68 lines
2.3 KiB
C
68 lines
2.3 KiB
C
|
/* Copyright 2018 The OpenXLA Authors.
|
||
|
|
|
||
|
|
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
|
||
|
|
|
||
|
|
http://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.
|
||
|
|
==============================================================================*/
|
||
|
|
|
||
|
|
#ifndef XLA_SERVICE_SCATTER_EXPANDER_H_
|
||
|
|
#define XLA_SERVICE_SCATTER_EXPANDER_H_
|
||
|
|
|
||
|
|
#include "xla/service/op_expander_pass.h"
|
||
|
|
|
||
|
|
namespace xla {
|
||
|
|
|
||
|
|
// This pass rewrites scatter operations into (roughly) while loops of
|
||
|
|
// dynamic-update-slices.
|
||
|
|
//
|
||
|
|
// This pass can be used in two ways:
|
||
|
|
//
|
||
|
|
// - kEliminateAllScatters: For backends that don't support scatter, this pass
|
||
|
|
// can convert every scatter into a loop.
|
||
|
|
//
|
||
|
|
// - kEliminateSimpleScatters: For backends that *do* support scatter, this
|
||
|
|
// pass can strength-reduce "simple" scatters -- specifically, scatters that
|
||
|
|
// can be represented without a loop -- to dynamic-update-slices.
|
||
|
|
//
|
||
|
|
// - kEliminateIndeterminisitcScatters: For backends that *do* support
|
||
|
|
// scatter, this pass converts scatters with potentially indeterminisitc
|
||
|
|
// behavior, because of non-unique indices or non-associative combiner
|
||
|
|
// functions. There may be false positives, but no false negatives, i.e.
|
||
|
|
// some scatters are converted even when deterministic in practice.
|
||
|
|
//
|
||
|
|
// Note that even in kEliminateSimpleScatters mode, this pass may still expand a
|
||
|
|
// scatter into a loop (with a trip-count of 1). It's up to other
|
||
|
|
// simplification passes to remove the loop.
|
||
|
|
class ScatterExpander : public OpExpanderPass {
|
||
|
|
public:
|
||
|
|
enum Mode {
|
||
|
|
kEliminateAllScatters,
|
||
|
|
kEliminateSimpleScatters,
|
||
|
|
kEliminateIndeterminisitcScatters,
|
||
|
|
};
|
||
|
|
|
||
|
|
explicit ScatterExpander(Mode m) : mode_(m) {}
|
||
|
|
|
||
|
|
absl::string_view name() const override { return "scatter_expander"; }
|
||
|
|
|
||
|
|
protected:
|
||
|
|
bool InstructionMatchesPattern(HloInstruction* inst) override;
|
||
|
|
|
||
|
|
StatusOr<HloInstruction*> ExpandInstruction(HloInstruction* inst) override;
|
||
|
|
|
||
|
|
private:
|
||
|
|
Mode mode_;
|
||
|
|
};
|
||
|
|
|
||
|
|
} // namespace xla
|
||
|
|
|
||
|
|
#endif // XLA_SERVICE_SCATTER_EXPANDER_H_
|