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 
21 using namespace clang::driver;
22 using namespace clang::driver::tools;
23 using namespace clang::driver::toolchains;
24 using namespace clang;
25 using 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.
29 static std::string getMultiarchTriple(const Driver &D,
30                                       const llvm::Triple &TargetTriple,
31                                       StringRef SysRoot) {
32     return (TargetTriple.getArchName() + "-" +
33             TargetTriple.getOSAndEnvironmentName()).str();
34 }
35 
36 std::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 
55 void 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   if (const Arg *A = Args.getLastArg(options::OPT_mexec_model_EQ)) {
81     StringRef CM = A->getValue();
82     if (CM == "command") {
83       // Use default values.
84     } else if (CM == "reactor") {
85       Crt1 = "crt1-reactor.o";
86       Entry = "_initialize";
87     } else {
88       ToolChain.getDriver().Diag(diag::err_drv_invalid_argument_to_option)
89           << CM << A->getOption().getName();
90     }
91   }
92   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles))
93     CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath(Crt1)));
94   if (Entry) {
95     CmdArgs.push_back(Args.MakeArgString("--entry"));
96     CmdArgs.push_back(Args.MakeArgString(Entry));
97   }
98 
99   AddLinkerInputs(ToolChain, Inputs, Args, CmdArgs, JA);
100 
101   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
102     if (ToolChain.ShouldLinkCXXStdlib(Args))
103       ToolChain.AddCXXStdlibLibArgs(Args, CmdArgs);
104 
105     if (Args.hasArg(options::OPT_pthread)) {
106       CmdArgs.push_back("-lpthread");
107       CmdArgs.push_back("--shared-memory");
108     }
109 
110     CmdArgs.push_back("-lc");
111     AddRunTimeLibs(ToolChain, ToolChain.getDriver(), CmdArgs, Args);
112   }
113 
114   CmdArgs.push_back("-o");
115   CmdArgs.push_back(Output.getFilename());
116 
117   C.addCommand(std::make_unique<Command>(
118       JA, *this, ResponseFileSupport::AtFileCurCP(), Linker, CmdArgs, Inputs));
119 
120   // When optimizing, if wasm-opt is available, run it.
121   if (Arg *A = Args.getLastArg(options::OPT_O_Group)) {
122     auto WasmOptPath = getToolChain().GetProgramPath("wasm-opt");
123     if (WasmOptPath != "wasm-opt") {
124       StringRef OOpt = "s";
125       if (A->getOption().matches(options::OPT_O4) ||
126           A->getOption().matches(options::OPT_Ofast))
127         OOpt = "4";
128       else if (A->getOption().matches(options::OPT_O0))
129         OOpt = "0";
130       else if (A->getOption().matches(options::OPT_O))
131         OOpt = A->getValue();
132 
133       if (OOpt != "0") {
134         const char *WasmOpt = Args.MakeArgString(WasmOptPath);
135         ArgStringList CmdArgs;
136         CmdArgs.push_back(Output.getFilename());
137         CmdArgs.push_back(Args.MakeArgString(llvm::Twine("-O") + OOpt));
138         CmdArgs.push_back("-o");
139         CmdArgs.push_back(Output.getFilename());
140         C.addCommand(std::make_unique<Command>(
141             JA, *this, ResponseFileSupport::AtFileCurCP(), WasmOpt, CmdArgs,
142             Inputs));
143       }
144     }
145   }
146 }
147 
148 /// Given a base library directory, append path components to form the
149 /// LTO directory.
150 static std::string AppendLTOLibDir(const std::string &Dir) {
151     // The version allows the path to be keyed to the specific version of
152     // LLVM in used, as the bitcode format is not stable.
153     return Dir + "/llvm-lto/" LLVM_VERSION_STRING;
154 }
155 
156 WebAssembly::WebAssembly(const Driver &D, const llvm::Triple &Triple,
157                          const llvm::opt::ArgList &Args)
158     : ToolChain(D, Triple, Args) {
159 
160   assert(Triple.isArch32Bit() != Triple.isArch64Bit());
161 
162   getProgramPaths().push_back(getDriver().getInstalledDir());
163 
164   auto SysRoot = getDriver().SysRoot;
165   if (getTriple().getOS() == llvm::Triple::UnknownOS) {
166     // Theoretically an "unknown" OS should mean no standard libraries, however
167     // it could also mean that a custom set of libraries is in use, so just add
168     // /lib to the search path. Disable multiarch in this case, to discourage
169     // paths containing "unknown" from acquiring meanings.
170     getFilePaths().push_back(SysRoot + "/lib");
171   } else {
172     const std::string MultiarchTriple =
173         getMultiarchTriple(getDriver(), Triple, SysRoot);
174     if (D.isUsingLTO()) {
175       // For LTO, enable use of lto-enabled sysroot libraries too, if available.
176       // Note that the directory is keyed to the LLVM revision, as LLVM's
177       // bitcode format is not stable.
178       auto Dir = AppendLTOLibDir(SysRoot + "/lib/" + MultiarchTriple);
179       getFilePaths().push_back(Dir);
180     }
181     getFilePaths().push_back(SysRoot + "/lib/" + MultiarchTriple);
182   }
183 }
184 
185 bool WebAssembly::IsMathErrnoDefault() const { return false; }
186 
187 bool WebAssembly::IsObjCNonFragileABIDefault() const { return true; }
188 
189 bool WebAssembly::UseObjCMixedDispatch() const { return true; }
190 
191 bool WebAssembly::isPICDefault() const { return false; }
192 
193 bool WebAssembly::isPIEDefault() const { return false; }
194 
195 bool WebAssembly::isPICDefaultForced() const { return false; }
196 
197 bool WebAssembly::IsIntegratedAssemblerDefault() const { return true; }
198 
199 bool WebAssembly::hasBlocksRuntime() const { return false; }
200 
201 // TODO: Support profiling.
202 bool WebAssembly::SupportsProfiling() const { return false; }
203 
204 bool WebAssembly::HasNativeLLVMSupport() const { return true; }
205 
206 void WebAssembly::addClangTargetOptions(const ArgList &DriverArgs,
207                                         ArgStringList &CC1Args,
208                                         Action::OffloadKind) const {
209   if (!DriverArgs.hasFlag(clang::driver::options::OPT_fuse_init_array,
210                           options::OPT_fno_use_init_array, true))
211     CC1Args.push_back("-fno-use-init-array");
212 
213   // '-pthread' implies atomics, bulk-memory, mutable-globals, and sign-ext
214   if (DriverArgs.hasFlag(options::OPT_pthread, options::OPT_no_pthread,
215                          false)) {
216     if (DriverArgs.hasFlag(options::OPT_mno_atomics, options::OPT_matomics,
217                            false))
218       getDriver().Diag(diag::err_drv_argument_not_allowed_with)
219           << "-pthread"
220           << "-mno-atomics";
221     if (DriverArgs.hasFlag(options::OPT_mno_bulk_memory,
222                            options::OPT_mbulk_memory, false))
223       getDriver().Diag(diag::err_drv_argument_not_allowed_with)
224           << "-pthread"
225           << "-mno-bulk-memory";
226     if (DriverArgs.hasFlag(options::OPT_mno_mutable_globals,
227                            options::OPT_mmutable_globals, false))
228       getDriver().Diag(diag::err_drv_argument_not_allowed_with)
229           << "-pthread"
230           << "-mno-mutable-globals";
231     if (DriverArgs.hasFlag(options::OPT_mno_sign_ext, options::OPT_msign_ext,
232                            false))
233       getDriver().Diag(diag::err_drv_argument_not_allowed_with)
234           << "-pthread"
235           << "-mno-sign-ext";
236     CC1Args.push_back("-target-feature");
237     CC1Args.push_back("+atomics");
238     CC1Args.push_back("-target-feature");
239     CC1Args.push_back("+bulk-memory");
240     CC1Args.push_back("-target-feature");
241     CC1Args.push_back("+mutable-globals");
242     CC1Args.push_back("-target-feature");
243     CC1Args.push_back("+sign-ext");
244   }
245 
246   if (!DriverArgs.hasFlag(options::OPT_mmutable_globals,
247                           options::OPT_mno_mutable_globals, false)) {
248     // -fPIC implies +mutable-globals because the PIC ABI used by the linker
249     // depends on importing and exporting mutable globals.
250     llvm::Reloc::Model RelocationModel;
251     unsigned PICLevel;
252     bool IsPIE;
253     std::tie(RelocationModel, PICLevel, IsPIE) =
254         ParsePICArgs(*this, DriverArgs);
255     if (RelocationModel == llvm::Reloc::PIC_) {
256       if (DriverArgs.hasFlag(options::OPT_mno_mutable_globals,
257                              options::OPT_mmutable_globals, false)) {
258         getDriver().Diag(diag::err_drv_argument_not_allowed_with)
259             << "-fPIC"
260             << "-mno-mutable-globals";
261       }
262       CC1Args.push_back("-target-feature");
263       CC1Args.push_back("+mutable-globals");
264     }
265   }
266 
267   if (DriverArgs.getLastArg(options::OPT_fwasm_exceptions)) {
268     // '-fwasm-exceptions' is not compatible with '-mno-exception-handling'
269     if (DriverArgs.hasFlag(options::OPT_mno_exception_handing,
270                            options::OPT_mexception_handing, false))
271       getDriver().Diag(diag::err_drv_argument_not_allowed_with)
272           << "-fwasm-exceptions"
273           << "-mno-exception-handling";
274     // '-fwasm-exceptions' is not compatible with '-mno-reference-types'
275     if (DriverArgs.hasFlag(options::OPT_mno_reference_types,
276                            options::OPT_mexception_handing, false))
277       getDriver().Diag(diag::err_drv_argument_not_allowed_with)
278           << "-fwasm-exceptions"
279           << "-mno-reference-types";
280     // '-fwasm-exceptions' is not compatible with
281     // '-mllvm -enable-emscripten-cxx-exceptions'
282     for (const Arg *A : DriverArgs.filtered(options::OPT_mllvm)) {
283       if (StringRef(A->getValue(0)) == "-enable-emscripten-cxx-exceptions")
284         getDriver().Diag(diag::err_drv_argument_not_allowed_with)
285             << "-fwasm-exceptions"
286             << "-mllvm -enable-emscripten-cxx-exceptions";
287     }
288     // '-fwasm-exceptions' implies exception-handling and reference-types
289     CC1Args.push_back("-target-feature");
290     CC1Args.push_back("+exception-handling");
291     CC1Args.push_back("-target-feature");
292     CC1Args.push_back("+reference-types");
293   }
294 }
295 
296 ToolChain::RuntimeLibType WebAssembly::GetDefaultRuntimeLibType() const {
297   return ToolChain::RLT_CompilerRT;
298 }
299 
300 ToolChain::CXXStdlibType
301 WebAssembly::GetCXXStdlibType(const ArgList &Args) const {
302   if (Arg *A = Args.getLastArg(options::OPT_stdlib_EQ)) {
303     StringRef Value = A->getValue();
304     if (Value != "libc++")
305       getDriver().Diag(diag::err_drv_invalid_stdlib_name)
306           << A->getAsString(Args);
307   }
308   return ToolChain::CST_Libcxx;
309 }
310 
311 void WebAssembly::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
312                                             ArgStringList &CC1Args) const {
313   if (DriverArgs.hasArg(clang::driver::options::OPT_nostdinc))
314     return;
315 
316   const Driver &D = getDriver();
317 
318   if (!DriverArgs.hasArg(options::OPT_nobuiltininc)) {
319     SmallString<128> P(D.ResourceDir);
320     llvm::sys::path::append(P, "include");
321     addSystemInclude(DriverArgs, CC1Args, P);
322   }
323 
324   if (DriverArgs.hasArg(options::OPT_nostdlibinc))
325     return;
326 
327   // Check for configure-time C include directories.
328   StringRef CIncludeDirs(C_INCLUDE_DIRS);
329   if (CIncludeDirs != "") {
330     SmallVector<StringRef, 5> dirs;
331     CIncludeDirs.split(dirs, ":");
332     for (StringRef dir : dirs) {
333       StringRef Prefix =
334           llvm::sys::path::is_absolute(dir) ? "" : StringRef(D.SysRoot);
335       addExternCSystemInclude(DriverArgs, CC1Args, Prefix + dir);
336     }
337     return;
338   }
339 
340   if (getTriple().getOS() != llvm::Triple::UnknownOS) {
341     const std::string MultiarchTriple =
342         getMultiarchTriple(D, getTriple(), D.SysRoot);
343     addSystemInclude(DriverArgs, CC1Args, D.SysRoot + "/include/" + MultiarchTriple);
344   }
345   addSystemInclude(DriverArgs, CC1Args, D.SysRoot + "/include");
346 }
347 
348 void WebAssembly::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
349                                                ArgStringList &CC1Args) const {
350   if (!DriverArgs.hasArg(options::OPT_nostdlibinc) &&
351       !DriverArgs.hasArg(options::OPT_nostdincxx)) {
352     if (getTriple().getOS() != llvm::Triple::UnknownOS) {
353       const std::string MultiarchTriple =
354           getMultiarchTriple(getDriver(), getTriple(), getDriver().SysRoot);
355       addSystemInclude(DriverArgs, CC1Args,
356                        getDriver().SysRoot + "/include/" + MultiarchTriple +
357                            "/c++/v1");
358     }
359     addSystemInclude(DriverArgs, CC1Args,
360                      getDriver().SysRoot + "/include/c++/v1");
361   }
362 }
363 
364 void WebAssembly::AddCXXStdlibLibArgs(const llvm::opt::ArgList &Args,
365                                       llvm::opt::ArgStringList &CmdArgs) const {
366 
367   switch (GetCXXStdlibType(Args)) {
368   case ToolChain::CST_Libcxx:
369     CmdArgs.push_back("-lc++");
370     CmdArgs.push_back("-lc++abi");
371     break;
372   case ToolChain::CST_Libstdcxx:
373     llvm_unreachable("invalid stdlib name");
374   }
375 }
376 
377 SanitizerMask WebAssembly::getSupportedSanitizers() const {
378   SanitizerMask Res = ToolChain::getSupportedSanitizers();
379   if (getTriple().isOSEmscripten()) {
380     Res |= SanitizerKind::Vptr | SanitizerKind::Leak | SanitizerKind::Address;
381   }
382   return Res;
383 }
384 
385 Tool *WebAssembly::buildLinker() const {
386   return new tools::wasm::Linker(*this);
387 }
388