[Driver] Make -print-libgcc-file-name print compiler-rt lib when used

Make the -print-libgcc-file-name option print an appropriate compiler
runtime library, that is libgcc.a if gcc runtime is used
and an appropriate compiler-rt library if that runtime is used.

The main use for this is to allow linking executables built with
-nodefaultlibs (e.g. to avoid linking to the standard C++ library) to
the compiler runtime library, e.g. using:

  clang++ ... -nodefaultlibs $(clang++ ... -print-libgcc-file-name)

in which case currently a program built like this linked to the gcc
runtime unconditionally. The patch fixes it to use compiler-rt libraries
instead when compiler-rt is the active runtime.

Differential Revision: https://reviews.llvm.org/D25338

llvm-svn: 283746

1 files changed, 9 insertions, 1 deletions

diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 8fc52b286e6..459f601814b 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -994,7 +994,15 @@ bool Driver::HandleImmediateArgs(const Compilation &C) {
   }
 
   if (C.getArgs().hasArg(options::OPT_print_libgcc_file_name)) {
-    llvm::outs() << GetFilePath("libgcc.a", TC) << "\n";
+    ToolChain::RuntimeLibType RLT = TC.GetRuntimeLibType(C.getArgs());
+    switch (RLT) {
+    case ToolChain::RLT_CompilerRT:
+      llvm::outs() << TC.getCompilerRT(C.getArgs(), "builtins") << "\n";
+      break;
+    case ToolChain::RLT_Libgcc:
+      llvm::outs() << GetFilePath("libgcc.a", TC) << "\n";
+      break;
+    }
     return false;
   }