1 //===--- WebAssembly.cpp - WebAssembly ToolChain Implementation -*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "WebAssembly.h"
11 #include "CommonArgs.h"
12 #include "clang/Driver/Compilation.h"
13 #include "clang/Driver/Driver.h"
14 #include "clang/Driver/DriverDiagnostic.h"
15 #include "clang/Driver/Options.h"
16 #include "llvm/Option/ArgList.h"
17 
18 using namespace clang::driver;
19 using namespace clang::driver::tools;
20 using namespace clang::driver::toolchains;
21 using namespace clang;
22 using namespace llvm::opt;
23 
24 wasm::Linker::Linker(const ToolChain &TC)
25     : GnuTool("wasm::Linker", "lld", TC) {}
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 bool wasm::Linker::isLinkJob() const { return true; }
37 
38 bool wasm::Linker::hasIntegratedCPP() const { return false; }
39 
40 void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
41                                 const InputInfo &Output,
42                                 const InputInfoList &Inputs,
43                                 const ArgList &Args,
44                                 const char *LinkingOutput) const {
45 
46   const ToolChain &ToolChain = getToolChain();
47   const char *Linker = Args.MakeArgString(ToolChain.GetLinkerPath());
48   ArgStringList CmdArgs;
49 
50   if (Args.hasArg(options::OPT_s))
51     CmdArgs.push_back("--strip-all");
52 
53   Args.AddAllArgs(CmdArgs, options::OPT_L);
54   Args.AddAllArgs(CmdArgs, options::OPT_u);
55   ToolChain.AddFilePathLibArgs(Args, CmdArgs);
56 
57   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles))
58     CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath("crt1.o")));
59 
60   AddLinkerInputs(ToolChain, Inputs, Args, CmdArgs, JA);
61 
62   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
63     if (ToolChain.ShouldLinkCXXStdlib(Args))
64       ToolChain.AddCXXStdlibLibArgs(Args, CmdArgs);
65 
66     if (Args.hasArg(options::OPT_pthread))
67       CmdArgs.push_back("-lpthread");
68 
69     CmdArgs.push_back("-lc");
70     AddRunTimeLibs(ToolChain, ToolChain.getDriver(), CmdArgs, Args);
71   }
72 
73   CmdArgs.push_back("-o");
74   CmdArgs.push_back(Output.getFilename());
75 
76   C.addCommand(llvm::make_unique<Command>(JA, *this, Linker, CmdArgs, Inputs));
77 }
78 
79 WebAssembly::WebAssembly(const Driver &D, const llvm::Triple &Triple,
80                          const llvm::opt::ArgList &Args)
81     : ToolChain(D, Triple, Args) {
82 
83   assert(Triple.isArch32Bit() != Triple.isArch64Bit());
84 
85   getProgramPaths().push_back(getDriver().getInstalledDir());
86 
87   if (getTriple().getOS() == llvm::Triple::UnknownOS) {
88     // Theoretically an "unknown" OS should mean no standard libraries, however
89     // it could also mean that a custom set of libraries is in use, so just add
90     // /lib to the search path. Disable multiarch in this case, to discourage
91     // paths containing "unknown" from acquiring meanings.
92     getFilePaths().push_back(getDriver().SysRoot + "/lib");
93   } else {
94     const std::string MultiarchTriple =
95         getMultiarchTriple(getDriver(), Triple, getDriver().SysRoot);
96     getFilePaths().push_back(getDriver().SysRoot + "/lib/" + MultiarchTriple);
97   }
98 }
99 
100 bool WebAssembly::IsMathErrnoDefault() const { return false; }
101 
102 bool WebAssembly::IsObjCNonFragileABIDefault() const { return true; }
103 
104 bool WebAssembly::UseObjCMixedDispatch() const { return true; }
105 
106 bool WebAssembly::isPICDefault() const { return false; }
107 
108 bool WebAssembly::isPIEDefault() const { return false; }
109 
110 bool WebAssembly::isPICDefaultForced() const { return false; }
111 
112 bool WebAssembly::IsIntegratedAssemblerDefault() const { return true; }
113 
114 bool WebAssembly::hasBlocksRuntime() const { return false; }
115 
116 // TODO: Support profiling.
117 bool WebAssembly::SupportsProfiling() const { return false; }
118 
119 bool WebAssembly::HasNativeLLVMSupport() const { return true; }
120 
121 void WebAssembly::addClangTargetOptions(const ArgList &DriverArgs,
122                                         ArgStringList &CC1Args,
123                                         Action::OffloadKind) const {
124   if (DriverArgs.hasFlag(clang::driver::options::OPT_fuse_init_array,
125                          options::OPT_fno_use_init_array, true))
126     CC1Args.push_back("-fuse-init-array");
127 }
128 
129 ToolChain::RuntimeLibType WebAssembly::GetDefaultRuntimeLibType() const {
130   return ToolChain::RLT_CompilerRT;
131 }
132 
133 ToolChain::CXXStdlibType
134 WebAssembly::GetCXXStdlibType(const ArgList &Args) const {
135   if (Arg *A = Args.getLastArg(options::OPT_stdlib_EQ)) {
136     StringRef Value = A->getValue();
137     if (Value != "libc++")
138       getDriver().Diag(diag::err_drv_invalid_stdlib_name)
139           << A->getAsString(Args);
140   }
141   return ToolChain::CST_Libcxx;
142 }
143 
144 void WebAssembly::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
145                                             ArgStringList &CC1Args) const {
146   if (!DriverArgs.hasArg(options::OPT_nostdinc)) {
147     if (getTriple().getOS() != llvm::Triple::UnknownOS) {
148       const std::string MultiarchTriple =
149           getMultiarchTriple(getDriver(), getTriple(), getDriver().SysRoot);
150       addSystemInclude(DriverArgs, CC1Args, getDriver().SysRoot + "/include/" + MultiarchTriple);
151     }
152     addSystemInclude(DriverArgs, CC1Args, getDriver().SysRoot + "/include");
153   }
154 }
155 
156 void WebAssembly::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
157                                                ArgStringList &CC1Args) const {
158   if (!DriverArgs.hasArg(options::OPT_nostdlibinc) &&
159       !DriverArgs.hasArg(options::OPT_nostdincxx)) {
160     if (getTriple().getOS() != llvm::Triple::UnknownOS) {
161       const std::string MultiarchTriple =
162           getMultiarchTriple(getDriver(), getTriple(), getDriver().SysRoot);
163       addSystemInclude(DriverArgs, CC1Args,
164                        getDriver().SysRoot + "/include/" + MultiarchTriple + "/c++/v1");
165     }
166     addSystemInclude(DriverArgs, CC1Args,
167                      getDriver().SysRoot + "/include/c++/v1");
168   }
169 }
170 
171 void WebAssembly::AddCXXStdlibLibArgs(const llvm::opt::ArgList &Args,
172                                       llvm::opt::ArgStringList &CmdArgs) const {
173 
174   switch (GetCXXStdlibType(Args)) {
175   case ToolChain::CST_Libcxx:
176     CmdArgs.push_back("-lc++");
177     CmdArgs.push_back("-lc++abi");
178     break;
179   case ToolChain::CST_Libstdcxx:
180     llvm_unreachable("invalid stdlib name");
181   }
182 }
183 
184 std::string WebAssembly::getThreadModel() const {
185   // The WebAssembly MVP does not yet support threads; for now, use the
186   // "single" threading model, which lowers atomics to non-atomic operations.
187   // When threading support is standardized and implemented in popular engines,
188   // this override should be removed.
189   return "single";
190 }
191 
192 Tool *WebAssembly::buildLinker() const {
193   return new tools::wasm::Linker(*this);
194 }
195