From 96f2ea3dd407792054ea3592e9d243f34695e4af Mon Sep 17 00:00:00 2001
From: Sanjin Sijaric <ssijaric@codeaurora.org>
Date: Sat, 27 Oct 2018 06:13:06 +0000
Subject: [ARM64][Windows] MCLayer support for exception handling

Add ARM64 unwind codes to MCLayer, as well SEH directives that will be emitted
by the frame lowering patch to follow.  We only emit unwind codes into object
object files for now.

Differential Revision: https://reviews.llvm.org/D50166

llvm-svn: 345450
---
 llvm/lib/CodeGen/AsmPrinter/WinException.cpp | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

(limited to 'llvm/lib/CodeGen/AsmPrinter/WinException.cpp')

diff --git a/llvm/lib/CodeGen/AsmPrinter/WinException.cpp b/llvm/lib/CodeGen/AsmPrinter/WinException.cpp
index eff73a58d8d..2a97a2fde43 100644
--- a/llvm/lib/CodeGen/AsmPrinter/WinException.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/WinException.cpp
@@ -42,6 +42,7 @@ WinException::WinException(AsmPrinter *A) : EHStreamer(A) {
   // MSVC's EH tables are always composed of 32-bit words.  All known 64-bit
   // platforms use an imagerel32 relocation to refer to symbols.
   useImageRel32 = (A->getDataLayout().getPointerSizeInBits() == 64);
+  isAArch64 = Asm->TM.getTargetTriple().isAArch64();
 }
 
 WinException::~WinException() {}
@@ -242,6 +243,17 @@ void WinException::endFunclet() {
     if (F.hasPersonalityFn())
       Per = classifyEHPersonality(F.getPersonalityFn()->stripPointerCasts());
 
+    // On funclet exit, we emit a fake "function" end marker, so that the call
+    // to EmitWinEHHandlerData below can calculate the size of the funclet or
+    // function.
+    if (isAArch64) {
+      Asm->OutStreamer->SwitchSection(CurrentFuncletTextSection);
+      Asm->OutStreamer->EmitWinCFIFuncletOrFuncEnd();
+      MCSection *XData = Asm->OutStreamer->getAssociatedXDataSection(
+          Asm->OutStreamer->getCurrentSectionOnly());
+      Asm->OutStreamer->SwitchSection(XData);
+    }
+
     // Emit an UNWIND_INFO struct describing the prologue.
     Asm->OutStreamer->EmitWinEHHandlerData();
 
@@ -286,7 +298,10 @@ const MCExpr *WinException::create32bitRef(const GlobalValue *GV) {
   return create32bitRef(Asm->getSymbol(GV));
 }
 
-const MCExpr *WinException::getLabelPlusOne(const MCSymbol *Label) {
+const MCExpr *WinException::getLabel(const MCSymbol *Label) {
+  if (isAArch64)
+    return MCSymbolRefExpr::create(Label, MCSymbolRefExpr::VK_COFF_IMGREL32,
+                                   Asm->OutContext);
   return MCBinaryExpr::createAdd(create32bitRef(Label),
                                  MCConstantExpr::create(1, Asm->OutContext),
                                  Asm->OutContext);
@@ -588,7 +603,6 @@ void WinException::emitSEHActionsForRange(const WinEHFuncInfo &FuncInfo,
                                           const MCSymbol *EndLabel, int State) {
   auto &OS = *Asm->OutStreamer;
   MCContext &Ctx = Asm->OutContext;
-
   bool VerboseAsm = OS.isVerboseAsm();
   auto AddComment = [&](const Twine &Comment) {
     if (VerboseAsm)
@@ -613,9 +627,9 @@ void WinException::emitSEHActionsForRange(const WinEHFuncInfo &FuncInfo,
     }
 
     AddComment("LabelStart");
-    OS.EmitValue(getLabelPlusOne(BeginLabel), 4);
+    OS.EmitValue(getLabel(BeginLabel), 4);
     AddComment("LabelEnd");
-    OS.EmitValue(getLabelPlusOne(EndLabel), 4);
+    OS.EmitValue(getLabel(EndLabel), 4);
     AddComment(UME.IsFinally ? "FinallyFunclet" : UME.Filter ? "FilterFunction"
                                                              : "CatchAll");
     OS.EmitValue(FilterOrFinally, 4);
@@ -799,7 +813,7 @@ void WinException::emitCXXFrameHandler3Table(const MachineFunction *MF) {
       //   TypeDescriptor *Type;
       //   int32_t         CatchObjOffset;
       //   void          (*Handler)();
-      //   int32_t         ParentFrameOffset; // x64 only
+      //   int32_t         ParentFrameOffset; // x64 and AArch64 only
       // };
       OS.EmitLabel(HandlerMapXData);
       for (const WinEHHandlerType &HT : TBME.HandlerArray) {
@@ -901,7 +915,7 @@ void WinException::computeIP2StateTable(
         ChangeLabel = StateChange.PreviousEndLabel;
       // Emit an entry indicating that PCs after 'Label' have this EH state.
       IPToStateTable.push_back(
-          std::make_pair(getLabelPlusOne(ChangeLabel), StateChange.NewState));
+          std::make_pair(getLabel(ChangeLabel), StateChange.NewState));
       // FIXME: assert that NewState is between CatchLow and CatchHigh.
     }
   }
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