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Diffstat (limited to 'compiler/enco/core/src/Transforms/IdenticalObjectReduction.cpp')
| -rw-r--r-- | compiler/enco/core/src/Transforms/IdenticalObjectReduction.cpp | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/compiler/enco/core/src/Transforms/IdenticalObjectReduction.cpp b/compiler/enco/core/src/Transforms/IdenticalObjectReduction.cpp new file mode 100644 index 000000000..cb996d2ac --- /dev/null +++ b/compiler/enco/core/src/Transforms/IdenticalObjectReduction.cpp @@ -0,0 +1,139 @@ +/* + * Copyright (c) 2018 Samsung Electronics Co., Ltd. All Rights Reserved + * + * 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. + */ + +#include "IdenticalObjectReduction.h" +#include "IRUtils.h" + +#include <set> + +namespace enco +{ + +void reduce_identical_object(enco::Code *code) +{ + auto m = code->module(); + + std::set<coco::Copy *> detached; + + // Preceding optimizations may generate "free" instructions. + // - i.e. an instruction not linked to a block + // + // Let's iterate over only a sequence of "bounded" instructions. + for (auto ins : instr_sequence(m)) + { + assert(ins != nullptr); + assert(ins->parent() != nullptr); + + auto copy = ins->asCopy(); + + if (copy == nullptr) + { + // Skip if instruction is not a copy + continue; + } + + // TODO Support non-Feature Objects + auto ifm = copy->from()->asFeature(); + auto ofm = copy->into()->asFeature(); + + assert(ofm->bag() != nullptr); + + if (ifm->layout()->id() != ofm->layout()->id()) + { + continue; + } + + if (ifm->layout()->id() != coco::FeatureLayouts::BHWC::uid()) + { + continue; + } + + // Skip if this copy produces network output + if (ofm->bag()->output()) + { + // TODO Optimize this case + // + // Note that the code under optimization is of the following form: + // + // %ifm <- Instr(...) + // %ofm <- Copy(%ifm) + // + // Let's assume that "Copy" is the only reader of %ifm (to be precise, its bag). + // + // Then, it is possible to rewrite the above fragment as follows: + // + // %ofm <- Instr(...) + // + continue; + } + + if (ofm->bag()->reads()->size() > 0) + { + // Let us consider the following code: + // + // Bag: + // %bag_0 = Bag(...) + // %bag_1 = Bag(...) + // %bag_2 = Bag(...) + // + // Object: + // %obj_0 = FeatureObject(bag: %bag_0) + // %obj_1 = FeatureObject(bag: %bag_1) + // + // Instr: + // copy an object from %obj_0 into %obj_1 + // shuffle values from %bag_1 into %bag_2 + // eval Conv2D with %obj_1 + // + // Identical Object Reduction (IOR) tries to eliminate the first copy via + // substitution (substitute all the occurrence of %obj_1 as use with %obj_0). + // + // Here is the code transformed by IOR: + // + // Bag: + // %bag_0 = Bag(...) + // %bag_1 = Bag(...) + // %bag_2 = Bag(...) + // + // Object: + // %obj_0 = FeatureObject(bag: %bag_0) + // %obj_1 = FeatureObject(bag: %bag_1) + // + // Instr: + // shuffle values from %bag_1 into %bag_2 + // eval Conv2D with %obj_0 + // + // Note that there is no updater of %bag_1 after IOR, and thus the behavior + // of the first shuffle instruction has changed. + // + // This examples shows that it is impossible to simply substitute %obj_1 + // with %obj_0 in the presence of readers over its backing bag. + continue; + } + + subst(copy->into(), copy->from()); + + copy->detach(); + detached.insert(copy); + } + + for (auto copy : detached) + { + m->entity()->instr()->destroy(copy); + } +} + +} // namespace enco |