areusch commented on a change in pull request #7398: URL: https://github.com/apache/tvm/pull/7398#discussion_r571341323
########## File path: src/target/metadata_module.cc ########## @@ -0,0 +1,108 @@ +/* + * 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 metadata_module.cc + * \brief Defines functions that build MetadataModules for C++ and C runtimes. + */ + +#include "metadata_module.h" + +#include "../runtime/meta_data.h" +#include "llvm/llvm_module.h" +#include "source/source_module.h" + +namespace tvm { +namespace codegen { + +/*! + * \brief Create a metadata module wrapper. The helper is used by different + * codegens, such as graph runtime codegen and the vm compiler. + * + * \param params The metadata for initialization of all modules. + * \param target_module the internal module that is compiled by tvm. + * \param ext_modules The external modules that needs to be imported inside the metadata + * module(s). + * \param target The target that all the modules are compiled for + * \return The created metadata module that manages initialization of metadata. + */ +runtime::Module CreateMetadataModule( + const std::unordered_map<std::string, runtime::NDArray>& params, + tvm::runtime::Module target_module, const Array<runtime::Module>& ext_modules, Target target) { + Array<tvm::runtime::Module> csource_modules; + Array<tvm::runtime::Module> binary_modules; + + auto DSOExportable = [](tvm::runtime::Module& mod) { + return !std::strcmp(mod->type_key(), "llvm") || !std::strcmp(mod->type_key(), "c"); + }; + + // Wrap all submodules in the initialization wrapper. + std::unordered_map<std::string, std::vector<std::string>> sym_metadata; + for (tvm::runtime::Module mod : ext_modules) { + auto pf_sym = mod.GetFunction("get_symbol"); + auto pf_var = mod.GetFunction("get_const_vars"); + std::vector<std::string> arrays; + if (pf_sym != nullptr && pf_var != nullptr) { + String symbol = pf_sym(); + Array<String> variables = pf_var(); + for (size_t i = 0; i < variables.size(); i++) { + arrays.push_back(variables[i].operator std::string()); + } + ICHECK_EQ(sym_metadata.count(symbol), 0U) << "Found duplicated symbol: " << symbol; + sym_metadata[symbol] = arrays; + } + // We only need loading of serialized constant data + // if there are constants present and required by the + // runtime module to be initialized by the binary + // metadata module. If not rest of the modules are + // wrapped in c-source metadata module. + + // TODO(@manupa-arm) : we should be able to use csource_metadata + // if the variables are empty when all the runtime modules implement get_func_names + if (arrays.empty() && DSOExportable(mod) && target->kind->name == "c") { + csource_modules.push_back(mod); + } else { + binary_modules.push_back(mod); + } + } + + if (target.defined() && + target->GetAttr<String>("runtime").value_or(String("")) == kTvmRuntimeCrt) { + if (target->kind->name == "c") { + csource_modules.push_back(target_module); + target_module = CreateCSourceCrtMetadataModule(csource_modules, target); + } else if (target->kind->name == "llvm") { + binary_modules.push_back(target_module); Review comment: okay so let me summarize my understanding: 1. at the end of the day, we want to produce a single module that imports all the others 2. This function gets the Module that implements target_host (`target_module`) plus a list of all the BYOC modules (`ext_modules`). 3. when building for the C++ runtime, we have runtime::MetadataModule for this root module. We assume each Module in`ext_modules` contains exactly one Relay function whose name is `get_symbol()` and which may use ConstantNodes whose values must be initialized from `get_const_vars()`. `get_func_names()` is unused because `dlsym` is used to resolve functions in the C++ runtime. 4. when building for the C runtime, we use either the CSourceMetadataModule from #7002 or LLVMCrtMetadataModule from this PR. These are both DSO-exportable. The CSourceMetadataModule queries function names from and imports all DSO-exportable modules which don't define any const_vars. Let's call these "CRT-exportable modules" since we don't have a good name for them. 5. Then, any modules which are: a) non-DSO-exportable, b) not codegen'd by c or llvm backend, OR c) not defining any const_vars are imported into the resulting metadata module. Presumably then the LLVM module should work the same way as the C-source one, the only change needed being that target->kind->name == "llvm" should also admit DSO-exportable functions to csource_modules. Then, I'd propose the following name changes: - csource_modules -> crt_exportable_modules - binary_modules -> non_crt_exportable_modules ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: [email protected]
