//===--- WebAssembly.cpp - WebAssembly ToolChain Implementation -*- 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 "WebAssembly.h"

#include "CommonArgs.h"

#include "Gnu.h"

#include "clang/Basic/Version.h"

#include "clang/Config/config.h"

#include "clang/Driver/Compilation.h"

#include "clang/Driver/Driver.h"

#include "clang/Driver/DriverDiagnostic.h"

#include "clang/Driver/Options.h"

#include "llvm/Option/ArgList.h"

#include "llvm/Support/FileSystem.h"

#include "llvm/Support/Path.h"

#include "llvm/Support/VirtualFileSystem.h"

using namespace clang::driver;

using namespace clang::driver::tools;

using namespace clang::driver::toolchains;

using namespace clang;

using namespace llvm::opt;

/// Following the conventions in https://wiki.debian.org/Multiarch/Tuples,

/// we remove the vendor field to form the multiarch triple.

std::string WebAssembly::getMultiarchTriple(const Driver &D,

                                            const llvm::Triple &TargetTriple,

                                            StringRef SysRoot) const {

    return (TargetTriple.getArchName() + "-" +

            TargetTriple.getOSAndEnvironmentName()).str();

}

std::string wasm::Linker::getLinkerPath(const ArgList &Args) const {

  const ToolChain &ToolChain = getToolChain();

  if (const Arg* A = Args.getLastArg(options::OPT_fuse_ld_EQ)) {

    StringRef UseLinker = A->getValue();

    if (!UseLinker.empty()) {

      if (llvm::sys::path::is_absolute(UseLinker) &&

          llvm::sys::fs::can_execute(UseLinker))

        return std::string(UseLinker);

      // Accept 'lld', and 'ld' as aliases for the default linker

      if (UseLinker != "lld" && UseLinker != "ld")

        ToolChain.getDriver().Diag(diag::err_drv_invalid_linker_name)

            << A->getAsString(Args);

    }

  }

  return ToolChain.GetProgramPath(ToolChain.getDefaultLinker());

}

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

                                const InputInfo &Output,

                                const InputInfoList &Inputs,

                                const ArgList &Args,

                                const char *LinkingOutput) const {

  const ToolChain &ToolChain = getToolChain();

  const char *Linker = Args.MakeArgString(getLinkerPath(Args));

  ArgStringList CmdArgs;

  CmdArgs.push_back("-m");

  if (ToolChain.getTriple().isArch64Bit())

    CmdArgs.push_back("wasm64");

  else

    CmdArgs.push_back("wasm32");

  if (Args.hasArg(options::OPT_s))

    CmdArgs.push_back("--strip-all");

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

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

  ToolChain.AddFilePathLibArgs(Args, CmdArgs);

  bool IsCommand = true;

  const char *Crt1;

  const char *Entry = nullptr;

  // When -shared is specified, use the reactor exec model unless

  // specified otherwise.

  if (Args.hasArg(options::OPT_shared))

    IsCommand = false;

  if (const Arg *A = Args.getLastArg(options::OPT_mexec_model_EQ)) {

    StringRef CM = A->getValue();

    if (CM == "command") {

      IsCommand = true;

    } else if (CM == "reactor") {

      IsCommand = false;

    } else {

      ToolChain.getDriver().Diag(diag::err_drv_invalid_argument_to_option)

          << CM << A->getOption().getName();

    }

  }

  if (IsCommand) {

    // If crt1-command.o exists, it supports new-style commands, so use it.

    // Otherwise, use the old crt1.o. This is a temporary transition measure.

    // Once WASI libc no longer needs to support LLVM versions which lack

    // support for new-style command, it can make crt1.o the same as

    // crt1-command.o. And once LLVM no longer needs to support WASI libc

    // versions before that, it can switch to using crt1-command.o.

    Crt1 = "crt1.o";

    if (ToolChain.GetFilePath("crt1-command.o") != "crt1-command.o")

      Crt1 = "crt1-command.o";

  } else {

    Crt1 = "crt1-reactor.o";

    Entry = "_initialize";

  }

  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles))

    CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath(Crt1)));

  if (Entry) {

    CmdArgs.push_back(Args.MakeArgString("--entry"));

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

  }

  if (Args.hasArg(options::OPT_shared))

    CmdArgs.push_back(Args.MakeArgString("-shared"));

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

  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {

    if (ToolChain.ShouldLinkCXXStdlib(Args))

      ToolChain.AddCXXStdlibLibArgs(Args, CmdArgs);

    if (Args.hasArg(options::OPT_pthread)) {

      CmdArgs.push_back("-lpthread");

      CmdArgs.push_back("--shared-memory");

    }

    CmdArgs.push_back("-lc");

    AddRunTimeLibs(ToolChain, ToolChain.getDriver(), CmdArgs, Args);

  }

  CmdArgs.push_back("-o");

  CmdArgs.push_back(Output.getFilename());

  C.addCommand(std::make_unique<Command>(JA, *this,

                                         ResponseFileSupport::AtFileCurCP(),

                                         Linker, CmdArgs, Inputs, Output));

  // When optimizing, if wasm-opt is available, run it.

  if (Arg *A = Args.getLastArg(options::OPT_O_Group)) {

    auto WasmOptPath = ToolChain.GetProgramPath("wasm-opt");

    if (WasmOptPath != "wasm-opt") {

      StringRef OOpt = "s";

      if (A->getOption().matches(options::OPT_O4) ||

          A->getOption().matches(options::OPT_Ofast))

        OOpt = "4";

      else if (A->getOption().matches(options::OPT_O0))

        OOpt = "0";

      else if (A->getOption().matches(options::OPT_O))

        OOpt = A->getValue();

      if (OOpt != "0") {

        const char *WasmOpt = Args.MakeArgString(WasmOptPath);

        ArgStringList CmdArgs;

        CmdArgs.push_back(Output.getFilename());

        CmdArgs.push_back(Args.MakeArgString(llvm::Twine("-O") + OOpt));

        CmdArgs.push_back("-o");

        CmdArgs.push_back(Output.getFilename());

        C.addCommand(std::make_unique<Command>(

            JA, *this, ResponseFileSupport::AtFileCurCP(), WasmOpt, CmdArgs,

            Inputs, Output));

      }

    }

  }

}

/// Given a base library directory, append path components to form the

/// LTO directory.

static std::string AppendLTOLibDir(const std::string &Dir) {

    // The version allows the path to be keyed to the specific version of

    // LLVM in used, as the bitcode format is not stable.

    return Dir + "/llvm-lto/" LLVM_VERSION_STRING;

}

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

                         const llvm::opt::ArgList &Args)

    : ToolChain(D, Triple, Args) {

  assert(Triple.isArch32Bit() != Triple.isArch64Bit());

  getProgramPaths().push_back(getDriver().getInstalledDir());

  auto SysRoot = getDriver().SysRoot;

  if (getTriple().getOS() == llvm::Triple::UnknownOS) {

    // Theoretically an "unknown" OS should mean no standard libraries, however

    // it could also mean that a custom set of libraries is in use, so just add

    // /lib to the search path. Disable multiarch in this case, to discourage

    // paths containing "unknown" from acquiring meanings.

    getFilePaths().push_back(SysRoot + "/lib");

  } else {

    const std::string MultiarchTriple =

        getMultiarchTriple(getDriver(), Triple, SysRoot);

    if (D.isUsingLTO()) {

      // For LTO, enable use of lto-enabled sysroot libraries too, if available.

      // Note that the directory is keyed to the LLVM revision, as LLVM's

      // bitcode format is not stable.

      auto Dir = AppendLTOLibDir(SysRoot + "/lib/" + MultiarchTriple);

      getFilePaths().push_back(Dir);

    }

    getFilePaths().push_back(SysRoot + "/lib/" + MultiarchTriple);

  }

}

bool WebAssembly::IsMathErrnoDefault() const { return false; }

bool WebAssembly::IsObjCNonFragileABIDefault() const { return true; }

bool WebAssembly::UseObjCMixedDispatch() const { return true; }

bool WebAssembly::isPICDefault() const { return false; }

bool WebAssembly::isPIEDefault(const llvm::opt::ArgList &Args) const {

  return false;

}

bool WebAssembly::isPICDefaultForced() const { return false; }

bool WebAssembly::hasBlocksRuntime() const { return false; }

// TODO: Support profiling.

bool WebAssembly::SupportsProfiling() const { return false; }

bool WebAssembly::HasNativeLLVMSupport() const { return true; }

void WebAssembly::addClangTargetOptions(const ArgList &DriverArgs,

                                        ArgStringList &CC1Args,

                                        Action::OffloadKind) const {

  if (!DriverArgs.hasFlag(clang::driver::options::OPT_fuse_init_array,

                          options::OPT_fno_use_init_array, true))

    CC1Args.push_back("-fno-use-init-array");

  // '-pthread' implies atomics, bulk-memory, mutable-globals, and sign-ext

  if (DriverArgs.hasFlag(options::OPT_pthread, options::OPT_no_pthread,

                         false)) {

    if (DriverArgs.hasFlag(options::OPT_mno_atomics, options::OPT_matomics,

                           false))

      getDriver().Diag(diag::err_drv_argument_not_allowed_with)

          << "-pthread"

          << "-mno-atomics";

    if (DriverArgs.hasFlag(options::OPT_mno_bulk_memory,

                           options::OPT_mbulk_memory, false))

      getDriver().Diag(diag::err_drv_argument_not_allowed_with)

          << "-pthread"

          << "-mno-bulk-memory";

    if (DriverArgs.hasFlag(options::OPT_mno_mutable_globals,

                           options::OPT_mmutable_globals, false))

      getDriver().Diag(diag::err_drv_argument_not_allowed_with)

          << "-pthread"

          << "-mno-mutable-globals";

    if (DriverArgs.hasFlag(options::OPT_mno_sign_ext, options::OPT_msign_ext,

                           false))

      getDriver().Diag(diag::err_drv_argument_not_allowed_with)

          << "-pthread"

          << "-mno-sign-ext";

    CC1Args.push_back("-target-feature");

    CC1Args.push_back("+atomics");

    CC1Args.push_back("-target-feature");

    CC1Args.push_back("+bulk-memory");

    CC1Args.push_back("-target-feature");

    CC1Args.push_back("+mutable-globals");

    CC1Args.push_back("-target-feature");

    CC1Args.push_back("+sign-ext");

  }

  if (!DriverArgs.hasFlag(options::OPT_mmutable_globals,

                          options::OPT_mno_mutable_globals, false)) {

    // -fPIC implies +mutable-globals because the PIC ABI used by the linker

    // depends on importing and exporting mutable globals.

    llvm::Reloc::Model RelocationModel;

    unsigned PICLevel;

    bool IsPIE;

    std::tie(RelocationModel, PICLevel, IsPIE) =

        ParsePICArgs(*this, DriverArgs);

    if (RelocationModel == llvm::Reloc::PIC_) {

      if (DriverArgs.hasFlag(options::OPT_mno_mutable_globals,

                             options::OPT_mmutable_globals, false)) {

        getDriver().Diag(diag::err_drv_argument_not_allowed_with)

            << "-fPIC"

            << "-mno-mutable-globals";

      }

      CC1Args.push_back("-target-feature");

      CC1Args.push_back("+mutable-globals");

    }

  }

  if (DriverArgs.getLastArg(options::OPT_fwasm_exceptions)) {

    // '-fwasm-exceptions' is not compatible with '-mno-exception-handling'

    if (DriverArgs.hasFlag(options::OPT_mno_exception_handing,

                           options::OPT_mexception_handing, false))

      getDriver().Diag(diag::err_drv_argument_not_allowed_with)

          << "-fwasm-exceptions"

          << "-mno-exception-handling";

    // '-fwasm-exceptions' is not compatible with

    // '-mllvm -enable-emscripten-cxx-exceptions'

    for (const Arg *A : DriverArgs.filtered(options::OPT_mllvm)) {

      if (StringRef(A->getValue(0)) == "-enable-emscripten-cxx-exceptions")

        getDriver().Diag(diag::err_drv_argument_not_allowed_with)

            << "-fwasm-exceptions"

            << "-mllvm -enable-emscripten-cxx-exceptions";

    }

    // '-fwasm-exceptions' implies exception-handling feature

    CC1Args.push_back("-target-feature");

    CC1Args.push_back("+exception-handling");

    // Backend needs -wasm-enable-eh to enable Wasm EH

    CC1Args.push_back("-mllvm");

    CC1Args.push_back("-wasm-enable-eh");

  }

  for (const Arg *A : DriverArgs.filtered(options::OPT_mllvm)) {

    StringRef Opt = A->getValue(0);

    if (Opt.startswith("-emscripten-cxx-exceptions-allowed")) {

      // '-mllvm -emscripten-cxx-exceptions-allowed' should be used with

      // '-mllvm -enable-emscripten-cxx-exceptions'

      bool EmEHArgExists = false;

      for (const Arg *A : DriverArgs.filtered(options::OPT_mllvm)) {

        if (StringRef(A->getValue(0)) == "-enable-emscripten-cxx-exceptions") {

          EmEHArgExists = true;

          break;

        }

      }

      if (!EmEHArgExists)

        getDriver().Diag(diag::err_drv_argument_only_allowed_with)

            << "-mllvm -emscripten-cxx-exceptions-allowed"

            << "-mllvm -enable-emscripten-cxx-exceptions";

      // Prevent functions specified in -emscripten-cxx-exceptions-allowed list

      // from being inlined before reaching the wasm backend.

      StringRef FuncNamesStr = Opt.split('=').second;

      SmallVector<StringRef, 4> FuncNames;

      FuncNamesStr.split(FuncNames, ',');

      for (auto Name : FuncNames) {

        CC1Args.push_back("-mllvm");

        CC1Args.push_back(DriverArgs.MakeArgString("--force-attribute=" + Name +

                                                   ":noinline"));

      }

    }

    if (Opt.startswith("-wasm-enable-sjlj")) {

      // '-mllvm -wasm-enable-sjlj' is not compatible with

      // '-mno-exception-handling'

      if (DriverArgs.hasFlag(options::OPT_mno_exception_handing,

                             options::OPT_mexception_handing, false))

        getDriver().Diag(diag::err_drv_argument_not_allowed_with)

            << "-mllvm -wasm-enable-sjlj"

            << "-mno-exception-handling";

      // '-mllvm -wasm-enable-sjlj' is not compatible with

      // '-mllvm -enable-emscripten-cxx-exceptions'

      // because we don't allow Emscripten EH + Wasm SjLj

      for (const Arg *A : DriverArgs.filtered(options::OPT_mllvm)) {

        if (StringRef(A->getValue(0)) == "-enable-emscripten-cxx-exceptions")

          getDriver().Diag(diag::err_drv_argument_not_allowed_with)

              << "-mllvm -wasm-enable-sjlj"

              << "-mllvm -enable-emscripten-cxx-exceptions";

      }

      // '-mllvm -wasm-enable-sjlj' is not compatible with

      // '-mllvm -enable-emscripten-sjlj'

      for (const Arg *A : DriverArgs.filtered(options::OPT_mllvm)) {

        if (StringRef(A->getValue(0)) == "-enable-emscripten-sjlj")

          getDriver().Diag(diag::err_drv_argument_not_allowed_with)

              << "-mllvm -wasm-enable-sjlj"

              << "-mllvm -enable-emscripten-sjlj";

      }

      // '-mllvm -wasm-enable-sjlj' implies exception-handling feature

      CC1Args.push_back("-target-feature");

      CC1Args.push_back("+exception-handling");

      // Backend needs '-exception-model=wasm' to use Wasm EH instructions

      CC1Args.push_back("-exception-model=wasm");

    }

  }

}

ToolChain::RuntimeLibType WebAssembly::GetDefaultRuntimeLibType() const {

  return ToolChain::RLT_CompilerRT;

}

ToolChain::CXXStdlibType

WebAssembly::GetCXXStdlibType(const ArgList &Args) const {

  if (Arg *A = Args.getLastArg(options::OPT_stdlib_EQ)) {

    StringRef Value = A->getValue();

    if (Value == "libc++")

      return ToolChain::CST_Libcxx;

    else if (Value == "libstdc++")

      return ToolChain::CST_Libstdcxx;

    else

      getDriver().Diag(diag::err_drv_invalid_stdlib_name)

          << A->getAsString(Args);

  }

  return ToolChain::CST_Libcxx;

}

void WebAssembly::AddClangSystemIncludeArgs(const ArgList &DriverArgs,

                                            ArgStringList &CC1Args) const {

  if (DriverArgs.hasArg(clang::driver::options::OPT_nostdinc))

    return;

  const Driver &D = getDriver();

  if (!DriverArgs.hasArg(options::OPT_nobuiltininc)) {

    SmallString<128> P(D.ResourceDir);

    llvm::sys::path::append(P, "include");

    addSystemInclude(DriverArgs, CC1Args, P);

  }

  if (DriverArgs.hasArg(options::OPT_nostdlibinc))

    return;

  // Check for configure-time C include directories.

  StringRef CIncludeDirs(C_INCLUDE_DIRS);

  if (CIncludeDirs != "") {

    SmallVector<StringRef, 5> dirs;

    CIncludeDirs.split(dirs, ":");

    for (StringRef dir : dirs) {

      StringRef Prefix =

          llvm::sys::path::is_absolute(dir) ? "" : StringRef(D.SysRoot);

      addExternCSystemInclude(DriverArgs, CC1Args, Prefix + dir);

    }

    return;

  }

  if (getTriple().getOS() != llvm::Triple::UnknownOS) {

    const std::string MultiarchTriple =

        getMultiarchTriple(D, getTriple(), D.SysRoot);

    addSystemInclude(DriverArgs, CC1Args, D.SysRoot + "/include/" + MultiarchTriple);

  }

  addSystemInclude(DriverArgs, CC1Args, D.SysRoot + "/include");

}

void WebAssembly::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,

                                               ArgStringList &CC1Args) const {

  if (DriverArgs.hasArg(options::OPT_nostdlibinc, options::OPT_nostdinc,

                        options::OPT_nostdincxx))

    return;

  switch (GetCXXStdlibType(DriverArgs)) {

  case ToolChain::CST_Libcxx:

    addLibCxxIncludePaths(DriverArgs, CC1Args);

    break;

  case ToolChain::CST_Libstdcxx:

    addLibStdCXXIncludePaths(DriverArgs, CC1Args);

    break;

  }

}

void WebAssembly::AddCXXStdlibLibArgs(const llvm::opt::ArgList &Args,

                                      llvm::opt::ArgStringList &CmdArgs) const {

  switch (GetCXXStdlibType(Args)) {

  case ToolChain::CST_Libcxx:

    CmdArgs.push_back("-lc++");

    if (Args.hasArg(options::OPT_fexperimental_library))

      CmdArgs.push_back("-lc++experimental");

    CmdArgs.push_back("-lc++abi");

    break;

  case ToolChain::CST_Libstdcxx:

    CmdArgs.push_back("-lstdc++");

    break;

  }

}

SanitizerMask WebAssembly::getSupportedSanitizers() const {

  SanitizerMask Res = ToolChain::getSupportedSanitizers();

  if (getTriple().isOSEmscripten()) {

    Res |= SanitizerKind::Vptr | SanitizerKind::Leak | SanitizerKind::Address;

  }

  // -fsanitize=function places two words before the function label, which are

  // -unsupported.

  Res &= ~SanitizerKind::Function;

  return Res;

}

Tool *WebAssembly::buildLinker() const {

  return new tools::wasm::Linker(*this);

}

void WebAssembly::addLibCxxIncludePaths(

    const llvm::opt::ArgList &DriverArgs,

    llvm::opt::ArgStringList &CC1Args) const {

  const Driver &D = getDriver();

  std::string SysRoot = computeSysRoot();

  std::string LibPath = SysRoot + "/include";

  const std::string MultiarchTriple =

      getMultiarchTriple(D, getTriple(), SysRoot);

  bool IsKnownOs = (getTriple().getOS() != llvm::Triple::UnknownOS);

  std::string Version = detectLibcxxVersion(LibPath);

  if (Version.empty())

    return;

  // First add the per-target include path if the OS is known.

  if (IsKnownOs) {

    std::string TargetDir = LibPath + "/" + MultiarchTriple + "/c++/" + Version;

    addSystemInclude(DriverArgs, CC1Args, TargetDir);

  }

  // Second add the generic one.

  addSystemInclude(DriverArgs, CC1Args, LibPath + "/c++/" + Version);

}

void WebAssembly::addLibStdCXXIncludePaths(

    const llvm::opt::ArgList &DriverArgs,

    llvm::opt::ArgStringList &CC1Args) const {

  // We cannot use GCCInstallationDetector here as the sysroot usually does

  // not contain a full GCC installation.

  // Instead, we search the given sysroot for /usr/include/xx, similar

  // to how we do it for libc++.

  const Driver &D = getDriver();

  std::string SysRoot = computeSysRoot();

  std::string LibPath = SysRoot + "/include";

  const std::string MultiarchTriple =

      getMultiarchTriple(D, getTriple(), SysRoot);

  bool IsKnownOs = (getTriple().getOS() != llvm::Triple::UnknownOS);

  // This is similar to detectLibcxxVersion()

  std::string Version;

  {

    std::error_code EC;

    Generic_GCC::GCCVersion MaxVersion =

        Generic_GCC::GCCVersion::Parse("0.0.0");

    SmallString<128> Path(LibPath);

    llvm::sys::path::append(Path, "c++");

    for (llvm::vfs::directory_iterator LI = getVFS().dir_begin(Path, EC), LE;

         !EC && 
LI != LE4
; 
LI = LI.increment(EC)3
) {

      StringRef VersionText = llvm::sys::path::filename(LI->path());

      if (VersionText[0] != 'v') {

        auto Version = Generic_GCC::GCCVersion::Parse(VersionText);

        if (Version > MaxVersion)

          MaxVersion = Version;

      }

    }

    if (MaxVersion.Major > 0)

      Version = MaxVersion.Text;

  }

  if (Version.empty())

    return;

  // First add the per-target include path if the OS is known.

  if (IsKnownOs) {

    std::string TargetDir = LibPath + "/c++/" + Version + "/" + MultiarchTriple;

    addSystemInclude(DriverArgs, CC1Args, TargetDir);

  }

  // Second add the generic one.

  addSystemInclude(DriverArgs, CC1Args, LibPath + "/c++/" + Version);

  // Third the backward one.

  addSystemInclude(DriverArgs, CC1Args, LibPath + "/c++/" + Version + "/backward");

}