Driver: Add a --rtlib={compiler-rt,libgcc} argument which I plan to use to allow
dual support for compiler-rt on Linux, during bringup.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@146094 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/Basic/DiagnosticDriverKinds.td b/include/clang/Basic/DiagnosticDriverKinds.td
index fdf1e4a..943d54b 100644
--- a/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/include/clang/Basic/DiagnosticDriverKinds.td
@@ -18,6 +18,10 @@
 def err_drv_unknown_language : Error<"language not recognized: '%0'">;
 def err_drv_invalid_arch_name : Error<
   "invalid arch name '%0'">;
+def err_drv_invalid_rtlib_name : Error<
+  "invalid runtime library name in argument '%0'">;
+def err_drv_unsupported_rtlib_for_platform : Error<
+  "unsupported runtime library '%0' for platform '%1'">;
 def err_drv_invalid_stdlib_name : Error<
   "invalid library name in argument '%0'">;
 def err_drv_invalid_opt_with_multiple_archs : Error<
diff --git a/include/clang/Driver/Options.td b/include/clang/Driver/Options.td
index 8cdf700..41240273 100644
--- a/include/clang/Driver/Options.td
+++ b/include/clang/Driver/Options.td
@@ -679,6 +679,7 @@
   HelpText<"Rewrite Objective-C source to C++">;
 def rdynamic : Flag<"-rdynamic">;
 def rpath : Separate<"-rpath">, Flags<[LinkerInput]>;
+def rtlib_EQ : Joined<"-rtlib=">;
 def r : Flag<"-r">;
 def save_temps : Flag<"-save-temps">, Flags<[DriverOption]>,
   HelpText<"Save intermediate compilation results">;
@@ -851,6 +852,8 @@
   HelpText<"Build a relocatable precompiled header">;
 def _resource_EQ : Joined<"--resource=">, Alias<fcompile_resource_EQ>;
 def _resource : Separate<"--resource">, Alias<fcompile_resource_EQ>;
+def _rtlib_EQ : Joined<"--rtlib=">, Alias<rtlib_EQ>;
+def _rtlib : Separate<"--rtlib">, Alias<rtlib_EQ>;
 def _save_temps : Flag<"--save-temps">, Alias<save_temps>;
 def _serialize_diags : Separate<"--serialize-diagnostics">, Flags<[DriverOption]>,
   HelpText<"Serialize compiler diagnostics to a file">;
diff --git a/include/clang/Driver/ToolChain.h b/include/clang/Driver/ToolChain.h
index 75ee574..56dbad7 100644
--- a/include/clang/Driver/ToolChain.h
+++ b/include/clang/Driver/ToolChain.h
@@ -39,6 +39,11 @@
     CST_Libstdcxx
   };
 
+  enum RuntimeLibType {
+    RLT_CompilerRT,
+    RLT_Libgcc
+  };
+
 private:
   const HostInfo &Host;
   const llvm::Triple Triple;
@@ -143,6 +148,11 @@
     return 0;
   }
 
+  /// GetDefaultRuntimeLibType - Get the default runtime library variant to use.
+  virtual RuntimeLibType GetDefaultRuntimeLibType() const {
+    return ToolChain::RLT_Libgcc;
+  }
+
   /// IsUnwindTablesDefault - Does this tool chain use -funwind-tables
   /// by default.
   virtual bool IsUnwindTablesDefault() const = 0;
@@ -202,6 +212,10 @@
   virtual void AddClangSystemIncludeArgs(const ArgList &DriverArgs,
                                          ArgStringList &CC1Args) const;
 
+  // GetRuntimeLibType - Determine the runtime library type to use with the
+  // given compilation arguments.
+  virtual RuntimeLibType GetRuntimeLibType(const ArgList &Args) const;
+
   // GetCXXStdlibType - Determine the C++ standard library type to use with the
   // given compilation arguments.
   virtual CXXStdlibType GetCXXStdlibType(const ArgList &Args) const;
diff --git a/lib/Driver/ToolChain.cpp b/lib/Driver/ToolChain.cpp
index 9453848..83c918e 100644
--- a/lib/Driver/ToolChain.cpp
+++ b/lib/Driver/ToolChain.cpp
@@ -216,6 +216,22 @@
   // Each toolchain should provide the appropriate include flags.
 }
 
+ToolChain::RuntimeLibType ToolChain::GetRuntimeLibType(
+  const ArgList &Args) const
+{
+  if (Arg *A = Args.getLastArg(options::OPT_rtlib_EQ)) {
+    StringRef Value = A->getValue(Args);
+    if (Value == "compiler-rt")
+      return ToolChain::RLT_CompilerRT;
+    if (Value == "libgcc")
+      return ToolChain::RLT_Libgcc;
+    getDriver().Diag(diag::err_drv_invalid_rtlib_name)
+      << A->getAsString(Args);
+  }
+
+  return GetDefaultRuntimeLibType();
+}
+
 ToolChain::CXXStdlibType ToolChain::GetCXXStdlibType(const ArgList &Args) const{
   if (Arg *A = Args.getLastArg(options::OPT_stdlib_EQ)) {
     StringRef Value = A->getValue(Args);
diff --git a/lib/Driver/ToolChains.cpp b/lib/Driver/ToolChains.cpp
index fa4cf41..29559a6 100644
--- a/lib/Driver/ToolChains.cpp
+++ b/lib/Driver/ToolChains.cpp
@@ -440,6 +440,16 @@
 
 void DarwinClang::AddLinkRuntimeLibArgs(const ArgList &Args,
                                         ArgStringList &CmdArgs) const {
+  // Darwin only supports the compiler-rt based runtime libraries.
+  switch (GetRuntimeLibType(Args)) {
+  case ToolChain::RLT_CompilerRT:
+    break;
+  default:
+    getDriver().Diag(diag::err_drv_unsupported_rtlib_for_platform)
+      << Args.getLastArg(options::OPT_rtlib_EQ)->getValue(Args) << "darwin";
+    return;
+  }
+
   // Darwin doesn't support real static executables, don't link any runtime
   // libraries with -static.
   if (Args.hasArg(options::OPT_static))
diff --git a/lib/Driver/ToolChains.h b/lib/Driver/ToolChains.h
index d150a97..f3a26e6 100644
--- a/lib/Driver/ToolChains.h
+++ b/lib/Driver/ToolChains.h
@@ -347,6 +347,9 @@
       (!isMacosxVersionLT(10, 6) ||
          (!isMacosxVersionLT(10, 5) && !KernelOrKext));
   }
+  virtual RuntimeLibType GetDefaultRuntimeLibType() const {
+    return ToolChain::RLT_CompilerRT;
+  }
   virtual const char *GetDefaultRelocationModel() const;
   virtual const char *GetForcedPicModel() const;