1//===--- WebAssembly.cpp - WebAssembly ToolChain Implementation -*- C++ -*-===//
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 "WebAssembly.h"
10#include "CommonArgs.h"
11#include "clang/Basic/Version.h"
12#include "clang/Config/config.h"
13#include "clang/Driver/Compilation.h"
14#include "clang/Driver/Driver.h"
15#include "clang/Driver/DriverDiagnostic.h"
16#include "clang/Driver/Options.h"
17#include "llvm/Support/FileSystem.h"
18#include "llvm/Support/Path.h"
19#include "llvm/Option/ArgList.h"
20
21using namespace clang::driver;
22using namespace clang::driver::tools;
23using namespace clang::driver::toolchains;
24using namespace clang;
25using namespace llvm::opt;
26
27/// Following the conventions in https://wiki.debian.org/Multiarch/Tuples,
28/// we remove the vendor field to form the multiarch triple.
29std::string WebAssembly::getMultiarchTriple(const Driver &D,
30                                            const llvm::Triple &TargetTriple,
31                                            StringRef SysRoot) const {
32    return (TargetTriple.getArchName() + "-" +
33            TargetTriple.getOSAndEnvironmentName()).str();
34}
35
36std::string wasm::Linker::getLinkerPath(const ArgList &Args) const {
37  const ToolChain &ToolChain = getToolChain();
38  if (const Arg* A = Args.getLastArg(options::OPT_fuse_ld_EQ)) {
39    StringRef UseLinker = A->getValue();
40    if (!UseLinker.empty()) {
41      if (llvm::sys::path::is_absolute(UseLinker) &&
42          llvm::sys::fs::can_execute(UseLinker))
43        return std::string(UseLinker);
44
45      // Accept 'lld', and 'ld' as aliases for the default linker
46      if (UseLinker != "lld" && UseLinker != "ld")
47        ToolChain.getDriver().Diag(diag::err_drv_invalid_linker_name)
48            << A->getAsString(Args);
49    }
50  }
51
52  return ToolChain.GetProgramPath(ToolChain.getDefaultLinker());
53}
54
55void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
56                                const InputInfo &Output,
57                                const InputInfoList &Inputs,
58                                const ArgList &Args,
59                                const char *LinkingOutput) const {
60
61  const ToolChain &ToolChain = getToolChain();
62  const char *Linker = Args.MakeArgString(getLinkerPath(Args));
63  ArgStringList CmdArgs;
64
65  CmdArgs.push_back("-m");
66  if (getToolChain().getTriple().isArch64Bit())
67    CmdArgs.push_back("wasm64");
68  else
69    CmdArgs.push_back("wasm32");
70
71  if (Args.hasArg(options::OPT_s))
72    CmdArgs.push_back("--strip-all");
73
74  Args.AddAllArgs(CmdArgs, options::OPT_L);
75  Args.AddAllArgs(CmdArgs, options::OPT_u);
76  ToolChain.AddFilePathLibArgs(Args, CmdArgs);
77
78  const char *Crt1 = "crt1.o";
79  const char *Entry = NULL;
80
81  // If crt1-command.o exists, it supports new-style commands, so use it.
82  // Otherwise, use the old crt1.o. This is a temporary transition measure.
83  // Once WASI libc no longer needs to support LLVM versions which lack
84  // support for new-style command, it can make crt1.o the same as
85  // crt1-command.o. And once LLVM no longer needs to support WASI libc
86  // versions before that, it can switch to using crt1-command.o.
87  if (ToolChain.GetFilePath("crt1-command.o") != "crt1-command.o")
88    Crt1 = "crt1-command.o";
89
90  if (const Arg *A = Args.getLastArg(options::OPT_mexec_model_EQ)) {
91    StringRef CM = A->getValue();
92    if (CM == "command") {
93      // Use default values.
94    } else if (CM == "reactor") {
95      Crt1 = "crt1-reactor.o";
96      Entry = "_initialize";
97    } else {
98      ToolChain.getDriver().Diag(diag::err_drv_invalid_argument_to_option)
99          << CM << A->getOption().getName();
100    }
101  }
102  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles))
103    CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath(Crt1)));
104  if (Entry) {
105    CmdArgs.push_back(Args.MakeArgString("--entry"));
106    CmdArgs.push_back(Args.MakeArgString(Entry));
107  }
108
109  AddLinkerInputs(ToolChain, Inputs, Args, CmdArgs, JA);
110
111  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
112    if (ToolChain.ShouldLinkCXXStdlib(Args))
113      ToolChain.AddCXXStdlibLibArgs(Args, CmdArgs);
114
115    if (Args.hasArg(options::OPT_pthread)) {
116      CmdArgs.push_back("-lpthread");
117      CmdArgs.push_back("--shared-memory");
118    }
119
120    CmdArgs.push_back("-lc");
121    AddRunTimeLibs(ToolChain, ToolChain.getDriver(), CmdArgs, Args);
122  }
123
124  CmdArgs.push_back("-o");
125  CmdArgs.push_back(Output.getFilename());
126
127  C.addCommand(std::make_unique<Command>(JA, *this,
128                                         ResponseFileSupport::AtFileCurCP(),
129                                         Linker, CmdArgs, Inputs, Output));
130
131  // When optimizing, if wasm-opt is available, run it.
132  if (Arg *A = Args.getLastArg(options::OPT_O_Group)) {
133    auto WasmOptPath = getToolChain().GetProgramPath("wasm-opt");
134    if (WasmOptPath != "wasm-opt") {
135      StringRef OOpt = "s";
136      if (A->getOption().matches(options::OPT_O4) ||
137          A->getOption().matches(options::OPT_Ofast))
138        OOpt = "4";
139      else if (A->getOption().matches(options::OPT_O0))
140        OOpt = "0";
141      else if (A->getOption().matches(options::OPT_O))
142        OOpt = A->getValue();
143
144      if (OOpt != "0") {
145        const char *WasmOpt = Args.MakeArgString(WasmOptPath);
146        ArgStringList CmdArgs;
147        CmdArgs.push_back(Output.getFilename());
148        CmdArgs.push_back(Args.MakeArgString(llvm::Twine("-O") + OOpt));
149        CmdArgs.push_back("-o");
150        CmdArgs.push_back(Output.getFilename());
151        C.addCommand(std::make_unique<Command>(
152            JA, *this, ResponseFileSupport::AtFileCurCP(), WasmOpt, CmdArgs,
153            Inputs, Output));
154      }
155    }
156  }
157}
158
159/// Given a base library directory, append path components to form the
160/// LTO directory.
161static std::string AppendLTOLibDir(const std::string &Dir) {
162    // The version allows the path to be keyed to the specific version of
163    // LLVM in used, as the bitcode format is not stable.
164    return Dir + "/llvm-lto/" LLVM_VERSION_STRING;
165}
166
167WebAssembly::WebAssembly(const Driver &D, const llvm::Triple &Triple,
168                         const llvm::opt::ArgList &Args)
169    : ToolChain(D, Triple, Args) {
170
171  assert(Triple.isArch32Bit() != Triple.isArch64Bit());
172
173  getProgramPaths().push_back(getDriver().getInstalledDir());
174
175  auto SysRoot = getDriver().SysRoot;
176  if (getTriple().getOS() == llvm::Triple::UnknownOS) {
177    // Theoretically an "unknown" OS should mean no standard libraries, however
178    // it could also mean that a custom set of libraries is in use, so just add
179    // /lib to the search path. Disable multiarch in this case, to discourage
180    // paths containing "unknown" from acquiring meanings.
181    getFilePaths().push_back(SysRoot + "/lib");
182  } else {
183    const std::string MultiarchTriple =
184        getMultiarchTriple(getDriver(), Triple, SysRoot);
185    if (D.isUsingLTO()) {
186      // For LTO, enable use of lto-enabled sysroot libraries too, if available.
187      // Note that the directory is keyed to the LLVM revision, as LLVM's
188      // bitcode format is not stable.
189      auto Dir = AppendLTOLibDir(SysRoot + "/lib/" + MultiarchTriple);
190      getFilePaths().push_back(Dir);
191    }
192    getFilePaths().push_back(SysRoot + "/lib/" + MultiarchTriple);
193  }
194}
195
196bool WebAssembly::IsMathErrnoDefault() const { return false; }
197
198bool WebAssembly::IsObjCNonFragileABIDefault() const { return true; }
199
200bool WebAssembly::UseObjCMixedDispatch() const { return true; }
201
202bool WebAssembly::isPICDefault() const { return false; }
203
204bool WebAssembly::isPIEDefault() const { return false; }
205
206bool WebAssembly::isPICDefaultForced() const { return false; }
207
208bool WebAssembly::IsIntegratedAssemblerDefault() const { return true; }
209
210bool WebAssembly::hasBlocksRuntime() const { return false; }
211
212// TODO: Support profiling.
213bool WebAssembly::SupportsProfiling() const { return false; }
214
215bool WebAssembly::HasNativeLLVMSupport() const { return true; }
216
217void WebAssembly::addClangTargetOptions(const ArgList &DriverArgs,
218                                        ArgStringList &CC1Args,
219                                        Action::OffloadKind) const {
220  if (!DriverArgs.hasFlag(clang::driver::options::OPT_fuse_init_array,
221                          options::OPT_fno_use_init_array, true))
222    CC1Args.push_back("-fno-use-init-array");
223
224  // '-pthread' implies atomics, bulk-memory, mutable-globals, and sign-ext
225  if (DriverArgs.hasFlag(options::OPT_pthread, options::OPT_no_pthread,
226                         false)) {
227    if (DriverArgs.hasFlag(options::OPT_mno_atomics, options::OPT_matomics,
228                           false))
229      getDriver().Diag(diag::err_drv_argument_not_allowed_with)
230          << "-pthread"
231          << "-mno-atomics";
232    if (DriverArgs.hasFlag(options::OPT_mno_bulk_memory,
233                           options::OPT_mbulk_memory, false))
234      getDriver().Diag(diag::err_drv_argument_not_allowed_with)
235          << "-pthread"
236          << "-mno-bulk-memory";
237    if (DriverArgs.hasFlag(options::OPT_mno_mutable_globals,
238                           options::OPT_mmutable_globals, false))
239      getDriver().Diag(diag::err_drv_argument_not_allowed_with)
240          << "-pthread"
241          << "-mno-mutable-globals";
242    if (DriverArgs.hasFlag(options::OPT_mno_sign_ext, options::OPT_msign_ext,
243                           false))
244      getDriver().Diag(diag::err_drv_argument_not_allowed_with)
245          << "-pthread"
246          << "-mno-sign-ext";
247    CC1Args.push_back("-target-feature");
248    CC1Args.push_back("+atomics");
249    CC1Args.push_back("-target-feature");
250    CC1Args.push_back("+bulk-memory");
251    CC1Args.push_back("-target-feature");
252    CC1Args.push_back("+mutable-globals");
253    CC1Args.push_back("-target-feature");
254    CC1Args.push_back("+sign-ext");
255  }
256
257  if (!DriverArgs.hasFlag(options::OPT_mmutable_globals,
258                          options::OPT_mno_mutable_globals, false)) {
259    // -fPIC implies +mutable-globals because the PIC ABI used by the linker
260    // depends on importing and exporting mutable globals.
261    llvm::Reloc::Model RelocationModel;
262    unsigned PICLevel;
263    bool IsPIE;
264    std::tie(RelocationModel, PICLevel, IsPIE) =
265        ParsePICArgs(*this, DriverArgs);
266    if (RelocationModel == llvm::Reloc::PIC_) {
267      if (DriverArgs.hasFlag(options::OPT_mno_mutable_globals,
268                             options::OPT_mmutable_globals, false)) {
269        getDriver().Diag(diag::err_drv_argument_not_allowed_with)
270            << "-fPIC"
271            << "-mno-mutable-globals";
272      }
273      CC1Args.push_back("-target-feature");
274      CC1Args.push_back("+mutable-globals");
275    }
276  }
277
278  if (DriverArgs.getLastArg(options::OPT_fwasm_exceptions)) {
279    // '-fwasm-exceptions' is not compatible with '-mno-exception-handling'
280    if (DriverArgs.hasFlag(options::OPT_mno_exception_handing,
281                           options::OPT_mexception_handing, false))
282      getDriver().Diag(diag::err_drv_argument_not_allowed_with)
283          << "-fwasm-exceptions"
284          << "-mno-exception-handling";
285    // '-fwasm-exceptions' is not compatible with
286    // '-mllvm -enable-emscripten-cxx-exceptions'
287    for (const Arg *A : DriverArgs.filtered(options::OPT_mllvm)) {
288      if (StringRef(A->getValue(0)) == "-enable-emscripten-cxx-exceptions")
289        getDriver().Diag(diag::err_drv_argument_not_allowed_with)
290            << "-fwasm-exceptions"
291            << "-mllvm -enable-emscripten-cxx-exceptions";
292    }
293    // '-fwasm-exceptions' implies exception-handling feature
294    CC1Args.push_back("-target-feature");
295    CC1Args.push_back("+exception-handling");
296  }
297
298  for (const Arg *A : DriverArgs.filtered(options::OPT_mllvm)) {
299    StringRef Opt = A->getValue(0);
300    if (Opt.startswith("-emscripten-cxx-exceptions-allowed")) {
301      // '-mllvm -emscripten-cxx-exceptions-allowed' should be used with
302      // '-mllvm -enable-emscripten-cxx-exceptions'
303      bool EmExceptionArgExists = false;
304      for (const Arg *A : DriverArgs.filtered(options::OPT_mllvm)) {
305        if (StringRef(A->getValue(0)) == "-enable-emscripten-cxx-exceptions") {
306          EmExceptionArgExists = true;
307          break;
308        }
309      }
310      if (!EmExceptionArgExists)
311        getDriver().Diag(diag::err_drv_argument_only_allowed_with)
312            << "-mllvm -emscripten-cxx-exceptions-allowed"
313            << "-mllvm -enable-emscripten-cxx-exceptions";
314
315      // Prevent functions specified in -emscripten-cxx-exceptions-allowed list
316      // from being inlined before reaching the wasm backend.
317      StringRef FuncNamesStr = Opt.split('=').second;
318      SmallVector<StringRef, 4> FuncNames;
319      FuncNamesStr.split(FuncNames, ',');
320      for (auto Name : FuncNames) {
321        CC1Args.push_back("-mllvm");
322        CC1Args.push_back(DriverArgs.MakeArgString("--force-attribute=" + Name +
323                                                   ":noinline"));
324      }
325    }
326  }
327}
328
329ToolChain::RuntimeLibType WebAssembly::GetDefaultRuntimeLibType() const {
330  return ToolChain::RLT_CompilerRT;
331}
332
333ToolChain::CXXStdlibType
334WebAssembly::GetCXXStdlibType(const ArgList &Args) const {
335  if (Arg *A = Args.getLastArg(options::OPT_stdlib_EQ)) {
336    StringRef Value = A->getValue();
337    if (Value != "libc++")
338      getDriver().Diag(diag::err_drv_invalid_stdlib_name)
339          << A->getAsString(Args);
340  }
341  return ToolChain::CST_Libcxx;
342}
343
344void WebAssembly::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
345                                            ArgStringList &CC1Args) const {
346  if (DriverArgs.hasArg(clang::driver::options::OPT_nostdinc))
347    return;
348
349  const Driver &D = getDriver();
350
351  if (!DriverArgs.hasArg(options::OPT_nobuiltininc)) {
352    SmallString<128> P(D.ResourceDir);
353    llvm::sys::path::append(P, "include");
354    addSystemInclude(DriverArgs, CC1Args, P);
355  }
356
357  if (DriverArgs.hasArg(options::OPT_nostdlibinc))
358    return;
359
360  // Check for configure-time C include directories.
361  StringRef CIncludeDirs(C_INCLUDE_DIRS);
362  if (CIncludeDirs != "") {
363    SmallVector<StringRef, 5> dirs;
364    CIncludeDirs.split(dirs, ":");
365    for (StringRef dir : dirs) {
366      StringRef Prefix =
367          llvm::sys::path::is_absolute(dir) ? "" : StringRef(D.SysRoot);
368      addExternCSystemInclude(DriverArgs, CC1Args, Prefix + dir);
369    }
370    return;
371  }
372
373  if (getTriple().getOS() != llvm::Triple::UnknownOS) {
374    const std::string MultiarchTriple =
375        getMultiarchTriple(D, getTriple(), D.SysRoot);
376    addSystemInclude(DriverArgs, CC1Args, D.SysRoot + "/include/" + MultiarchTriple);
377  }
378  addSystemInclude(DriverArgs, CC1Args, D.SysRoot + "/include");
379}
380
381void WebAssembly::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
382                                               ArgStringList &CC1Args) const {
383  if (!DriverArgs.hasArg(options::OPT_nostdlibinc) &&
384      !DriverArgs.hasArg(options::OPT_nostdincxx)) {
385    if (getTriple().getOS() != llvm::Triple::UnknownOS) {
386      const std::string MultiarchTriple =
387          getMultiarchTriple(getDriver(), getTriple(), getDriver().SysRoot);
388      addSystemInclude(DriverArgs, CC1Args,
389                       getDriver().SysRoot + "/include/" + MultiarchTriple +
390                           "/c++/v1");
391    }
392    addSystemInclude(DriverArgs, CC1Args,
393                     getDriver().SysRoot + "/include/c++/v1");
394  }
395}
396
397void WebAssembly::AddCXXStdlibLibArgs(const llvm::opt::ArgList &Args,
398                                      llvm::opt::ArgStringList &CmdArgs) const {
399
400  switch (GetCXXStdlibType(Args)) {
401  case ToolChain::CST_Libcxx:
402    CmdArgs.push_back("-lc++");
403    CmdArgs.push_back("-lc++abi");
404    break;
405  case ToolChain::CST_Libstdcxx:
406    llvm_unreachable("invalid stdlib name");
407  }
408}
409
410SanitizerMask WebAssembly::getSupportedSanitizers() const {
411  SanitizerMask Res = ToolChain::getSupportedSanitizers();
412  if (getTriple().isOSEmscripten()) {
413    Res |= SanitizerKind::Vptr | SanitizerKind::Leak | SanitizerKind::Address;
414  }
415  return Res;
416}
417
418Tool *WebAssembly::buildLinker() const {
419  return new tools::wasm::Linker(*this);
420}
421