wehub-resource-sync
95 lines
2.9 KiB
C++
95 lines
2.9 KiB
C++
// Copyright (c) 2024 PaddlePaddle Authors. All Rights Reserved.
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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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// http://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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#pragma once
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#include "paddle/cinn/pass/pass.h"
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namespace cinn {
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namespace optim {
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class IfFoldPass : public StmtPass {
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public:
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IfFoldPass() : StmtPass("if_fold") {}
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LogicalResult Run(ir::stmt::StmtRef stmt) override;
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};
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/**
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* Simplify several consecutively nested `IfThenElse` with equal to 0 conditions
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* into one with simplified conditions.
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*
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* This pass is used when there are nested `IfThenElse` in a block, and their
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* conditions are all equal to zero, and these conditions can be mathematically
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* proven to be simplifiable.
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*
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* When applied, the continuously nested `IfThenElse` will be converted into an
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* equivalent `IfThenElse` in IR.
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*
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* Performance impact: This pass primarily addresses code size and readability.
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* By reducing the number of redundant condition checks, it may also slightly
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* improve branch prediction and reduce instruction cache pressure.
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*
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* Examples:
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* case1: All if can be simplified.
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* if ((((((256 * j) + ((1024 * i) + k)) / 56) / 56) == 0)) {
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* if ((((((256 * j) + ((1024 * i) + k)) / 56) % 56) == 0)) {
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* if (((((256 * j) + ((1024 * i) + k)) % 56) == 0)) {
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* int32 a = 1
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* }
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* }
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* }
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* can be simplified to:
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* if (((((i * 1024ll) + k) + (j * 256ll)) == 0)) {
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* int32 a = 1
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* }
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*
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* case2: All if can be simplified and the inner one has false branch.
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* if ((((((256 * j) + ((1024 * i) + k)) / 56) / 56) == 0)) {
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* if ((((((256 * j) + ((1024 * i) + k)) / 56) % 56) == 0)) {
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* if (((((256 * j) + ((1024 * i) + k)) % 56) == 0)) {
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* int32 a = 1
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* int32 b = 1
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* } else {
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* int32 c = 1
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* }
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* }
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* }
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* can be simplified to:
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* if (((((i * 1024ll) + k) + (j * 256ll)) == 0)) {
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* int32 a = 1
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* int32 b = 1
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* } else {
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* int32 c = 1
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* }
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*
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* case3: The inner one can not be simplified.
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* if ((((((256 * j) + ((1024 * i) + k)) / 56) / 56) == 0)) {
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* if ((((((256 * j) + ((1024 * i) + k)) / 56) % 56) == 0)) {
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* if (((((256 * j) + ((1024 * i) + k)) % 56) == 0)) {
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* if (l <= 0)) {
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* int32 a = 1
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* }
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* }
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* }
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* }
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* can be simplified to:
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* if (((((i * 1024ll) + k) + (j * 256ll)) == 0)) {
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* if (l <= 0)) {
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* int32 a = 1
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* }
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* }
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*/
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std::unique_ptr<StmtPass> CreateIfFoldPass();
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} // namespace optim
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} // namespace cinn
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