junrushao1994 commented on a change in pull request #8716: URL: https://github.com/apache/tvm/pull/8716#discussion_r690080073
########## File path: src/tir/transforms/unify_thread_binding.cc ########## @@ -0,0 +1,126 @@ +/* + * 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 unify_thread_binding.cc + */ + +#include <tvm/tir/analysis.h> +#include <tvm/tir/stmt_functor.h> +#include <tvm/tir/transform.h> + +#include "ir_utils.h" + +namespace tvm { +namespace tir { + +/*! + * \brief A mutator which searches AttrStmts of thread bindings and changes the `node` field IterVar + * of the AttrStmts, so that for one kind of thread binding (except "vthread"), all such thread + * bindings use the same IterVar + */ +class ThreadBindingUnifier : public StmtExprMutator { + public: + static Stmt Unify(const PrimFunc& f) { return ThreadBindingUnifier().VisitStmt(f->body); } + + private: + Stmt VisitStmt_(const AttrStmtNode* attr) final { + // If this AttrStmt is not thread binding attribute, return as usual. + if (attr->attr_key != attr::thread_extent && attr->attr_key != attr::virtual_thread) { + return StmtMutator::VisitStmt_(attr); + } + + // Step 1. Fetch the old IterVar. + IterVar old_iter_var = Downcast<IterVar>(attr->node); + IterVar new_iter_var; + + // Step 2. See if an IterVar for this kind of thread binding was created before. If so, we use + // the created IterVar. Otherwise, we create a new IterVar for this thread binding and store the + // IterVar in mapping `thread_tag2iter_var_map_`. + Map<String, IterVar>::iterator it = thread_tag2iter_var_map_.find(old_iter_var->thread_tag); + if (it != thread_tag2iter_var_map_.end()) { + new_iter_var = (*it).second; + CHECK(ExprDeepEqual()(old_iter_var->dom->extent, (*it).second->dom->extent)) + << "ValueError: All loops that are bound to `" << old_iter_var->thread_tag + << "` should have the same extent. However, there are two loops with extent " + << (*it).second->dom->extent << " and " << old_iter_var->dom->extent + << ", which are not equal"; + } else { + ObjectPtr<IterVarNode> p_new_iter_var = make_object<IterVarNode>(*old_iter_var.get()); + p_new_iter_var->var = Var(old_iter_var->thread_tag); + new_iter_var = IterVar(p_new_iter_var); + // We don't unify thread bindings of "vthread". + if (old_iter_var->thread_tag != "vthread") { + thread_tag2iter_var_map_.Set(old_iter_var->thread_tag, new_iter_var); + } + } + + // Step 3. We will substitute the occurrences of the old variable in the old IterVar with the + // new variable in further mutation. Thus, we store the mapping entry. + var_substitution_map_.Set(old_iter_var->var, new_iter_var->var); + + // Step 4. Mutate recursively, and update the AttrStmt with the new IterVar. + AttrStmt new_attr = Downcast<AttrStmt>(StmtMutator::VisitStmt_(attr)); + ObjectPtr<AttrStmtNode> p_new_attr = CopyOnWrite(new_attr.get()); + p_new_attr->node = new_iter_var; + return Stmt(p_new_attr); + } + + PrimExpr VisitExpr_(const VarNode* var) final { + // If this variable appears as a key in `var_substitution_map_`, we substitute it with its + // corresponding value in the mapping. + Map<Var, Var>::iterator it = var_substitution_map_.find(GetRef<Var>(var)); + return it != var_substitution_map_.end() ? (*it).second : GetRef<Var>(var); + } + + /*! + * \brief A mapping from a thread tag to its corresponding IterVar that is shared by all + * occurrences of the thread tag + * */ + Map<String, IterVar> thread_tag2iter_var_map_; + /*! \brief A mapping from old variables to new variables, which is used for substitution */ + Map<Var, Var> var_substitution_map_; +}; + +PrimFunc UnifyThreadBinding(PrimFunc f) { + // Only apply this pass to TIR that is not from TE schedules + if (!IsFromLegacyTESchedule(f)) { + PrimFuncNode* fptr = f.CopyOnWrite(); + fptr->body = ThreadBindingUnifier::Unify(f); Review comment: Let's also tweak the signature of `ThreadBindingUnifier::Unify` here ```suggestion fptr->body = ThreadBindingUnifier::Unify(std::move(f->body)); ``` -- 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]
