text: // Copyright (c) 2017 Pierre Moreau
  //
  // Licensed 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.
  
  #include <cstring>
  #include <iostream>
  #include <vector>
  
  #include "source/spirv_target_env.h"
  #include "source/table.h"
  #include "spirv-tools/libspirv.hpp"
  #include "spirv-tools/linker.hpp"
  #include "tools/io.h"
  
  void print_usage(char* argv0) {
    std::string target_env_list = spvTargetEnvList(27, 95);
    printf(
        R"(%s - Link SPIR-V binary files together.
  
  USAGE: %s [options] <filename> [<filename> ...]
  
  The SPIR-V binaries are read from the different <filename>.
  
  NOTE: The linker is a work in progress.
  
  Options:
    -h, --help              Print this help.
    -o                      Name of the resulting linked SPIR-V binary.
    --create-library        Link the binaries into a library, keeping all exported symbols.
    --allow-partial-linkage Allow partial linkage by accepting imported symbols to be unresolved.
    --verify-ids            Verify that IDs in the resulting modules are truly unique.
    --version               Display linker version information
    --target-env            {%s}
                            Use validation rules from the specified environment.
  )",
        argv0, argv0, target_env_list.c_str());
  }
  
  int main(int argc, char** argv) {
    std::vector<const char*> inFiles;
    const char* outFile = nullptr;
    spv_target_env target_env = SPV_ENV_UNIVERSAL_1_0;
    spvtools::LinkerOptions options;
    bool continue_processing = true;
    int return_code = 0;
  
    for (int argi = 1; continue_processing && argi < argc; ++argi) {
      const char* cur_arg = argv[argi];
      if ('-' == cur_arg[0]) {
        if (0 == strcmp(cur_arg, "-o")) {
          if (argi + 1 < argc) {
            if (!outFile) {
              outFile = argv[++argi];
            } else {
              fprintf(stderr, "error: More than one output file specified\n");
              continue_processing = false;
              return_code = 1;
            }
          } else {
            fprintf(stderr, "error: Missing argument to %s\n", cur_arg);
            continue_processing = false;
            return_code = 1;
          }
        } else if (0 == strcmp(cur_arg, "--create-library")) {
          options.SetCreateLibrary(true);
        } else if (0 == strcmp(cur_arg, "--verify-ids")) {
          options.SetVerifyIds(true);
        } else if (0 == strcmp(cur_arg, "--allow-partial-linkage")) {
          options.SetAllowPartialLinkage(true);
        } else if (0 == strcmp(cur_arg, "--version")) {
          printf("%s\n", spvSoftwareVersionDetailsString());
          // TODO(dneto): Add OpenCL 2.2 at least.
          printf("Targets:\n  %s\n  %s\n  %s\n",
                 spvTargetEnvDescription(SPV_ENV_UNIVERSAL_1_1),
                 spvTargetEnvDescription(SPV_ENV_VULKAN_1_0),
                 spvTargetEnvDescription(SPV_ENV_UNIVERSAL_1_2));
          continue_processing = false;
          return_code = 0;
        } else if (0 == strcmp(cur_arg, "--help") || 0 == strcmp(cur_arg, "-h")) {
          print_usage(argv[0]);
          continue_processing = false;
          return_code = 0;
        } else if (0 == strcmp(cur_arg, "--target-env")) {
          if (argi + 1 < argc) {
            const auto env_str = argv[++argi];
            if (!spvParseTargetEnv(env_str, &target_env)) {
              fprintf(stderr, "error: Unrecognized target env: %s\n", env_str);
              continue_processing = false;
              return_code = 1;
            }
          } else {
            fprintf(stderr, "error: Missing argument to --target-env\n");
            continue_processing = false;
            return_code = 1;
          }
        }
      } else {
        inFiles.push_back(cur_arg);
      }
    }
  
    // Exit if command line parsing was not successful.
    if (!continue_processing) {
      return return_code;
    }
  
    if (inFiles.empty()) {
      fprintf(stderr, "error: No input file specified\n");
      return 1;
    }
  
    std::vector<std::vector<uint32_t>> contents(inFiles.size());
    for (size_t i = 0u; i < inFiles.size(); ++i) {
      if (!ReadFile<uint32_t>(inFiles[i], "rb", &contents[i])) return 1;
    }
  
    const spvtools::MessageConsumer consumer = [](spv_message_level_t level,
                                                  const char*,
                                                  const spv_position_t& position,
                                                  const char* message) {
      switch (level) {
        case SPV_MSG_FATAL:
        case SPV_MSG_INTERNAL_ERROR:
        case SPV_MSG_ERROR:
          std::cerr << "error: " << position.index << ": " << message
                    << std::endl;
          break;
        case SPV_MSG_WARNING:
          std::cout << "warning: " << position.index << ": " << message
                    << std::endl;
          break;
        case SPV_MSG_INFO:
          std::cout << "info: " << position.index << ": " << message << std::endl;
          break;
        default:
          break;
      }
    };
    spvtools::Context context(target_env);
    context.SetMessageConsumer(consumer);
  
    std::vector<uint32_t> linkingResult;
    spv_result_t status = Link(context, contents, &linkingResult, options);
  
    if (!WriteFile<uint32_t>(outFile, "wb", linkingResult.data(),
                             linkingResult.size()))
      return 1;
  
    return status == SPV_SUCCESS ? 0 : 1;
  }
  