[WinEH] Make llvm.x86.seh.recoverfp work on x64

It adjusts from RSP-after-prologue to RBP, which is what SEH filters
need to do before they can use llvm.localrecover.

Fixes SEH filter captures, which were broken in r250088.

Issue reported by Alex Crichton.

llvm-svn: 255707

3 files changed, 34 insertions, 14 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/WinException.cpp b/llvm/lib/CodeGen/AsmPrinter/WinException.cpp
index e2994172415..c4f650e89e0 100644
--- a/llvm/lib/CodeGen/AsmPrinter/WinException.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/WinException.cpp
@@ -506,8 +506,18 @@ InvokeStateChangeIterator &InvokeStateChangeIterator::scan() {
 void WinException::emitCSpecificHandlerTable(const MachineFunction *MF) {
   auto &OS = *Asm->OutStreamer;
   MCContext &Ctx = Asm->OutContext;
-
   const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
+
+  // Emit a label assignment with the SEH frame offset so we can use it for
+  // llvm.x86.seh.recoverfp.
+  StringRef FLinkageName =
+      GlobalValue::getRealLinkageName(MF->getFunction()->getName());
+  MCSymbol *ParentFrameOffset =
+      Ctx.getOrCreateParentFrameOffsetSymbol(FLinkageName);
+  const MCExpr *MCOffset =
+      MCConstantExpr::create(FuncInfo.SEHSetFrameOffset, Ctx);
+  Asm->OutStreamer->EmitAssignment(ParentFrameOffset, MCOffset);
+
   // Use the assembler to compute the number of table entries through label
   // difference and division.
   MCSymbol *TableBegin =
diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp
index 7841a84326b..828dd7eca71 100644
--- a/llvm/lib/Target/X86/X86FrameLowering.cpp
+++ b/llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -912,9 +912,11 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF,
   uint64_t MaxAlign = calculateMaxStackAlign(MF); // Desired stack alignment.
   uint64_t StackSize = MFI->getStackSize();    // Number of bytes to allocate.
   bool IsFunclet = MBB.isEHFuncletEntry();
+  EHPersonality Personality = EHPersonality::Unknown;
+  if (Fn->hasPersonalityFn())
+    Personality = classifyEHPersonality(Fn->getPersonalityFn());
   bool FnHasClrFunclet =
-      MMI.hasEHFunclets() &&
-      classifyEHPersonality(Fn->getPersonalityFn()) == EHPersonality::CoreCLR;
+      MMI.hasEHFunclets() && Personality == EHPersonality::CoreCLR;
   bool IsClrFunclet = IsFunclet && FnHasClrFunclet;
   bool HasFP = hasFP(MF);
   bool IsWin64CC = STI.isCallingConvWin64(Fn->getCallingConv());
@@ -1250,19 +1252,21 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF,
           .addReg(SPOrEstablisher);
 
     // If this is not a funclet, emit the CFI describing our frame pointer.
-    if (NeedsWinCFI && !IsFunclet)
+    if (NeedsWinCFI && !IsFunclet) {
       BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_SetFrame))
           .addImm(FramePtr)
           .addImm(SEHFrameOffset)
           .setMIFlag(MachineInstr::FrameSetup);
+      if (isAsynchronousEHPersonality(Personality))
+        MF.getWinEHFuncInfo()->SEHSetFrameOffset = SEHFrameOffset;
+    }
   } else if (IsFunclet && STI.is32Bit()) {
     // Reset EBP / ESI to something good for funclets.
     MBBI = restoreWin32EHStackPointers(MBB, MBBI, DL);
     // If we're a catch funclet, we can be returned to via catchret. Save ESP
     // into the registration node so that the runtime will restore it for us.
     if (!MBB.isCleanupFuncletEntry()) {
-      assert(classifyEHPersonality(Fn->getPersonalityFn()) ==
-             EHPersonality::MSVC_CXX);
+      assert(Personality == EHPersonality::MSVC_CXX);
       unsigned FrameReg;
       int FI = MF.getWinEHFuncInfo()->EHRegNodeFrameIndex;
       int64_t EHRegOffset = getFrameIndexReference(MF, FI, FrameReg);
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index fa4370085ea..e34534050cc 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -16173,12 +16173,12 @@ static int getSEHRegistrationNodeSize(const Function *Fn) {
       "can only recover FP for 32-bit MSVC EH personality functions");
 }
 
-/// When the 32-bit MSVC runtime transfers control to us, either to an outlined
+/// When the MSVC runtime transfers control to us, either to an outlined
 /// function or when returning to a parent frame after catching an exception, we
 /// recover the parent frame pointer by doing arithmetic on the incoming EBP.
 /// Here's the math:
 ///   RegNodeBase = EntryEBP - RegNodeSize
-///   ParentFP = RegNodeBase - RegNodeFrameOffset
+///   ParentFP = RegNodeBase - ParentFrameOffset
 /// Subtracting RegNodeSize takes us to the offset of the registration node, and
 /// subtracting the offset (negative on x86) takes us back to the parent FP.
 static SDValue recoverFramePointer(SelectionDAG &DAG, const Function *Fn,
@@ -16195,22 +16195,28 @@ static SDValue recoverFramePointer(SelectionDAG &DAG, const Function *Fn,
   if (!Fn->hasPersonalityFn())
     return EntryEBP;
 
-  int RegNodeSize = getSEHRegistrationNodeSize(Fn);
-
   // Get an MCSymbol that will ultimately resolve to the frame offset of the EH
-  // registration.
+  // registration, or the .set_setframe offset.
   MCSymbol *OffsetSym =
       MF.getMMI().getContext().getOrCreateParentFrameOffsetSymbol(
           GlobalValue::getRealLinkageName(Fn->getName()));
   SDValue OffsetSymVal = DAG.getMCSymbol(OffsetSym, PtrVT);
-  SDValue RegNodeFrameOffset =
+  SDValue ParentFrameOffset =
       DAG.getNode(ISD::LOCAL_RECOVER, dl, PtrVT, OffsetSymVal);
 
+  // Return EntryEBP + ParentFrameOffset for x64. This adjusts from RSP after
+  // prologue to RBP in the parent function.
+  const X86Subtarget &Subtarget =
+      static_cast<const X86Subtarget &>(DAG.getSubtarget());
+  if (Subtarget.is64Bit())
+    return DAG.getNode(ISD::ADD, dl, PtrVT, EntryEBP, ParentFrameOffset);
+
+  int RegNodeSize = getSEHRegistrationNodeSize(Fn);
   // RegNodeBase = EntryEBP - RegNodeSize
-  // ParentFP = RegNodeBase - RegNodeFrameOffset
+  // ParentFP = RegNodeBase - ParentFrameOffset
   SDValue RegNodeBase = DAG.getNode(ISD::SUB, dl, PtrVT, EntryEBP,
                                     DAG.getConstant(RegNodeSize, dl, PtrVT));
-  return DAG.getNode(ISD::SUB, dl, PtrVT, RegNodeBase, RegNodeFrameOffset);
+  return DAG.getNode(ISD::SUB, dl, PtrVT, RegNodeBase, ParentFrameOffset);
 }
 
 static SDValue LowerINTRINSIC_WO_CHAIN(SDValue Op, const X86Subtarget *Subtarget,