areusch commented on a change in pull request #7398: URL: https://github.com/apache/tvm/pull/7398#discussion_r575558778
########## 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: yeah that seems right. I think we've come to similar conclusions. I think there are a couple of larger issues to be resolved here: 1. When targeting the C runtime, an entirely different strategy than MetadataModule is needed to export Modules which don't run on the target_host CPU. This isn't well-defined yet. [Model Library Format RFC](https://discuss.tvm.apache.org/t/rfc-tvm-model-library-format/9121) also touches on this, but doesn't resolve it. 2. Related to resolving this conundrum: the model of the C++ runtime is that some library running on target_host parses binary configuration data in MetadataModule and then configures any runtime libraries or accelerators. This is generally used to implement BYOC. C runtime does not want to require any startup procedure that involves parsing binary blobs using RAM--instead, this must happen at code-generation time. This means that we need to do a better job here of organizing Module according to the DLContext which will be executing those modules. Here we've mostly fixed problem 1. In future PR and RFC, we can work to address problem 2. Let me know if that makes sense to you! ---------------------------------------------------------------- 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]
