Let Clang invoke CloudABI's linker.

Now that CloudABI's target information and header search logic for Clang
has been submitted, the only thing that remains to be done is adding
support for CloudABI's linker.

CloudABI uses Binutils ld, although there is some work to use lld
instead. This means that this code is largely based on what we use on
FreeBSD. There are some exceptions, however:

- Only static linking is performed. CloudABI does not support any
  dynamically linked executables.
- CloudABI uses compiler-rt, libc++ and libc++abi unconditionally. Link
  in these libraries instead of using libgcc_s, libstdc++, etc.
- We must ensure that the .eh_frame_hdr is present to make C++
  exceptions work properly.


Differential Revision:	http://reviews.llvm.org/D8250

llvm-svn: 233269

clang/lib/Driver/Driver.cpp

@@ -2030,6 +2030,9 @@ const ToolChain &Driver::getToolChain(const ArgList &Args,
   ToolChain *&TC = ToolChains[Target.str()];
   if (!TC) {
     switch (Target.getOS()) {
+    case llvm::Triple::CloudABI:
+      TC = new toolchains::CloudABI(*this, Target, Args);
+      break;
     case llvm::Triple::Darwin:
     case llvm::Triple::MacOSX:
     case llvm::Triple::IOS:

clang/lib/Driver/ToolChains.cpp

@@ -2340,6 +2340,36 @@ bool TCEToolChain::isPICDefaultForced() const {
   return false;
 }
 
+// CloudABI - CloudABI tool chain which can call ld(1) directly.
+
+CloudABI::CloudABI(const Driver &D, const llvm::Triple &Triple,
+                   const ArgList &Args)
+    : Generic_ELF(D, Triple, Args) {
+  SmallString<128> P(getDriver().Dir);
+  llvm::sys::path::append(P, "..", getTriple().str(), "lib");
+  getFilePaths().push_back(P.str());
+}
+
+void CloudABI::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
+                                            ArgStringList &CC1Args) const {
+  if (DriverArgs.hasArg(options::OPT_nostdlibinc) &&
+      DriverArgs.hasArg(options::OPT_nostdincxx))
+    return;
+
+  SmallString<128> P(getDriver().Dir);
+  llvm::sys::path::append(P, "..", getTriple().str(), "include/c++/v1");
+  addSystemInclude(DriverArgs, CC1Args, P.str());
+}
+
+void CloudABI::AddCXXStdlibLibArgs(const ArgList &Args,
+                                   ArgStringList &CmdArgs) const {
+  CmdArgs.push_back("-lc++");
+  CmdArgs.push_back("-lc++abi");
+  CmdArgs.push_back("-lunwind");
+}
+
+Tool *CloudABI::buildLinker() const { return new tools::cloudabi::Link(*this); }
+
 /// OpenBSD - OpenBSD tool chain which can call as(1) and ld(1) directly.
 
 OpenBSD::OpenBSD(const Driver &D, const llvm::Triple& Triple, const ArgList &Args)

clang/lib/Driver/ToolChains.h

@@ -512,6 +512,31 @@ public:
                              llvm::opt::ArgStringList &CC1Args) const override;
 };
 
+class LLVM_LIBRARY_VISIBILITY CloudABI : public Generic_ELF {
+public:
+  CloudABI(const Driver &D, const llvm::Triple &Triple,
+           const llvm::opt::ArgList &Args);
+  bool HasNativeLLVMSupport() const override { return true; }
+
+  bool IsMathErrnoDefault() const override { return false; }
+  bool IsObjCNonFragileABIDefault() const override { return true; }
+
+  CXXStdlibType GetCXXStdlibType(const llvm::opt::ArgList &Args)
+      const override {
+    return ToolChain::CST_Libcxx;
+  }
+  void AddClangCXXStdlibIncludeArgs(
+      const llvm::opt::ArgList &DriverArgs,
+      llvm::opt::ArgStringList &CC1Args) const override;
+  void AddCXXStdlibLibArgs(const llvm::opt::ArgList &Args,
+                           llvm::opt::ArgStringList &CmdArgs) const override;
+
+  bool isPIEDefault() const override { return false; }
+
+protected:
+  Tool *buildLinker() const override;
+};
+
 class LLVM_LIBRARY_VISIBILITY Solaris : public Generic_GCC {
 public:
   Solaris(const Driver &D, const llvm::Triple &Triple,

clang/lib/Driver/Tools.cpp

@@ -5725,6 +5725,76 @@ const char *Clang::getDependencyFileName(const ArgList &Args,
   return Args.MakeArgString(Res + ".d");
 }
 
+void cloudabi::Link::ConstructJob(Compilation &C, const JobAction &JA,
+                                  const InputInfo &Output,
+                                  const InputInfoList &Inputs,
+                                  const ArgList &Args,
+                                  const char *LinkingOutput) const {
+  const ToolChain &ToolChain = getToolChain();
+  const Driver &D = ToolChain.getDriver();
+  ArgStringList CmdArgs;
+
+  // Silence warning for "clang -g foo.o -o foo"
+  Args.ClaimAllArgs(options::OPT_g_Group);
+  // and "clang -emit-llvm foo.o -o foo"
+  Args.ClaimAllArgs(options::OPT_emit_llvm);
+  // and for "clang -w foo.o -o foo". Other warning options are already
+  // handled somewhere else.
+  Args.ClaimAllArgs(options::OPT_w);
+
+  if (!D.SysRoot.empty())
+    CmdArgs.push_back(Args.MakeArgString("--sysroot=" + D.SysRoot));
+
+  // CloudABI only supports static linkage.
+  CmdArgs.push_back("-Bstatic");
+  CmdArgs.push_back("--eh-frame-hdr");
+  CmdArgs.push_back("--gc-sections");
+
+  if (Output.isFilename()) {
+    CmdArgs.push_back("-o");
+    CmdArgs.push_back(Output.getFilename());
+  } else {
+    assert(Output.isNothing() && "Invalid output.");
+  }
+
+  if (!Args.hasArg(options::OPT_nostdlib) &&
+      !Args.hasArg(options::OPT_nostartfiles)) {
+    CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath("crt0.o")));
+    CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath("crtbegin.o")));
+  }
+
+  Args.AddAllArgs(CmdArgs, options::OPT_L);
+  const ToolChain::path_list &Paths = ToolChain.getFilePaths();
+  for (const auto &Path : Paths)
+    CmdArgs.push_back(Args.MakeArgString(StringRef("-L") + Path));
+  Args.AddAllArgs(CmdArgs, options::OPT_T_Group);
+  Args.AddAllArgs(CmdArgs, options::OPT_e);
+  Args.AddAllArgs(CmdArgs, options::OPT_s);
+  Args.AddAllArgs(CmdArgs, options::OPT_t);
+  Args.AddAllArgs(CmdArgs, options::OPT_Z_Flag);
+  Args.AddAllArgs(CmdArgs, options::OPT_r);
+
+  if (D.IsUsingLTO(ToolChain, Args))
+    AddGoldPlugin(ToolChain, Args, CmdArgs);
+
+  AddLinkerInputs(ToolChain, Inputs, Args, CmdArgs);
+
+  if (!Args.hasArg(options::OPT_nostdlib) &&
+      !Args.hasArg(options::OPT_nodefaultlibs)) {
+    if (D.CCCIsCXX())
+      ToolChain.AddCXXStdlibLibArgs(Args, CmdArgs);
+    CmdArgs.push_back("-lc");
+    CmdArgs.push_back("-lcompiler_rt");
+  }
+
+  if (!Args.hasArg(options::OPT_nostdlib) &&
+      !Args.hasArg(options::OPT_nostartfiles))
+    CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath("crtend.o")));
+
+  const char *Exec = Args.MakeArgString(ToolChain.GetLinkerPath());
+  C.addCommand(llvm::make_unique<Command>(JA, *this, Exec, CmdArgs));
+}
+
 void darwin::Assemble::ConstructJob(Compilation &C, const JobAction &JA,
                                     const InputInfo &Output,
                                     const InputInfoList &Inputs,

clang/lib/Driver/Tools.h

@@ -248,6 +248,22 @@ namespace ppc {
   bool hasPPCAbiArg(const llvm::opt::ArgList &Args, const char *Value);
 }
 
+  /// cloudabi -- Directly call GNU Binutils linker
+namespace cloudabi {
+class LLVM_LIBRARY_VISIBILITY Link : public GnuTool {
+public:
+  Link(const ToolChain &TC) : GnuTool("cloudabi::Link", "linker", TC) {}
+
+  bool hasIntegratedCPP() const override { return false; }
+  bool isLinkJob() const override { return true; }
+
+  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 cloudabi
+
 namespace darwin {
   llvm::Triple::ArchType getArchTypeForMachOArchName(StringRef Str);
   void setTripleTypeForMachOArchName(llvm::Triple &T, StringRef Str);

clang/test/Driver/cloudabi.c

@@ -0,0 +1,3 @@
+// RUN: %clang %s -### -target x86_64-unknown-cloudabi 2>&1 | FileCheck %s
+// CHECK: "-cc1" "-triple" "x86_64-unknown-cloudabi"
+// CHECK: "-Bstatic" "--eh-frame-hdr" "--gc-sections" "-o" "a.out" "crt0.o" "crtbegin.o" "{{.*}}" "{{.*}}" "-lc" "-lcompiler_rt" "crtend.o"

clang/test/Driver/cloudabi.cpp

@@ -0,0 +1,3 @@
+// RUN: %clangxx %s -### -target x86_64-unknown-cloudabi 2>&1 | FileCheck %s
+// CHECK: "-cc1" "-triple" "x86_64-unknown-cloudabi"
+// CHECK: "-Bstatic" "--eh-frame-hdr" "--gc-sections" "-o" "a.out" "crt0.o" "crtbegin.o" "{{.*}}" "{{.*}}" "-lc++" "-lc++abi" "-lunwind" "-lc" "-lcompiler_rt" "crtend.o"