Fixes Mono LLVM usage on Windows x64.

* Adjust mono's LLVM calling convention to use win64 calling convention.
* Emit both Windows native unwind info + Dwarf unwind info for mono methods.
* Don't emit native personality handlers for mono methods.

lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -256,7 +256,10 @@ bool AsmPrinter::doInitialization(Module &M) {
     switch (MAI->getWinEHEncodingType()) {
     default: llvm_unreachable("unsupported unwinding information encoding");
     case WinEH::EncodingType::Itanium:
-      ES = new Win64Exception(this);
+      if (!EnableMonoEH)
+        ES = new Win64Exception(this);
+      else
+        ES = new Win64Exception(this, true);
       break;
     }
     break;

lib/CodeGen/AsmPrinter/DwarfMonoException.cpp

@@ -396,7 +396,6 @@ void DwarfMonoException::EmitMonoLSDA(const FunctionEHFrameInfo *EFI) {
           [](const LandingPadInfo *L,
 			 const LandingPadInfo *R) { return L->TypeIds < R->TypeIds; });
 
-  assert(Asm->MAI->getExceptionHandlingType() == ExceptionHandling::DwarfCFI);
 
   // The type_info itself is emitted
   int TTypeEncoding = dwarf::DW_EH_PE_udata4;

lib/CodeGen/AsmPrinter/Win64Exception.cpp

@@ -39,7 +39,11 @@ using namespace llvm;
 
 Win64Exception::Win64Exception(AsmPrinter *A)
   : EHStreamer(A), shouldEmitPersonality(false), shouldEmitLSDA(false),
-    shouldEmitMoves(false) {}
+    shouldEmitMoves(false), disableEmitPersonality(false) {}
+
+Win64Exception::Win64Exception (AsmPrinter *A, bool disableEmitPersonality)
+  : EHStreamer(A), shouldEmitPersonality(false), shouldEmitLSDA(false),
+    shouldEmitMoves(false), disableEmitPersonality(disableEmitPersonality) {}
 
 Win64Exception::~Win64Exception() {}
 
@@ -62,8 +66,9 @@ void Win64Exception::beginFunction(const MachineFunction *MF) {
   unsigned PerEncoding = TLOF.getPersonalityEncoding();
   const Function *Per = MMI->getPersonalities()[MMI->getPersonalityIndex()];
 
-  shouldEmitPersonality = hasLandingPads &&
-    PerEncoding != dwarf::DW_EH_PE_omit && Per;
+  if (!disableEmitPersonality)
+    shouldEmitPersonality = hasLandingPads &&
+      PerEncoding != dwarf::DW_EH_PE_omit && Per;
 
   unsigned LSDAEncoding = TLOF.getLSDAEncoding();
   shouldEmitLSDA = shouldEmitPersonality &&

lib/CodeGen/AsmPrinter/Win64Exception.h

@@ -29,11 +29,15 @@ class Win64Exception : public EHStreamer {
   /// Per-function flag to indicate if frame moves info should be emitted.
   bool shouldEmitMoves;
 
+  /// Per-function flag to indicate if personality info should be disabled.
+  bool disableEmitPersonality;
+
 public:
   //===--------------------------------------------------------------------===//
   // Main entry points.
   //
   Win64Exception(AsmPrinter *A);
+  Win64Exception(AsmPrinter *A, bool disableEmitPersonality);
   virtual ~Win64Exception();
 
   /// Emit all exception information that should come after the content.

lib/Target/X86/X86CallingConv.td

@@ -383,7 +383,9 @@ def CC_X86_64_AnyReg : CallingConv<[
 
 def CC_X86_64_Mono : CallingConv<[
   CCIfInReg<CCAssignToReg<[R10]>>,
-
+  // Mingw64 and native Win64 use Win64 CC
+  CCIfSubtarget<"isTargetWin64()", CCDelegateTo<CC_X86_Win64_C>>,
+  // Otherwise, drop to normal X86-64 CC
   CCDelegateTo<CC_X86_64_C>
 ]>;
 

lib/Target/X86/X86FrameLowering.cpp

@@ -473,8 +473,9 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF) const {
       MF.getTarget().getMCAsmInfo()->getExceptionHandlingType() ==
       ExceptionHandling::WinEH; // Not necessarily synonymous with IsWin64.
   bool NeedsWinEH = IsWinEH && Fn->needsUnwindTableEntry();
-  bool NeedsDwarfCFI =
-      !IsWinEH && (MMI.hasDebugInfo() || Fn->needsUnwindTableEntry());
+  bool NeedsDwarfCFI = Fn->getCallingConv() == CallingConv::Mono ?
+      (MMI.hasDebugInfo() || Fn->needsUnwindTableEntry()) :
+      !IsWinEH && (MMI.hasDebugInfo () || Fn->needsUnwindTableEntry ());
   bool UseLEA = STI.useLeaForSP();
   unsigned StackAlign = getStackAlignment();
   unsigned SlotSize = RegInfo->getSlotSize();