-recognize-kernels)",
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# Convert the bulk of the program to ranked tensors with known dtype.
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# This is the input to the backend layer that we are aiming for.
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# First, unilaterally convert public functions to tensor.
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# The way this pass is currently written, this implies that
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# as pipeline authors, we are restricting our users to not be able to see
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# updates to "out params" on their public functions.
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# This is deemed ok for now.
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"numpy-public-functions-to-tensor",
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# Convert the bulk of non-ABI-visible arrays to tensors.
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"func(numpy-array-to-tensor)",
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# Do shape and dtype refinement.
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# We could do it sooner, but the pass currently doesn't have transfer
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# functions for array ops.
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"func(torch-refine-types)",
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# Propagate to ABI return types the shape/dtype information discovered by
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# the previous pass. Doing this is ABI-compatible for our backends.
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"numpy-refine-public-return",
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# Clean up a few stray array/tensor conversion remnants.
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"func(numpy-array-to-tensor)",
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# Lower to TCP (+ guards) which is the input to codegen backends.
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# Most of this should be subsumed by aten->linalg+guards conversions.
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# (the guard generation will be automated from the linalg Op DSL)
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"func(convert-aten-to-linalg)",
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"func(convert-aten-to-tcf)",
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"func(convert-tcf-to-std)",
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"func(convert-elementwise-to-linalg)",
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"npcomp-verify-backend-contract",
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)
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def lower_module(imported_module: Module):
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"""Compiles an imported module, with a flat list of functions.
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Args:
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imported_module: The MLIR module consisting of funcs and globals in
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the torch dialect. It is lowered in place.
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Returns:
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The imported_module, for convenience chaining methods.
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"""
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with imported_module.context as context:
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if logging.debug_enabled():
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logging.debug("Initial PyTorch IR:\n{}", imported_module)
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# Frontend.
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pipeline_str = ",".join(TORCH_TO_TCP_PASSES)
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if logging.debug_enabled():
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logging.debug("Running Torch->TCP pipeline '{}'", pipeline_str)
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pm = PassManager.parse(pipeline_str)
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pm.run(imported_module)
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if logging.debug_enabled():
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logging.debug("TCP IR:\n{}", imported_module)
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return imported_module
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def lower_object_graph(imported_module: Module):
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"""Lowers an imported module that has TorchScript object graph semantics.
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Args:
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imported_module: The MLIR module consisting of IR as imported by the
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torch_mlir.import_module. It is lowered in place.
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Returns:
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The imported_module, for convenience chaining methods.
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"""
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with imported_module.context as context:
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if logging.debug_enabled():
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logging.debug("Initial PyTorch object graph IR:\n{}", imported_module)
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# Object graph lowering.
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pipeline_str = ",".join(OBJECT_GRAPH_LOWERING_PASSES)
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if logging.debug_enabled():
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logging.debug(
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"Running Torch object graph lowering pipeline '{}'", pipeline_str)
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pm = PassManager.parse(pipeline_str)
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pm.run(imported_module)
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return lower_module(imported_module)
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