[WebAssembly] Support -stdlib=libc++ switch

Referenced implementation from Fuchsia and Darwin Toolchain.
Still only support CST_Libcxx.  Now checks that the argument
is really '-stdlib=libc++', and display error.

Also, now will pass -lc++ and -lc++abi to the linker.

Patch by Patrick Cheng!

Differential Revision: https://reviews.llvm.org/D41937

llvm-svn: 322382

2 files changed, 22 insertions, 0 deletions

diff --git a/clang/lib/Driver/ToolChains/WebAssembly.cpp b/clang/lib/Driver/ToolChains/WebAssembly.cpp
index 42de430cb19..94f7279bbdb 100644
--- a/clang/lib/Driver/ToolChains/WebAssembly.cpp
+++ b/clang/lib/Driver/ToolChains/WebAssembly.cpp
@@ -11,6 +11,7 @@
 #include "CommonArgs.h"
 #include "clang/Driver/Compilation.h"
 #include "clang/Driver/Driver.h"
+#include "clang/Driver/DriverDiagnostic.h"
 #include "clang/Driver/Options.h"
 #include "llvm/Option/ArgList.h"
 
@@ -117,6 +118,12 @@ ToolChain::RuntimeLibType WebAssembly::GetDefaultRuntimeLibType() const {
 }
 
 ToolChain::CXXStdlibType WebAssembly::GetCXXStdlibType(const ArgList &Args) const {
+  if (Arg *A = Args.getLastArg(options::OPT_stdlib_EQ)) {
+    StringRef Value = A->getValue();
+    if (Value != "libc++")
+      getDriver().Diag(diag::err_drv_invalid_stdlib_name)
+          << A->getAsString(Args);
+  }
   return ToolChain::CST_Libcxx;
 }
 
@@ -134,6 +141,19 @@ void WebAssembly::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
                      getDriver().SysRoot + "/include/c++/v1");
 }
 
+void WebAssembly::AddCXXStdlibLibArgs(const llvm::opt::ArgList &Args,
+                                      llvm::opt::ArgStringList &CmdArgs) const {
+
+  switch (GetCXXStdlibType(Args)) {
+  case ToolChain::CST_Libcxx:
+    CmdArgs.push_back("-lc++");
+    CmdArgs.push_back("-lc++abi");
+    break;
+  case ToolChain::CST_Libstdcxx:
+    llvm_unreachable("invalid stdlib name");
+  }
+}
+
 std::string WebAssembly::getThreadModel() const {
   // The WebAssembly MVP does not yet support threads; for now, use the
   // "single" threading model, which lowers atomics to non-atomic operations.
diff --git a/clang/lib/Driver/ToolChains/WebAssembly.h b/clang/lib/Driver/ToolChains/WebAssembly.h
index 8784e12dfb0..cdbb34ff919 100644
--- a/clang/lib/Driver/ToolChains/WebAssembly.h
+++ b/clang/lib/Driver/ToolChains/WebAssembly.h
@@ -62,6 +62,8 @@ private:
   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;
   std::string getThreadModel() const override;
 
   const char *getDefaultLinker() const override {