junrushao1994 commented on a change in pull request #9360: URL: https://github.com/apache/tvm/pull/9360#discussion_r748664114
########## File path: src/tir/transforms/lower_cross_thread_reduction.cc ########## @@ -0,0 +1,590 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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. + */ + +/*! + * \file lower_cross_thread_reduction.cc + */ +#include <tvm/arith/analyzer.h> +#include <tvm/tir/analysis.h> +#include <tvm/tir/stmt_functor.h> +#include <tvm/tir/transform.h> + +#include "../schedule/analysis.h" +#include "ir_utils.h" + +namespace tvm { +namespace tir { + +/*! + * \brief Check the dominant property of a block: + * the block is the only writer of its output, dominating the reader of its output buffers + * \param scope_block The scope block of the block to be checked + * \param block The block whose dominant property is to be checked + * \return A boolean indicating if the block is a dominant block + */ +bool IsDominantBlock(const Block& scope_block, const Block& block) { + // Step 1. Count the number of writers for each buffer written by the scope block. + std::unordered_map<const BufferNode*, int> buffer_writer_cnt; + PreOrderVisit(scope_block->body, [&buffer_writer_cnt](const ObjectRef& obj) { + if (const auto* block = obj.as<BlockNode>()) { + for (const BufferRegion& buffer_region : block->writes) { + ++buffer_writer_cnt[buffer_region->buffer.get()]; + } + return false; + } + return true; + }); + // Step 2. Check whether `block` is the only writer of its outputs. + for (const BufferRegion& buffer_region : block->writes) { + ICHECK(buffer_writer_cnt.count(buffer_region->buffer.get())); + if (buffer_writer_cnt[buffer_region->buffer.get()] != 1) { + return false; + } + } + return true; +} + +/*! + * \brief Check whether the input block is a reduction block. + * \param block_realize The block to be checked + * \param loop_range_map The mapping from the loop variables outside the input block to their ranges + * \param scope_block The scope block of the input block + * \param analyzer The analyzer + * \return A boolean indicating whether the input block is a reduction block. + * \note A similar check has been implemented in "src/tir/schedule/analysis.h", but that check is + * based on `tir.Schedule`. Here we have no schedule information, and thus we must implement the + * check again. + */ +bool IsReductionBlock(const BlockRealize& block_realize, const Map<Var, Range>& loop_range_map, Review comment: we cannot because the lowering process doesn't have access to cached flags in BlockScope - need recalculation -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
