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   if (Args.hasArg(options::OPT_s))
66     CmdArgs.push_back("--strip-all");
67 
68   Args.AddAllArgs(CmdArgs, options::OPT_L);
69   Args.AddAllArgs(CmdArgs, options::OPT_u);
70   ToolChain.AddFilePathLibArgs(Args, CmdArgs);
71 
72   const char *Crt1 = "crt1.o";
73   const char *Entry = NULL;
74   if (const Arg *A = Args.getLastArg(options::OPT_mexec_model_EQ)) {
75     StringRef CM = A->getValue();
76     if (CM == "command") {
77       // Use default values.
78     } else if (CM == "reactor") {
79       Crt1 = "crt1-reactor.o";
80       Entry = "_initialize";
81     } else {
82       ToolChain.getDriver().Diag(diag::err_drv_invalid_argument_to_option)
83           << CM << A->getOption().getName();
84     }
85   }
86   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles))
87     CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath(Crt1)));
88   if (Entry) {
89     CmdArgs.push_back(Args.MakeArgString("--entry"));
90     CmdArgs.push_back(Args.MakeArgString(Entry));
91   }
92 
93   AddLinkerInputs(ToolChain, Inputs, Args, CmdArgs, JA);
94 
95   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
96     if (ToolChain.ShouldLinkCXXStdlib(Args))
97       ToolChain.AddCXXStdlibLibArgs(Args, CmdArgs);
98 
99     if (Args.hasArg(options::OPT_pthread)) {
100       CmdArgs.push_back("-lpthread");
101       CmdArgs.push_back("--shared-memory");
102     }
103 
104     CmdArgs.push_back("-lc");
105     AddRunTimeLibs(ToolChain, ToolChain.getDriver(), CmdArgs, Args);
106   }
107 
108   CmdArgs.push_back("-o");
109   CmdArgs.push_back(Output.getFilename());
110 
111   C.addCommand(std::make_unique<Command>(JA, *this, Linker, CmdArgs, Inputs));
112 
113   // When optimizing, if wasm-opt is available, run it.
114   if (Arg *A = Args.getLastArg(options::OPT_O_Group)) {
115     auto WasmOptPath = getToolChain().GetProgramPath("wasm-opt");
116     if (WasmOptPath != "wasm-opt") {
117       StringRef OOpt = "s";
118       if (A->getOption().matches(options::OPT_O4) ||
119           A->getOption().matches(options::OPT_Ofast))
120         OOpt = "4";
121       else if (A->getOption().matches(options::OPT_O0))
122         OOpt = "0";
123       else if (A->getOption().matches(options::OPT_O))
124         OOpt = A->getValue();
125 
126       if (OOpt != "0") {
127         const char *WasmOpt = Args.MakeArgString(WasmOptPath);
128         ArgStringList CmdArgs;
129         CmdArgs.push_back(Output.getFilename());
130         CmdArgs.push_back(Args.MakeArgString(llvm::Twine("-O") + OOpt));
131         CmdArgs.push_back("-o");
132         CmdArgs.push_back(Output.getFilename());
133         C.addCommand(std::make_unique<Command>(JA, *this, WasmOpt, CmdArgs, Inputs));
134       }
135     }
136   }
137 }
138 
139 /// Given a base library directory, append path components to form the
140 /// LTO directory.
141 static std::string AppendLTOLibDir(const std::string &Dir) {
142     // The version allows the path to be keyed to the specific version of
143     // LLVM in used, as the bitcode format is not stable.
144     return Dir + "/llvm-lto/" LLVM_VERSION_STRING;
145 }
146 
147 WebAssembly::WebAssembly(const Driver &D, const llvm::Triple &Triple,
148                          const llvm::opt::ArgList &Args)
149     : ToolChain(D, Triple, Args) {
150 
151   assert(Triple.isArch32Bit() != Triple.isArch64Bit());
152 
153   getProgramPaths().push_back(getDriver().getInstalledDir());
154 
155   auto SysRoot = getDriver().SysRoot;
156   if (getTriple().getOS() == llvm::Triple::UnknownOS) {
157     // Theoretically an "unknown" OS should mean no standard libraries, however
158     // it could also mean that a custom set of libraries is in use, so just add
159     // /lib to the search path. Disable multiarch in this case, to discourage
160     // paths containing "unknown" from acquiring meanings.
161     getFilePaths().push_back(SysRoot + "/lib");
162   } else {
163     const std::string MultiarchTriple =
164         getMultiarchTriple(getDriver(), Triple, SysRoot);
165     if (D.isUsingLTO()) {
166       // For LTO, enable use of lto-enabled sysroot libraries too, if available.
167       // Note that the directory is keyed to the LLVM revision, as LLVM's
168       // bitcode format is not stable.
169       auto Dir = AppendLTOLibDir(SysRoot + "/lib/" + MultiarchTriple);
170       getFilePaths().push_back(Dir);
171     }
172     getFilePaths().push_back(SysRoot + "/lib/" + MultiarchTriple);
173   }
174 }
175 
176 bool WebAssembly::IsMathErrnoDefault() const { return false; }
177 
178 bool WebAssembly::IsObjCNonFragileABIDefault() const { return true; }
179 
180 bool WebAssembly::UseObjCMixedDispatch() const { return true; }
181 
182 bool WebAssembly::isPICDefault() const { return false; }
183 
184 bool WebAssembly::isPIEDefault() const { return false; }
185 
186 bool WebAssembly::isPICDefaultForced() const { return false; }
187 
188 bool WebAssembly::IsIntegratedAssemblerDefault() const { return true; }
189 
190 bool WebAssembly::hasBlocksRuntime() const { return false; }
191 
192 // TODO: Support profiling.
193 bool WebAssembly::SupportsProfiling() const { return false; }
194 
195 bool WebAssembly::HasNativeLLVMSupport() const { return true; }
196 
197 void WebAssembly::addClangTargetOptions(const ArgList &DriverArgs,
198                                         ArgStringList &CC1Args,
199                                         Action::OffloadKind) const {
200   if (!DriverArgs.hasFlag(clang::driver::options::OPT_fuse_init_array,
201                           options::OPT_fno_use_init_array, true))
202     CC1Args.push_back("-fno-use-init-array");
203 
204   // '-pthread' implies atomics, bulk-memory, mutable-globals, and sign-ext
205   if (DriverArgs.hasFlag(options::OPT_pthread, options::OPT_no_pthread,
206                          false)) {
207     if (DriverArgs.hasFlag(options::OPT_mno_atomics, options::OPT_matomics,
208                            false))
209       getDriver().Diag(diag::err_drv_argument_not_allowed_with)
210           << "-pthread"
211           << "-mno-atomics";
212     if (DriverArgs.hasFlag(options::OPT_mno_bulk_memory,
213                            options::OPT_mbulk_memory, false))
214       getDriver().Diag(diag::err_drv_argument_not_allowed_with)
215           << "-pthread"
216           << "-mno-bulk-memory";
217     if (DriverArgs.hasFlag(options::OPT_mno_mutable_globals,
218                            options::OPT_mmutable_globals, false))
219       getDriver().Diag(diag::err_drv_argument_not_allowed_with)
220           << "-pthread"
221           << "-mno-mutable-globals";
222     if (DriverArgs.hasFlag(options::OPT_mno_sign_ext, options::OPT_msign_ext,
223                            false))
224       getDriver().Diag(diag::err_drv_argument_not_allowed_with)
225           << "-pthread"
226           << "-mno-sign-ext";
227     CC1Args.push_back("-target-feature");
228     CC1Args.push_back("+atomics");
229     CC1Args.push_back("-target-feature");
230     CC1Args.push_back("+bulk-memory");
231     CC1Args.push_back("-target-feature");
232     CC1Args.push_back("+mutable-globals");
233     CC1Args.push_back("-target-feature");
234     CC1Args.push_back("+sign-ext");
235   }
236 
237   if (DriverArgs.getLastArg(options::OPT_fwasm_exceptions)) {
238     // '-fwasm-exceptions' is not compatible with '-mno-exception-handling'
239     if (DriverArgs.hasFlag(options::OPT_mno_exception_handing,
240                            options::OPT_mexception_handing, false))
241       getDriver().Diag(diag::err_drv_argument_not_allowed_with)
242           << "-fwasm-exceptions"
243           << "-mno-exception-handling";
244     // '-fwasm-exceptions' is not compatible with '-mno-reference-types'
245     if (DriverArgs.hasFlag(options::OPT_mno_reference_types,
246                            options::OPT_mexception_handing, false))
247       getDriver().Diag(diag::err_drv_argument_not_allowed_with)
248           << "-fwasm-exceptions"
249           << "-mno-reference-types";
250     // '-fwasm-exceptions' is not compatible with
251     // '-mllvm -enable-emscripten-cxx-exceptions'
252     for (const Arg *A : DriverArgs.filtered(options::OPT_mllvm)) {
253       if (StringRef(A->getValue(0)) == "-enable-emscripten-cxx-exceptions")
254         getDriver().Diag(diag::err_drv_argument_not_allowed_with)
255             << "-fwasm-exceptions"
256             << "-mllvm -enable-emscripten-cxx-exceptions";
257     }
258     // '-fwasm-exceptions' implies exception-handling and reference-types
259     CC1Args.push_back("-target-feature");
260     CC1Args.push_back("+exception-handling");
261     CC1Args.push_back("-target-feature");
262     CC1Args.push_back("+reference-types");
263   }
264 }
265 
266 ToolChain::RuntimeLibType WebAssembly::GetDefaultRuntimeLibType() const {
267   return ToolChain::RLT_CompilerRT;
268 }
269 
270 ToolChain::CXXStdlibType
271 WebAssembly::GetCXXStdlibType(const ArgList &Args) const {
272   if (Arg *A = Args.getLastArg(options::OPT_stdlib_EQ)) {
273     StringRef Value = A->getValue();
274     if (Value != "libc++")
275       getDriver().Diag(diag::err_drv_invalid_stdlib_name)
276           << A->getAsString(Args);
277   }
278   return ToolChain::CST_Libcxx;
279 }
280 
281 void WebAssembly::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
282                                             ArgStringList &CC1Args) const {
283   if (DriverArgs.hasArg(clang::driver::options::OPT_nostdinc))
284     return;
285 
286   const Driver &D = getDriver();
287 
288   if (!DriverArgs.hasArg(options::OPT_nobuiltininc)) {
289     SmallString<128> P(D.ResourceDir);
290     llvm::sys::path::append(P, "include");
291     addSystemInclude(DriverArgs, CC1Args, P);
292   }
293 
294   if (DriverArgs.hasArg(options::OPT_nostdlibinc))
295     return;
296 
297   // Check for configure-time C include directories.
298   StringRef CIncludeDirs(C_INCLUDE_DIRS);
299   if (CIncludeDirs != "") {
300     SmallVector<StringRef, 5> dirs;
301     CIncludeDirs.split(dirs, ":");
302     for (StringRef dir : dirs) {
303       StringRef Prefix =
304           llvm::sys::path::is_absolute(dir) ? "" : StringRef(D.SysRoot);
305       addExternCSystemInclude(DriverArgs, CC1Args, Prefix + dir);
306     }
307     return;
308   }
309 
310   if (getTriple().getOS() != llvm::Triple::UnknownOS) {
311     const std::string MultiarchTriple =
312         getMultiarchTriple(D, getTriple(), D.SysRoot);
313     addSystemInclude(DriverArgs, CC1Args, D.SysRoot + "/include/" + MultiarchTriple);
314   }
315   addSystemInclude(DriverArgs, CC1Args, D.SysRoot + "/include");
316 }
317 
318 void WebAssembly::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
319                                                ArgStringList &CC1Args) const {
320   if (!DriverArgs.hasArg(options::OPT_nostdlibinc) &&
321       !DriverArgs.hasArg(options::OPT_nostdincxx)) {
322     if (getTriple().getOS() != llvm::Triple::UnknownOS) {
323       const std::string MultiarchTriple =
324           getMultiarchTriple(getDriver(), getTriple(), getDriver().SysRoot);
325       addSystemInclude(DriverArgs, CC1Args,
326                        getDriver().SysRoot + "/include/" + MultiarchTriple +
327                            "/c++/v1");
328     }
329     addSystemInclude(DriverArgs, CC1Args,
330                      getDriver().SysRoot + "/include/c++/v1");
331   }
332 }
333 
334 void WebAssembly::AddCXXStdlibLibArgs(const llvm::opt::ArgList &Args,
335                                       llvm::opt::ArgStringList &CmdArgs) const {
336 
337   switch (GetCXXStdlibType(Args)) {
338   case ToolChain::CST_Libcxx:
339     CmdArgs.push_back("-lc++");
340     CmdArgs.push_back("-lc++abi");
341     break;
342   case ToolChain::CST_Libstdcxx:
343     llvm_unreachable("invalid stdlib name");
344   }
345 }
346 
347 SanitizerMask WebAssembly::getSupportedSanitizers() const {
348   SanitizerMask Res = ToolChain::getSupportedSanitizers();
349   if (getTriple().isOSEmscripten()) {
350     Res |= SanitizerKind::Vptr | SanitizerKind::Leak | SanitizerKind::Address;
351   }
352   return Res;
353 }
354 
355 Tool *WebAssembly::buildLinker() const {
356   return new tools::wasm::Linker(*this);
357 }
358