// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

#include "toolchain/codegen/codegen.h"

#include <memory>
#include <optional>
#include <string>

#include "common/check.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/MC/TargetRegistry.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/TargetParser/Host.h"
#include "toolchain/diagnostics/diagnostic_consumer.h"

namespace Carbon {

auto CodeGen::Make(llvm::Module* module, llvm::StringRef target_triple_str,
                   Diagnostics::Consumer* consumer) -> std::optional<CodeGen> {
  std::string error;
  const llvm::Target* target =
      llvm::TargetRegistry::lookupTarget(target_triple_str, error);
  CARBON_CHECK(target, "Target should be validated before codegen: {0}", error);

  llvm::Triple target_triple(target_triple_str);
  module->setTargetTriple(target_triple);

  constexpr llvm::StringLiteral CPU = "generic";
  constexpr llvm::StringLiteral Features = "";

  llvm::TargetOptions target_opts;
  CodeGen codegen(module,
                  consumer ? consumer : &Diagnostics::ConsoleConsumer());
  codegen.target_machine_.reset(target->createTargetMachine(
      target_triple, CPU, Features, target_opts, llvm::Reloc::PIC_));
  return codegen;
}

auto CodeGen::EmitAssembly(llvm::raw_pwrite_stream& out) -> bool {
  return EmitCode(out, llvm::CodeGenFileType::AssemblyFile);
}

auto CodeGen::EmitObject(llvm::raw_pwrite_stream& out) -> bool {
  return EmitCode(out, llvm::CodeGenFileType::ObjectFile);
}

auto CodeGen::EmitCode(llvm::raw_pwrite_stream& out,
                       llvm::CodeGenFileType file_type) -> bool {
  module_->setDataLayout(target_machine_->createDataLayout());

  // Using the legacy PM to generate the assembly since the new PM
  // does not work with this yet.
  // TODO: Make the new PM work with the codegen pipeline.
  llvm::legacy::PassManager pass;
  // Note that this returns true on an error.
  if (target_machine_->addPassesToEmitFile(pass, out, nullptr, file_type)) {
    CARBON_DIAGNOSTIC(CodeGenUnableToEmit, Error,
                      "unable to emit to this file");
    emitter_.Emit(module_->getName(), CodeGenUnableToEmit);
    return false;
  }

  pass.run(*module_);
  return true;
}

}  // namespace Carbon
