text: /*
   * Copyright 2016 Google Inc.
   *
   * Use of this source code is governed by a BSD-style license that can be
   * found in the LICENSE file.
   */
  
  #define SK_OPTS_NS skslc_standalone
  #include "src/opts/SkChecksum_opts.h"
  #include "src/opts/SkVM_opts.h"
  
  #include "src/gpu/GrShaderUtils.h"
  #include "src/sksl/SkSLCompiler.h"
  #include "src/sksl/SkSLDehydrator.h"
  #include "src/sksl/SkSLFileOutputStream.h"
  #include "src/sksl/SkSLIRGenerator.h"
  #include "src/sksl/SkSLStringStream.h"
  #include "src/sksl/SkSLUtil.h"
  #include "src/sksl/codegen/SkSLPipelineStageCodeGenerator.h"
  #include "src/sksl/codegen/SkSLVMCodeGenerator.h"
  #include "src/sksl/ir/SkSLEnum.h"
  #include "src/sksl/ir/SkSLUnresolvedFunction.h"
  
  #include "spirv-tools/libspirv.hpp"
  
  #include <fstream>
  #include <limits.h>
  #include <stdarg.h>
  #include <stdio.h>
  
  void SkDebugf(const char format[], ...) {
      va_list args;
      va_start(args, format);
      vfprintf(stderr, format, args);
      va_end(args);
  }
  
  namespace SkOpts {
      decltype(hash_fn) hash_fn = skslc_standalone::hash_fn;
      decltype(interpret_skvm) interpret_skvm = skslc_standalone::interpret_skvm;
  }
  
  enum class ResultCode {
      kSuccess = 0,
      kCompileError = 1,
      kInputError = 2,
      kOutputError = 3,
      kConfigurationError = 4,
  };
  
  static std::unique_ptr<SkWStream> as_SkWStream(SkSL::OutputStream& s) {
      struct Adapter : public SkWStream {
      public:
          Adapter(SkSL::OutputStream& out) : fOut(out), fBytesWritten(0) {}
  
          bool write(const void* buffer, size_t size) override {
              fOut.write(buffer, size);
              fBytesWritten += size;
              return true;
          }
          void flush() override {}
          size_t bytesWritten() const override { return fBytesWritten; }
  
      private:
          SkSL::OutputStream& fOut;
          size_t fBytesWritten;
      };
  
      return std::make_unique<Adapter>(s);
  }
  
  // Given the path to a file (e.g. src/gpu/effects/GrFooFragmentProcessor.fp) and the expected
  // filename prefix and suffix (e.g. "Gr" and ".fp"), returns the "base name" of the
  // file (in this case, 'FooFragmentProcessor'). If no match, returns the empty string.
  static SkSL::String base_name(const SkSL::String& fpPath, const char* prefix, const char* suffix) {
      SkSL::String result;
      const char* end = &*fpPath.end();
      const char* fileName = end;
      // back up until we find a slash
      while (fileName != fpPath && '/' != *(fileName - 1) && '\\' != *(fileName - 1)) {
          --fileName;
      }
      if (!strncmp(fileName, prefix, strlen(prefix)) &&
          !strncmp(end - strlen(suffix), suffix, strlen(suffix))) {
          result.append(fileName + strlen(prefix), end - fileName - strlen(prefix) - strlen(suffix));
      }
      return result;
  }
  
  // Given a string containing an SkSL program, searches for a #pragma settings comment, like so:
  //    /*#pragma settings Default Sharpen*/
  // The passed-in Settings object will be updated accordingly. Any number of options can be provided.
  static bool detect_shader_settings(const SkSL::String& text,
                                     SkSL::Program::Settings* settings,
                                     const SkSL::ShaderCapsClass** caps) {
      using Factory = SkSL::ShaderCapsFactory;
  
      // Find a matching comment and isolate the name portion.
      static constexpr char kPragmaSettings[] = "/*#pragma settings ";
      const char* settingsPtr = strstr(text.c_str(), kPragmaSettings);
      if (settingsPtr != nullptr) {
          // Subtract one here in order to preserve the leading space, which is necessary to allow
          // consumeSuffix to find the first item.
          settingsPtr += strlen(kPragmaSettings) - 1;
  
          const char* settingsEnd = strstr(settingsPtr, "*/");
          if (settingsEnd != nullptr) {
              SkSL::String settingsText{settingsPtr, size_t(settingsEnd - settingsPtr)};
  
              // Apply settings as requested. Since they can come in any order, repeat until we've
              // consumed them all.
              for (;;) {
                  const size_t startingLength = settingsText.length();
  
                  if (settingsText.consumeSuffix(" AddAndTrueToLoopCondition")) {
                      static auto s_addAndTrueCaps = Factory::AddAndTrueToLoopCondition();
                      *caps = s_addAndTrueCaps.get();
                  }
                  if (settingsText.consumeSuffix(" BlendModesFailRandomlyForAllZeroVec")) {
                      static auto s_blendZeroCaps = Factory::BlendModesFailRandomlyForAllZeroVec();
                      *caps = s_blendZeroCaps.get();
                  }
                  if (settingsText.consumeSuffix(" CannotUseFractForNegativeValues")) {
                      static auto s_negativeFractCaps = Factory::CannotUseFractForNegativeValues();
                      *caps = s_negativeFractCaps.get();
                  }
                  if (settingsText.consumeSuffix(" CannotUseFragCoord")) {
                      static auto s_noFragCoordCaps = Factory::CannotUseFragCoord();
                      *caps = s_noFragCoordCaps.get();
                  }
                  if (settingsText.consumeSuffix(" CannotUseMinAndAbsTogether")) {
                      static auto s_minAbsCaps = Factory::CannotUseMinAndAbsTogether();
                      *caps = s_minAbsCaps.get();
                  }
                  if (settingsText.consumeSuffix(" Default")) {
                      static auto s_defaultCaps = Factory::Default();
                      *caps = s_defaultCaps.get();
                  }
                  if (settingsText.consumeSuffix(" EmulateAbsIntFunction")) {
                      static auto s_emulateAbsIntCaps = Factory::EmulateAbsIntFunction();
                      *caps = s_emulateAbsIntCaps.get();
                  }
                  if (settingsText.consumeSuffix(" FragCoordsOld")) {
                      static auto s_fragCoordsOld = Factory::FragCoordsOld();
                      *caps = s_fragCoordsOld.get();
                  }
                  if (settingsText.consumeSuffix(" FragCoordsNew")) {
                      static auto s_fragCoordsNew = Factory::FragCoordsNew();
                      *caps = s_fragCoordsNew.get();
                  }
                  if (settingsText.consumeSuffix(" GeometryShaderExtensionString")) {
                      static auto s_geometryExtCaps = Factory::GeometryShaderExtensionString();
                      *caps = s_geometryExtCaps.get();
                  }
                  if (settingsText.consumeSuffix(" GeometryShaderSupport")) {
                      static auto s_geometryShaderCaps = Factory::GeometryShaderSupport();
                      *caps = s_geometryShaderCaps.get();
                  }
                  if (settingsText.consumeSuffix(" GSInvocationsExtensionString")) {
                      static auto s_gsInvocationCaps = Factory::GSInvocationsExtensionString();
                      *caps = s_gsInvocationCaps.get();
                  }
                  if (settingsText.consumeSuffix(" IncompleteShortIntPrecision")) {
                      static auto s_incompleteShortIntCaps = Factory::IncompleteShortIntPrecision();
                      *caps = s_incompleteShortIntCaps.get();
                  }
                  if (settingsText.consumeSuffix(" MustGuardDivisionEvenAfterExplicitZeroCheck")) {
                      static auto s_div0Caps = Factory::MustGuardDivisionEvenAfterExplicitZeroCheck();
                      *caps = s_div0Caps.get();
                  }
                  if (settingsText.consumeSuffix(" MustForceNegatedAtanParamToFloat")) {
                      static auto s_negativeAtanCaps = Factory::MustForceNegatedAtanParamToFloat();
                      *caps = s_negativeAtanCaps.get();
                  }
                  if (settingsText.consumeSuffix(" NoGSInvocationsSupport")) {
                      static auto s_noGSInvocations = Factory::NoGSInvocationsSupport();
                      *caps = s_noGSInvocations.get();
                  }
                  if (settingsText.consumeSuffix(" RemovePowWithConstantExponent")) {
                      static auto s_powCaps = Factory::RemovePowWithConstantExponent();
                      *caps = s_powCaps.get();
                  }
                  if (settingsText.consumeSuffix(" RewriteDoWhileLoops")) {
                      static auto s_rewriteLoopCaps = Factory::RewriteDoWhileLoops();
                      *caps = s_rewriteLoopCaps.get();
                  }
                  if (settingsText.consumeSuffix(" RewriteMatrixVectorMultiply")) {
                      static auto s_rewriteMatVecMulCaps = Factory::RewriteMatrixVectorMultiply();
                      *caps = s_rewriteMatVecMulCaps.get();
                  }
                  if (settingsText.consumeSuffix(" ShaderDerivativeExtensionString")) {
                      static auto s_derivativeCaps = Factory::ShaderDerivativeExtensionString();
                      *caps = s_derivativeCaps.get();
                  }
                  if (settingsText.consumeSuffix(" UnfoldShortCircuitAsTernary")) {
                      static auto s_ternaryCaps = Factory::UnfoldShortCircuitAsTernary();
                      *caps = s_ternaryCaps.get();
                  }
                  if (settingsText.consumeSuffix(" UsesPrecisionModifiers")) {
                      static auto s_precisionCaps = Factory::UsesPrecisionModifiers();
                      *caps = s_precisionCaps.get();
                  }
                  if (settingsText.consumeSuffix(" Version110")) {
                      static auto s_version110Caps = Factory::Version110();
                      *caps = s_version110Caps.get();
                  }
                  if (settingsText.consumeSuffix(" Version450Core")) {
                      static auto s_version450CoreCaps = Factory::Version450Core();
                      *caps = s_version450CoreCaps.get();
                  }
                  if (settingsText.consumeSuffix(" FlipY")) {
                      settings->fFlipY = true;
                  }
                  if (settingsText.consumeSuffix(" ForceHighPrecision")) {
                      settings->fForceHighPrecision = true;
                  }
                  if (settingsText.consumeSuffix(" NoInline")) {
                      settings->fInlineThreshold = 0;
                  }
                  if (settingsText.consumeSuffix(" InlineThresholdMax")) {
                      settings->fInlineThreshold = INT_MAX;
                  }
                  if (settingsText.consumeSuffix(" Sharpen")) {
                      settings->fSharpenTextures = true;
                  }
  
                  if (settingsText.empty()) {
                      break;
                  }
                  if (settingsText.length() == startingLength) {
                      printf("Unrecognized #pragma settings: %s\n", settingsText.c_str());
                      return false;
                  }
              }
          }
      }
  
      return true;
  }
  
  /**
   * Displays a usage banner; used when the command line arguments don't make sense.
   */
  static void show_usage() {
      printf("usage: skslc <input> <output> <flags>\n"
             "       skslc <worklist>\n"
             "\n"
             "Allowed flags:\n"
             "--settings:   honor embedded /*#pragma settings*/ comments.\n"
             "--nosettings: ignore /*#pragma settings*/ comments\n");
  }
  
  /**
   * Handle a single input.
   */
  ResultCode processCommand(std::vector<SkSL::String>& args) {
      bool honorSettings = true;
      if (args.size() == 4) {
          // Handle four-argument case: `skslc in.sksl out.glsl --settings`
          const SkSL::String& settingsArg = args[3];
          if (settingsArg == "--settings") {
              honorSettings = true;
          } else if (settingsArg == "--nosettings") {
              honorSettings = false;
          } else {
              printf("unrecognized flag: %s\n\n", settingsArg.c_str());
              show_usage();
              return ResultCode::kInputError;
          }
      } else if (args.size() != 3) {
          show_usage();
          return ResultCode::kInputError;
      }
  
      SkSL::ProgramKind kind;
      const SkSL::String& inputPath = args[1];
      if (inputPath.endsWith(".vert")) {
          kind = SkSL::ProgramKind::kVertex;
      } else if (inputPath.endsWith(".frag") || inputPath.endsWith(".sksl")) {
          kind = SkSL::ProgramKind::kFragment;
      } else if (inputPath.endsWith(".geom")) {
          kind = SkSL::ProgramKind::kGeometry;
      } else if (inputPath.endsWith(".fp")) {
          kind = SkSL::ProgramKind::kFragmentProcessor;
      } else if (inputPath.endsWith(".rte")) {
          kind = SkSL::ProgramKind::kRuntimeEffect;
      } else {
          printf("input filename must end in '.vert', '.frag', '.geom', '.fp', '.rte', or '.sksl'\n");
          return ResultCode::kInputError;
      }
  
      std::ifstream in(inputPath);
      SkSL::String text((std::istreambuf_iterator<char>(in)),
                         std::istreambuf_iterator<char>());
      if (in.rdstate()) {
          printf("error reading '%s'\n", inputPath.c_str());
          return ResultCode::kInputError;
      }
  
      SkSL::Program::Settings settings;
      const SkSL::ShaderCapsClass* caps = &SkSL::standaloneCaps;
      if (honorSettings) {
          if (!detect_shader_settings(text, &settings, &caps)) {
              return ResultCode::kInputError;
          }
      }
  
      const SkSL::String& outputPath = args[2];
      auto emitCompileError = [&](SkSL::FileOutputStream& out, const char* errorText) {
          // Overwrite the compiler output, if any, with an error message.
          out.close();
          SkSL::FileOutputStream errorStream(outputPath);
          errorStream.writeText("### Compilation failed:\n\n");
          errorStream.writeText(errorText);
          errorStream.close();
          // Also emit the error directly to stdout.
          puts(errorText);
      };
  
      auto compileProgram = [&](const auto& writeFn) -> ResultCode {
          SkSL::FileOutputStream out(outputPath);
          SkSL::Compiler compiler(caps);
          if (!out.isValid()) {
              printf("error writing '%s'\n", outputPath.c_str());
              return ResultCode::kOutputError;
          }
          std::unique_ptr<SkSL::Program> program = compiler.convertProgram(kind, text, settings);
          if (!program || !writeFn(compiler, *program, out)) {
              emitCompileError(out, compiler.errorText().c_str());
              return ResultCode::kCompileError;
          }
          if (!out.close()) {
              printf("error writing '%s'\n", outputPath.c_str());
              return ResultCode::kOutputError;
          }
          return ResultCode::kSuccess;
      };
  
      if (outputPath.endsWith(".spirv")) {
          return compileProgram(
                  [](SkSL::Compiler& compiler, SkSL::Program& program, SkSL::OutputStream& out) {
                      return compiler.toSPIRV(program, out);
                  });
      } else if (outputPath.endsWith(".asm.frag") || outputPath.endsWith(".asm.vert") ||
                 outputPath.endsWith(".asm.geom")) {
          return compileProgram(
                  [](SkSL::Compiler& compiler, SkSL::Program& program, SkSL::OutputStream& out) {
                      // Compile program to SPIR-V assembly in a string-stream.
                      SkSL::StringStream assembly;
                      if (!compiler.toSPIRV(program, assembly)) {
                          return false;
                      }
                      // Convert the string-stream to a SPIR-V disassembly.
                      spvtools::SpirvTools tools(SPV_ENV_VULKAN_1_0);
                      const SkSL::String& spirv(assembly.str());
                      std::string disassembly;
                      if (!tools.Disassemble((const uint32_t*)spirv.data(),
                                             spirv.size() / 4, &disassembly)) {
                          return false;
                      }
                      // Finally, write the disassembly to our output stream.
                      out.write(disassembly.data(), disassembly.size());
                      return true;
                  });
      } else if (outputPath.endsWith(".glsl")) {
          return compileProgram(
                  [](SkSL::Compiler& compiler, SkSL::Program& program, SkSL::OutputStream& out) {
                      return compiler.toGLSL(program, out);
                  });
      } else if (outputPath.endsWith(".metal")) {
          return compileProgram(
                  [](SkSL::Compiler& compiler, SkSL::Program& program, SkSL::OutputStream& out) {
                      return compiler.toMetal(program, out);
                  });
      } else if (outputPath.endsWith(".h")) {
          settings.fReplaceSettings = false;
          settings.fPermitInvalidStaticTests = true;
          return compileProgram(
                  [&](SkSL::Compiler& compiler, SkSL::Program& program, SkSL::OutputStream& out) {
                      return compiler.toH(program, base_name(inputPath.c_str(), "Gr", ".fp"), out);
                  });
      } else if (outputPath.endsWith(".dsl.cpp")) {
          settings.fReplaceSettings = false;
          settings.fPermitInvalidStaticTests = true;
          return compileProgram(
                  [&](SkSL::Compiler& compiler, SkSL::Program& program, SkSL::OutputStream& out) {
                      return compiler.toDSLCPP(program, base_name(inputPath.c_str(), "Gr", ".fp"),
                                               out);
                  });
      } else if (outputPath.endsWith(".cpp")) {
          settings.fReplaceSettings = false;
          settings.fPermitInvalidStaticTests = true;
          return compileProgram(
                  [&](SkSL::Compiler& compiler, SkSL::Program& program, SkSL::OutputStream& out) {
                      return compiler.toCPP(program, base_name(inputPath.c_str(), "Gr", ".fp"), out);
                  });
      } else if (outputPath.endsWith(".skvm")) {
          return compileProgram(
                  [](SkSL::Compiler&, SkSL::Program& program, SkSL::OutputStream& out) {
                      skvm::Builder builder{skvm::Features{}};
                      if (!SkSL::testingOnly_ProgramToSkVMShader(program, &builder)) {
                          return false;
                      }
  
                      std::unique_ptr<SkWStream> redirect = as_SkWStream(out);
                      builder.done().dump(redirect.get());
                      return true;
                  });
      } else if (outputPath.endsWith(".stage")) {
          return compileProgram(
                  [](SkSL::Compiler&, SkSL::Program& program, SkSL::OutputStream& out) {
                      class Callbacks : public SkSL::PipelineStage::Callbacks {
                      public:
                          using String = SkSL::String;
  
                          String getMangledName(const char* name) override {
                              return String(name) + "_0";
                          }
  
                          String declareUniform(const SkSL::VarDeclaration* decl) override {
                              fOutput += decl->description();
                              return decl->var().name();
                          }
  
                          void defineFunction(const char* decl,
                                              const char* body,
                                              bool /*isMain*/) override {
                              fOutput += String(decl) + "{" + body + "}";
                          }
  
                          void defineStruct(const char* definition) override {
                              fOutput += definition;
                          }
  
                          void declareGlobal(const char* declaration) override {
                              fOutput += declaration;
                          }
  
                          String sampleChild(int index, String coords) override {
                              return String::printf("sample(child_%d%s%s)",
                                                    index,
                                                    coords.empty() ? "" : ", ",
                                                    coords.c_str());
                          }
                          String sampleChildWithMatrix(int index, String matrix) override {
                              return String::printf("sample(child_%d%s%s)",
                                                    index,
                                                    matrix.empty() ? "" : ", ",
                                                    matrix.c_str());
                          }
  
                          String              fOutput;
                      };
                      Callbacks callbacks;
                      SkSL::PipelineStage::ConvertProgram(program, "_coords", "_inColor", &callbacks);
                      out.writeString(GrShaderUtils::PrettyPrint(callbacks.fOutput));
                      return true;
                  });
      } else if (outputPath.endsWith(".dehydrated.sksl")) {
          SkSL::FileOutputStream out(outputPath);
          SkSL::Compiler compiler(caps);
          if (!out.isValid()) {
              printf("error writing '%s'\n", outputPath.c_str());
              return ResultCode::kOutputError;
          }
          SkSL::LoadedModule module =
                  compiler.loadModule(kind, SkSL::Compiler::MakeModulePath(inputPath.c_str()),
                                      /*base=*/nullptr, /*dehydrate=*/true);
          SkSL::Dehydrator dehydrator;
          dehydrator.write(*module.fSymbols);
          dehydrator.write(module.fElements);
          SkSL::String baseName = base_name(inputPath, "", ".sksl");
          SkSL::StringStream buffer;
          dehydrator.finish(buffer);
          const SkSL::String& data = buffer.str();
          out.printf("static uint8_t SKSL_INCLUDE_%s[] = {", baseName.c_str());
          for (size_t i = 0; i < data.length(); ++i) {
              out.printf("%s%d,", dehydrator.prefixAtOffset(i), uint8_t(data[i]));
          }
          out.printf("};\n");
          out.printf("static constexpr size_t SKSL_INCLUDE_%s_LENGTH = sizeof(SKSL_INCLUDE_%s);\n",
                     baseName.c_str(), baseName.c_str());
          if (!out.close()) {
              printf("error writing '%s'\n", outputPath.c_str());
              return ResultCode::kOutputError;
          }
      } else {
          printf("expected output path to end with one of: .glsl, .metal, .spirv, .asm.frag, .skvm, "
                 ".stage, .asm.vert, .asm.geom, .cpp, .h (got '%s')\n", outputPath.c_str());
          return ResultCode::kConfigurationError;
      }
      return ResultCode::kSuccess;
  }
  
  /**
   * Processes multiple inputs in a single invocation of skslc.
   */
  ResultCode processWorklist(const char* worklistPath) {
      SkSL::String inputPath(worklistPath);
      if (!inputPath.endsWith(".worklist")) {
          printf("expected .worklist file, found: %s\n\n", worklistPath);
          show_usage();
          return ResultCode::kConfigurationError;
      }
  
      // The worklist contains one line per argument to pass to skslc. When a blank line is reached,
      // those arguments will be passed to `processCommand`.
      auto resultCode = ResultCode::kSuccess;
      std::vector<SkSL::String> args = {"skslc"};
      std::ifstream in(worklistPath);
      for (SkSL::String line; std::getline(in, line); ) {
          if (in.rdstate()) {
              printf("error reading '%s'\n", worklistPath);
              return ResultCode::kInputError;
          }
  
          if (!line.empty()) {
              // We found an argument. Remember it.
              args.push_back(std::move(line));
          } else {
              // We found a blank line. If we have any arguments stored up, process them as a command.
              if (!args.empty()) {
                  ResultCode outcome = processCommand(args);
                  resultCode = std::max(resultCode, outcome);
  
                  // Clear every argument except the first ("skslc").
                  args.resize(1);
              }
          }
      }
  
      // If the worklist ended with a list of arguments but no blank line, process those now.
      if (args.size() > 1) {
          ResultCode outcome = processCommand(args);
          resultCode = std::max(resultCode, outcome);
      }
  
      // Return the "worst" status we encountered. For our purposes, compilation errors are the least
      // serious, because they are expected to occur in unit tests. Other types of errors are not
      // expected at all during a build.
      return resultCode;
  }
  
  int main(int argc, const char** argv) {
      if (argc == 2) {
          // Worklists are the only two-argument case for skslc, and we don't intend to support
          // nested worklists, so we can process them here.
          return (int)processWorklist(argv[1]);
      } else {
          // Process non-worklist inputs.
          std::vector<SkSL::String> args;
          for (int index=0; index<argc; ++index) {
              args.push_back(argv[index]);
          }
  
          return (int)processCommand(args);
      }
  }
  