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