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