[Driver] Consolidate tools and toolchains by target platform. (NFC)

Summary:
(This is a move-only refactoring patch. There are no functionality changes.)

This patch splits apart the Clang driver's tool and toolchain implementation
files. Each target platform toolchain is moved to its own file, along with the
closest-related tools. Each target platform toolchain has separate headers and
implementation files, so the hierarchy of classes is unchanged.

There are some remaining shared free functions, mostly from Tools.cpp. Several
of these move to their own architecture-specific files, similar to r296056. Some
of them are only used by a single target platform; since the tools and
toolchains are now together, some helpers now live in a platform-specific file.
The balance are helpers related to manipulating argument lists, so they are now
in a new file pair, CommonArgs.h and .cpp.

I've tried to cluster the code logically, which is fairly straightforward for
most of the target platforms and shared architectures. I think I've made
reasonable choices for these, as well as the various shared helpers; but of
course, I'm happy to hear feedback in the review.

There are some particular things I don't like about this patch, but haven't been
able to find a better overall solution. The first is the proliferation of files:
there are several files that are tiny because the toolchain is not very
different from its base (usually the Gnu tools/toolchain). I think this is
mostly a reflection of the true complexity, though, so it may not be "fixable"
in any reasonable sense. The second thing I don't like are the includes like
"../Something.h". I've avoided this largely by clustering into the current file
structure. However, a few of these includes remain, and in those cases it
doesn't make sense to me to sink an existing file any deeper.

Reviewers: rsmith, mehdi_amini, compnerd, rnk, javed.absar

Subscribers: emaste, jfb, danalbert, srhines, dschuff, jyknight, nemanjai, nhaehnle, mgorny, cfe-commits

Differential Revision: https://reviews.llvm.org/D30372

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@297250 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 898 insertions, 0 deletions

diff --git a/lib/Driver/ToolChains/Linux.cpp b/lib/Driver/ToolChains/Linux.cpp
new file mode 100644
index 0000000000..e87ef08e90
--- /dev/null
+++ b/lib/Driver/ToolChains/Linux.cpp
@@ -0,0 +1,898 @@
+//===--- Linux.h - Linux ToolChain Implementations --------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Linux.h"
+#include "Arch/ARM.h"
+#include "Arch/Mips.h"
+#include "Arch/PPC.h"
+#include "CommonArgs.h"
+#include "clang/Basic/VirtualFileSystem.h"
+#include "clang/Config/config.h"
+#include "clang/Driver/Distro.h"
+#include "clang/Driver/Driver.h"
+#include "clang/Driver/Options.h"
+#include "clang/Driver/SanitizerArgs.h"
+#include "llvm/Option/ArgList.h"
+#include "llvm/ProfileData/InstrProf.h"
+#include "llvm/Support/Path.h"
+#include <system_error>
+
+using namespace clang::driver;
+using namespace clang::driver::toolchains;
+using namespace clang;
+using namespace llvm::opt;
+
+using tools::addPathIfExists;
+
+/// \brief Get our best guess at the multiarch triple for a target.
+///
+/// Debian-based systems are starting to use a multiarch setup where they use
+/// a target-triple directory in the library and header search paths.
+/// Unfortunately, this triple does not align with the vanilla target triple,
+/// so we provide a rough mapping here.
+static std::string getMultiarchTriple(const Driver &D,
+                                      const llvm::Triple &TargetTriple,
+                                      StringRef SysRoot) {
+  llvm::Triple::EnvironmentType TargetEnvironment =
+      TargetTriple.getEnvironment();
+
+  // For most architectures, just use whatever we have rather than trying to be
+  // clever.
+  switch (TargetTriple.getArch()) {
+  default:
+    break;
+
+  // We use the existence of '/lib/<triple>' as a directory to detect some
+  // common linux triples that don't quite match the Clang triple for both
+  // 32-bit and 64-bit targets. Multiarch fixes its install triples to these
+  // regardless of what the actual target triple is.
+  case llvm::Triple::arm:
+  case llvm::Triple::thumb:
+    if (TargetEnvironment == llvm::Triple::GNUEABIHF) {
+      if (D.getVFS().exists(SysRoot + "/lib/arm-linux-gnueabihf"))
+        return "arm-linux-gnueabihf";
+    } else {
+      if (D.getVFS().exists(SysRoot + "/lib/arm-linux-gnueabi"))
+        return "arm-linux-gnueabi";
+    }
+    break;
+  case llvm::Triple::armeb:
+  case llvm::Triple::thumbeb:
+    if (TargetEnvironment == llvm::Triple::GNUEABIHF) {
+      if (D.getVFS().exists(SysRoot + "/lib/armeb-linux-gnueabihf"))
+        return "armeb-linux-gnueabihf";
+    } else {
+      if (D.getVFS().exists(SysRoot + "/lib/armeb-linux-gnueabi"))
+        return "armeb-linux-gnueabi";
+    }
+    break;
+  case llvm::Triple::x86:
+    if (D.getVFS().exists(SysRoot + "/lib/i386-linux-gnu"))
+      return "i386-linux-gnu";
+    break;
+  case llvm::Triple::x86_64:
+    // We don't want this for x32, otherwise it will match x86_64 libs
+    if (TargetEnvironment != llvm::Triple::GNUX32 &&
+        D.getVFS().exists(SysRoot + "/lib/x86_64-linux-gnu"))
+      return "x86_64-linux-gnu";
+    break;
+  case llvm::Triple::aarch64:
+    if (D.getVFS().exists(SysRoot + "/lib/aarch64-linux-gnu"))
+      return "aarch64-linux-gnu";
+    break;
+  case llvm::Triple::aarch64_be:
+    if (D.getVFS().exists(SysRoot + "/lib/aarch64_be-linux-gnu"))
+      return "aarch64_be-linux-gnu";
+    break;
+  case llvm::Triple::mips:
+    if (D.getVFS().exists(SysRoot + "/lib/mips-linux-gnu"))
+      return "mips-linux-gnu";
+    break;
+  case llvm::Triple::mipsel:
+    if (D.getVFS().exists(SysRoot + "/lib/mipsel-linux-gnu"))
+      return "mipsel-linux-gnu";
+    break;
+  case llvm::Triple::mips64:
+    if (D.getVFS().exists(SysRoot + "/lib/mips64-linux-gnu"))
+      return "mips64-linux-gnu";
+    if (D.getVFS().exists(SysRoot + "/lib/mips64-linux-gnuabi64"))
+      return "mips64-linux-gnuabi64";
+    break;
+  case llvm::Triple::mips64el:
+    if (D.getVFS().exists(SysRoot + "/lib/mips64el-linux-gnu"))
+      return "mips64el-linux-gnu";
+    if (D.getVFS().exists(SysRoot + "/lib/mips64el-linux-gnuabi64"))
+      return "mips64el-linux-gnuabi64";
+    break;
+  case llvm::Triple::ppc:
+    if (D.getVFS().exists(SysRoot + "/lib/powerpc-linux-gnuspe"))
+      return "powerpc-linux-gnuspe";
+    if (D.getVFS().exists(SysRoot + "/lib/powerpc-linux-gnu"))
+      return "powerpc-linux-gnu";
+    break;
+  case llvm::Triple::ppc64:
+    if (D.getVFS().exists(SysRoot + "/lib/powerpc64-linux-gnu"))
+      return "powerpc64-linux-gnu";
+    break;
+  case llvm::Triple::ppc64le:
+    if (D.getVFS().exists(SysRoot + "/lib/powerpc64le-linux-gnu"))
+      return "powerpc64le-linux-gnu";
+    break;
+  case llvm::Triple::sparc:
+    if (D.getVFS().exists(SysRoot + "/lib/sparc-linux-gnu"))
+      return "sparc-linux-gnu";
+    break;
+  case llvm::Triple::sparcv9:
+    if (D.getVFS().exists(SysRoot + "/lib/sparc64-linux-gnu"))
+      return "sparc64-linux-gnu";
+    break;
+  case llvm::Triple::systemz:
+    if (D.getVFS().exists(SysRoot + "/lib/s390x-linux-gnu"))
+      return "s390x-linux-gnu";
+    break;
+  }
+  return TargetTriple.str();
+}
+
+static StringRef getOSLibDir(const llvm::Triple &Triple, const ArgList &Args) {
+  if (tools::isMipsArch(Triple.getArch())) {
+    if (Triple.isAndroid()) {
+      StringRef CPUName;
+      StringRef ABIName;
+      tools::mips::getMipsCPUAndABI(Args, Triple, CPUName, ABIName);
+      if (CPUName == "mips32r6")
+        return "libr6";
+      if (CPUName == "mips32r2")
+        return "libr2";
+    }
+    // lib32 directory has a special meaning on MIPS targets.
+    // It contains N32 ABI binaries. Use this folder if produce
+    // code for N32 ABI only.
+    if (tools::mips::hasMipsAbiArg(Args, "n32"))
+      return "lib32";
+    return Triple.isArch32Bit() ? "lib" : "lib64";
+  }
+
+  // It happens that only x86 and PPC use the 'lib32' variant of oslibdir, and
+  // using that variant while targeting other architectures causes problems
+  // because the libraries are laid out in shared system roots that can't cope
+  // with a 'lib32' library search path being considered. So we only enable
+  // them when we know we may need it.
+  //
+  // FIXME: This is a bit of a hack. We should really unify this code for
+  // reasoning about oslibdir spellings with the lib dir spellings in the
+  // GCCInstallationDetector, but that is a more significant refactoring.
+  if (Triple.getArch() == llvm::Triple::x86 ||
+      Triple.getArch() == llvm::Triple::ppc)
+    return "lib32";
+
+  if (Triple.getArch() == llvm::Triple::x86_64 &&
+      Triple.getEnvironment() == llvm::Triple::GNUX32)
+    return "libx32";
+
+  return Triple.isArch32Bit() ? "lib" : "lib64";
+}
+
+static void addMultilibsFilePaths(const Driver &D, const MultilibSet &Multilibs,
+                                  const Multilib &Multilib,
+                                  StringRef InstallPath,
+                                  ToolChain::path_list &Paths) {
+  if (const auto &PathsCallback = Multilibs.filePathsCallback())
+    for (const auto &Path : PathsCallback(Multilib))
+      addPathIfExists(D, InstallPath + Path, Paths);
+}
+
+Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
+    : Generic_ELF(D, Triple, Args) {
+  GCCInstallation.init(Triple, Args);
+  Multilibs = GCCInstallation.getMultilibs();
+  llvm::Triple::ArchType Arch = Triple.getArch();
+  std::string SysRoot = computeSysRoot();
+
+  // Cross-compiling binutils and GCC installations (vanilla and openSUSE at
+  // least) put various tools in a triple-prefixed directory off of the parent
+  // of the GCC installation. We use the GCC triple here to ensure that we end
+  // up with tools that support the same amount of cross compiling as the
+  // detected GCC installation. For example, if we find a GCC installation
+  // targeting x86_64, but it is a bi-arch GCC installation, it can also be
+  // used to target i386.
+  // FIXME: This seems unlikely to be Linux-specific.
+  ToolChain::path_list &PPaths = getProgramPaths();
+  PPaths.push_back(Twine(GCCInstallation.getParentLibPath() + "/../" +
+                         GCCInstallation.getTriple().str() + "/bin")
+                       .str());
+
+  Distro Distro(D.getVFS());
+
+  if (Distro.IsOpenSUSE() || Distro.IsUbuntu()) {
+    ExtraOpts.push_back("-z");
+    ExtraOpts.push_back("relro");
+  }
+
+  if (Arch == llvm::Triple::arm || Arch == llvm::Triple::thumb)
+    ExtraOpts.push_back("-X");
+
+  const bool IsAndroid = Triple.isAndroid();
+  const bool IsMips = tools::isMipsArch(Arch);
+  const bool IsHexagon = Arch == llvm::Triple::hexagon;
+
+  if (IsMips && !SysRoot.empty())
+    ExtraOpts.push_back("--sysroot=" + SysRoot);
+
+  // Do not use 'gnu' hash style for Mips targets because .gnu.hash
+  // and the MIPS ABI require .dynsym to be sorted in different ways.
+  // .gnu.hash needs symbols to be grouped by hash code whereas the MIPS
+  // ABI requires a mapping between the GOT and the symbol table.
+  // Android loader does not support .gnu.hash.
+  // Hexagon linker/loader does not support .gnu.hash
+  if (!IsMips && !IsAndroid && !IsHexagon) {
+    if (Distro.IsRedhat() || Distro.IsOpenSUSE() ||
+        (Distro.IsUbuntu() && Distro >= Distro::UbuntuMaverick))
+      ExtraOpts.push_back("--hash-style=gnu");
+
+    if (Distro.IsDebian() || Distro.IsOpenSUSE() || Distro == Distro::UbuntuLucid ||
+        Distro == Distro::UbuntuJaunty || Distro == Distro::UbuntuKarmic)
+      ExtraOpts.push_back("--hash-style=both");
+  }
+
+  if (Distro.IsRedhat() && Distro != Distro::RHEL5 && Distro != Distro::RHEL6)
+    ExtraOpts.push_back("--no-add-needed");
+
+#ifdef ENABLE_LINKER_BUILD_ID
+  ExtraOpts.push_back("--build-id");
+#endif
+
+  if (Distro.IsOpenSUSE())
+    ExtraOpts.push_back("--enable-new-dtags");
+
+  // The selection of paths to try here is designed to match the patterns which
+  // the GCC driver itself uses, as this is part of the GCC-compatible driver.
+  // This was determined by running GCC in a fake filesystem, creating all
+  // possible permutations of these directories, and seeing which ones it added
+  // to the link paths.
+  path_list &Paths = getFilePaths();
+
+  const std::string OSLibDir = getOSLibDir(Triple, Args);
+  const std::string MultiarchTriple = getMultiarchTriple(D, Triple, SysRoot);
+
+  // Add the multilib suffixed paths where they are available.
+  if (GCCInstallation.isValid()) {
+    const llvm::Triple &GCCTriple = GCCInstallation.getTriple();
+    const std::string &LibPath = GCCInstallation.getParentLibPath();
+    const Multilib &Multilib = GCCInstallation.getMultilib();
+    const MultilibSet &Multilibs = GCCInstallation.getMultilibs();
+
+    // Add toolchain / multilib specific file paths.
+    addMultilibsFilePaths(D, Multilibs, Multilib,
+                          GCCInstallation.getInstallPath(), Paths);
+
+    // Sourcery CodeBench MIPS toolchain holds some libraries under
+    // a biarch-like suffix of the GCC installation.
+    addPathIfExists(D, GCCInstallation.getInstallPath() + Multilib.gccSuffix(),
+                    Paths);
+
+    // GCC cross compiling toolchains will install target libraries which ship
+    // as part of the toolchain under <prefix>/<triple>/<libdir> rather than as
+    // any part of the GCC installation in
+    // <prefix>/<libdir>/gcc/<triple>/<version>. This decision is somewhat
+    // debatable, but is the reality today. We need to search this tree even
+    // when we have a sysroot somewhere else. It is the responsibility of
+    // whomever is doing the cross build targeting a sysroot using a GCC
+    // installation that is *not* within the system root to ensure two things:
+    //
+    //  1) Any DSOs that are linked in from this tree or from the install path
+    //     above must be present on the system root and found via an
+    //     appropriate rpath.
+    //  2) There must not be libraries installed into
+    //     <prefix>/<triple>/<libdir> unless they should be preferred over
+    //     those within the system root.
+    //
+    // Note that this matches the GCC behavior. See the below comment for where
+    // Clang diverges from GCC's behavior.
+    addPathIfExists(D, LibPath + "/../" + GCCTriple.str() + "/lib/../" +
+                           OSLibDir + Multilib.osSuffix(),
+                    Paths);
+
+    // If the GCC installation we found is inside of the sysroot, we want to
+    // prefer libraries installed in the parent prefix of the GCC installation.
+    // It is important to *not* use these paths when the GCC installation is
+    // outside of the system root as that can pick up unintended libraries.
+    // This usually happens when there is an external cross compiler on the
+    // host system, and a more minimal sysroot available that is the target of
+    // the cross. Note that GCC does include some of these directories in some
+    // configurations but this seems somewhere between questionable and simply
+    // a bug.
+    if (StringRef(LibPath).startswith(SysRoot)) {
+      addPathIfExists(D, LibPath + "/" + MultiarchTriple, Paths);
+      addPathIfExists(D, LibPath + "/../" + OSLibDir, Paths);
+    }
+  }
+
+  // Similar to the logic for GCC above, if we currently running Clang inside
+  // of the requested system root, add its parent library paths to
+  // those searched.
+  // FIXME: It's not clear whether we should use the driver's installed
+  // directory ('Dir' below) or the ResourceDir.
+  if (StringRef(D.Dir).startswith(SysRoot)) {
+    addPathIfExists(D, D.Dir + "/../lib/" + MultiarchTriple, Paths);
+    addPathIfExists(D, D.Dir + "/../" + OSLibDir, Paths);
+  }
+
+  addPathIfExists(D, SysRoot + "/lib/" + MultiarchTriple, Paths);
+  addPathIfExists(D, SysRoot + "/lib/../" + OSLibDir, Paths);
+  addPathIfExists(D, SysRoot + "/usr/lib/" + MultiarchTriple, Paths);
+  addPathIfExists(D, SysRoot + "/usr/lib/../" + OSLibDir, Paths);
+
+  // Try walking via the GCC triple path in case of biarch or multiarch GCC
+  // installations with strange symlinks.
+  if (GCCInstallation.isValid()) {
+    addPathIfExists(D,
+                    SysRoot + "/usr/lib/" + GCCInstallation.getTriple().str() +
+                        "/../../" + OSLibDir,
+                    Paths);
+
+    // Add the 'other' biarch variant path
+    Multilib BiarchSibling;
+    if (GCCInstallation.getBiarchSibling(BiarchSibling)) {
+      addPathIfExists(D, GCCInstallation.getInstallPath() +
+                             BiarchSibling.gccSuffix(),
+                      Paths);
+    }
+
+    // See comments above on the multilib variant for details of why this is
+    // included even from outside the sysroot.
+    const std::string &LibPath = GCCInstallation.getParentLibPath();
+    const llvm::Triple &GCCTriple = GCCInstallation.getTriple();
+    const Multilib &Multilib = GCCInstallation.getMultilib();
+    addPathIfExists(D, LibPath + "/../" + GCCTriple.str() + "/lib" +
+                           Multilib.osSuffix(),
+                    Paths);
+
+    // See comments above on the multilib variant for details of why this is
+    // only included from within the sysroot.
+    if (StringRef(LibPath).startswith(SysRoot))
+      addPathIfExists(D, LibPath, Paths);
+  }
+
+  // Similar to the logic for GCC above, if we are currently running Clang
+  // inside of the requested system root, add its parent library path to those
+  // searched.
+  // FIXME: It's not clear whether we should use the driver's installed
+  // directory ('Dir' below) or the ResourceDir.
+  if (StringRef(D.Dir).startswith(SysRoot))
+    addPathIfExists(D, D.Dir + "/../lib", Paths);
+
+  addPathIfExists(D, SysRoot + "/lib", Paths);
+  addPathIfExists(D, SysRoot + "/usr/lib", Paths);
+}
+
+/// \brief Parse a GCCVersion object out of a string of text.
+///
+/// This is the primary means of forming GCCVersion objects.
+/*static*/
+Generic_GCC::GCCVersion Linux::GCCVersion::Parse(StringRef VersionText) {
+  const GCCVersion BadVersion = {VersionText.str(), -1, -1, -1, "", "", ""};
+  std::pair<StringRef, StringRef> First = VersionText.split('.');
+  std::pair<StringRef, StringRef> Second = First.second.split('.');
+
+  GCCVersion GoodVersion = {VersionText.str(), -1, -1, -1, "", "", ""};
+  if (First.first.getAsInteger(10, GoodVersion.Major) || GoodVersion.Major < 0)
+    return BadVersion;
+  GoodVersion.MajorStr = First.first.str();
+  if (First.second.empty())
+    return GoodVersion;
+  if (Second.first.getAsInteger(10, GoodVersion.Minor) || GoodVersion.Minor < 0)
+    return BadVersion;
+  GoodVersion.MinorStr = Second.first.str();
+
+  // First look for a number prefix and parse that if present. Otherwise just
+  // stash the entire patch string in the suffix, and leave the number
+  // unspecified. This covers versions strings such as:
+  //   5        (handled above)
+  //   4.4
+  //   4.4.0
+  //   4.4.x
+  //   4.4.2-rc4
+  //   4.4.x-patched
+  // And retains any patch number it finds.
+  StringRef PatchText = GoodVersion.PatchSuffix = Second.second.str();
+  if (!PatchText.empty()) {
+    if (size_t EndNumber = PatchText.find_first_not_of("0123456789")) {
+      // Try to parse the number and any suffix.
+      if (PatchText.slice(0, EndNumber).getAsInteger(10, GoodVersion.Patch) ||
+          GoodVersion.Patch < 0)
+        return BadVersion;
+      GoodVersion.PatchSuffix = PatchText.substr(EndNumber);
+    }
+  }
+
+  return GoodVersion;
+}
+
+bool Linux::HasNativeLLVMSupport() const { return true; }
+
+Tool *Linux::buildLinker() const { return new tools::gnutools::Linker(*this); }
+
+Tool *Linux::buildAssembler() const {
+  return new tools::gnutools::Assembler(*this);
+}
+
+std::string Linux::computeSysRoot() const {
+  if (!getDriver().SysRoot.empty())
+    return getDriver().SysRoot;
+
+  if (!GCCInstallation.isValid() || !tools::isMipsArch(getTriple().getArch()))
+    return std::string();
+
+  // Standalone MIPS toolchains use different names for sysroot folder
+  // and put it into different places. Here we try to check some known
+  // variants.
+
+  const StringRef InstallDir = GCCInstallation.getInstallPath();
+  const StringRef TripleStr = GCCInstallation.getTriple().str();
+  const Multilib &Multilib = GCCInstallation.getMultilib();
+
+  std::string Path =
+      (InstallDir + "/../../../../" + TripleStr + "/libc" + Multilib.osSuffix())
+          .str();
+
+  if (getVFS().exists(Path))
+    return Path;
+
+  Path = (InstallDir + "/../../../../sysroot" + Multilib.osSuffix()).str();
+
+  if (getVFS().exists(Path))
+    return Path;
+
+  return std::string();
+}
+
+std::string Linux::getDynamicLinker(const ArgList &Args) const {
+  const llvm::Triple::ArchType Arch = getArch();
+  const llvm::Triple &Triple = getTriple();
+
+  const Distro Distro(getDriver().getVFS());
+
+  if (Triple.isAndroid())
+    return Triple.isArch64Bit() ? "/system/bin/linker64" : "/system/bin/linker";
+
+  if (Triple.isMusl()) {
+    std::string ArchName;
+    bool IsArm = false;
+
+    switch (Arch) {
+    case llvm::Triple::arm:
+    case llvm::Triple::thumb:
+      ArchName = "arm";
+      IsArm = true;
+      break;
+    case llvm::Triple::armeb:
+    case llvm::Triple::thumbeb:
+      ArchName = "armeb";
+      IsArm = true;
+      break;
+    default:
+      ArchName = Triple.getArchName().str();
+    }
+    if (IsArm &&
+        (Triple.getEnvironment() == llvm::Triple::MuslEABIHF ||
+         tools::arm::getARMFloatABI(*this, Args) == tools::arm::FloatABI::Hard))
+      ArchName += "hf";
+
+    return "/lib/ld-musl-" + ArchName + ".so.1";
+  }
+
+  std::string LibDir;
+  std::string Loader;
+
+  switch (Arch) {
+  default:
+    llvm_unreachable("unsupported architecture");
+
+  case llvm::Triple::aarch64:
+    LibDir = "lib";
+    Loader = "ld-linux-aarch64.so.1";
+    break;
+  case llvm::Triple::aarch64_be:
+    LibDir = "lib";
+    Loader = "ld-linux-aarch64_be.so.1";
+    break;
+  case llvm::Triple::arm:
+  case llvm::Triple::thumb:
+  case llvm::Triple::armeb:
+  case llvm::Triple::thumbeb: {
+    const bool HF =
+        Triple.getEnvironment() == llvm::Triple::GNUEABIHF ||
+        tools::arm::getARMFloatABI(*this, Args) == tools::arm::FloatABI::Hard;
+
+    LibDir = "lib";
+    Loader = HF ? "ld-linux-armhf.so.3" : "ld-linux.so.3";
+    break;
+  }
+  case llvm::Triple::mips:
+  case llvm::Triple::mipsel:
+  case llvm::Triple::mips64:
+  case llvm::Triple::mips64el: {
+    bool LE = (Triple.getArch() == llvm::Triple::mipsel) ||
+              (Triple.getArch() == llvm::Triple::mips64el);
+    bool IsNaN2008 = tools::mips::isNaN2008(Args, Triple);
+
+    LibDir = "lib" + tools::mips::getMipsABILibSuffix(Args, Triple);
+
+    if (tools::mips::isUCLibc(Args))
+      Loader = IsNaN2008 ? "ld-uClibc-mipsn8.so.0" : "ld-uClibc.so.0";
+    else if (!Triple.hasEnvironment() &&
+             Triple.getVendor() == llvm::Triple::VendorType::MipsTechnologies)
+      Loader = LE ? "ld-musl-mipsel.so.1" : "ld-musl-mips.so.1";
+    else
+      Loader = IsNaN2008 ? "ld-linux-mipsn8.so.1" : "ld.so.1";
+
+    break;
+  }
+  case llvm::Triple::ppc:
+    LibDir = "lib";
+    Loader = "ld.so.1";
+    break;
+  case llvm::Triple::ppc64:
+    LibDir = "lib64";
+    Loader =
+        (tools::ppc::hasPPCAbiArg(Args, "elfv2")) ? "ld64.so.2" : "ld64.so.1";
+    break;
+  case llvm::Triple::ppc64le:
+    LibDir = "lib64";
+    Loader =
+        (tools::ppc::hasPPCAbiArg(Args, "elfv1")) ? "ld64.so.1" : "ld64.so.2";
+    break;
+  case llvm::Triple::sparc:
+  case llvm::Triple::sparcel:
+    LibDir = "lib";
+    Loader = "ld-linux.so.2";
+    break;
+  case llvm::Triple::sparcv9:
+    LibDir = "lib64";
+    Loader = "ld-linux.so.2";
+    break;
+  case llvm::Triple::systemz:
+    LibDir = "lib";
+    Loader = "ld64.so.1";
+    break;
+  case llvm::Triple::x86:
+    LibDir = "lib";
+    Loader = "ld-linux.so.2";
+    break;
+  case llvm::Triple::x86_64: {
+    bool X32 = Triple.getEnvironment() == llvm::Triple::GNUX32;
+
+    LibDir = X32 ? "libx32" : "lib64";
+    Loader = X32 ? "ld-linux-x32.so.2" : "ld-linux-x86-64.so.2";
+    break;
+  }
+  }
+
+  if (Distro == Distro::Exherbo && (Triple.getVendor() == llvm::Triple::UnknownVendor ||
+                                    Triple.getVendor() == llvm::Triple::PC))
+    return "/usr/" + Triple.str() + "/lib/" + Loader;
+  return "/" + LibDir + "/" + Loader;
+}
+
+void Linux::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
+                                      ArgStringList &CC1Args) const {
+  const Driver &D = getDriver();
+  std::string SysRoot = computeSysRoot();
+
+  if (DriverArgs.hasArg(clang::driver::options::OPT_nostdinc))
+    return;
+
+  if (!DriverArgs.hasArg(options::OPT_nostdlibinc))
+    addSystemInclude(DriverArgs, CC1Args, SysRoot + "/usr/local/include");
+
+  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(SysRoot) : "";
+      addExternCSystemInclude(DriverArgs, CC1Args, Prefix + dir);
+    }
+    return;
+  }
+
+  // Lacking those, try to detect the correct set of system includes for the
+  // target triple.
+
+  // Add include directories specific to the selected multilib set and multilib.
+  if (GCCInstallation.isValid()) {
+    const auto &Callback = Multilibs.includeDirsCallback();
+    if (Callback) {
+      for (const auto &Path : Callback(GCCInstallation.getMultilib()))
+        addExternCSystemIncludeIfExists(
+            DriverArgs, CC1Args, GCCInstallation.getInstallPath() + Path);
+    }
+  }
+
+  // Implement generic Debian multiarch support.
+  const StringRef X86_64MultiarchIncludeDirs[] = {
+      "/usr/include/x86_64-linux-gnu",
+
+      // FIXME: These are older forms of multiarch. It's not clear that they're
+      // in use in any released version of Debian, so we should consider
+      // removing them.
+      "/usr/include/i686-linux-gnu/64", "/usr/include/i486-linux-gnu/64"};
+  const StringRef X86MultiarchIncludeDirs[] = {
+      "/usr/include/i386-linux-gnu",
+
+      // FIXME: These are older forms of multiarch. It's not clear that they're
+      // in use in any released version of Debian, so we should consider
+      // removing them.
+      "/usr/include/x86_64-linux-gnu/32", "/usr/include/i686-linux-gnu",
+      "/usr/include/i486-linux-gnu"};
+  const StringRef AArch64MultiarchIncludeDirs[] = {
+      "/usr/include/aarch64-linux-gnu"};
+  const StringRef ARMMultiarchIncludeDirs[] = {
+      "/usr/include/arm-linux-gnueabi"};
+  const StringRef ARMHFMultiarchIncludeDirs[] = {
+      "/usr/include/arm-linux-gnueabihf"};
+  const StringRef ARMEBMultiarchIncludeDirs[] = {
+      "/usr/include/armeb-linux-gnueabi"};
+  const StringRef ARMEBHFMultiarchIncludeDirs[] = {
+      "/usr/include/armeb-linux-gnueabihf"};
+  const StringRef MIPSMultiarchIncludeDirs[] = {"/usr/include/mips-linux-gnu"};
+  const StringRef MIPSELMultiarchIncludeDirs[] = {
+      "/usr/include/mipsel-linux-gnu"};
+  const StringRef MIPS64MultiarchIncludeDirs[] = {
+      "/usr/include/mips64-linux-gnu", "/usr/include/mips64-linux-gnuabi64"};
+  const StringRef MIPS64ELMultiarchIncludeDirs[] = {
+      "/usr/include/mips64el-linux-gnu",
+      "/usr/include/mips64el-linux-gnuabi64"};
+  const StringRef PPCMultiarchIncludeDirs[] = {
+      "/usr/include/powerpc-linux-gnu"};
+  const StringRef PPC64MultiarchIncludeDirs[] = {
+      "/usr/include/powerpc64-linux-gnu"};
+  const StringRef PPC64LEMultiarchIncludeDirs[] = {
+      "/usr/include/powerpc64le-linux-gnu"};
+  const StringRef SparcMultiarchIncludeDirs[] = {
+      "/usr/include/sparc-linux-gnu"};
+  const StringRef Sparc64MultiarchIncludeDirs[] = {
+      "/usr/include/sparc64-linux-gnu"};
+  const StringRef SYSTEMZMultiarchIncludeDirs[] = {
+      "/usr/include/s390x-linux-gnu"};
+  ArrayRef<StringRef> MultiarchIncludeDirs;
+  switch (getTriple().getArch()) {
+  case llvm::Triple::x86_64:
+    MultiarchIncludeDirs = X86_64MultiarchIncludeDirs;
+    break;
+  case llvm::Triple::x86:
+    MultiarchIncludeDirs = X86MultiarchIncludeDirs;
+    break;
+  case llvm::Triple::aarch64:
+  case llvm::Triple::aarch64_be:
+    MultiarchIncludeDirs = AArch64MultiarchIncludeDirs;
+    break;
+  case llvm::Triple::arm:
+  case llvm::Triple::thumb:
+    if (getTriple().getEnvironment() == llvm::Triple::GNUEABIHF)
+      MultiarchIncludeDirs = ARMHFMultiarchIncludeDirs;
+    else
+      MultiarchIncludeDirs = ARMMultiarchIncludeDirs;
+    break;
+  case llvm::Triple::armeb:
+  case llvm::Triple::thumbeb:
+    if (getTriple().getEnvironment() == llvm::Triple::GNUEABIHF)
+      MultiarchIncludeDirs = ARMEBHFMultiarchIncludeDirs;
+    else
+      MultiarchIncludeDirs = ARMEBMultiarchIncludeDirs;
+    break;
+  case llvm::Triple::mips:
+    MultiarchIncludeDirs = MIPSMultiarchIncludeDirs;
+    break;
+  case llvm::Triple::mipsel:
+    MultiarchIncludeDirs = MIPSELMultiarchIncludeDirs;
+    break;
+  case llvm::Triple::mips64:
+    MultiarchIncludeDirs = MIPS64MultiarchIncludeDirs;
+    break;
+  case llvm::Triple::mips64el:
+    MultiarchIncludeDirs = MIPS64ELMultiarchIncludeDirs;
+    break;
+  case llvm::Triple::ppc:
+    MultiarchIncludeDirs = PPCMultiarchIncludeDirs;
+    break;
+  case llvm::Triple::ppc64:
+    MultiarchIncludeDirs = PPC64MultiarchIncludeDirs;
+    break;
+  case llvm::Triple::ppc64le:
+    MultiarchIncludeDirs = PPC64LEMultiarchIncludeDirs;
+    break;
+  case llvm::Triple::sparc:
+    MultiarchIncludeDirs = SparcMultiarchIncludeDirs;
+    break;
+  case llvm::Triple::sparcv9:
+    MultiarchIncludeDirs = Sparc64MultiarchIncludeDirs;
+    break;
+  case llvm::Triple::systemz:
+    MultiarchIncludeDirs = SYSTEMZMultiarchIncludeDirs;
+    break;
+  default:
+    break;
+  }
+  for (StringRef Dir : MultiarchIncludeDirs) {
+    if (D.getVFS().exists(SysRoot + Dir)) {
+      addExternCSystemInclude(DriverArgs, CC1Args, SysRoot + Dir);
+      break;
+    }
+  }
+
+  if (getTriple().getOS() == llvm::Triple::RTEMS)
+    return;
+
+  // Add an include of '/include' directly. This isn't provided by default by
+  // system GCCs, but is often used with cross-compiling GCCs, and harmless to
+  // add even when Clang is acting as-if it were a system compiler.
+  addExternCSystemInclude(DriverArgs, CC1Args, SysRoot + "/include");
+
+  addExternCSystemInclude(DriverArgs, CC1Args, SysRoot + "/usr/include");
+}
+
+static std::string DetectLibcxxIncludePath(StringRef base) {
+  std::error_code EC;
+  int MaxVersion = 0;
+  std::string MaxVersionString = "";
+  for (llvm::sys::fs::directory_iterator LI(base, EC), LE; !EC && LI != LE;
+       LI = LI.increment(EC)) {
+    StringRef VersionText = llvm::sys::path::filename(LI->path());
+    int Version;
+    if (VersionText[0] == 'v' &&
+        !VersionText.slice(1, StringRef::npos).getAsInteger(10, Version)) {
+      if (Version > MaxVersion) {
+        MaxVersion = Version;
+        MaxVersionString = VersionText;
+      }
+    }
+  }
+  return MaxVersion ? (base + "/" + MaxVersionString).str() : "";
+}
+
+std::string Linux::findLibCxxIncludePath() const {
+  const std::string LibCXXIncludePathCandidates[] = {
+      DetectLibcxxIncludePath(getDriver().Dir + "/../include/c++"),
+      // If this is a development, non-installed, clang, libcxx will
+      // not be found at ../include/c++ but it likely to be found at
+      // one of the following two locations:
+      DetectLibcxxIncludePath(getDriver().SysRoot + "/usr/local/include/c++"),
+      DetectLibcxxIncludePath(getDriver().SysRoot + "/usr/include/c++") };
+  for (const auto &IncludePath : LibCXXIncludePathCandidates) {
+    if (IncludePath.empty() || !getVFS().exists(IncludePath))
+      continue;
+    // Use the first candidate that exists.
+    return IncludePath;
+  }
+  return "";
+}
+
+void Linux::addLibStdCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
+                                     llvm::opt::ArgStringList &CC1Args) const {
+  // We need a detected GCC installation on Linux to provide libstdc++'s
+  // headers.
+  if (!GCCInstallation.isValid())
+    return;
+
+  // By default, look for the C++ headers in an include directory adjacent to
+  // the lib directory of the GCC installation. Note that this is expect to be
+  // equivalent to '/usr/include/c++/X.Y' in almost all cases.
+  StringRef LibDir = GCCInstallation.getParentLibPath();
+  StringRef InstallDir = GCCInstallation.getInstallPath();
+  StringRef TripleStr = GCCInstallation.getTriple().str();
+  const Multilib &Multilib = GCCInstallation.getMultilib();
+  const std::string GCCMultiarchTriple = getMultiarchTriple(
+      getDriver(), GCCInstallation.getTriple(), getDriver().SysRoot);
+  const std::string TargetMultiarchTriple =
+      getMultiarchTriple(getDriver(), getTriple(), getDriver().SysRoot);
+  const GCCVersion &Version = GCCInstallation.getVersion();
+
+  // The primary search for libstdc++ supports multiarch variants.
+  if (addLibStdCXXIncludePaths(LibDir.str() + "/../include",
+                               "/c++/" + Version.Text, TripleStr,
+                               GCCMultiarchTriple, TargetMultiarchTriple,
+                               Multilib.includeSuffix(), DriverArgs, CC1Args))
+    return;
+
+  // Otherwise, fall back on a bunch of options which don't use multiarch
+  // layouts for simplicity.
+  const std::string LibStdCXXIncludePathCandidates[] = {
+      // Gentoo is weird and places its headers inside the GCC install,
+      // so if the first attempt to find the headers fails, try these patterns.
+      InstallDir.str() + "/include/g++-v" + Version.Text,
+      InstallDir.str() + "/include/g++-v" + Version.MajorStr + "." +
+          Version.MinorStr,
+      InstallDir.str() + "/include/g++-v" + Version.MajorStr,
+      // Android standalone toolchain has C++ headers in yet another place.
+      LibDir.str() + "/../" + TripleStr.str() + "/include/c++/" + Version.Text,
+      // Freescale SDK C++ headers are directly in <sysroot>/usr/include/c++,
+      // without a subdirectory corresponding to the gcc version.
+      LibDir.str() + "/../include/c++",
+  };
+
+  for (const auto &IncludePath : LibStdCXXIncludePathCandidates) {
+    if (addLibStdCXXIncludePaths(IncludePath, /*Suffix*/ "", TripleStr,
+                                 /*GCCMultiarchTriple*/ "",
+                                 /*TargetMultiarchTriple*/ "",
+                                 Multilib.includeSuffix(), DriverArgs, CC1Args))
+      break;
+  }
+}
+
+void Linux::AddCudaIncludeArgs(const ArgList &DriverArgs,
+                               ArgStringList &CC1Args) const {
+  CudaInstallation.AddCudaIncludeArgs(DriverArgs, CC1Args);
+}
+
+void Linux::AddIAMCUIncludeArgs(const ArgList &DriverArgs,
+                                ArgStringList &CC1Args) const {
+  if (GCCInstallation.isValid()) {
+    CC1Args.push_back("-isystem");
+    CC1Args.push_back(DriverArgs.MakeArgString(
+        GCCInstallation.getParentLibPath() + "/../" +
+        GCCInstallation.getTriple().str() + "/include"));
+  }
+}
+
+bool Linux::isPIEDefault() const { return getSanitizerArgs().requiresPIE(); }
+
+SanitizerMask Linux::getSupportedSanitizers() const {
+  const bool IsX86 = getTriple().getArch() == llvm::Triple::x86;
+  const bool IsX86_64 = getTriple().getArch() == llvm::Triple::x86_64;
+  const bool IsMIPS64 = getTriple().getArch() == llvm::Triple::mips64 ||
+                        getTriple().getArch() == llvm::Triple::mips64el;
+  const bool IsPowerPC64 = getTriple().getArch() == llvm::Triple::ppc64 ||
+                           getTriple().getArch() == llvm::Triple::ppc64le;
+  const bool IsAArch64 = getTriple().getArch() == llvm::Triple::aarch64 ||
+                         getTriple().getArch() == llvm::Triple::aarch64_be;
+  SanitizerMask Res = ToolChain::getSupportedSanitizers();
+  Res |= SanitizerKind::Address;
+  Res |= SanitizerKind::KernelAddress;
+  Res |= SanitizerKind::Vptr;
+  Res |= SanitizerKind::SafeStack;
+  if (IsX86_64 || IsMIPS64 || IsAArch64)
+    Res |= SanitizerKind::DataFlow;
+  if (IsX86_64 || IsMIPS64 || IsAArch64 || IsX86)
+    Res |= SanitizerKind::Leak;
+  if (IsX86_64 || IsMIPS64 || IsAArch64 || IsPowerPC64)
+    Res |= SanitizerKind::Thread;
+  if (IsX86_64 || IsMIPS64 || IsPowerPC64 || IsAArch64)
+    Res |= SanitizerKind::Memory;
+  if (IsX86_64 || IsMIPS64)
+    Res |= SanitizerKind::Efficiency;
+  if (IsX86 || IsX86_64) {
+    Res |= SanitizerKind::Function;
+  }
+  return Res;
+}
+
+void Linux::addProfileRTLibs(const llvm::opt::ArgList &Args,
+                             llvm::opt::ArgStringList &CmdArgs) const {
+  if (!needsProfileRT(Args)) return;
+
+  // Add linker option -u__llvm_runtime_variable to cause runtime
+  // initialization module to be linked in.
+  if (!Args.hasArg(options::OPT_coverage))
+    CmdArgs.push_back(Args.MakeArgString(
+        Twine("-u", llvm::getInstrProfRuntimeHookVarName())));
+  ToolChain::addProfileRTLibs(Args, CmdArgs);
+}