lib/Driver/ToolChains/WebAssembly.cpp

//===--- 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 "clang/Driver/Compilation.h"
#include "clang/Driver/Driver.h"
#include "clang/Driver/DriverDiagnostic.h"
#include "clang/Driver/Options.h"
#include "llvm/Option/ArgList.h"

using namespace clang::driver;
using namespace clang::driver::tools;
using namespace clang::driver::toolchains;
using namespace clang;
using namespace llvm::opt;

void parseThreadArgs(const Driver &Driver, const ArgList &DriverArgs,
                     bool &Pthread, StringRef &ThreadModel,
                     bool CheckForErrors = true) {
  // Default value for -pthread / -mthread-model options, each being false /
  // "single".
  Pthread =
      DriverArgs.hasFlag(options::OPT_pthread, options::OPT_no_pthread, false);
  ThreadModel =
      DriverArgs.getLastArgValue(options::OPT_mthread_model, "single");
  if (!CheckForErrors)
    return;

  // Did user explicitly specify -mthread-model / -pthread?
  bool HasThreadModel = DriverArgs.hasArg(options::OPT_mthread_model);
  bool HasPthread = Pthread && DriverArgs.hasArg(options::OPT_pthread);
  // '-pthread' cannot be used with '-mthread-model single'
  if (HasPthread && HasThreadModel && ThreadModel == "single")
    Driver.Diag(diag::err_drv_argument_not_allowed_with)
        << "-pthread" << "-mthread-model single";
}

wasm::Linker::Linker(const ToolChain &TC)
    : GnuTool("wasm::Linker", "lld", TC) {}

/// Following the conventions in https://wiki.debian.org/Multiarch/Tuples,
/// we remove the vendor field to form the multiarch triple.
static std::string getMultiarchTriple(const Driver &D,
                                      const llvm::Triple &TargetTriple,
                                      StringRef SysRoot) {
    return (TargetTriple.getArchName() + "-" +
            TargetTriple.getOSAndEnvironmentName()).str();
}

bool wasm::Linker::isLinkJob() const { return true; }

bool wasm::Linker::hasIntegratedCPP() const { return false; }

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(ToolChain.GetLinkerPath());
  ArgStringList CmdArgs;

  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);

  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles))
    CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath("crt1.o")));

  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("-lc");
    AddRunTimeLibs(ToolChain, ToolChain.getDriver(), CmdArgs, Args);
  }

  CmdArgs.push_back("-o");
  CmdArgs.push_back(Output.getFilename());

  C.addCommand(llvm::make_unique<Command>(JA, *this, Linker, CmdArgs, Inputs));
}

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());

  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(getDriver().SysRoot + "/lib");
  } else {
    const std::string MultiarchTriple =
        getMultiarchTriple(getDriver(), Triple, getDriver().SysRoot);
    getFilePaths().push_back(getDriver().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 { return false; }

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

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

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("-fuse-init-array");

  // Either '-mthread-model posix' or '-pthread' sets '-target-feature
  // +atomics'. We intentionally didn't create '-matomics' and set the atomics
  // target feature here depending on the other two options.
  bool Pthread = false;
  StringRef ThreadModel = "";
  parseThreadArgs(getDriver(), DriverArgs, Pthread, ThreadModel);
  if (Pthread || ThreadModel != "single") {
    CC1Args.push_back("-target-feature");
    CC1Args.push_back("+atomics");
  }
}

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++")
      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(options::OPT_nostdinc)) {
    if (getTriple().getOS() != llvm::Triple::UnknownOS) {
      const std::string MultiarchTriple =
          getMultiarchTriple(getDriver(), getTriple(), getDriver().SysRoot);
      addSystemInclude(DriverArgs, CC1Args, getDriver().SysRoot + "/include/" + MultiarchTriple);
    }
    addSystemInclude(DriverArgs, CC1Args, getDriver().SysRoot + "/include");
  }
}

void WebAssembly::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
                                               ArgStringList &CC1Args) const {
  if (!DriverArgs.hasArg(options::OPT_nostdlibinc) &&
      !DriverArgs.hasArg(options::OPT_nostdincxx)) {
    if (getTriple().getOS() != llvm::Triple::UnknownOS) {
      const std::string MultiarchTriple =
          getMultiarchTriple(getDriver(), getTriple(), getDriver().SysRoot);
      addSystemInclude(DriverArgs, CC1Args,
                       getDriver().SysRoot + "/include/" + MultiarchTriple + "/c++/v1");
    }
    addSystemInclude(DriverArgs, CC1Args,
                     getDriver().SysRoot + "/include/c++/v1");
  }
}

void WebAssembly::AddCXXStdlibLibArgs(const llvm::opt::ArgList &Args,
                                      llvm::opt::ArgStringList &CmdArgs) const {

  switch (GetCXXStdlibType(Args)) {
  case ToolChain::CST_Libcxx:
    CmdArgs.push_back("-lc++");
    CmdArgs.push_back("-lc++abi");
    break;
  case ToolChain::CST_Libstdcxx:
    llvm_unreachable("invalid stdlib name");
  }
}

std::string WebAssembly::getThreadModel(const ArgList &DriverArgs) const {
  // The WebAssembly MVP does not yet support threads. We set this to "posix"
  // when '-pthread' is set.
  bool Pthread = false;
  StringRef ThreadModel = "";
  parseThreadArgs(getDriver(), DriverArgs, Pthread, ThreadModel, false);
  if (Pthread)
    return "posix";
  return ThreadModel;
}

Tool *WebAssembly::buildLinker() const {
  return new tools::wasm::Linker(*this);
}