//===--- AVR.cpp - AVR ToolChain Implementations ----------------*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

#include "AVR.h"

#include "CommonArgs.h"

#include "InputInfo.h"

#include "clang/Driver/Compilation.h"

#include "clang/Driver/DriverDiagnostic.h"

#include "clang/Driver/Options.h"

#include "llvm/ADT/Optional.h"

#include "llvm/ADT/StringSwitch.h"

#include "llvm/MC/MCSubtargetInfo.h"

#include "llvm/MC/SubtargetFeature.h"

#include "llvm/Option/ArgList.h"

#include "llvm/Support/FileSystem.h"

using namespace clang::driver;

using namespace clang::driver::toolchains;

using namespace clang::driver::tools;

using namespace clang;

using namespace llvm::opt;

namespace {

// TODO: Consider merging this into the AVR device table

// array in Targets/AVR.cpp.

llvm::Optional<StringRef> GetMcuFamilyName(StringRef MCU) {

  return llvm::StringSwitch<llvm::Optional<StringRef>>(MCU)

      .Case("atmega328", Optional<StringRef>("avr5"))

      .Case("atmega328p", Optional<StringRef>("avr5"))

      .Default(Optional<StringRef>());

}

const StringRef PossibleAVRLibcLocations[] = {

    "/usr/avr",

    "/usr/lib/avr",

};

} // end anonymous namespace

/// AVR Toolchain

AVRToolChain::AVRToolChain(const Driver &D, const llvm::Triple &Triple,

                           const ArgList &Args)

    : Generic_ELF(D, Triple, Args), LinkStdlib(false) {

  GCCInstallation.init(Triple, Args);

  // Only add default libraries if the user hasn't explicitly opted out.

  if (!Args.hasArg(options::OPT_nostdlib) &&

      !Args.hasArg(options::OPT_nodefaultlibs) &&

      !Args.hasArg(options::OPT_c /* does not apply when not linking */)) {

    std::string CPU = getCPUName(Args, Triple);

    if (CPU.empty()) {

      // We cannot link any standard libraries without an MCU specified.

      D.Diag(diag::warn_drv_avr_mcu_not_specified);

    } else {

      Optional<StringRef> FamilyName = GetMcuFamilyName(CPU);

      Optional<std::string> AVRLibcRoot = findAVRLibcInstallation();

      if (!FamilyName.hasValue()) {

        // We do not have an entry for this CPU in the family

        // mapping table yet.

        D.Diag(diag::warn_drv_avr_family_linking_stdlibs_not_implemented)

            << CPU;

      } else if (!GCCInstallation.isValid()) {

        // No avr-gcc found and so no runtime linked.

        D.Diag(diag::warn_drv_avr_gcc_not_found);

      } else if (!AVRLibcRoot.hasValue()) {

        // No avr-libc found and so no runtime linked.

        D.Diag(diag::warn_drv_avr_libc_not_found);

      } else { // We have enough information to link stdlibs

        std::string GCCRoot = std::string(GCCInstallation.getInstallPath());

        std::string LibcRoot = AVRLibcRoot.getValue();

        getFilePaths().push_back(LibcRoot + std::string("/lib/") +

                                 std::string(*FamilyName));

        getFilePaths().push_back(GCCRoot + std::string("/") +

                                 std::string(*FamilyName));

        LinkStdlib = true;

      }

    }

    if (!LinkStdlib)

      D.Diag(diag::warn_drv_avr_stdlib_not_linked);

  }

}

Tool *AVRToolChain::buildLinker() const {

  return new tools::AVR::Linker(getTriple(), *this, LinkStdlib);

}

void AVR::Linker::ConstructJob(Compilation &C, const JobAction &JA,

                               const InputInfo &Output,

                               const InputInfoList &Inputs,

                               const ArgList &Args,

                               const char *LinkingOutput) const {

  // Compute information about the target AVR.

  std::string CPU = getCPUName(Args, getToolChain().getTriple());

  llvm::Optional<StringRef> FamilyName = GetMcuFamilyName(CPU);

  std::string Linker = getToolChain().GetProgramPath(getShortName());

  ArgStringList CmdArgs;

  AddLinkerInputs(getToolChain(), Inputs, Args, CmdArgs, JA);

  CmdArgs.push_back("-o");

  CmdArgs.push_back(Output.getFilename());

  // Enable garbage collection of unused sections.

  CmdArgs.push_back("--gc-sections");

  // Add library search paths before we specify libraries.

  Args.AddAllArgs(CmdArgs, options::OPT_L);

  getToolChain().AddFilePathLibArgs(Args, CmdArgs);

  // If the family name is known, we can link with the device-specific libgcc.

  // Without it, libgcc will simply not be linked. This matches avr-gcc

  // behavior.

  if (LinkStdlib) {

    assert(!CPU.empty() && "CPU name must be known in order to link stdlibs");

    // Add the object file for the CRT.

    std::string CrtFileName = std::string("-l:crt") + CPU + std::string(".o");

    CmdArgs.push_back(Args.MakeArgString(CrtFileName));

    CmdArgs.push_back("-lgcc");

    CmdArgs.push_back("-lm");

    CmdArgs.push_back("-lc");

    // Add the link library specific to the MCU.

    CmdArgs.push_back(Args.MakeArgString(std::string("-l") + CPU));

    // Specify the family name as the emulation mode to use.

    // This is almost always required because otherwise avr-ld

    // will assume 'avr2' and warn about the program being larger

    // than the bare minimum supports.

    CmdArgs.push_back(Args.MakeArgString(std::string("-m") + *FamilyName));

  }

  C.addCommand(

      std::make_unique<Command>(JA, *this, ResponseFileSupport::AtFileCurCP(),

                                Args.MakeArgString(Linker), CmdArgs, Inputs));

}

llvm::Optional<std::string> AVRToolChain::findAVRLibcInstallation() const {

  for (StringRef PossiblePath : PossibleAVRLibcLocations) {

    // Return the first avr-libc installation that exists.

    if (llvm::sys::fs::is_directory(PossiblePath))

      return Optional<std::string>(std::string(PossiblePath));

  }

  return llvm::None;

}