1//===-- MSVC.cpp - MSVC ToolChain Implementations -------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "MSVC.h"
10#include "CommonArgs.h"
11#include "Darwin.h"
12#include "clang/Basic/CharInfo.h"
13#include "clang/Basic/Version.h"
14#include "clang/Config/config.h"
15#include "clang/Driver/Compilation.h"
16#include "clang/Driver/Driver.h"
17#include "clang/Driver/DriverDiagnostic.h"
18#include "clang/Driver/Options.h"
19#include "clang/Driver/SanitizerArgs.h"
20#include "llvm/ADT/StringExtras.h"
21#include "llvm/Option/Arg.h"
22#include "llvm/Option/ArgList.h"
23#include "llvm/Support/ConvertUTF.h"
24#include "llvm/Support/ErrorHandling.h"
25#include "llvm/Support/FileSystem.h"
26#include "llvm/Support/MemoryBuffer.h"
27#include "llvm/Support/Path.h"
28#include "llvm/Support/Process.h"
29#include "llvm/Support/VirtualFileSystem.h"
30#include "llvm/TargetParser/Host.h"
31#include <cstdio>
32
33#ifdef _WIN32
34 #define WIN32_LEAN_AND_MEAN
35 #define NOGDI
36 #ifndef NOMINMAX
37 #define NOMINMAX
38 #endif
39 #include <windows.h>
40#endif
41
42using namespace clang::driver;
43using namespace clang::driver::toolchains;
44using namespace clang::driver::tools;
45using namespace clang;
46using namespace llvm::opt;
47
48static bool canExecute(llvm::vfs::FileSystem &VFS, StringRef Path) {
49 auto Status = VFS.status(Path);
50 if (!Status)
51 return false;
52 return (Status->getPermissions() & llvm::sys::fs::perms::all_exe) != 0;
53}
54
55// Try to find Exe from a Visual Studio distribution. This first tries to find
56// an installed copy of Visual Studio and, failing that, looks in the PATH,
57// making sure that whatever executable that's found is not a same-named exe
58// from clang itself to prevent clang from falling back to itself.
59static std::string FindVisualStudioExecutable(const ToolChain &TC,
60 const char *Exe) {
61 const auto &MSVC = static_cast<const toolchains::MSVCToolChain &>(TC);
62 SmallString<128> FilePath(
63 MSVC.getSubDirectoryPath(Type: llvm::SubDirectoryType::Bin));
64 llvm::sys::path::append(path&: FilePath, a: Exe);
65 return std::string(canExecute(VFS&: TC.getVFS(), Path: FilePath) ? FilePath.str() : Exe);
66}
67
68void visualstudio::Linker::ConstructJob(Compilation &C, const JobAction &JA,
69 const InputInfo &Output,
70 const InputInfoList &Inputs,
71 const ArgList &Args,
72 const char *LinkingOutput) const {
73 ArgStringList CmdArgs;
74
75 auto &TC = static_cast<const toolchains::MSVCToolChain &>(getToolChain());
76
77 assert((Output.isFilename() || Output.isNothing()) && "invalid output");
78 if (Output.isFilename())
79 CmdArgs.push_back(
80 Elt: Args.MakeArgString(Str: std::string("-out:") + Output.getFilename()));
81
82 if (Args.hasArg(options::OPT_marm64x))
83 CmdArgs.push_back(Elt: "-machine:arm64x");
84 else if (TC.getTriple().isWindowsArm64EC())
85 CmdArgs.push_back(Elt: "-machine:arm64ec");
86
87 if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles) &&
88 !C.getDriver().IsCLMode() && !C.getDriver().IsFlangMode()) {
89 CmdArgs.push_back(Elt: "-defaultlib:libcmt");
90 CmdArgs.push_back(Elt: "-defaultlib:oldnames");
91 }
92
93 // If the VC environment hasn't been configured (perhaps because the user
94 // did not run vcvarsall), try to build a consistent link environment. If
95 // the environment variable is set however, assume the user knows what
96 // they're doing. If the user passes /vctoolsdir or /winsdkdir, trust that
97 // over env vars.
98 if (const Arg *A = Args.getLastArg(options::OPT__SLASH_diasdkdir,
99 options::OPT__SLASH_winsysroot)) {
100 // cl.exe doesn't find the DIA SDK automatically, so this too requires
101 // explicit flags and doesn't automatically look in "DIA SDK" relative
102 // to the path we found for VCToolChainPath.
103 llvm::SmallString<128> DIAPath(A->getValue());
104 if (A->getOption().getID() == options::OPT__SLASH_winsysroot)
105 llvm::sys::path::append(path&: DIAPath, a: "DIA SDK");
106
107 // The DIA SDK always uses the legacy vc arch, even in new MSVC versions.
108 llvm::sys::path::append(path&: DIAPath, a: "lib",
109 b: llvm::archToLegacyVCArch(Arch: TC.getArch()));
110 CmdArgs.push_back(Elt: Args.MakeArgString(Str: Twine("-libpath:") + DIAPath));
111 }
112 if (!llvm::sys::Process::GetEnv(name: "LIB") ||
113 Args.getLastArg(options::OPT__SLASH_vctoolsdir,
114 options::OPT__SLASH_winsysroot)) {
115 CmdArgs.push_back(Elt: Args.MakeArgString(
116 Str: Twine("-libpath:") +
117 TC.getSubDirectoryPath(Type: llvm::SubDirectoryType::Lib)));
118 CmdArgs.push_back(Elt: Args.MakeArgString(
119 Str: Twine("-libpath:") +
120 TC.getSubDirectoryPath(Type: llvm::SubDirectoryType::Lib, SubdirParent: "atlmfc")));
121 }
122 if (!llvm::sys::Process::GetEnv(name: "LIB") ||
123 Args.getLastArg(options::OPT__SLASH_winsdkdir,
124 options::OPT__SLASH_winsysroot)) {
125 if (TC.useUniversalCRT()) {
126 std::string UniversalCRTLibPath;
127 if (TC.getUniversalCRTLibraryPath(Args, path&: UniversalCRTLibPath))
128 CmdArgs.push_back(
129 Elt: Args.MakeArgString(Str: Twine("-libpath:") + UniversalCRTLibPath));
130 }
131 std::string WindowsSdkLibPath;
132 if (TC.getWindowsSDKLibraryPath(Args, path&: WindowsSdkLibPath))
133 CmdArgs.push_back(
134 Elt: Args.MakeArgString(Str: std::string("-libpath:") + WindowsSdkLibPath));
135 }
136
137 if (C.getDriver().IsFlangMode()) {
138 addFortranRuntimeLibraryPath(TC, Args, CmdArgs);
139 addFortranRuntimeLibs(TC, Args, CmdArgs);
140
141 // Inform the MSVC linker that we're generating a console application, i.e.
142 // one with `main` as the "user-defined" entry point. The `main` function is
143 // defined in flang's runtime libraries.
144 CmdArgs.push_back(Elt: "/subsystem:console");
145 }
146
147 // Add the compiler-rt library directories to libpath if they exist to help
148 // the linker find the various sanitizer, builtin, and profiling runtimes.
149 for (const auto &LibPath : TC.getLibraryPaths()) {
150 if (TC.getVFS().exists(Path: LibPath))
151 CmdArgs.push_back(Elt: Args.MakeArgString(Str: "-libpath:" + LibPath));
152 }
153 auto CRTPath = TC.getCompilerRTPath();
154 if (TC.getVFS().exists(Path: CRTPath))
155 CmdArgs.push_back(Elt: Args.MakeArgString(Str: "-libpath:" + CRTPath));
156
157 if (!C.getDriver().IsCLMode() && Args.hasArg(options::OPT_L))
158 for (const auto &LibPath : Args.getAllArgValues(options::OPT_L))
159 CmdArgs.push_back(Args.MakeArgString("-libpath:" + LibPath));
160
161 CmdArgs.push_back(Elt: "-nologo");
162
163 if (Args.hasArg(options::OPT_g_Group, options::OPT__SLASH_Z7))
164 CmdArgs.push_back(Elt: "-debug");
165
166 // If we specify /hotpatch, let the linker add padding in front of each
167 // function, like MSVC does.
168 if (Args.hasArg(options::OPT_fms_hotpatch, options::OPT__SLASH_hotpatch))
169 CmdArgs.push_back(Elt: "-functionpadmin");
170
171 // Pass on /Brepro if it was passed to the compiler.
172 // Note that /Brepro maps to -mno-incremental-linker-compatible.
173 bool DefaultIncrementalLinkerCompatible =
174 C.getDefaultToolChain().getTriple().isWindowsMSVCEnvironment();
175 if (!Args.hasFlag(options::OPT_mincremental_linker_compatible,
176 options::OPT_mno_incremental_linker_compatible,
177 DefaultIncrementalLinkerCompatible))
178 CmdArgs.push_back(Elt: "-Brepro");
179
180 bool DLL = Args.hasArg(options::OPT__SLASH_LD, options::OPT__SLASH_LDd,
181 options::OPT_shared);
182 if (DLL) {
183 CmdArgs.push_back(Elt: Args.MakeArgString(Str: "-dll"));
184
185 SmallString<128> ImplibName(Output.getFilename());
186 llvm::sys::path::replace_extension(path&: ImplibName, extension: "lib");
187 CmdArgs.push_back(Elt: Args.MakeArgString(Str: std::string("-implib:") + ImplibName));
188 }
189
190 if (TC.getSanitizerArgs(JobArgs: Args).needsFuzzer()) {
191 if (!Args.hasArg(options::OPT_shared))
192 CmdArgs.push_back(
193 Elt: Args.MakeArgString(Str: std::string("-wholearchive:") +
194 TC.getCompilerRTArgString(Args, Component: "fuzzer")));
195 CmdArgs.push_back(Elt: Args.MakeArgString(Str: "-debug"));
196 // Prevent the linker from padding sections we use for instrumentation
197 // arrays.
198 CmdArgs.push_back(Elt: Args.MakeArgString(Str: "-incremental:no"));
199 }
200
201 if (TC.getSanitizerArgs(JobArgs: Args).needsAsanRt()) {
202 CmdArgs.push_back(Elt: Args.MakeArgString(Str: "-debug"));
203 CmdArgs.push_back(Elt: Args.MakeArgString(Str: "-incremental:no"));
204 if (TC.getSanitizerArgs(JobArgs: Args).needsSharedRt() ||
205 Args.hasArg(options::OPT__SLASH_MD, options::OPT__SLASH_MDd)) {
206 for (const auto &Lib : {"asan_dynamic", "asan_dynamic_runtime_thunk"})
207 CmdArgs.push_back(Elt: TC.getCompilerRTArgString(Args, Component: Lib));
208 // Make sure the dynamic runtime thunk is not optimized out at link time
209 // to ensure proper SEH handling.
210 CmdArgs.push_back(Elt: Args.MakeArgString(
211 Str: TC.getArch() == llvm::Triple::x86
212 ? "-include:___asan_seh_interceptor"
213 : "-include:__asan_seh_interceptor"));
214 // Make sure the linker consider all object files from the dynamic runtime
215 // thunk.
216 CmdArgs.push_back(Elt: Args.MakeArgString(Str: std::string("-wholearchive:") +
217 TC.getCompilerRT(Args, Component: "asan_dynamic_runtime_thunk")));
218 } else if (DLL) {
219 CmdArgs.push_back(Elt: TC.getCompilerRTArgString(Args, Component: "asan_dll_thunk"));
220 } else {
221 for (const auto &Lib : {"asan", "asan_cxx"}) {
222 CmdArgs.push_back(Elt: TC.getCompilerRTArgString(Args, Component: Lib));
223 // Make sure the linker consider all object files from the static lib.
224 // This is necessary because instrumented dlls need access to all the
225 // interface exported by the static lib in the main executable.
226 CmdArgs.push_back(Elt: Args.MakeArgString(Str: std::string("-wholearchive:") +
227 TC.getCompilerRT(Args, Component: Lib)));
228 }
229 }
230 }
231
232 Args.AddAllArgValues(Output&: CmdArgs, options::Id0: OPT__SLASH_link);
233
234 // Control Flow Guard checks
235 for (const Arg *A : Args.filtered(options::OPT__SLASH_guard)) {
236 StringRef GuardArgs = A->getValue();
237 if (GuardArgs.equals_insensitive("cf") ||
238 GuardArgs.equals_insensitive("cf,nochecks")) {
239 // MSVC doesn't yet support the "nochecks" modifier.
240 CmdArgs.push_back("-guard:cf");
241 } else if (GuardArgs.equals_insensitive("cf-")) {
242 CmdArgs.push_back("-guard:cf-");
243 } else if (GuardArgs.equals_insensitive("ehcont")) {
244 CmdArgs.push_back("-guard:ehcont");
245 } else if (GuardArgs.equals_insensitive("ehcont-")) {
246 CmdArgs.push_back("-guard:ehcont-");
247 }
248 }
249
250 if (Args.hasFlag(options::OPT_fopenmp, options::OPT_fopenmp_EQ,
251 options::OPT_fno_openmp, false)) {
252 CmdArgs.push_back(Elt: "-nodefaultlib:vcomp.lib");
253 CmdArgs.push_back(Elt: "-nodefaultlib:vcompd.lib");
254 CmdArgs.push_back(Elt: Args.MakeArgString(Str: std::string("-libpath:") +
255 TC.getDriver().Dir + "/../lib"));
256 switch (TC.getDriver().getOpenMPRuntime(Args)) {
257 case Driver::OMPRT_OMP:
258 CmdArgs.push_back(Elt: "-defaultlib:libomp.lib");
259 break;
260 case Driver::OMPRT_IOMP5:
261 CmdArgs.push_back(Elt: "-defaultlib:libiomp5md.lib");
262 break;
263 case Driver::OMPRT_GOMP:
264 break;
265 case Driver::OMPRT_Unknown:
266 // Already diagnosed.
267 break;
268 }
269 }
270
271 // Add compiler-rt lib in case if it was explicitly
272 // specified as an argument for --rtlib option.
273 if (!Args.hasArg(options::OPT_nostdlib)) {
274 AddRunTimeLibs(TC, D: TC.getDriver(), CmdArgs, Args);
275 }
276
277 StringRef Linker =
278 Args.getLastArgValue(options::Id: OPT_fuse_ld_EQ, CLANG_DEFAULT_LINKER);
279 if (Linker.empty())
280 Linker = "link";
281 // We need to translate 'lld' into 'lld-link'.
282 else if (Linker.equals_insensitive(RHS: "lld"))
283 Linker = "lld-link";
284
285 if (Linker == "lld-link") {
286 for (Arg *A : Args.filtered(options::OPT_vfsoverlay))
287 CmdArgs.push_back(
288 Args.MakeArgString(std::string("/vfsoverlay:") + A->getValue()));
289
290 if (C.getDriver().isUsingLTO() &&
291 Args.hasFlag(options::OPT_gsplit_dwarf, options::OPT_gno_split_dwarf,
292 false))
293 CmdArgs.push_back(Elt: Args.MakeArgString(Str: Twine("/dwodir:") +
294 Output.getFilename() + "_dwo"));
295 }
296
297 // Add filenames, libraries, and other linker inputs.
298 for (const auto &Input : Inputs) {
299 if (Input.isFilename()) {
300 CmdArgs.push_back(Elt: Input.getFilename());
301 continue;
302 }
303
304 const Arg &A = Input.getInputArg();
305
306 // Render -l options differently for the MSVC linker.
307 if (A.getOption().matches(options::ID: OPT_l)) {
308 StringRef Lib = A.getValue();
309 const char *LinkLibArg;
310 if (Lib.ends_with(Suffix: ".lib"))
311 LinkLibArg = Args.MakeArgString(Str: Lib);
312 else
313 LinkLibArg = Args.MakeArgString(Str: Lib + ".lib");
314 CmdArgs.push_back(Elt: LinkLibArg);
315 continue;
316 }
317
318 // Otherwise, this is some other kind of linker input option like -Wl, -z,
319 // or -L. Render it, even if MSVC doesn't understand it.
320 A.renderAsInput(Args, Output&: CmdArgs);
321 }
322
323 addHIPRuntimeLibArgs(TC, C, Args, CmdArgs);
324
325 TC.addProfileRTLibs(Args, CmdArgs);
326
327 std::vector<const char *> Environment;
328
329 // We need to special case some linker paths. In the case of the regular msvc
330 // linker, we need to use a special search algorithm.
331 llvm::SmallString<128> linkPath;
332 if (Linker.equals_insensitive(RHS: "link")) {
333 // If we're using the MSVC linker, it's not sufficient to just use link
334 // from the program PATH, because other environments like GnuWin32 install
335 // their own link.exe which may come first.
336 linkPath = FindVisualStudioExecutable(TC, Exe: "link.exe");
337
338 if (!TC.FoundMSVCInstall() && !canExecute(VFS&: TC.getVFS(), Path: linkPath)) {
339 llvm::SmallString<128> ClPath;
340 ClPath = TC.GetProgramPath(Name: "cl.exe");
341 if (canExecute(VFS&: TC.getVFS(), Path: ClPath)) {
342 linkPath = llvm::sys::path::parent_path(path: ClPath);
343 llvm::sys::path::append(path&: linkPath, a: "link.exe");
344 if (!canExecute(VFS&: TC.getVFS(), Path: linkPath))
345 C.getDriver().Diag(clang::diag::DiagID: warn_drv_msvc_not_found);
346 } else {
347 C.getDriver().Diag(clang::diag::DiagID: warn_drv_msvc_not_found);
348 }
349 }
350
351 // Clang handles passing the proper asan libs to the linker, which goes
352 // against link.exe's /INFERASANLIBS which automatically finds asan libs.
353 if (TC.getSanitizerArgs(JobArgs: Args).needsAsanRt())
354 CmdArgs.push_back(Elt: "/INFERASANLIBS:NO");
355
356#ifdef _WIN32
357 // When cross-compiling with VS2017 or newer, link.exe expects to have
358 // its containing bin directory at the top of PATH, followed by the
359 // native target bin directory.
360 // e.g. when compiling for x86 on an x64 host, PATH should start with:
361 // /bin/Hostx64/x86;/bin/Hostx64/x64
362 // This doesn't attempt to handle llvm::ToolsetLayout::DevDivInternal.
363 if (TC.getIsVS2017OrNewer() &&
364 llvm::Triple(llvm::sys::getProcessTriple()).getArch() != TC.getArch()) {
365 auto HostArch = llvm::Triple(llvm::sys::getProcessTriple()).getArch();
366
367 auto EnvBlockWide =
368 std::unique_ptr<wchar_t[], decltype(&FreeEnvironmentStringsW)>(
369 GetEnvironmentStringsW(), FreeEnvironmentStringsW);
370 if (!EnvBlockWide)
371 goto SkipSettingEnvironment;
372
373 size_t EnvCount = 0;
374 size_t EnvBlockLen = 0;
375 while (EnvBlockWide[EnvBlockLen] != L'\0') {
376 ++EnvCount;
377 EnvBlockLen += std::wcslen(&EnvBlockWide[EnvBlockLen]) +
378 1 /*string null-terminator*/;
379 }
380 ++EnvBlockLen; // add the block null-terminator
381
382 std::string EnvBlock;
383 if (!llvm::convertUTF16ToUTF8String(
384 llvm::ArrayRef<char>(reinterpret_cast<char *>(EnvBlockWide.get()),
385 EnvBlockLen * sizeof(EnvBlockWide[0])),
386 EnvBlock))
387 goto SkipSettingEnvironment;
388
389 Environment.reserve(EnvCount);
390
391 // Now loop over each string in the block and copy them into the
392 // environment vector, adjusting the PATH variable as needed when we
393 // find it.
394 for (const char *Cursor = EnvBlock.data(); *Cursor != '\0';) {
395 llvm::StringRef EnvVar(Cursor);
396 if (EnvVar.starts_with_insensitive("path=")) {
397 constexpr size_t PrefixLen = 5; // strlen("path=")
398 Environment.push_back(Args.MakeArgString(
399 EnvVar.substr(0, PrefixLen) +
400 TC.getSubDirectoryPath(llvm::SubDirectoryType::Bin) +
401 llvm::Twine(llvm::sys::EnvPathSeparator) +
402 TC.getSubDirectoryPath(llvm::SubDirectoryType::Bin, HostArch) +
403 (EnvVar.size() > PrefixLen
404 ? llvm::Twine(llvm::sys::EnvPathSeparator) +
405 EnvVar.substr(PrefixLen)
406 : "")));
407 } else {
408 Environment.push_back(Args.MakeArgString(EnvVar));
409 }
410 Cursor += EnvVar.size() + 1 /*null-terminator*/;
411 }
412 }
413 SkipSettingEnvironment:;
414#endif
415 } else {
416 linkPath = TC.GetProgramPath(Name: Linker.str().c_str());
417 }
418
419 auto LinkCmd = std::make_unique<Command>(
420 args: JA, args: *this, args: ResponseFileSupport::AtFileUTF16(),
421 args: Args.MakeArgString(Str: linkPath), args&: CmdArgs, args: Inputs, args: Output);
422 if (!Environment.empty())
423 LinkCmd->setEnvironment(Environment);
424 C.addCommand(C: std::move(LinkCmd));
425}
426
427MSVCToolChain::MSVCToolChain(const Driver &D, const llvm::Triple &Triple,
428 const ArgList &Args)
429 : ToolChain(D, Triple, Args), CudaInstallation(D, Triple, Args),
430 RocmInstallation(D, Triple, Args) {
431 getProgramPaths().push_back(Elt: getDriver().Dir);
432
433 std::optional<llvm::StringRef> VCToolsDir, VCToolsVersion;
434 if (Arg *A = Args.getLastArg(options::OPT__SLASH_vctoolsdir))
435 VCToolsDir = A->getValue();
436 if (Arg *A = Args.getLastArg(options::OPT__SLASH_vctoolsversion))
437 VCToolsVersion = A->getValue();
438 if (Arg *A = Args.getLastArg(options::OPT__SLASH_winsdkdir))
439 WinSdkDir = A->getValue();
440 if (Arg *A = Args.getLastArg(options::OPT__SLASH_winsdkversion))
441 WinSdkVersion = A->getValue();
442 if (Arg *A = Args.getLastArg(options::OPT__SLASH_winsysroot))
443 WinSysRoot = A->getValue();
444
445 // Check the command line first, that's the user explicitly telling us what to
446 // use. Check the environment next, in case we're being invoked from a VS
447 // command prompt. Failing that, just try to find the newest Visual Studio
448 // version we can and use its default VC toolchain.
449 llvm::findVCToolChainViaCommandLine(VFS&: getVFS(), VCToolsDir, VCToolsVersion,
450 WinSysRoot, Path&: VCToolChainPath, VSLayout) ||
451 llvm::findVCToolChainViaEnvironment(VFS&: getVFS(), Path&: VCToolChainPath,
452 VSLayout) ||
453 llvm::findVCToolChainViaSetupConfig(VFS&: getVFS(), VCToolsVersion,
454 Path&: VCToolChainPath, VSLayout) ||
455 llvm::findVCToolChainViaRegistry(Path&: VCToolChainPath, VSLayout);
456}
457
458Tool *MSVCToolChain::buildLinker() const {
459 return new tools::visualstudio::Linker(*this);
460}
461
462Tool *MSVCToolChain::buildAssembler() const {
463 if (getTriple().isOSBinFormatMachO())
464 return new tools::darwin::Assembler(*this);
465 getDriver().Diag(clang::diag::DiagID: err_no_external_assembler);
466 return nullptr;
467}
468
469ToolChain::UnwindTableLevel
470MSVCToolChain::getDefaultUnwindTableLevel(const ArgList &Args) const {
471 // Don't emit unwind tables by default for MachO targets.
472 if (getTriple().isOSBinFormatMachO())
473 return UnwindTableLevel::None;
474
475 // All non-x86_32 Windows targets require unwind tables. However, LLVM
476 // doesn't know how to generate them for all targets, so only enable
477 // the ones that are actually implemented.
478 if (getArch() == llvm::Triple::x86_64 || getArch() == llvm::Triple::arm ||
479 getArch() == llvm::Triple::thumb || getArch() == llvm::Triple::aarch64)
480 return UnwindTableLevel::Asynchronous;
481
482 return UnwindTableLevel::None;
483}
484
485bool MSVCToolChain::isPICDefault() const {
486 return getArch() == llvm::Triple::x86_64 ||
487 getArch() == llvm::Triple::aarch64;
488}
489
490bool MSVCToolChain::isPIEDefault(const llvm::opt::ArgList &Args) const {
491 return false;
492}
493
494bool MSVCToolChain::isPICDefaultForced() const {
495 return getArch() == llvm::Triple::x86_64 ||
496 getArch() == llvm::Triple::aarch64;
497}
498
499void MSVCToolChain::AddCudaIncludeArgs(const ArgList &DriverArgs,
500 ArgStringList &CC1Args) const {
501 CudaInstallation->AddCudaIncludeArgs(DriverArgs, CC1Args);
502}
503
504void MSVCToolChain::AddHIPIncludeArgs(const ArgList &DriverArgs,
505 ArgStringList &CC1Args) const {
506 RocmInstallation->AddHIPIncludeArgs(DriverArgs, CC1Args);
507}
508
509void MSVCToolChain::AddHIPRuntimeLibArgs(const ArgList &Args,
510 ArgStringList &CmdArgs) const {
511 CmdArgs.append(IL: {Args.MakeArgString(Str: StringRef("-libpath:") +
512 RocmInstallation->getLibPath()),
513 "amdhip64.lib"});
514}
515
516void MSVCToolChain::printVerboseInfo(raw_ostream &OS) const {
517 CudaInstallation->print(OS);
518 RocmInstallation->print(OS);
519}
520
521std::string
522MSVCToolChain::getSubDirectoryPath(llvm::SubDirectoryType Type,
523 llvm::StringRef SubdirParent) const {
524 return llvm::getSubDirectoryPath(Type, VSLayout, VCToolChainPath, TargetArch: getArch(),
525 SubdirParent);
526}
527
528std::string
529MSVCToolChain::getSubDirectoryPath(llvm::SubDirectoryType Type,
530 llvm::Triple::ArchType TargetArch) const {
531 return llvm::getSubDirectoryPath(Type, VSLayout, VCToolChainPath, TargetArch,
532 SubdirParent: "");
533}
534
535// Find the most recent version of Universal CRT or Windows 10 SDK.
536// vcvarsqueryregistry.bat from Visual Studio 2015 sorts entries in the include
537// directory by name and uses the last one of the list.
538// So we compare entry names lexicographically to find the greatest one.
539// Gets the library path required to link against the Windows SDK.
540bool MSVCToolChain::getWindowsSDKLibraryPath(const ArgList &Args,
541 std::string &path) const {
542 std::string sdkPath;
543 int sdkMajor = 0;
544 std::string windowsSDKIncludeVersion;
545 std::string windowsSDKLibVersion;
546
547 path.clear();
548 if (!llvm::getWindowsSDKDir(VFS&: getVFS(), WinSdkDir, WinSdkVersion, WinSysRoot,
549 Path&: sdkPath, Major&: sdkMajor, WindowsSDKIncludeVersion&: windowsSDKIncludeVersion,
550 WindowsSDKLibVersion&: windowsSDKLibVersion))
551 return false;
552
553 llvm::SmallString<128> libPath(sdkPath);
554 llvm::sys::path::append(path&: libPath, a: "Lib");
555 if (sdkMajor >= 10)
556 if (!(WinSdkDir.has_value() || WinSysRoot.has_value()) &&
557 WinSdkVersion.has_value())
558 windowsSDKLibVersion = *WinSdkVersion;
559 if (sdkMajor >= 8)
560 llvm::sys::path::append(path&: libPath, a: windowsSDKLibVersion, b: "um");
561 return llvm::appendArchToWindowsSDKLibPath(SDKMajor: sdkMajor, LibPath: libPath, Arch: getArch(),
562 path);
563}
564
565bool MSVCToolChain::useUniversalCRT() const {
566 return llvm::useUniversalCRT(VSLayout, VCToolChainPath, TargetArch: getArch(), VFS&: getVFS());
567}
568
569bool MSVCToolChain::getUniversalCRTLibraryPath(const ArgList &Args,
570 std::string &Path) const {
571 std::string UniversalCRTSdkPath;
572 std::string UCRTVersion;
573
574 Path.clear();
575 if (!llvm::getUniversalCRTSdkDir(VFS&: getVFS(), WinSdkDir, WinSdkVersion,
576 WinSysRoot, Path&: UniversalCRTSdkPath,
577 UCRTVersion))
578 return false;
579
580 if (!(WinSdkDir.has_value() || WinSysRoot.has_value()) &&
581 WinSdkVersion.has_value())
582 UCRTVersion = *WinSdkVersion;
583
584 StringRef ArchName = llvm::archToWindowsSDKArch(Arch: getArch());
585 if (ArchName.empty())
586 return false;
587
588 llvm::SmallString<128> LibPath(UniversalCRTSdkPath);
589 llvm::sys::path::append(path&: LibPath, a: "Lib", b: UCRTVersion, c: "ucrt", d: ArchName);
590
591 Path = std::string(LibPath);
592 return true;
593}
594
595static VersionTuple getMSVCVersionFromExe(const std::string &BinDir) {
596 VersionTuple Version;
597#ifdef _WIN32
598 SmallString<128> ClExe(BinDir);
599 llvm::sys::path::append(ClExe, "cl.exe");
600
601 std::wstring ClExeWide;
602 if (!llvm::ConvertUTF8toWide(ClExe.c_str(), ClExeWide))
603 return Version;
604
605 const DWORD VersionSize = ::GetFileVersionInfoSizeW(ClExeWide.c_str(),
606 nullptr);
607 if (VersionSize == 0)
608 return Version;
609
610 SmallVector<uint8_t, 4 * 1024> VersionBlock(VersionSize);
611 if (!::GetFileVersionInfoW(ClExeWide.c_str(), 0, VersionSize,
612 VersionBlock.data()))
613 return Version;
614
615 VS_FIXEDFILEINFO *FileInfo = nullptr;
616 UINT FileInfoSize = 0;
617 if (!::VerQueryValueW(VersionBlock.data(), L"\\",
618 reinterpret_cast<LPVOID *>(&FileInfo), &FileInfoSize) ||
619 FileInfoSize < sizeof(*FileInfo))
620 return Version;
621
622 const unsigned Major = (FileInfo->dwFileVersionMS >> 16) & 0xFFFF;
623 const unsigned Minor = (FileInfo->dwFileVersionMS ) & 0xFFFF;
624 const unsigned Micro = (FileInfo->dwFileVersionLS >> 16) & 0xFFFF;
625
626 Version = VersionTuple(Major, Minor, Micro);
627#endif
628 return Version;
629}
630
631void MSVCToolChain::AddSystemIncludeWithSubfolder(
632 const ArgList &DriverArgs, ArgStringList &CC1Args,
633 const std::string &folder, const Twine &subfolder1, const Twine &subfolder2,
634 const Twine &subfolder3) const {
635 llvm::SmallString<128> path(folder);
636 llvm::sys::path::append(path, a: subfolder1, b: subfolder2, c: subfolder3);
637 addSystemInclude(DriverArgs, CC1Args, Path: path);
638}
639
640void MSVCToolChain::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
641 ArgStringList &CC1Args) const {
642 if (DriverArgs.hasArg(options::OPT_nostdinc))
643 return;
644
645 if (!DriverArgs.hasArg(options::OPT_nobuiltininc)) {
646 AddSystemIncludeWithSubfolder(DriverArgs, CC1Args, folder: getDriver().ResourceDir,
647 subfolder1: "include");
648 }
649
650 // Add %INCLUDE%-like directories from the -imsvc flag.
651 for (const auto &Path : DriverArgs.getAllArgValues(options::OPT__SLASH_imsvc))
652 addSystemInclude(DriverArgs, CC1Args, Path);
653
654 auto AddSystemIncludesFromEnv = [&](StringRef Var) -> bool {
655 if (auto Val = llvm::sys::Process::GetEnv(name: Var)) {
656 SmallVector<StringRef, 8> Dirs;
657 StringRef(*Val).split(A&: Dirs, Separator: ";", /*MaxSplit=*/-1, /*KeepEmpty=*/false);
658 if (!Dirs.empty()) {
659 addSystemIncludes(DriverArgs, CC1Args, Paths: Dirs);
660 return true;
661 }
662 }
663 return false;
664 };
665
666 // Add %INCLUDE%-like dirs via /external:env: flags.
667 for (const auto &Var :
668 DriverArgs.getAllArgValues(options::OPT__SLASH_external_env)) {
669 AddSystemIncludesFromEnv(Var);
670 }
671
672 // Add DIA SDK include if requested.
673 if (const Arg *A = DriverArgs.getLastArg(options::OPT__SLASH_diasdkdir,
674 options::OPT__SLASH_winsysroot)) {
675 // cl.exe doesn't find the DIA SDK automatically, so this too requires
676 // explicit flags and doesn't automatically look in "DIA SDK" relative
677 // to the path we found for VCToolChainPath.
678 llvm::SmallString<128> DIASDKPath(A->getValue());
679 if (A->getOption().getID() == options::OPT__SLASH_winsysroot)
680 llvm::sys::path::append(path&: DIASDKPath, a: "DIA SDK");
681 AddSystemIncludeWithSubfolder(DriverArgs, CC1Args, folder: std::string(DIASDKPath),
682 subfolder1: "include");
683 }
684
685 if (DriverArgs.hasArg(options::OPT_nostdlibinc))
686 return;
687
688 // Honor %INCLUDE% and %EXTERNAL_INCLUDE%. It should have essential search
689 // paths set by vcvarsall.bat. Skip if the user expressly set a vctoolsdir.
690 if (!DriverArgs.getLastArg(options::OPT__SLASH_vctoolsdir,
691 options::OPT__SLASH_winsysroot)) {
692 bool Found = AddSystemIncludesFromEnv("INCLUDE");
693 Found |= AddSystemIncludesFromEnv("EXTERNAL_INCLUDE");
694 if (Found)
695 return;
696 }
697
698 // When built with access to the proper Windows APIs, try to actually find
699 // the correct include paths first.
700 if (!VCToolChainPath.empty()) {
701 addSystemInclude(DriverArgs, CC1Args,
702 Path: getSubDirectoryPath(Type: llvm::SubDirectoryType::Include));
703 addSystemInclude(
704 DriverArgs, CC1Args,
705 Path: getSubDirectoryPath(Type: llvm::SubDirectoryType::Include, SubdirParent: "atlmfc"));
706
707 if (useUniversalCRT()) {
708 std::string UniversalCRTSdkPath;
709 std::string UCRTVersion;
710 if (llvm::getUniversalCRTSdkDir(VFS&: getVFS(), WinSdkDir, WinSdkVersion,
711 WinSysRoot, Path&: UniversalCRTSdkPath,
712 UCRTVersion)) {
713 if (!(WinSdkDir.has_value() || WinSysRoot.has_value()) &&
714 WinSdkVersion.has_value())
715 UCRTVersion = *WinSdkVersion;
716 AddSystemIncludeWithSubfolder(DriverArgs, CC1Args, folder: UniversalCRTSdkPath,
717 subfolder1: "Include", subfolder2: UCRTVersion, subfolder3: "ucrt");
718 }
719 }
720
721 std::string WindowsSDKDir;
722 int major = 0;
723 std::string windowsSDKIncludeVersion;
724 std::string windowsSDKLibVersion;
725 if (llvm::getWindowsSDKDir(VFS&: getVFS(), WinSdkDir, WinSdkVersion, WinSysRoot,
726 Path&: WindowsSDKDir, Major&: major, WindowsSDKIncludeVersion&: windowsSDKIncludeVersion,
727 WindowsSDKLibVersion&: windowsSDKLibVersion)) {
728 if (major >= 10)
729 if (!(WinSdkDir.has_value() || WinSysRoot.has_value()) &&
730 WinSdkVersion.has_value())
731 windowsSDKIncludeVersion = windowsSDKLibVersion = *WinSdkVersion;
732 if (major >= 8) {
733 // Note: windowsSDKIncludeVersion is empty for SDKs prior to v10.
734 // Anyway, llvm::sys::path::append is able to manage it.
735 AddSystemIncludeWithSubfolder(DriverArgs, CC1Args, folder: WindowsSDKDir,
736 subfolder1: "Include", subfolder2: windowsSDKIncludeVersion,
737 subfolder3: "shared");
738 AddSystemIncludeWithSubfolder(DriverArgs, CC1Args, folder: WindowsSDKDir,
739 subfolder1: "Include", subfolder2: windowsSDKIncludeVersion,
740 subfolder3: "um");
741 AddSystemIncludeWithSubfolder(DriverArgs, CC1Args, folder: WindowsSDKDir,
742 subfolder1: "Include", subfolder2: windowsSDKIncludeVersion,
743 subfolder3: "winrt");
744 if (major >= 10) {
745 llvm::VersionTuple Tuple;
746 if (!Tuple.tryParse(string: windowsSDKIncludeVersion) &&
747 Tuple.getSubminor().value_or(u: 0) >= 17134) {
748 AddSystemIncludeWithSubfolder(DriverArgs, CC1Args, folder: WindowsSDKDir,
749 subfolder1: "Include", subfolder2: windowsSDKIncludeVersion,
750 subfolder3: "cppwinrt");
751 }
752 }
753 } else {
754 AddSystemIncludeWithSubfolder(DriverArgs, CC1Args, folder: WindowsSDKDir,
755 subfolder1: "Include");
756 }
757 }
758
759 return;
760 }
761
762#if defined(_WIN32)
763 // As a fallback, select default install paths.
764 // FIXME: Don't guess drives and paths like this on Windows.
765 const StringRef Paths[] = {
766 "C:/Program Files/Microsoft Visual Studio 10.0/VC/include",
767 "C:/Program Files/Microsoft Visual Studio 9.0/VC/include",
768 "C:/Program Files/Microsoft Visual Studio 9.0/VC/PlatformSDK/Include",
769 "C:/Program Files/Microsoft Visual Studio 8/VC/include",
770 "C:/Program Files/Microsoft Visual Studio 8/VC/PlatformSDK/Include"
771 };
772 addSystemIncludes(DriverArgs, CC1Args, Paths);
773#endif
774}
775
776void MSVCToolChain::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
777 ArgStringList &CC1Args) const {
778 // FIXME: There should probably be logic here to find libc++ on Windows.
779}
780
781VersionTuple MSVCToolChain::computeMSVCVersion(const Driver *D,
782 const ArgList &Args) const {
783 bool IsWindowsMSVC = getTriple().isWindowsMSVCEnvironment();
784 VersionTuple MSVT = ToolChain::computeMSVCVersion(D, Args);
785 if (MSVT.empty())
786 MSVT = getTriple().getEnvironmentVersion();
787 if (MSVT.empty() && IsWindowsMSVC)
788 MSVT =
789 getMSVCVersionFromExe(BinDir: getSubDirectoryPath(Type: llvm::SubDirectoryType::Bin));
790 if (MSVT.empty() &&
791 Args.hasFlag(options::OPT_fms_extensions, options::OPT_fno_ms_extensions,
792 IsWindowsMSVC)) {
793 // -fms-compatibility-version=19.33 is default, aka 2022, 17.3
794 // NOTE: when changing this value, also update
795 // clang/docs/CommandGuide/clang.rst and clang/docs/UsersManual.rst
796 // accordingly.
797 MSVT = VersionTuple(19, 33);
798 }
799 return MSVT;
800}
801
802std::string
803MSVCToolChain::ComputeEffectiveClangTriple(const ArgList &Args,
804 types::ID InputType) const {
805 // The MSVC version doesn't care about the architecture, even though it
806 // may look at the triple internally.
807 VersionTuple MSVT = computeMSVCVersion(/*D=*/nullptr, Args);
808 MSVT = VersionTuple(MSVT.getMajor(), MSVT.getMinor().value_or(u: 0),
809 MSVT.getSubminor().value_or(u: 0));
810
811 // For the rest of the triple, however, a computed architecture name may
812 // be needed.
813 llvm::Triple Triple(ToolChain::ComputeEffectiveClangTriple(Args, InputType));
814 if (Triple.getEnvironment() == llvm::Triple::MSVC) {
815 StringRef ObjFmt = Triple.getEnvironmentName().split(Separator: '-').second;
816 if (ObjFmt.empty())
817 Triple.setEnvironmentName((Twine("msvc") + MSVT.getAsString()).str());
818 else
819 Triple.setEnvironmentName(
820 (Twine("msvc") + MSVT.getAsString() + Twine('-') + ObjFmt).str());
821 }
822 return Triple.getTriple();
823}
824
825SanitizerMask MSVCToolChain::getSupportedSanitizers() const {
826 SanitizerMask Res = ToolChain::getSupportedSanitizers();
827 Res |= SanitizerKind::Address;
828 Res |= SanitizerKind::PointerCompare;
829 Res |= SanitizerKind::PointerSubtract;
830 Res |= SanitizerKind::Fuzzer;
831 Res |= SanitizerKind::FuzzerNoLink;
832 Res &= ~SanitizerKind::CFIMFCall;
833 return Res;
834}
835
836static void TranslateOptArg(Arg *A, llvm::opt::DerivedArgList &DAL,
837 bool SupportsForcingFramePointer,
838 const char *ExpandChar, const OptTable &Opts) {
839 assert(A->getOption().matches(options::OPT__SLASH_O));
840
841 StringRef OptStr = A->getValue();
842 for (size_t I = 0, E = OptStr.size(); I != E; ++I) {
843 const char &OptChar = *(OptStr.data() + I);
844 switch (OptChar) {
845 default:
846 break;
847 case '1':
848 case '2':
849 case 'x':
850 case 'd':
851 // Ignore /O[12xd] flags that aren't the last one on the command line.
852 // Only the last one gets expanded.
853 if (&OptChar != ExpandChar) {
854 A->claim();
855 break;
856 }
857 if (OptChar == 'd') {
858 DAL.AddFlagArg(A, Opts.getOption(options::OPT_O0));
859 } else {
860 if (OptChar == '1') {
861 DAL.AddJoinedArg(A, Opts.getOption(options::OPT_O), "s");
862 } else if (OptChar == '2' || OptChar == 'x') {
863 DAL.AddFlagArg(A, Opts.getOption(options::OPT_fbuiltin));
864 DAL.AddJoinedArg(A, Opts.getOption(options::OPT_O), "2");
865 }
866 if (SupportsForcingFramePointer &&
867 !DAL.hasArgNoClaim(options::OPT_fno_omit_frame_pointer))
868 DAL.AddFlagArg(A, Opts.getOption(options::OPT_fomit_frame_pointer));
869 if (OptChar == '1' || OptChar == '2')
870 DAL.AddFlagArg(A, Opts.getOption(options::OPT_ffunction_sections));
871 }
872 break;
873 case 'b':
874 if (I + 1 != E && isdigit(OptStr[I + 1])) {
875 switch (OptStr[I + 1]) {
876 case '0':
877 DAL.AddFlagArg(A, Opts.getOption(options::OPT_fno_inline));
878 break;
879 case '1':
880 DAL.AddFlagArg(A, Opts.getOption(options::OPT_finline_hint_functions));
881 break;
882 case '2':
883 DAL.AddFlagArg(A, Opts.getOption(options::OPT_finline_functions));
884 break;
885 }
886 ++I;
887 }
888 break;
889 case 'g':
890 A->claim();
891 break;
892 case 'i':
893 if (I + 1 != E && OptStr[I + 1] == '-') {
894 ++I;
895 DAL.AddFlagArg(A, Opts.getOption(options::OPT_fno_builtin));
896 } else {
897 DAL.AddFlagArg(A, Opts.getOption(options::OPT_fbuiltin));
898 }
899 break;
900 case 's':
901 DAL.AddJoinedArg(A, Opts.getOption(options::OPT_O), "s");
902 break;
903 case 't':
904 DAL.AddJoinedArg(A, Opts.getOption(options::OPT_O), "2");
905 break;
906 case 'y': {
907 bool OmitFramePointer = true;
908 if (I + 1 != E && OptStr[I + 1] == '-') {
909 OmitFramePointer = false;
910 ++I;
911 }
912 if (SupportsForcingFramePointer) {
913 if (OmitFramePointer)
914 DAL.AddFlagArg(A,
915 Opts.getOption(options::OPT_fomit_frame_pointer));
916 else
917 DAL.AddFlagArg(
918 A, Opts.getOption(options::OPT_fno_omit_frame_pointer));
919 } else {
920 // Don't warn about /Oy- in x86-64 builds (where
921 // SupportsForcingFramePointer is false). The flag having no effect
922 // there is a compiler-internal optimization, and people shouldn't have
923 // to special-case their build files for x86-64 clang-cl.
924 A->claim();
925 }
926 break;
927 }
928 }
929 }
930}
931
932static void TranslateDArg(Arg *A, llvm::opt::DerivedArgList &DAL,
933 const OptTable &Opts) {
934 assert(A->getOption().matches(options::OPT_D));
935
936 StringRef Val = A->getValue();
937 size_t Hash = Val.find(C: '#');
938 if (Hash == StringRef::npos || Hash > Val.find(C: '=')) {
939 DAL.append(A);
940 return;
941 }
942
943 std::string NewVal = std::string(Val);
944 NewVal[Hash] = '=';
945 DAL.AddJoinedArg(A, Opts.getOption(options::OPT_D), NewVal);
946}
947
948static void TranslatePermissive(Arg *A, llvm::opt::DerivedArgList &DAL,
949 const OptTable &Opts) {
950 DAL.AddFlagArg(A, Opts.getOption(options::OPT__SLASH_Zc_twoPhase_));
951 DAL.AddFlagArg(A, Opts.getOption(options::OPT_fno_operator_names));
952}
953
954static void TranslatePermissiveMinus(Arg *A, llvm::opt::DerivedArgList &DAL,
955 const OptTable &Opts) {
956 DAL.AddFlagArg(A, Opts.getOption(options::OPT__SLASH_Zc_twoPhase));
957 DAL.AddFlagArg(A, Opts.getOption(options::OPT_foperator_names));
958}
959
960llvm::opt::DerivedArgList *
961MSVCToolChain::TranslateArgs(const llvm::opt::DerivedArgList &Args,
962 StringRef BoundArch,
963 Action::OffloadKind OFK) const {
964 DerivedArgList *DAL = new DerivedArgList(Args.getBaseArgs());
965 const OptTable &Opts = getDriver().getOpts();
966
967 // /Oy and /Oy- don't have an effect on X86-64
968 bool SupportsForcingFramePointer = getArch() != llvm::Triple::x86_64;
969
970 // The -O[12xd] flag actually expands to several flags. We must desugar the
971 // flags so that options embedded can be negated. For example, the '-O2' flag
972 // enables '-Oy'. Expanding '-O2' into its constituent flags allows us to
973 // correctly handle '-O2 -Oy-' where the trailing '-Oy-' disables a single
974 // aspect of '-O2'.
975 //
976 // Note that this expansion logic only applies to the *last* of '[12xd]'.
977
978 // First step is to search for the character we'd like to expand.
979 const char *ExpandChar = nullptr;
980 for (Arg *A : Args.filtered(options::OPT__SLASH_O)) {
981 StringRef OptStr = A->getValue();
982 for (size_t I = 0, E = OptStr.size(); I != E; ++I) {
983 char OptChar = OptStr[I];
984 char PrevChar = I > 0 ? OptStr[I - 1] : '0';
985 if (PrevChar == 'b') {
986 // OptChar does not expand; it's an argument to the previous char.
987 continue;
988 }
989 if (OptChar == '1' || OptChar == '2' || OptChar == 'x' || OptChar == 'd')
990 ExpandChar = OptStr.data() + I;
991 }
992 }
993
994 for (Arg *A : Args) {
995 if (A->getOption().matches(options::OPT__SLASH_O)) {
996 // The -O flag actually takes an amalgam of other options. For example,
997 // '/Ogyb2' is equivalent to '/Og' '/Oy' '/Ob2'.
998 TranslateOptArg(A, DAL&: *DAL, SupportsForcingFramePointer, ExpandChar, Opts);
999 } else if (A->getOption().matches(options::OPT_D)) {
1000 // Translate -Dfoo#bar into -Dfoo=bar.
1001 TranslateDArg(A, DAL&: *DAL, Opts);
1002 } else if (A->getOption().matches(options::OPT__SLASH_permissive)) {
1003 // Expand /permissive
1004 TranslatePermissive(A, DAL&: *DAL, Opts);
1005 } else if (A->getOption().matches(options::OPT__SLASH_permissive_)) {
1006 // Expand /permissive-
1007 TranslatePermissiveMinus(A, DAL&: *DAL, Opts);
1008 } else if (OFK != Action::OFK_HIP) {
1009 // HIP Toolchain translates input args by itself.
1010 DAL->append(A);
1011 }
1012 }
1013
1014 return DAL;
1015}
1016
1017void MSVCToolChain::addClangTargetOptions(
1018 const ArgList &DriverArgs, ArgStringList &CC1Args,
1019 Action::OffloadKind DeviceOffloadKind) const {
1020 // MSVC STL kindly allows removing all usages of typeid by defining
1021 // _HAS_STATIC_RTTI to 0. Do so, when compiling with -fno-rtti
1022 if (DriverArgs.hasFlag(options::OPT_fno_rtti, options::OPT_frtti,
1023 /*Default=*/false))
1024 CC1Args.push_back(Elt: "-D_HAS_STATIC_RTTI=0");
1025
1026 if (Arg *A = DriverArgs.getLastArgNoClaim(options::OPT_marm64x))
1027 A->ignoreTargetSpecific();
1028}
1029

source code of clang/lib/Driver/ToolChains/MSVC.cpp