[WebAssembly] Initial linking support.

This begins minimal support for invoking 'ld' from clang for WebAssembly
targets.

Differential Revision: http://reviews.llvm.org/D15586

llvm-svn: 255848

clang/lib/Driver/ToolChains.cpp

@@ -4418,6 +4418,13 @@ Tool *MyriadToolChain::buildLinker() const {
   return new tools::Myriad::Linker(*this);
 }
 
+WebAssembly::WebAssembly(const Driver &D, const llvm::Triple &Triple,
+                         const llvm::opt::ArgList &Args)
+  : ToolChain(D, Triple, Args) {
+  // Use LLD by default.
+  DefaultLinker = "lld";
+}
+
 bool WebAssembly::IsMathErrnoDefault() const { return false; }
 
 bool WebAssembly::IsObjCNonFragileABIDefault() const { return true; }
@@ -4440,6 +4447,8 @@ bool WebAssembly::hasBlocksRuntime() const { return false; }
 // TODO: Support profiling.
 bool WebAssembly::SupportsProfiling() const { return false; }
 
+bool WebAssembly::HasNativeLLVMSupport() const { return true; }
+
 void WebAssembly::addClangTargetOptions(const ArgList &DriverArgs,
                                         ArgStringList &CC1Args) const {
   if (DriverArgs.hasFlag(options::OPT_fuse_init_array,
@@ -4447,6 +4456,10 @@ void WebAssembly::addClangTargetOptions(const ArgList &DriverArgs,
     CC1Args.push_back("-fuse-init-array");
 }
 
+Tool *WebAssembly::buildLinker() const {
+  return new tools::wasm::Linker(*this);
+}
+
 PS4CPU::PS4CPU(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
     : Generic_ELF(D, Triple, Args) {
   if (Args.hasArg(options::OPT_static))

clang/lib/Driver/ToolChains.h

@@ -1088,8 +1088,7 @@ private:
 class LLVM_LIBRARY_VISIBILITY WebAssembly final : public ToolChain {
 public:
   WebAssembly(const Driver &D, const llvm::Triple &Triple,
-              const llvm::opt::ArgList &Args)
-      : ToolChain(D, Triple, Args) {}
+              const llvm::opt::ArgList &Args);
 
 private:
   bool IsMathErrnoDefault() const override;
@@ -1102,8 +1101,11 @@ private:
   bool hasBlocksRuntime() const override;
   bool SupportsObjCGC() const override;
   bool SupportsProfiling() const override;
+  bool HasNativeLLVMSupport() const override;
   void addClangTargetOptions(const llvm::opt::ArgList &DriverArgs,
                              llvm::opt::ArgStringList &CC1Args) const override;
+
+  Tool *buildLinker() const override;
 };
 
 class LLVM_LIBRARY_VISIBILITY PS4CPU : public Generic_ELF {

clang/lib/Driver/Tools.cpp

@@ -6439,6 +6439,34 @@ void amdgpu::Linker::ConstructJob(Compilation &C, const JobAction &JA,
 }
 // AMDGPU tools end.
 
+wasm::Linker::Linker(const ToolChain &TC)
+  : GnuTool("wasm::Linker", "lld", TC) {}
+
+bool wasm::Linker::isLinkJob() const {
+  return true;
+}
+
+bool wasm::Linker::hasIntegratedCPP() const {
+  return false;
+}
+
+void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
+                                const InputInfo &Output,
+                                const InputInfoList &Inputs,
+                                const ArgList &Args,
+                                const char *LinkingOutput) const {
+  const char *Linker = Args.MakeArgString(getToolChain().GetLinkerPath());
+  ArgStringList CmdArgs;
+  CmdArgs.push_back("-flavor");
+  CmdArgs.push_back("ld");
+  CmdArgs.push_back("-target");
+  CmdArgs.push_back(Args.MakeArgString(getToolChain().getTripleString()));
+  AddLinkerInputs(getToolChain(), Inputs, Args, CmdArgs);
+  CmdArgs.push_back("-o");
+  CmdArgs.push_back(Output.getFilename());
+  C.addCommand(llvm::make_unique<Command>(JA, *this, Linker, CmdArgs, Inputs));
+}
+
 const std::string arm::getARMArch(StringRef Arch, const llvm::Triple &Triple) {
   std::string MArch;
   if (!Arch.empty())

clang/lib/Driver/Tools.h

@@ -245,6 +245,21 @@ public:
 
 } // end namespace amdgpu
 
+namespace wasm {
+
+class LLVM_LIBRARY_VISIBILITY Linker : public GnuTool {
+public:
+  explicit Linker(const ToolChain &TC);
+  bool isLinkJob() const override;
+  bool hasIntegratedCPP() const override;
+  void ConstructJob(Compilation &C, const JobAction &JA,
+                    const InputInfo &Output, const InputInfoList &Inputs,
+                    const llvm::opt::ArgList &TCArgs,
+                    const char *LinkingOutput) const override;
+};
+
+} // end namespace wasm
+
 namespace arm {
 std::string getARMTargetCPU(StringRef CPU, StringRef Arch,
                             const llvm::Triple &Triple);