[Driver] Enable --rtlib option for MSVC target

This enables "--rtlib compiler-rt" option under MSVC environment.

Patch by Roman Shirokiy.

Differential Revision: http://reviews.llvm.org/D17453

llvm-svn: 263422

1 files changed, 16 insertions, 1 deletions

diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index f51e1f67788..1e46434ef9a 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -8948,7 +8948,16 @@ static void AddRunTimeLibs(const ToolChain &TC, const Driver &D,
     }
     break;
   case ToolChain::RLT_Libgcc:
-    AddLibgcc(TC.getTriple(), D, CmdArgs, Args);
+    // Make sure libgcc is not used under MSVC environment by default
+    if (TC.getTriple().isKnownWindowsMSVCEnvironment()) {
+      // Issue error diagnostic if libgcc is explicitly specified
+      // through command line as --rtlib option argument.
+      if (Args.hasArg(options::OPT_rtlib_EQ)) {
+        TC.getDriver().Diag(diag::err_drv_unsupported_rtlib_for_platform)
+            << Args.getLastArg(options::OPT_rtlib_EQ)->getValue() << "MSVC";
+      }
+    } else
+      AddLibgcc(TC.getTriple(), D, CmdArgs, Args);
     break;
   }
 }
@@ -9754,6 +9763,12 @@ void visualstudio::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     }
   }
 
+  // Add compiler-rt lib in case if it was explicitly
+  // specified as an argument for --rtlib option.
+  if (!Args.hasArg(options::OPT_nostdlib)) {
+    AddRunTimeLibs(TC, TC.getDriver(), CmdArgs, Args);
+  }
+
   // Add filenames, libraries, and other linker inputs.
   for (const auto &Input : Inputs) {
     if (Input.isFilename()) {