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/Driver/Compilation.h"
12 #include "clang/Driver/Driver.h"
13 #include "clang/Driver/DriverDiagnostic.h"
14 #include "clang/Driver/Options.h"
15 #include "llvm/Support/FileSystem.h"
16 #include "llvm/Support/Path.h"
17 #include "llvm/Option/ArgList.h"
18 
19 using namespace clang::driver;
20 using namespace clang::driver::tools;
21 using namespace clang::driver::toolchains;
22 using namespace clang;
23 using namespace llvm::opt;
24 
25 wasm::Linker::Linker(const ToolChain &TC)
26     : GnuTool("wasm::Linker", "lld", TC) {}
27 
28 /// Following the conventions in https://wiki.debian.org/Multiarch/Tuples,
29 /// we remove the vendor field to form the multiarch triple.
30 static std::string getMultiarchTriple(const Driver &D,
31                                       const llvm::Triple &TargetTriple,
32                                       StringRef SysRoot) {
33     return (TargetTriple.getArchName() + "-" +
34             TargetTriple.getOSAndEnvironmentName()).str();
35 }
36 
37 bool wasm::Linker::isLinkJob() const { return true; }
38 
39 bool wasm::Linker::hasIntegratedCPP() const { return false; }
40 
41 std::string wasm::Linker::getLinkerPath(const ArgList &Args) const {
42   const ToolChain &ToolChain = getToolChain();
43   if (const Arg* A = Args.getLastArg(options::OPT_fuse_ld_EQ)) {
44     StringRef UseLinker = A->getValue();
45     if (!UseLinker.empty()) {
46       if (llvm::sys::path::is_absolute(UseLinker) &&
47           llvm::sys::fs::can_execute(UseLinker))
48         return UseLinker;
49 
50       // Accept 'lld', and 'ld' as aliases for the default linker
51       if (UseLinker != "lld" && UseLinker != "ld")
52         ToolChain.getDriver().Diag(diag::err_drv_invalid_linker_name)
53             << A->getAsString(Args);
54     }
55   }
56 
57   return ToolChain.GetProgramPath(ToolChain.getDefaultLinker());
58 }
59 
60 void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
61                                 const InputInfo &Output,
62                                 const InputInfoList &Inputs,
63                                 const ArgList &Args,
64                                 const char *LinkingOutput) const {
65 
66   const ToolChain &ToolChain = getToolChain();
67   const char *Linker = Args.MakeArgString(getLinkerPath(Args));
68   ArgStringList CmdArgs;
69 
70   if (Args.hasArg(options::OPT_s))
71     CmdArgs.push_back("--strip-all");
72 
73   Args.AddAllArgs(CmdArgs, options::OPT_L);
74   Args.AddAllArgs(CmdArgs, options::OPT_u);
75   ToolChain.AddFilePathLibArgs(Args, CmdArgs);
76 
77   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles))
78     CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath("crt1.o")));
79 
80   AddLinkerInputs(ToolChain, Inputs, Args, CmdArgs, JA);
81 
82   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
83     if (ToolChain.ShouldLinkCXXStdlib(Args))
84       ToolChain.AddCXXStdlibLibArgs(Args, CmdArgs);
85 
86     if (Args.hasArg(options::OPT_pthread)) {
87       CmdArgs.push_back("-lpthread");
88       CmdArgs.push_back("--shared-memory");
89     }
90 
91     CmdArgs.push_back("-lc");
92     AddRunTimeLibs(ToolChain, ToolChain.getDriver(), CmdArgs, Args);
93   }
94 
95   CmdArgs.push_back("-o");
96   CmdArgs.push_back(Output.getFilename());
97 
98   C.addCommand(llvm::make_unique<Command>(JA, *this, Linker, CmdArgs, Inputs));
99 }
100 
101 WebAssembly::WebAssembly(const Driver &D, const llvm::Triple &Triple,
102                          const llvm::opt::ArgList &Args)
103     : ToolChain(D, Triple, Args) {
104 
105   assert(Triple.isArch32Bit() != Triple.isArch64Bit());
106 
107   getProgramPaths().push_back(getDriver().getInstalledDir());
108 
109   if (getTriple().getOS() == llvm::Triple::UnknownOS) {
110     // Theoretically an "unknown" OS should mean no standard libraries, however
111     // it could also mean that a custom set of libraries is in use, so just add
112     // /lib to the search path. Disable multiarch in this case, to discourage
113     // paths containing "unknown" from acquiring meanings.
114     getFilePaths().push_back(getDriver().SysRoot + "/lib");
115   } else {
116     const std::string MultiarchTriple =
117         getMultiarchTriple(getDriver(), Triple, getDriver().SysRoot);
118     getFilePaths().push_back(getDriver().SysRoot + "/lib/" + MultiarchTriple);
119   }
120 }
121 
122 bool WebAssembly::IsMathErrnoDefault() const { return false; }
123 
124 bool WebAssembly::IsObjCNonFragileABIDefault() const { return true; }
125 
126 bool WebAssembly::UseObjCMixedDispatch() const { return true; }
127 
128 bool WebAssembly::isPICDefault() const { return false; }
129 
130 bool WebAssembly::isPIEDefault() const { return false; }
131 
132 bool WebAssembly::isPICDefaultForced() const { return false; }
133 
134 bool WebAssembly::IsIntegratedAssemblerDefault() const { return true; }
135 
136 bool WebAssembly::hasBlocksRuntime() const { return false; }
137 
138 // TODO: Support profiling.
139 bool WebAssembly::SupportsProfiling() const { return false; }
140 
141 bool WebAssembly::HasNativeLLVMSupport() const { return true; }
142 
143 void WebAssembly::addClangTargetOptions(const ArgList &DriverArgs,
144                                         ArgStringList &CC1Args,
145                                         Action::OffloadKind) const {
146   if (DriverArgs.hasFlag(clang::driver::options::OPT_fuse_init_array,
147                          options::OPT_fno_use_init_array, true))
148     CC1Args.push_back("-fuse-init-array");
149 
150   // '-pthread' implies '-target-feature +atomics'
151   if (DriverArgs.hasFlag(options::OPT_pthread, options::OPT_no_pthread,
152                          false)) {
153     if (DriverArgs.hasFlag(options::OPT_mno_atomics, options::OPT_matomics,
154                            false))
155       getDriver().Diag(diag::err_drv_argument_not_allowed_with)
156           << "-pthread"
157           << "-mno-atomics";
158     CC1Args.push_back("-target-feature");
159     CC1Args.push_back("+atomics");
160   }
161 }
162 
163 ToolChain::RuntimeLibType WebAssembly::GetDefaultRuntimeLibType() const {
164   return ToolChain::RLT_CompilerRT;
165 }
166 
167 ToolChain::CXXStdlibType
168 WebAssembly::GetCXXStdlibType(const ArgList &Args) const {
169   if (Arg *A = Args.getLastArg(options::OPT_stdlib_EQ)) {
170     StringRef Value = A->getValue();
171     if (Value != "libc++")
172       getDriver().Diag(diag::err_drv_invalid_stdlib_name)
173           << A->getAsString(Args);
174   }
175   return ToolChain::CST_Libcxx;
176 }
177 
178 void WebAssembly::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
179                                             ArgStringList &CC1Args) const {
180   if (!DriverArgs.hasArg(options::OPT_nostdinc)) {
181     if (getTriple().getOS() != llvm::Triple::UnknownOS) {
182       const std::string MultiarchTriple =
183           getMultiarchTriple(getDriver(), getTriple(), getDriver().SysRoot);
184       addSystemInclude(DriverArgs, CC1Args, getDriver().SysRoot + "/include/" + MultiarchTriple);
185     }
186     addSystemInclude(DriverArgs, CC1Args, getDriver().SysRoot + "/include");
187   }
188 }
189 
190 void WebAssembly::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
191                                                ArgStringList &CC1Args) const {
192   if (!DriverArgs.hasArg(options::OPT_nostdlibinc) &&
193       !DriverArgs.hasArg(options::OPT_nostdincxx)) {
194     if (getTriple().getOS() != llvm::Triple::UnknownOS) {
195       const std::string MultiarchTriple =
196           getMultiarchTriple(getDriver(), getTriple(), getDriver().SysRoot);
197       addSystemInclude(DriverArgs, CC1Args,
198                        getDriver().SysRoot + "/include/" + MultiarchTriple + "/c++/v1");
199     }
200     addSystemInclude(DriverArgs, CC1Args,
201                      getDriver().SysRoot + "/include/c++/v1");
202   }
203 }
204 
205 void WebAssembly::AddCXXStdlibLibArgs(const llvm::opt::ArgList &Args,
206                                       llvm::opt::ArgStringList &CmdArgs) const {
207 
208   switch (GetCXXStdlibType(Args)) {
209   case ToolChain::CST_Libcxx:
210     CmdArgs.push_back("-lc++");
211     CmdArgs.push_back("-lc++abi");
212     break;
213   case ToolChain::CST_Libstdcxx:
214     llvm_unreachable("invalid stdlib name");
215   }
216 }
217 
218 Tool *WebAssembly::buildLinker() const {
219   return new tools::wasm::Linker(*this);
220 }
221