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