[Clang][Driver] Revise Cygwin ToolChain to call linker directly

clang/lib/Driver/ToolChain.cpp

@@ -684,6 +684,8 @@ static StringRef getArchNameForCompilerRTLib(const ToolChain &TC,
 StringRef ToolChain::getOSLibName() const {
   if (Triple.isOSDarwin())
     return "darwin";
+  if (Triple.isWindowsCygwinEnvironment())
+    return "cygwin";
 
   switch (Triple.getOS()) {
   case llvm::Triple::FreeBSD:

clang/lib/Driver/ToolChains/Cygwin.cpp

@@ -9,6 +9,7 @@
 #include "Cygwin.h"
 #include "clang/Config/config.h"
 #include "clang/Driver/CommonArgs.h"
+#include "clang/Driver/Compilation.h"
 #include "clang/Driver/Driver.h"
 #include "clang/Driver/Options.h"
 #include "llvm/Support/Path.h"
@@ -30,6 +31,8 @@ Cygwin::Cygwin(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
   Generic_GCC::PushPPaths(PPaths);
 
   path_list &Paths = getFilePaths();
+  if (GCCInstallation.isValid())
+    Paths.push_back(GCCInstallation.getInstallPath().str());
 
   Generic_GCC::AddMultiarchPaths(D, SysRoot, "lib", Paths);
 
@@ -107,3 +110,289 @@ void Cygwin::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
   addExternCSystemInclude(DriverArgs, CC1Args, SysRoot + "/usr/include");
   addExternCSystemInclude(DriverArgs, CC1Args, SysRoot + "/usr/include/w32api");
 }
+
+void cygwin::Linker::ConstructJob(Compilation &C, const JobAction &JA,
+                                  const InputInfo &Output,
+                                  const InputInfoList &Inputs,
+                                  const ArgList &Args,
+                                  const char *LinkingOutput) const {
+  const auto &ToolChain = getToolChain();
+  const Driver &D = ToolChain.getDriver();
+
+  const bool IsStatic = Args.hasArg(options::OPT_static);
+
+  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));
+
+  if (Args.hasArg(options::OPT_s))
+    CmdArgs.push_back("-s");
+
+  CmdArgs.push_back("-m");
+  switch (ToolChain.getArch()) {
+  case llvm::Triple::x86:
+    CmdArgs.push_back("i386pe");
+    break;
+  case llvm::Triple::x86_64:
+    CmdArgs.push_back("i386pep");
+    break;
+  case llvm::Triple::arm:
+  case llvm::Triple::thumb:
+    // FIXME: this is incorrect for WinCE
+    CmdArgs.push_back("thumb2pe");
+    break;
+  case llvm::Triple::aarch64:
+    if (Args.hasArg(options::OPT_marm64x))
+      CmdArgs.push_back("arm64xpe");
+    else if (ToolChain.getEffectiveTriple().isWindowsArm64EC())
+      CmdArgs.push_back("arm64ecpe");
+    else
+      CmdArgs.push_back("arm64pe");
+    break;
+  case llvm::Triple::mipsel:
+    CmdArgs.push_back("mipspe");
+    break;
+  default:
+    D.Diag(diag::err_target_unknown_triple)
+        << ToolChain.getEffectiveTriple().str();
+  }
+
+  Arg *SubsysArg =
+      Args.getLastArg(options::OPT_mwindows, options::OPT_mconsole);
+  if (SubsysArg && SubsysArg->getOption().matches(options::OPT_mwindows)) {
+    CmdArgs.push_back("--subsystem");
+    CmdArgs.push_back("windows");
+  } else if (SubsysArg &&
+             SubsysArg->getOption().matches(options::OPT_mconsole)) {
+    CmdArgs.push_back("--subsystem");
+    CmdArgs.push_back("console");
+  }
+
+  CmdArgs.push_back("--wrap=_Znwm");
+  CmdArgs.push_back("--wrap=_Znam");
+  CmdArgs.push_back("--wrap=_ZdlPv");
+  CmdArgs.push_back("--wrap=_ZdaPv");
+  CmdArgs.push_back("--wrap=_ZnwmRKSt9nothrow_t");
+  CmdArgs.push_back("--wrap=_ZnamRKSt9nothrow_t");
+  CmdArgs.push_back("--wrap=_ZdlPvRKSt9nothrow_t");
+  CmdArgs.push_back("--wrap=_ZdaPvRKSt9nothrow_t");
+
+  if (Args.hasArg(options::OPT_mdll))
+    CmdArgs.push_back("--dll");
+  else if (Args.hasArg(options::OPT_shared))
+    CmdArgs.push_back("--shared");
+  if (Args.hasArg(options::OPT_static))
+    CmdArgs.push_back("-Bstatic");
+  else
+    CmdArgs.push_back("-Bdynamic");
+
+  CmdArgs.push_back("--dll-search-prefix=cyg");
+
+  CmdArgs.push_back("-o");
+  const char *OutputFile = Output.getFilename();
+  // GCC implicitly adds an .exe extension if it is given an output file name
+  // that lacks an extension.
+  // GCC used to do this only when the compiler itself runs on windows, but
+  // since GCC 8 it does the same when cross compiling as well.
+  if (!llvm::sys::path::has_extension(OutputFile)) {
+    CmdArgs.push_back(Args.MakeArgString(Twine(OutputFile) + ".exe"));
+    OutputFile = CmdArgs.back();
+  } else
+    CmdArgs.push_back(OutputFile);
+
+  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles,
+                   options::OPT_r)) {
+    const bool IsShared = Args.hasArg(options::OPT_shared);
+    if (Args.hasArg(options::OPT_mdll) || IsShared) {
+      CmdArgs.push_back("-e");
+      CmdArgs.push_back(ToolChain.getArch() == llvm::Triple::x86
+                            ? "__cygwin_dll_entry@12"
+                            : "_cygwin_dll_entry");
+      CmdArgs.push_back("--enable-auto-image-base");
+    }
+
+    if (!Args.hasArg(options::OPT_mdll) && !IsShared)
+      CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath("crt0.o")));
+    if (ToolChain.GetRuntimeLibType(Args) == ToolChain::RLT_CompilerRT) {
+      std::string crtbegin =
+          ToolChain.getCompilerRT(Args, "crtbegin", ToolChain::FT_Object);
+      if (ToolChain.getVFS().exists(crtbegin)) {
+        std::string P;
+        P = crtbegin;
+        CmdArgs.push_back(Args.MakeArgString(P));
+      }
+    }
+    if (IsShared)
+      CmdArgs.push_back(
+          Args.MakeArgString(ToolChain.GetFilePath("crtbeginS.o")));
+    else
+      CmdArgs.push_back(
+          Args.MakeArgString(ToolChain.GetFilePath("crtbegin.o")));
+
+    // Add crtfastmath.o if available and fast math is enabled.
+    ToolChain.addFastMathRuntimeIfAvailable(Args, CmdArgs);
+  }
+
+  Args.addAllArgs(CmdArgs, {options::OPT_L, options::OPT_u});
+
+  ToolChain.AddFilePathLibArgs(Args, CmdArgs);
+
+  if (D.isUsingLTO())
+    tools::addLTOOptions(ToolChain, Args, CmdArgs, Output, Inputs,
+                         D.getLTOMode() == LTOK_Thin);
+
+  if (Args.hasArg(options::OPT_Z_Xlinker__no_demangle))
+    CmdArgs.push_back("--no-demangle");
+
+  bool NeedsSanitizerDeps =
+      tools::addSanitizerRuntimes(ToolChain, Args, CmdArgs);
+  bool NeedsXRayDeps = tools::addXRayRuntime(ToolChain, Args, CmdArgs);
+  tools::addLinkerCompressDebugSectionsOption(ToolChain, Args, CmdArgs);
+  tools::AddLinkerInputs(ToolChain, Inputs, Args, CmdArgs, JA);
+
+  bool saw_high_entropy_va = false;
+  bool saw_dynamicbase = false;
+  bool saw_nxcompat = false;
+  for (const char *Arg : CmdArgs) {
+    if (StringRef(Arg) == "-high-entropy-va" ||
+        StringRef(Arg) == "--high-entropy-va" ||
+        StringRef(Arg) == "-disable-high-entropy-va" ||
+        StringRef(Arg) == "--disable-high-entropy-va")
+      saw_high_entropy_va = true;
+    if (StringRef(Arg) == "-dynamicbase" || StringRef(Arg) == "--dynamicbase" ||
+        StringRef(Arg) == "-disable-dynamicbase" ||
+        StringRef(Arg) == "--disable-dynamicbase")
+      saw_dynamicbase = true;
+    if (StringRef(Arg) == "-nxcompat" || StringRef(Arg) == "--nxcompat" ||
+        StringRef(Arg) == "-disable-nxcompat" ||
+        StringRef(Arg) == "--disable-nxcompat")
+      saw_dynamicbase = true;
+  }
+  if (!saw_high_entropy_va)
+    CmdArgs.push_back("--disable-high-entropy-va");
+  if (!saw_dynamicbase)
+    CmdArgs.push_back("--disable-dynamicbase");
+  if (!saw_nxcompat)
+    CmdArgs.push_back("--disable-nxcompat");
+
+  tools::addHIPRuntimeLibArgs(ToolChain, C, Args, CmdArgs);
+
+  // The profile runtime also needs access to system libraries.
+  getToolChain().addProfileRTLibs(Args, CmdArgs);
+
+  if (D.CCCIsCXX() &&
+      !Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs,
+                   options::OPT_r)) {
+    if (ToolChain.ShouldLinkCXXStdlib(Args)) {
+      bool OnlyLibstdcxxStatic = Args.hasArg(options::OPT_static_libstdcxx) &&
+                                 !Args.hasArg(options::OPT_static);
+      if (OnlyLibstdcxxStatic)
+        CmdArgs.push_back("-Bstatic");
+      ToolChain.AddCXXStdlibLibArgs(Args, CmdArgs);
+      if (OnlyLibstdcxxStatic)
+        CmdArgs.push_back("-Bdynamic");
+    }
+    CmdArgs.push_back("-lm");
+  }
+
+  // Silence warnings when linking C code with a C++ '-stdlib' argument.
+  Args.ClaimAllArgs(options::OPT_stdlib_EQ);
+
+  // Additional linker set-up and flags for Fortran. This is required in order
+  // to generate executables. As Fortran runtime depends on the C runtime,
+  // these dependencies need to be listed before the C runtime below (i.e.
+  // AddRunTimeLibs).
+  if (D.IsFlangMode() &&
+      !Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
+    ToolChain.addFortranRuntimeLibraryPath(Args, CmdArgs);
+    ToolChain.addFortranRuntimeLibs(Args, CmdArgs);
+    CmdArgs.push_back("-lm");
+  }
+
+  if (!Args.hasArg(options::OPT_nostdlib, options::OPT_r)) {
+    if (!Args.hasArg(options::OPT_nodefaultlibs)) {
+      if (IsStatic)
+        CmdArgs.push_back("--start-group");
+
+      if (NeedsSanitizerDeps)
+        tools::linkSanitizerRuntimeDeps(ToolChain, Args, CmdArgs);
+
+      if (NeedsXRayDeps)
+        tools::linkXRayRuntimeDeps(ToolChain, Args, CmdArgs);
+
+      bool WantPthread = Args.hasArg(options::OPT_pthread) ||
+                         Args.hasArg(options::OPT_pthreads);
+
+      // Use the static OpenMP runtime with -static-openmp
+      bool StaticOpenMP = Args.hasArg(options::OPT_static_openmp) &&
+                          !Args.hasArg(options::OPT_static);
+
+      // FIXME: Only pass GompNeedsRT = true for platforms with libgomp that
+      // require librt. Most modern Linux platforms do, but some may not.
+      if (tools::addOpenMPRuntime(C, CmdArgs, ToolChain, Args, StaticOpenMP,
+                                  JA.isHostOffloading(Action::OFK_OpenMP),
+                                  /* GompNeedsRT= */ true))
+        // OpenMP runtimes implies pthreads when using the GNU toolchain.
+        // FIXME: Does this really make sense for all GNU toolchains?
+        WantPthread = true;
+
+      tools::AddRunTimeLibs(ToolChain, D, CmdArgs, Args);
+
+      if (WantPthread)
+        CmdArgs.push_back("-lpthread");
+
+      if (Args.hasArg(options::OPT_fsplit_stack))
+        CmdArgs.push_back("--wrap=pthread_create");
+
+      if (!Args.hasArg(options::OPT_nolibc))
+        CmdArgs.push_back("-lc");
+
+      // Cygwin specific
+      CmdArgs.push_back("-lcygwin");
+      if (Args.hasArg(options::OPT_mwindows)) {
+        CmdArgs.push_back("-lgdi32");
+        CmdArgs.push_back("-lcomdlg32");
+      }
+      CmdArgs.push_back("-ladvapi32");
+      CmdArgs.push_back("-lshell32");
+      CmdArgs.push_back("-luser32");
+      CmdArgs.push_back("-lkernel32");
+
+      if (IsStatic)
+        CmdArgs.push_back("--end-group");
+      else
+        tools::AddRunTimeLibs(ToolChain, D, CmdArgs, Args);
+    }
+
+    if (!Args.hasArg(options::OPT_nostartfiles)) {
+      if (ToolChain.GetRuntimeLibType(Args) == ToolChain::RLT_CompilerRT) {
+        std::string crtend =
+            ToolChain.getCompilerRT(Args, "crtend", ToolChain::FT_Object);
+        if (ToolChain.getVFS().exists(crtend)) {
+          std::string P;
+          P = crtend;
+          CmdArgs.push_back(Args.MakeArgString(P));
+        }
+      }
+      CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath("crtend.o")));
+    }
+  }
+
+  Args.addAllArgs(CmdArgs, {options::OPT_T, options::OPT_t});
+
+  const char *Exec = Args.MakeArgString(ToolChain.GetLinkerPath());
+  C.addCommand(std::make_unique<Command>(JA, *this,
+                                         ResponseFileSupport::AtFileCurCP(),
+                                         Exec, CmdArgs, Inputs, Output));
+}
+
+auto Cygwin::buildLinker() const -> Tool * { return new cygwin::Linker(*this); }

clang/lib/Driver/ToolChains/Cygwin.h

@@ -27,7 +27,25 @@ class LLVM_LIBRARY_VISIBILITY Cygwin : public Generic_GCC {
   void
   AddClangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
                             llvm::opt::ArgStringList &CC1Args) const override;
+
+protected:
+  Tool *buildLinker() const override;
+};
+
+namespace cygwin {
+class LLVM_LIBRARY_VISIBILITY Linker final : public Tool {
+public:
+  Linker(const ToolChain &TC) : Tool("cygwin::Linker", "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 cygwin
 
 } // end namespace toolchains
 } // end namespace driver