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//===--- ToolChains.cpp - ToolChain Implementations -----------------------===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
#include "MSVC.h"
#include "CommonArgs.h"
#include "Darwin.h"
#include "clang/Basic/CharInfo.h"
#include "clang/Basic/Version.h"
#include "clang/Driver/Compilation.h"
#include "clang/Driver/Driver.h"
#include "clang/Driver/DriverDiagnostic.h"
#include "clang/Driver/Options.h"
#include "clang/Driver/SanitizerArgs.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Option/Arg.h"
#include "llvm/Option/ArgList.h"
#include "llvm/Support/ConvertUTF.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/Process.h"
#include <cstdio>
#ifdef _WIN32
#define NOGDI
#ifndef NOMINMAX
#define NOMINMAX
#include <windows.h>
#ifdef _MSC_VER
// Don't support SetupApi on MinGW.
// Make sure this comes before MSVCSetupApi.h
#include <comdef.h>
#include "MSVCSetupApi.h"
#include "llvm/Support/COM.h"
_COM_SMARTPTR_TYPEDEF(ISetupConfiguration, __uuidof(ISetupConfiguration));
_COM_SMARTPTR_TYPEDEF(ISetupConfiguration2, __uuidof(ISetupConfiguration2));
_COM_SMARTPTR_TYPEDEF(ISetupHelper, __uuidof(ISetupHelper));
_COM_SMARTPTR_TYPEDEF(IEnumSetupInstances, __uuidof(IEnumSetupInstances));
_COM_SMARTPTR_TYPEDEF(ISetupInstance, __uuidof(ISetupInstance));
_COM_SMARTPTR_TYPEDEF(ISetupInstance2, __uuidof(ISetupInstance2));
using namespace clang::driver;
using namespace clang::driver::toolchains;
using namespace clang::driver::tools;
using namespace clang;
using namespace llvm::opt;
// Defined below.
// Forward declare this so there aren't too many things above the constructor.
static bool getSystemRegistryString(const char *keyPath, const char *valueName,
std::string &value, std::string *phValue);
// Check various environment variables to try and find a toolchain.
static bool findVCToolChainViaEnvironment(std::string &Path,
MSVCToolChain::ToolsetLayout &VSLayout) {
// These variables are typically set by vcvarsall.bat
// when launching a developer command prompt.
if (llvm::Optional<std::string> VCToolsInstallDir =
llvm::sys::Process::GetEnv("VCToolsInstallDir")) {
// This is only set by newer Visual Studios, and it leads straight to
// the toolchain directory.
Path = std::move(*VCToolsInstallDir);
VSLayout = MSVCToolChain::ToolsetLayout::VS2017OrNewer;
return true;
if (llvm::Optional<std::string> VCInstallDir =
llvm::sys::Process::GetEnv("VCINSTALLDIR")) {
// If the previous variable isn't set but this one is, then we've found
// an older Visual Studio. This variable is set by newer Visual Studios too,
// so this check has to appear second.
// In older Visual Studios, the VC directory is the toolchain.
Path = std::move(*VCInstallDir);
VSLayout = MSVCToolChain::ToolsetLayout::OlderVS;
return true;
// We couldn't find any VC environment variables. Let's walk through PATH and
// see if it leads us to a VC toolchain bin directory. If it does, pick the
// first one that we find.
if (llvm::Optional<std::string> PathEnv =
llvm::sys::Process::GetEnv("PATH")) {
llvm::SmallVector<llvm::StringRef, 8> PathEntries;
llvm::StringRef(*PathEnv).split(PathEntries, llvm::sys::EnvPathSeparator);
for (llvm::StringRef PathEntry : PathEntries) {
if (PathEntry.empty())
llvm::SmallString<256> ExeTestPath;
// If cl.exe doesn't exist, then this definitely isn't a VC toolchain.
ExeTestPath = PathEntry;
llvm::sys::path::append(ExeTestPath, "cl.exe");
if (!llvm::sys::fs::exists(ExeTestPath))
// cl.exe existing isn't a conclusive test for a VC toolchain; clang also
// has a cl.exe. So let's check for link.exe too.
ExeTestPath = PathEntry;
llvm::sys::path::append(ExeTestPath, "link.exe");
if (!llvm::sys::fs::exists(ExeTestPath))
// whatever/VC/bin --> old toolchain, VC dir is toolchain dir.
llvm::StringRef TestPath = PathEntry;
bool IsBin = llvm::sys::path::filename(TestPath).equals_lower("bin");
if (!IsBin) {
// Strip any architecture subdir like "amd64".
TestPath = llvm::sys::path::parent_path(TestPath);
IsBin = llvm::sys::path::filename(TestPath).equals_lower("bin");
if (IsBin) {
llvm::StringRef ParentPath = llvm::sys::path::parent_path(TestPath);
llvm::StringRef ParentFilename = llvm::sys::path::filename(ParentPath);
if (ParentFilename == "VC") {
Path = ParentPath;
VSLayout = MSVCToolChain::ToolsetLayout::OlderVS;
return true;
if (ParentFilename == "x86ret" || ParentFilename == "x86chk"
|| ParentFilename == "amd64ret" || ParentFilename == "amd64chk") {
Path = ParentPath;
VSLayout = MSVCToolChain::ToolsetLayout::DevDivInternal;
return true;
} else {
// This could be a new (>=VS2017) toolchain. If it is, we should find
// path components with these prefixes when walking backwards through
// the path.
// Note: empty strings match anything.
llvm::StringRef ExpectedPrefixes[] = {"", "Host", "bin", "",
"MSVC", "Tools", "VC"};
auto It = llvm::sys::path::rbegin(PathEntry);
auto End = llvm::sys::path::rend(PathEntry);
for (llvm::StringRef Prefix : ExpectedPrefixes) {
if (It == End)
goto NotAToolChain;
if (!It->startswith(Prefix))
goto NotAToolChain;
// We've found a new toolchain!
// Back up 3 times (/bin/Host/arch) to get the root path.
llvm::StringRef ToolChainPath(PathEntry);
for (int i = 0; i < 3; ++i)
ToolChainPath = llvm::sys::path::parent_path(ToolChainPath);
Path = ToolChainPath;
VSLayout = MSVCToolChain::ToolsetLayout::VS2017OrNewer;
return true;
return false;
// Query the Setup Config server for installs, then pick the newest version
// and find its default VC toolchain.
// This is the preferred way to discover new Visual Studios, as they're no
// longer listed in the registry.
static bool findVCToolChainViaSetupConfig(std::string &Path,
MSVCToolChain::ToolsetLayout &VSLayout) {
#if !defined(USE_MSVC_SETUP_API)
return false;
// FIXME: This really should be done once in the top-level program's main
// function, as it may have already been initialized with a different
// threading model otherwise.
llvm::sys::InitializeCOMRAII COM(llvm::sys::COMThreadingMode::SingleThreaded);
// _com_ptr_t will throw a _com_error if a COM calls fail.
// The LLVM coding standards forbid exception handling, so we'll have to
// stop them from being thrown in the first place.
// The destructor will put the regular error handler back when we leave
// this scope.
struct SuppressCOMErrorsRAII {
static void __stdcall handler(HRESULT hr, IErrorInfo *perrinfo) {}
SuppressCOMErrorsRAII() { _set_com_error_handler(handler); }
~SuppressCOMErrorsRAII() { _set_com_error_handler(_com_raise_error); }
} COMErrorSuppressor;
ISetupConfigurationPtr Query;
HR = Query.CreateInstance(__uuidof(SetupConfiguration));
return false;
IEnumSetupInstancesPtr EnumInstances;
HR = ISetupConfiguration2Ptr(Query)->EnumAllInstances(&EnumInstances);
return false;
ISetupInstancePtr Instance;
HR = EnumInstances->Next(1, &Instance, nullptr);
if (HR != S_OK)
return false;
ISetupInstancePtr NewestInstance;
Optional<uint64_t> NewestVersionNum;
do {
bstr_t VersionString;
uint64_t VersionNum;
HR = Instance->GetInstallationVersion(VersionString.GetAddress());
HR = ISetupHelperPtr(Query)->ParseVersion(VersionString, &VersionNum);
if (!NewestVersionNum || (VersionNum > NewestVersionNum)) {
NewestInstance = Instance;
NewestVersionNum = VersionNum;
} while ((HR = EnumInstances->Next(1, &Instance, nullptr)) == S_OK);
if (!NewestInstance)
return false;
bstr_t VCPathWide;
HR = NewestInstance->ResolvePath(L"VC", VCPathWide.GetAddress());
return false;
std::string VCRootPath;
llvm::convertWideToUTF8(std::wstring(VCPathWide), VCRootPath);
llvm::SmallString<256> ToolsVersionFilePath(VCRootPath);
llvm::sys::path::append(ToolsVersionFilePath, "Auxiliary", "Build",
auto ToolsVersionFile = llvm::MemoryBuffer::getFile(ToolsVersionFilePath);
if (!ToolsVersionFile)
return false;
llvm::SmallString<256> ToolchainPath(VCRootPath);
llvm::sys::path::append(ToolchainPath, "Tools", "MSVC",
if (!llvm::sys::fs::is_directory(ToolchainPath))
return false;
Path = ToolchainPath.str();
VSLayout = MSVCToolChain::ToolsetLayout::VS2017OrNewer;
return true;
// Look in the registry for Visual Studio installs, and use that to get
// a toolchain path. VS2017 and newer don't get added to the registry.
// So if we find something here, we know that it's an older version.
static bool findVCToolChainViaRegistry(std::string &Path,
MSVCToolChain::ToolsetLayout &VSLayout) {
std::string VSInstallPath;
if (getSystemRegistryString(R"(SOFTWARE\Microsoft\VisualStudio\$VERSION)",
"InstallDir", VSInstallPath, nullptr) ||
"InstallDir", VSInstallPath, nullptr)) {
if (!VSInstallPath.empty()) {
llvm::SmallString<256> VCPath(llvm::StringRef(
VSInstallPath.c_str(), VSInstallPath.find(R"(\Common7\IDE)")));
llvm::sys::path::append(VCPath, "VC");
Path = VCPath.str();
VSLayout = MSVCToolChain::ToolsetLayout::OlderVS;
return true;
return false;
// Try to find Exe from a Visual Studio distribution. This first tries to find
// an installed copy of Visual Studio and, failing that, looks in the PATH,
// making sure that whatever executable that's found is not a same-named exe
// from clang itself to prevent clang from falling back to itself.
static std::string FindVisualStudioExecutable(const ToolChain &TC,
const char *Exe) {
const auto &MSVC = static_cast<const toolchains::MSVCToolChain &>(TC);
SmallString<128> FilePath(MSVC.getSubDirectoryPath(
llvm::sys::path::append(FilePath, Exe);
return llvm::sys::fs::can_execute(FilePath) ? FilePath.str() : Exe;
void visualstudio::Linker::ConstructJob(Compilation &C, const JobAction &JA,
const InputInfo &Output,
const InputInfoList &Inputs,
const ArgList &Args,
const char *LinkingOutput) const {
ArgStringList CmdArgs;
auto &TC = static_cast<const toolchains::MSVCToolChain &>(getToolChain());
assert((Output.isFilename() || Output.isNothing()) && "invalid output");
if (Output.isFilename())
Args.MakeArgString(std::string("-out:") + Output.getFilename()));
if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles) &&
if (!llvm::sys::Process::GetEnv("LIB")) {
// If the VC environment hasn't been configured (perhaps because the user
// did not run vcvarsall), try to build a consistent link environment. If
// the environment variable is set however, assume the user knows what
// they're doing.
Twine("-libpath:") +
if (TC.useUniversalCRT()) {
std::string UniversalCRTLibPath;
if (TC.getUniversalCRTLibraryPath(UniversalCRTLibPath))
Args.MakeArgString(Twine("-libpath:") + UniversalCRTLibPath));
std::string WindowsSdkLibPath;
if (TC.getWindowsSDKLibraryPath(WindowsSdkLibPath))
Args.MakeArgString(std::string("-libpath:") + WindowsSdkLibPath));
if (!C.getDriver().IsCLMode() && Args.hasArg(options::OPT_L))
for (const auto &LibPath : Args.getAllArgValues(options::OPT_L))
CmdArgs.push_back(Args.MakeArgString("-libpath:" + LibPath));
if (Args.hasArg(options::OPT_g_Group, options::OPT__SLASH_Z7,
bool DLL = Args.hasArg(options::OPT__SLASH_LD, options::OPT__SLASH_LDd,
if (DLL) {
SmallString<128> ImplibName(Output.getFilename());
llvm::sys::path::replace_extension(ImplibName, "lib");
CmdArgs.push_back(Args.MakeArgString(std::string("-implib:") + ImplibName));
if (TC.getSanitizerArgs().needsAsanRt()) {
if (TC.getSanitizerArgs().needsSharedRt() ||
Args.hasArg(options::OPT__SLASH_MD, options::OPT__SLASH_MDd)) {
for (const auto &Lib : {"asan_dynamic", "asan_dynamic_runtime_thunk"})
CmdArgs.push_back(TC.getCompilerRTArgString(Args, Lib));
// Make sure the dynamic runtime thunk is not optimized out at link time
// to ensure proper SEH handling.
TC.getArch() == llvm::Triple::x86
? "-include:___asan_seh_interceptor"
: "-include:__asan_seh_interceptor"));
// Make sure the linker consider all object files from the dynamic runtime
// thunk.
CmdArgs.push_back(Args.MakeArgString(std::string("-wholearchive:") +
TC.getCompilerRT(Args, "asan_dynamic_runtime_thunk")));
} else if (DLL) {
CmdArgs.push_back(TC.getCompilerRTArgString(Args, "asan_dll_thunk"));
} else {
for (const auto &Lib : {"asan", "asan_cxx"}) {
CmdArgs.push_back(TC.getCompilerRTArgString(Args, Lib));
// Make sure the linker consider all object files from the static lib.
// This is necessary because instrumented dlls need access to all the
// interface exported by the static lib in the main executable.
CmdArgs.push_back(Args.MakeArgString(std::string("-wholearchive:") +
TC.getCompilerRT(Args, Lib)));
Args.AddAllArgValues(CmdArgs, options::OPT__SLASH_link);
if (Args.hasFlag(options::OPT_fopenmp, options::OPT_fopenmp_EQ,
options::OPT_fno_openmp, false)) {
CmdArgs.push_back(Args.MakeArgString(std::string("-libpath:") +
TC.getDriver().Dir + "/../lib"));
switch (TC.getDriver().getOpenMPRuntime(Args)) {
case Driver::OMPRT_OMP:
case Driver::OMPRT_IOMP5:
case Driver::OMPRT_GOMP:
case Driver::OMPRT_Unknown:
// Already diagnosed.
// Add compiler-rt lib in case if it was explicitly
// specified as an argument for --rtlib option.
if (!Args.hasArg(options::OPT_nostdlib)) {
AddRunTimeLibs(TC, TC.getDriver(), CmdArgs, Args);
// Add filenames, libraries, and other linker inputs.
for (const auto &Input : Inputs) {
if (Input.isFilename()) {
const Arg &A = Input.getInputArg();
// Render -l options differently for the MSVC linker.
if (A.getOption().matches(options::OPT_l)) {
StringRef Lib = A.getValue();
const char *LinkLibArg;
if (Lib.endswith(".lib"))
LinkLibArg = Args.MakeArgString(Lib);
LinkLibArg = Args.MakeArgString(Lib + ".lib");
// Otherwise, this is some other kind of linker input option like -Wl, -z,
// or -L. Render it, even if MSVC doesn't understand it.
A.renderAsInput(Args, CmdArgs);
TC.addProfileRTLibs(Args, CmdArgs);
std::vector<const char *> Environment;
// We need to special case some linker paths. In the case of lld, we need to
// translate 'lld' into 'lld-link', and in the case of the regular msvc
// linker, we need to use a special search algorithm.
llvm::SmallString<128> linkPath;
StringRef Linker = Args.getLastArgValue(options::OPT_fuse_ld_EQ, "link");
if (Linker.equals_lower("lld"))
Linker = "lld-link";
if (Linker.equals_lower("link")) {
// If we're using the MSVC linker, it's not sufficient to just use link
// from the program PATH, because other environments like GnuWin32 install
// their own link.exe which may come first.
linkPath = FindVisualStudioExecutable(TC, "link.exe");
if (!TC.FoundMSVCInstall() && !llvm::sys::fs::can_execute(linkPath))
#ifdef _WIN32
// When cross-compiling with VS2017 or newer, link.exe expects to have
// its containing bin directory at the top of PATH, followed by the
// native target bin directory.
// e.g. when compiling for x86 on an x64 host, PATH should start with:
// /bin/HostX64/x86;/bin/HostX64/x64
// This doesn't attempt to handle ToolsetLayout::DevDivInternal.
if (TC.getIsVS2017OrNewer() &&
llvm::Triple(llvm::sys::getProcessTriple()).getArch() != TC.getArch()) {
auto HostArch = llvm::Triple(llvm::sys::getProcessTriple()).getArch();
auto EnvBlockWide =
std::unique_ptr<wchar_t[], decltype(&FreeEnvironmentStringsW)>(
GetEnvironmentStringsW(), FreeEnvironmentStringsW);
if (!EnvBlockWide)
goto SkipSettingEnvironment;
size_t EnvCount = 0;
size_t EnvBlockLen = 0;
while (EnvBlockWide[EnvBlockLen] != L'\0') {
EnvBlockLen += std::wcslen(&EnvBlockWide[EnvBlockLen]) +
1 /*string null-terminator*/;
++EnvBlockLen; // add the block null-terminator
std::string EnvBlock;
if (!llvm::convertUTF16ToUTF8String(
llvm::ArrayRef<char>(reinterpret_cast<char *>(EnvBlockWide.get()),
EnvBlockLen * sizeof(EnvBlockWide[0])),
goto SkipSettingEnvironment;
// Now loop over each string in the block and copy them into the
// environment vector, adjusting the PATH variable as needed when we
// find it.
for (const char *Cursor =; *Cursor != '\0';) {
llvm::StringRef EnvVar(Cursor);
if (EnvVar.startswith_lower("path=")) {
using SubDirectoryType = toolchains::MSVCToolChain::SubDirectoryType;
constexpr size_t PrefixLen = 5; // strlen("path=")
EnvVar.substr(0, PrefixLen) +
TC.getSubDirectoryPath(SubDirectoryType::Bin) +
llvm::Twine(llvm::sys::EnvPathSeparator) +
TC.getSubDirectoryPath(SubDirectoryType::Bin, HostArch) +
(EnvVar.size() > PrefixLen
? llvm::Twine(llvm::sys::EnvPathSeparator) +
: "")));
} else {
Cursor += EnvVar.size() + 1 /*null-terminator*/;
} else {
linkPath = TC.GetProgramPath(Linker.str().c_str());
auto LinkCmd = llvm::make_unique<Command>(
JA, *this, Args.MakeArgString(linkPath), CmdArgs, Inputs);
if (!Environment.empty())
void visualstudio::Compiler::ConstructJob(Compilation &C, const JobAction &JA,
const InputInfo &Output,
const InputInfoList &Inputs,
const ArgList &Args,
const char *LinkingOutput) const {
C.addCommand(GetCommand(C, JA, Output, Inputs, Args, LinkingOutput));
std::unique_ptr<Command> visualstudio::Compiler::GetCommand(
Compilation &C, const JobAction &JA, const InputInfo &Output,
const InputInfoList &Inputs, const ArgList &Args,
const char *LinkingOutput) const {
ArgStringList CmdArgs;
CmdArgs.push_back("/c"); // Compile only.
CmdArgs.push_back("/W0"); // No warnings.
// The goal is to be able to invoke this tool correctly based on
// any flag accepted by clang-cl.
// These are spelled the same way in clang and cl.exe,.
Args.AddAllArgs(CmdArgs, {options::OPT_D, options::OPT_U, options::OPT_I});
// Optimization level.
if (Arg *A = Args.getLastArg(options::OPT_fbuiltin, options::OPT_fno_builtin))
CmdArgs.push_back(A->getOption().getID() == options::OPT_fbuiltin ? "/Oi"
: "/Oi-");
if (Arg *A = Args.getLastArg(options::OPT_O, options::OPT_O0)) {
if (A->getOption().getID() == options::OPT_O0) {
} else {
StringRef OptLevel = A->getValue();
if (OptLevel == "s" || OptLevel == "z")
if (Arg *A = Args.getLastArg(options::OPT_fomit_frame_pointer,
CmdArgs.push_back(A->getOption().getID() == options::OPT_fomit_frame_pointer
? "/Oy"
: "/Oy-");
if (!Args.hasArg(options::OPT_fwritable_strings))
// Flags for which clang-cl has an alias.
// FIXME: How can we ensure this stays in sync with relevant clang-cl options?
if (Args.hasFlag(options::OPT__SLASH_GR_, options::OPT__SLASH_GR,
if (Args.hasFlag(options::OPT__SLASH_GS_, options::OPT__SLASH_GS,
if (Arg *A = Args.getLastArg(options::OPT_ffunction_sections,
CmdArgs.push_back(A->getOption().getID() == options::OPT_ffunction_sections
? "/Gy"
: "/Gy-");
if (Arg *A = Args.getLastArg(options::OPT_fdata_sections,
A->getOption().getID() == options::OPT_fdata_sections ? "/Gw" : "/Gw-");
if (Args.hasArg(options::OPT_fsyntax_only))
if (Args.hasArg(options::OPT_g_Flag, options::OPT_gline_tables_only,
std::vector<std::string> Includes =
for (const auto &Include : Includes)
CmdArgs.push_back(Args.MakeArgString(std::string("/FI") + Include));
// Flags that can simply be passed through.
Args.AddAllArgs(CmdArgs, options::OPT__SLASH_LD);
Args.AddAllArgs(CmdArgs, options::OPT__SLASH_LDd);
Args.AddAllArgs(CmdArgs, options::OPT__SLASH_GX);
Args.AddAllArgs(CmdArgs, options::OPT__SLASH_GX_);
Args.AddAllArgs(CmdArgs, options::OPT__SLASH_EH);
Args.AddAllArgs(CmdArgs, options::OPT__SLASH_Zl);
// The order of these flags is relevant, so pick the last one.
if (Arg *A = Args.getLastArg(options::OPT__SLASH_MD, options::OPT__SLASH_MDd,
options::OPT__SLASH_MT, options::OPT__SLASH_MTd))
A->render(Args, CmdArgs);
// Use MSVC's default threadsafe statics behaviour unless there was a flag.
if (Arg *A = Args.getLastArg(options::OPT_fthreadsafe_statics,
options::OPT_fno_threadsafe_statics)) {
CmdArgs.push_back(A->getOption().getID() == options::OPT_fthreadsafe_statics
? "/Zc:threadSafeInit"
: "/Zc:threadSafeInit-");
// Pass through all unknown arguments so that the fallback command can see
// them too.
Args.AddAllArgs(CmdArgs, options::OPT_UNKNOWN);
// Input filename.
assert(Inputs.size() == 1);
const InputInfo &II = Inputs[0];
assert(II.getType() == types::TY_C || II.getType() == types::TY_CXX);
CmdArgs.push_back(II.getType() == types::TY_C ? "/Tc" : "/Tp");
if (II.isFilename())
II.getInputArg().renderAsInput(Args, CmdArgs);
// Output filename.
assert(Output.getType() == types::TY_Object);
const char *Fo =
Args.MakeArgString(std::string("/Fo") + Output.getFilename());
std::string Exec = FindVisualStudioExecutable(getToolChain(), "cl.exe");
return llvm::make_unique<Command>(JA, *this, Args.MakeArgString(Exec),
CmdArgs, Inputs);
MSVCToolChain::MSVCToolChain(const Driver &D, const llvm::Triple &Triple,
const ArgList &Args)
: ToolChain(D, Triple, Args), CudaInstallation(D, Triple, Args) {
if (getDriver().getInstalledDir() != getDriver().Dir)
// Check the environment first, since that's probably the user telling us
// what they want to use.
// Failing that, just try to find the newest Visual Studio version we can
// and use its default VC toolchain.
findVCToolChainViaEnvironment(VCToolChainPath, VSLayout) ||
findVCToolChainViaSetupConfig(VCToolChainPath, VSLayout) ||
findVCToolChainViaRegistry(VCToolChainPath, VSLayout);
Tool *MSVCToolChain::buildLinker() const {
return new tools::visualstudio::Linker(*this);
Tool *MSVCToolChain::buildAssembler() const {
if (getTriple().isOSBinFormatMachO())
return new tools::darwin::Assembler(*this);
return nullptr;
bool MSVCToolChain::IsIntegratedAssemblerDefault() const {
return true;
bool MSVCToolChain::IsUnwindTablesDefault(const ArgList &Args) const {
// Emit unwind tables by default on Win64. All non-x86_32 Windows platforms
// such as ARM and PPC actually require unwind tables, but LLVM doesn't know
// how to generate them yet.
// Don't emit unwind tables by default for MachO targets.
if (getTriple().isOSBinFormatMachO())
return false;
return getArch() == llvm::Triple::x86_64;
bool MSVCToolChain::isPICDefault() const {
return getArch() == llvm::Triple::x86_64;
bool MSVCToolChain::isPIEDefault() const {
return false;
bool MSVCToolChain::isPICDefaultForced() const {
return getArch() == llvm::Triple::x86_64;
void MSVCToolChain::AddCudaIncludeArgs(const ArgList &DriverArgs,
ArgStringList &CC1Args) const {
CudaInstallation.AddCudaIncludeArgs(DriverArgs, CC1Args);
void MSVCToolChain::printVerboseInfo(raw_ostream &OS) const {
// Windows SDKs and VC Toolchains group their contents into subdirectories based
// on the target architecture. This function converts an llvm::Triple::ArchType
// to the corresponding subdirectory name.
static const char *llvmArchToWindowsSDKArch(llvm::Triple::ArchType Arch) {
using ArchType = llvm::Triple::ArchType;
switch (Arch) {
case ArchType::x86:
return "x86";
case ArchType::x86_64:
return "x64";
case ArchType::arm:
return "arm";
case ArchType::aarch64:
return "arm64";
return "";
// Similar to the above function, but for Visual Studios before VS2017.
static const char *llvmArchToLegacyVCArch(llvm::Triple::ArchType Arch) {
using ArchType = llvm::Triple::ArchType;
switch (Arch) {
case ArchType::x86:
// x86 is default in legacy VC toolchains.
// e.g. x86 libs are directly in /lib as opposed to /lib/x86.
return "";
case ArchType::x86_64:
return "amd64";
case ArchType::arm:
return "arm";
case ArchType::aarch64:
return "arm64";
return "";
// Similar to the above function, but for DevDiv internal builds.
static const char *llvmArchToDevDivInternalArch(llvm::Triple::ArchType Arch) {
using ArchType = llvm::Triple::ArchType;
switch (Arch) {
case ArchType::x86:
return "i386";
case ArchType::x86_64:
return "amd64";
case ArchType::arm:
return "arm";
case ArchType::aarch64:
return "arm64";
return "";
// Get the path to a specific subdirectory in the current toolchain for
// a given target architecture.
// VS2017 changed the VC toolchain layout, so this should be used instead
// of hardcoding paths.
MSVCToolChain::getSubDirectoryPath(SubDirectoryType Type,
llvm::Triple::ArchType TargetArch) const {
const char *SubdirName;
const char *IncludeName;
switch (VSLayout) {
case ToolsetLayout::OlderVS:
SubdirName = llvmArchToLegacyVCArch(TargetArch);
IncludeName = "include";
case ToolsetLayout::VS2017OrNewer:
SubdirName = llvmArchToWindowsSDKArch(TargetArch);
IncludeName = "include";
case ToolsetLayout::DevDivInternal:
SubdirName = llvmArchToDevDivInternalArch(TargetArch);
IncludeName = "inc";
llvm::SmallString<256> Path(VCToolChainPath);
switch (Type) {
case SubDirectoryType::Bin:
if (VSLayout == ToolsetLayout::VS2017OrNewer) {
const bool HostIsX64 =
const char *const HostName = HostIsX64 ? "HostX64" : "HostX86";
llvm::sys::path::append(Path, "bin", HostName, SubdirName);
} else { // OlderVS or DevDivInternal
llvm::sys::path::append(Path, "bin", SubdirName);
case SubDirectoryType::Include:
llvm::sys::path::append(Path, IncludeName);
case SubDirectoryType::Lib:
llvm::sys::path::append(Path, "lib", SubdirName);
return Path.str();
#ifdef _WIN32
static bool readFullStringValue(HKEY hkey, const char *valueName,
std::string &value) {
std::wstring WideValueName;
if (!llvm::ConvertUTF8toWide(valueName, WideValueName))
return false;
DWORD result = 0;
DWORD valueSize = 0;
DWORD type = 0;
// First just query for the required size.
result = RegQueryValueExW(hkey, WideValueName.c_str(), NULL, &type, NULL,
if (result != ERROR_SUCCESS || type != REG_SZ || !valueSize)
return false;
std::vector<BYTE> buffer(valueSize);
result = RegQueryValueExW(hkey, WideValueName.c_str(), NULL, NULL, &buffer[0],
if (result == ERROR_SUCCESS) {
std::wstring WideValue(reinterpret_cast<const wchar_t *>(,
valueSize / sizeof(wchar_t));
if (valueSize && WideValue.back() == L'\0') {
// The destination buffer must be empty as an invariant of the conversion
// function; but this function is sometimes called in a loop that passes in
// the same buffer, however. Simply clear it out so we can overwrite it.
return llvm::convertWideToUTF8(WideValue, value);
return false;
/// Read registry string.
/// This also supports a means to look for high-versioned keys by use
/// of a $VERSION placeholder in the key path.
/// $VERSION in the key path is a placeholder for the version number,
/// causing the highest value path to be searched for and used.
/// I.e. "SOFTWARE\\Microsoft\\VisualStudio\\$VERSION".
/// There can be additional characters in the component. Only the numeric
/// characters are compared. This function only searches HKLM.
static bool getSystemRegistryString(const char *keyPath, const char *valueName,
std::string &value, std::string *phValue) {
#ifndef _WIN32
return false;
long lResult;
bool returnValue = false;
const char *placeHolder = strstr(keyPath, "$VERSION");
std::string bestName;
// If we have a $VERSION placeholder, do the highest-version search.
if (placeHolder) {
const char *keyEnd = placeHolder - 1;
const char *nextKey = placeHolder;
// Find end of previous key.
while ((keyEnd > keyPath) && (*keyEnd != '\\'))
// Find end of key containing $VERSION.
while (*nextKey && (*nextKey != '\\'))
size_t partialKeyLength = keyEnd - keyPath;
char partialKey[256];
if (partialKeyLength >= sizeof(partialKey))
partialKeyLength = sizeof(partialKey) - 1;
strncpy(partialKey, keyPath, partialKeyLength);
partialKey[partialKeyLength] = '\0';
HKEY hTopKey = NULL;
lResult = RegOpenKeyExA(hRootKey, partialKey, 0, KEY_READ | KEY_WOW64_32KEY,
if (lResult == ERROR_SUCCESS) {
char keyName[256];
double bestValue = 0.0;
DWORD index, size = sizeof(keyName) - 1;
for (index = 0; RegEnumKeyExA(hTopKey, index, keyName, &size, NULL, NULL,
index++) {
const char *sp = keyName;
while (*sp && !isDigit(*sp))
if (!*sp)
const char *ep = sp + 1;
while (*ep && (isDigit(*ep) || (*ep == '.')))
char numBuf[32];
strncpy(numBuf, sp, sizeof(numBuf) - 1);
numBuf[sizeof(numBuf) - 1] = '\0';
double dvalue = strtod(numBuf, NULL);
if (dvalue > bestValue) {
// Test that InstallDir is indeed there before keeping this index.
// Open the chosen key path remainder.
bestName = keyName;
// Append rest of key.
lResult = RegOpenKeyExA(hTopKey, bestName.c_str(), 0,
KEY_READ | KEY_WOW64_32KEY, &hKey);
if (lResult == ERROR_SUCCESS) {
if (readFullStringValue(hKey, valueName, value)) {
bestValue = dvalue;
if (phValue)
*phValue = bestName;
returnValue = true;
size = sizeof(keyName) - 1;
} else {
lResult =
RegOpenKeyExA(hRootKey, keyPath, 0, KEY_READ | KEY_WOW64_32KEY, &hKey);
if (lResult == ERROR_SUCCESS) {
if (readFullStringValue(hKey, valueName, value))
returnValue = true;
if (phValue)
return returnValue;
#endif // _WIN32
// Find the most recent version of Universal CRT or Windows 10 SDK.
// vcvarsqueryregistry.bat from Visual Studio 2015 sorts entries in the include
// directory by name and uses the last one of the list.
// So we compare entry names lexicographically to find the greatest one.
static bool getWindows10SDKVersionFromPath(const std::string &SDKPath,
std::string &SDKVersion) {
std::error_code EC;
llvm::SmallString<128> IncludePath(SDKPath);
llvm::sys::path::append(IncludePath, "Include");
for (llvm::sys::fs::directory_iterator DirIt(IncludePath, EC), DirEnd;
DirIt != DirEnd && !EC; DirIt.increment(EC)) {
if (!llvm::sys::fs::is_directory(DirIt->path()))
StringRef CandidateName = llvm::sys::path::filename(DirIt->path());
// If WDK is installed, there could be subfolders like "wdf" in the
// "Include" directory.
// Allow only directories which names start with "10.".
if (!CandidateName.startswith("10."))
if (CandidateName > SDKVersion)
SDKVersion = CandidateName;
return !SDKVersion.empty();
/// Get Windows SDK installation directory.
static bool getWindowsSDKDir(std::string &Path, int &Major,
std::string &WindowsSDKIncludeVersion,
std::string &WindowsSDKLibVersion) {
std::string RegistrySDKVersion;
// Try the Windows registry.
if (!getSystemRegistryString(
"SOFTWARE\\Microsoft\\Microsoft SDKs\\Windows\\$VERSION",
"InstallationFolder", Path, &RegistrySDKVersion))
return false;
if (Path.empty() || RegistrySDKVersion.empty())
return false;
Major = 0;
std::sscanf(RegistrySDKVersion.c_str(), "v%d.", &Major);
if (Major <= 7)
return true;
if (Major == 8) {
// Windows SDK 8.x installs libraries in a folder whose names depend on the
// version of the OS you're targeting. By default choose the newest, which
// usually corresponds to the version of the OS you've installed the SDK on.
const char *Tests[] = {"winv6.3", "win8", "win7"};
for (const char *Test : Tests) {
llvm::SmallString<128> TestPath(Path);
llvm::sys::path::append(TestPath, "Lib", Test);
if (llvm::sys::fs::exists(TestPath.c_str())) {
WindowsSDKLibVersion = Test;
return !WindowsSDKLibVersion.empty();
if (Major == 10) {
if (!getWindows10SDKVersionFromPath(Path, WindowsSDKIncludeVersion))
return false;
WindowsSDKLibVersion = WindowsSDKIncludeVersion;
return true;
// Unsupported SDK version
return false;
// Gets the library path required to link against the Windows SDK.
bool MSVCToolChain::getWindowsSDKLibraryPath(std::string &path) const {
std::string sdkPath;
int sdkMajor = 0;
std::string windowsSDKIncludeVersion;
std::string windowsSDKLibVersion;
if (!getWindowsSDKDir(sdkPath, sdkMajor, windowsSDKIncludeVersion,
return false;
llvm::SmallString<128> libPath(sdkPath);
llvm::sys::path::append(libPath, "Lib");
if (sdkMajor >= 8) {
llvm::sys::path::append(libPath, windowsSDKLibVersion, "um",
} else {
switch (getArch()) {
// In Windows SDK 7.x, x86 libraries are directly in the Lib folder.
case llvm::Triple::x86:
case llvm::Triple::x86_64:
llvm::sys::path::append(libPath, "x64");
case llvm::Triple::arm:
// It is not necessary to link against Windows SDK 7.x when targeting ARM.
return false;
return false;
path = libPath.str();
return true;
// Check if the Include path of a specified version of Visual Studio contains
// specific header files. If not, they are probably shipped with Universal CRT.
bool MSVCToolChain::useUniversalCRT() const {
llvm::SmallString<128> TestPath(
llvm::sys::path::append(TestPath, "stdlib.h");
return !llvm::sys::fs::exists(TestPath);
static bool getUniversalCRTSdkDir(std::string &Path, std::string &UCRTVersion) {
// vcvarsqueryregistry.bat for Visual Studio 2015 queries the registry
// for the specific key "KitsRoot10". So do we.
if (!getSystemRegistryString(
"SOFTWARE\\Microsoft\\Windows Kits\\Installed Roots", "KitsRoot10",
Path, nullptr))
return false;
return getWindows10SDKVersionFromPath(Path, UCRTVersion);
bool MSVCToolChain::getUniversalCRTLibraryPath(std::string &Path) const {
std::string UniversalCRTSdkPath;
std::string UCRTVersion;
if (!getUniversalCRTSdkDir(UniversalCRTSdkPath, UCRTVersion))
return false;
StringRef ArchName = llvmArchToWindowsSDKArch(getArch());
if (ArchName.empty())
return false;
llvm::SmallString<128> LibPath(UniversalCRTSdkPath);
llvm::sys::path::append(LibPath, "Lib", UCRTVersion, "ucrt", ArchName);
Path = LibPath.str();
return true;
static VersionTuple getMSVCVersionFromTriple(const llvm::Triple &Triple) {
unsigned Major, Minor, Micro;
Triple.getEnvironmentVersion(Major, Minor, Micro);
if (Major || Minor || Micro)
return VersionTuple(Major, Minor, Micro);
return VersionTuple();
static VersionTuple getMSVCVersionFromExe(const std::string &BinDir) {
VersionTuple Version;
#ifdef _WIN32
SmallString<128> ClExe(BinDir);
llvm::sys::path::append(ClExe, "cl.exe");
std::wstring ClExeWide;
if (!llvm::ConvertUTF8toWide(ClExe.c_str(), ClExeWide))
return Version;
const DWORD VersionSize = ::GetFileVersionInfoSizeW(ClExeWide.c_str(),
if (VersionSize == 0)
return Version;
SmallVector<uint8_t, 4 * 1024> VersionBlock(VersionSize);
if (!::GetFileVersionInfoW(ClExeWide.c_str(), 0, VersionSize,
return Version;
VS_FIXEDFILEINFO *FileInfo = nullptr;
UINT FileInfoSize = 0;
if (!::VerQueryValueW(, L"\\",
reinterpret_cast<LPVOID *>(&FileInfo), &FileInfoSize) ||
FileInfoSize < sizeof(*FileInfo))
return Version;
const unsigned Major = (FileInfo->dwFileVersionMS >> 16) & 0xFFFF;
const unsigned Minor = (FileInfo->dwFileVersionMS ) & 0xFFFF;
const unsigned Micro = (FileInfo->dwFileVersionLS >> 16) & 0xFFFF;
Version = VersionTuple(Major, Minor, Micro);
return Version;
void MSVCToolChain::AddSystemIncludeWithSubfolder(
const ArgList &DriverArgs, ArgStringList &CC1Args,
const std::string &folder, const Twine &subfolder1, const Twine &subfolder2,
const Twine &subfolder3) const {
llvm::SmallString<128> path(folder);
llvm::sys::path::append(path, subfolder1, subfolder2, subfolder3);
addSystemInclude(DriverArgs, CC1Args, path);
void MSVCToolChain::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
ArgStringList &CC1Args) const {
if (DriverArgs.hasArg(options::OPT_nostdinc))
if (!DriverArgs.hasArg(options::OPT_nobuiltininc)) {
AddSystemIncludeWithSubfolder(DriverArgs, CC1Args, getDriver().ResourceDir,
// Add %INCLUDE%-like directories from the -imsvc flag.
for (const auto &Path : DriverArgs.getAllArgValues(options::OPT__SLASH_imsvc))
addSystemInclude(DriverArgs, CC1Args, Path);
if (DriverArgs.hasArg(options::OPT_nostdlibinc))
// Honor %INCLUDE%. It should know essential search paths with vcvarsall.bat.
if (llvm::Optional<std::string> cl_include_dir =
llvm::sys::Process::GetEnv("INCLUDE")) {
SmallVector<StringRef, 8> Dirs;
.split(Dirs, ";", /*MaxSplit=*/-1, /*KeepEmpty=*/false);
for (StringRef Dir : Dirs)
addSystemInclude(DriverArgs, CC1Args, Dir);
if (!Dirs.empty())
// When built with access to the proper Windows APIs, try to actually find
// the correct include paths first.
if (!VCToolChainPath.empty()) {
addSystemInclude(DriverArgs, CC1Args,
if (useUniversalCRT()) {
std::string UniversalCRTSdkPath;
std::string UCRTVersion;
if (getUniversalCRTSdkDir(UniversalCRTSdkPath, UCRTVersion)) {
AddSystemIncludeWithSubfolder(DriverArgs, CC1Args, UniversalCRTSdkPath,
"Include", UCRTVersion, "ucrt");
std::string WindowsSDKDir;
int major;
std::string windowsSDKIncludeVersion;
std::string windowsSDKLibVersion;
if (getWindowsSDKDir(WindowsSDKDir, major, windowsSDKIncludeVersion,
windowsSDKLibVersion)) {
if (major >= 8) {
// Note: windowsSDKIncludeVersion is empty for SDKs prior to v10.
// Anyway, llvm::sys::path::append is able to manage it.
AddSystemIncludeWithSubfolder(DriverArgs, CC1Args, WindowsSDKDir,
"include", windowsSDKIncludeVersion,
AddSystemIncludeWithSubfolder(DriverArgs, CC1Args, WindowsSDKDir,
"include", windowsSDKIncludeVersion,
AddSystemIncludeWithSubfolder(DriverArgs, CC1Args, WindowsSDKDir,
"include", windowsSDKIncludeVersion,
} else {
AddSystemIncludeWithSubfolder(DriverArgs, CC1Args, WindowsSDKDir,
#if defined(_WIN32)
// As a fallback, select default install paths.
// FIXME: Don't guess drives and paths like this on Windows.
const StringRef Paths[] = {
"C:/Program Files/Microsoft Visual Studio 10.0/VC/include",
"C:/Program Files/Microsoft Visual Studio 9.0/VC/include",
"C:/Program Files/Microsoft Visual Studio 9.0/VC/PlatformSDK/Include",
"C:/Program Files/Microsoft Visual Studio 8/VC/include",
"C:/Program Files/Microsoft Visual Studio 8/VC/PlatformSDK/Include"
addSystemIncludes(DriverArgs, CC1Args, Paths);
void MSVCToolChain::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
ArgStringList &CC1Args) const {
// FIXME: There should probably be logic here to find libc++ on Windows.
VersionTuple MSVCToolChain::computeMSVCVersion(const Driver *D,
const ArgList &Args) const {
bool IsWindowsMSVC = getTriple().isWindowsMSVCEnvironment();
VersionTuple MSVT = ToolChain::computeMSVCVersion(D, Args);
if (MSVT.empty())
MSVT = getMSVCVersionFromTriple(getTriple());
if (MSVT.empty() && IsWindowsMSVC)
MSVT = getMSVCVersionFromExe(getSubDirectoryPath(SubDirectoryType::Bin));
if (MSVT.empty() &&
Args.hasFlag(options::OPT_fms_extensions, options::OPT_fno_ms_extensions,
IsWindowsMSVC)) {
// -fms-compatibility-version=19.11 is default, aka 2017
MSVT = VersionTuple(19, 11);
return MSVT;
MSVCToolChain::ComputeEffectiveClangTriple(const ArgList &Args,
types::ID InputType) const {
// The MSVC version doesn't care about the architecture, even though it
// may look at the triple internally.
VersionTuple MSVT = computeMSVCVersion(/*D=*/nullptr, Args);
MSVT = VersionTuple(MSVT.getMajor(), MSVT.getMinor().getValueOr(0),
// For the rest of the triple, however, a computed architecture name may
// be needed.
llvm::Triple Triple(ToolChain::ComputeEffectiveClangTriple(Args, InputType));
if (Triple.getEnvironment() == llvm::Triple::MSVC) {
StringRef ObjFmt = Triple.getEnvironmentName().split('-').second;
if (ObjFmt.empty())
Triple.setEnvironmentName((Twine("msvc") + MSVT.getAsString()).str());
(Twine("msvc") + MSVT.getAsString() + Twine('-') + ObjFmt).str());
return Triple.getTriple();
SanitizerMask MSVCToolChain::getSupportedSanitizers() const {
SanitizerMask Res = ToolChain::getSupportedSanitizers();
Res |= SanitizerKind::Address;
Res &= ~SanitizerKind::CFIMFCall;
return Res;
static void TranslateOptArg(Arg *A, llvm::opt::DerivedArgList &DAL,
bool SupportsForcingFramePointer,
const char *ExpandChar, const OptTable &Opts) {
StringRef OptStr = A->getValue();
for (size_t I = 0, E = OptStr.size(); I != E; ++I) {
const char &OptChar = *( + I);
switch (OptChar) {
case '1':
case '2':
case 'x':
case 'd':
// Ignore /O[12xd] flags that aren't the last one on the command line.
// Only the last one gets expanded.
if (&OptChar != ExpandChar) {
if (OptChar == 'd') {
DAL.AddFlagArg(A, Opts.getOption(options::OPT_O0));
} else {
if (OptChar == '1') {
DAL.AddJoinedArg(A, Opts.getOption(options::OPT_O), "s");
} else if (OptChar == '2' || OptChar == 'x') {
DAL.AddFlagArg(A, Opts.getOption(options::OPT_fbuiltin));
DAL.AddJoinedArg(A, Opts.getOption(options::OPT_O), "2");
if (SupportsForcingFramePointer &&
DAL.AddFlagArg(A, Opts.getOption(options::OPT_fomit_frame_pointer));
if (OptChar == '1' || OptChar == '2')
DAL.AddFlagArg(A, Opts.getOption(options::OPT_ffunction_sections));
case 'b':
if (I + 1 != E && isdigit(OptStr[I + 1])) {
switch (OptStr[I + 1]) {
case '0':
DAL.AddFlagArg(A, Opts.getOption(options::OPT_fno_inline));
case '1':
DAL.AddFlagArg(A, Opts.getOption(options::OPT_finline_hint_functions));
case '2':
DAL.AddFlagArg(A, Opts.getOption(options::OPT_finline_functions));
case 'g':
case 'i':
if (I + 1 != E && OptStr[I + 1] == '-') {
DAL.AddFlagArg(A, Opts.getOption(options::OPT_fno_builtin));
} else {
DAL.AddFlagArg(A, Opts.getOption(options::OPT_fbuiltin));
case 's':
DAL.AddJoinedArg(A, Opts.getOption(options::OPT_O), "s");
case 't':
DAL.AddJoinedArg(A, Opts.getOption(options::OPT_O), "2");
case 'y': {
bool OmitFramePointer = true;
if (I + 1 != E && OptStr[I + 1] == '-') {
OmitFramePointer = false;
if (SupportsForcingFramePointer) {
if (OmitFramePointer)
A, Opts.getOption(options::OPT_fno_omit_frame_pointer));
} else {
// Don't warn about /Oy- in 64-bit builds (where
// SupportsForcingFramePointer is false). The flag having no effect
// there is a compiler-internal optimization, and people shouldn't have
// to special-case their build files for 64-bit clang-cl.
static void TranslateDArg(Arg *A, llvm::opt::DerivedArgList &DAL,
const OptTable &Opts) {
StringRef Val = A->getValue();
size_t Hash = Val.find('#');
if (Hash == StringRef::npos || Hash > Val.find('=')) {
std::string NewVal = Val;
NewVal[Hash] = '=';
DAL.AddJoinedArg(A, Opts.getOption(options::OPT_D), NewVal);
llvm::opt::DerivedArgList *
MSVCToolChain::TranslateArgs(const llvm::opt::DerivedArgList &Args,
StringRef BoundArch, Action::OffloadKind) const {
DerivedArgList *DAL = new DerivedArgList(Args.getBaseArgs());
const OptTable &Opts = getDriver().getOpts();
// /Oy and /Oy- only has an effect under X86-32.
bool SupportsForcingFramePointer = getArch() == llvm::Triple::x86;
// The -O[12xd] flag actually expands to several flags. We must desugar the
// flags so that options embedded can be negated. For example, the '-O2' flag
// enables '-Oy'. Expanding '-O2' into its constituent flags allows us to
// correctly handle '-O2 -Oy-' where the trailing '-Oy-' disables a single
// aspect of '-O2'.
// Note that this expansion logic only applies to the *last* of '[12xd]'.
// First step is to search for the character we'd like to expand.
const char *ExpandChar = nullptr;
for (Arg *A : Args.filtered(options::OPT__SLASH_O)) {
StringRef OptStr = A->getValue();
for (size_t I = 0, E = OptStr.size(); I != E; ++I) {
char OptChar = OptStr[I];
char PrevChar = I > 0 ? OptStr[I - 1] : '0';
if (PrevChar == 'b') {
// OptChar does not expand; it's an argument to the previous char.
if (OptChar == '1' || OptChar == '2' || OptChar == 'x' || OptChar == 'd')
ExpandChar = + I;
for (Arg *A : Args) {
if (A->getOption().matches(options::OPT__SLASH_O)) {
// The -O flag actually takes an amalgam of other options. For example,
// '/Ogyb2' is equivalent to '/Og' '/Oy' '/Ob2'.
TranslateOptArg(A, *DAL, SupportsForcingFramePointer, ExpandChar, Opts);
} else if (A->getOption().matches(options::OPT_D)) {
// Translate -Dfoo#bar into -Dfoo=bar.
TranslateDArg(A, *DAL, Opts);
} else {
return DAL;