From ee1e5b9d368525de4bcdebc8cb470bdc4e70aec4 Mon Sep 17 00:00:00 2001
From: Albert Ziegenhagel <albert.ziegenhagel@scai.fraunhofer.de>
Date: Thu, 26 Oct 2017 17:09:30 +0200
Subject: [PATCH] Add support to set linker flags for flang on windows

---
 lib/Driver/ToolChains/CommonArgs.cpp |  2 +-
 lib/Driver/ToolChains/CommonArgs.h   |  2 +
 lib/Driver/ToolChains/MSVC.cpp       | 56 ++++++++++++++++++++++++++++
 lib/Driver/ToolChains/MSVC.h         |  3 ++
 4 files changed, 62 insertions(+), 1 deletion(-)

diff --git a/lib/Driver/ToolChains/CommonArgs.cpp b/lib/Driver/ToolChains/CommonArgs.cpp
index fe22b76556..969656b364 100644
--- a/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/lib/Driver/ToolChains/CommonArgs.cpp
@@ -67,7 +67,7 @@ bool tools::needFortranLibs(const Driver &D, const ArgList &Args) {
 }
 
 /// \brief Determine if Fortran "main" object is needed
-static bool needFortranMain(const Driver &D, const ArgList &Args) {
+bool tools::needFortranMain(const Driver &D, const ArgList &Args) {
   return (needFortranLibs(D, Args)
        && (!Args.hasArg(options::OPT_Mnomain) ||
            !Args.hasArg(options::OPT_no_fortran_main)));
diff --git a/lib/Driver/ToolChains/CommonArgs.h b/lib/Driver/ToolChains/CommonArgs.h
index 70ac75b2de..8bfdf162b9 100644
--- a/lib/Driver/ToolChains/CommonArgs.h
+++ b/lib/Driver/ToolChains/CommonArgs.h
@@ -22,6 +22,8 @@ namespace tools {
 
 bool needFortranLibs(const Driver &D, const llvm::opt::ArgList &Args);
 
+bool needFortranMain(const Driver &D, const llvm::opt::ArgList &Args);
+
 void addPathIfExists(const Driver &D, const Twine &Path,
                      ToolChain::path_list &Paths);
 
diff --git a/lib/Driver/ToolChains/MSVC.cpp b/lib/Driver/ToolChains/MSVC.cpp
index 7978a6941c..e71af6a1e7 100644
--- a/lib/Driver/ToolChains/MSVC.cpp
+++ b/lib/Driver/ToolChains/MSVC.cpp
@@ -372,6 +372,16 @@ void visualstudio::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back(Args.MakeArgString(std::string("-implib:") + ImplibName));
   }
 
+  // Add Fortran runtime libraries
+  if (needFortranLibs(TC.getDriver(), Args)) {
+    TC.AddFortranStdlibLibArgs(Args, CmdArgs);
+  } else {
+  // Claim "no Flang libraries" arguments if any
+    for (auto Arg : Args.filtered(options::OPT_noFlangLibs)) {
+      Arg->claim();
+    }
+  }
+
   if (TC.getSanitizerArgs().needsAsanRt()) {
     CmdArgs.push_back(Args.MakeArgString("-debug"));
     CmdArgs.push_back(Args.MakeArgString("-incremental:no"));
@@ -1255,6 +1265,52 @@ void MSVCToolChain::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
   // FIXME: There should probably be logic here to find libc++ on Windows.
 }
 
+void MSVCToolChain::AddFortranStdlibLibArgs(const ArgList &Args,
+                                            ArgStringList &CmdArgs) const {
+  bool staticFlangLibs = false;
+  bool useOpenMP = false;
+
+  const auto &D = getDriver();
+
+  if (Args.hasArg(options::OPT_staticFlangLibs)) {
+    for (auto *A: Args.filtered(options::OPT_staticFlangLibs)) {
+      A->claim();
+      staticFlangLibs = true;
+    }
+  }
+
+  Arg *A = Args.getLastArg(options::OPT_mp, options::OPT_nomp,
+                           options::OPT_fopenmp, options::OPT_fno_openmp);
+  if (A &&
+      (A->getOption().matches(options::OPT_mp) ||
+       A->getOption().matches(options::OPT_fopenmp))) {
+      useOpenMP = true;
+  }
+
+  CmdArgs.push_back(Args.MakeArgString(std::string("-libpath:") +
+                                        D.Dir + "/../lib"));
+
+  if (needFortranMain(D, Args)) {
+    CmdArgs.push_back("-defaultlib:flangmain");
+    CmdArgs.push_back("-subsystem:console");
+  }
+
+  if (staticFlangLibs) {
+    CmdArgs.push_back("-defaultlib:libflang");
+    CmdArgs.push_back("-defaultlib:libflangrti");
+    if (!useOpenMP) {
+      CmdArgs.push_back("-defaultlib:libompstub");
+    }
+  }
+  else {
+    CmdArgs.push_back("-defaultlib:flang");
+    CmdArgs.push_back("-defaultlib:flangrti");
+    if (!useOpenMP) {
+      CmdArgs.push_back("-defaultlib:ompstub");
+    }
+  }
+}
+
 VersionTuple MSVCToolChain::computeMSVCVersion(const Driver *D,
                                                const ArgList &Args) const {
   bool IsWindowsMSVC = getTriple().isWindowsMSVCEnvironment();
diff --git a/lib/Driver/ToolChains/MSVC.h b/lib/Driver/ToolChains/MSVC.h
index 854f88a36f..440542743a 100644
--- a/lib/Driver/ToolChains/MSVC.h
+++ b/lib/Driver/ToolChains/MSVC.h
@@ -106,6 +106,9 @@ class LLVM_LIBRARY_VISIBILITY MSVCToolChain : public ToolChain {
       const llvm::opt::ArgList &DriverArgs,
       llvm::opt::ArgStringList &CC1Args) const override;
 
+  void AddFortranStdlibLibArgs(const llvm::opt::ArgList &DriverArgs,
+                               llvm::opt::ArgStringList &CC1Args) const override;
+
   void AddCudaIncludeArgs(const llvm::opt::ArgList &DriverArgs,
                           llvm::opt::ArgStringList &CC1Args) const override;