[WinEH] Add CoreCLR EH table emission

[JosephTremoulet]

Summary

Emit the handler and clause locations immediately after the standard
xdata.
Clauses are emitted in the same order and format used to communiate them
to the CLR Execution Engine.
Add a lit test to verify correct table generation on a small but
interesting example function.

[JosephTremoulet]

Rebase

[JosephTremoulet]

rebase

[andrew.w.kaylor]

lib/CodeGen/AsmPrinter/WinException.cpp

924

typo - "regino"

941

What do you mean by "the xdata proper" and is this the same thing you are referring to as "the standard xdata" in the review description?

961

I've found that we've been kind of sloppy in the terminology we're using in comments to describe EH states. When you say "the state of the handler" do you mean the EH state of the code inside the handler or the EH state which is handled by that handler at the most recent invoke?

971

So this is the EH state of code inside the handler? The low state if the handler has multiple states?

983

Can you add some sort of debug check to account for the possibility that a poorly constructed ClrEHUnwindMap skips past AncestorState (i.e. state 2 unwinds to state 0 but AncestorState was 1)?

1037

typo - "a labels"

1058

Again, it seems like there is a possibility here of jumping over PendingState.

lib/CodeGen/AsmPrinter/WinException.h

72

Is there a reason only one of these parameters (for the two functions above) is const? It seems like they all could be.

[JosephTremoulet]

• Address Andy's feedback
• Rebase

[JosephTremoulet]

Thanks for the review! I believe I've incorporated everything.

lib/CodeGen/AsmPrinter/WinException.cpp

941

Yes. I've expanded the comment to be more verbose.

961

Part of the complication here is that nothing in the CLR docs/code has this notion of "EH states". I was referring to these things as states because it's the logical counterpart of what gets computed in ComputeStateNumbering for the other personalities. Really the "states" as they're used here are identifiers for the handlers and/or for the funclets (handlers and funclets have a 1:1 correspondence for CLR EH), and specifically they're the index of the corresponding entry in the unwind map. I've updated the comments throughout this function to be a bit more careful/verbose about that, let me know if you think further editing would be helpful.

971

Hopefully this is clear given the above. "Low state" doesn't really mean anything to me. I'm talking about MBB membership here, so "the handler" means the funclet that this MBB is a (top-level) member of.

983

Sure. I've added a check above that parent states are strictly less than child states, which will guarantee this loop terminates, and added an explicit assertion that PendingState never reaches NullState to be more easily diagnosable than the bounds assertion in the vector access.

1058

This one I didn't change, since the PendingState we're walking to here was set to AncestorState in the call to RewindPendingTo a few lines above, which in turn was computed by getAncestor(..., NewState). So if we jumped over PendingState here it would be a bug in getAncestor, not bad input. I think the implicit check in the vector indexer is sufficient.

lib/CodeGen/AsmPrinter/WinException.h

72

They can and should be. Fixed, thanks.

[rnk]

Some comments. I'm mainly interested in sharing the logic around EH_LABEL before committing this.

lib/CodeGen/AsmPrinter/WinException.cpp

906–907

Do you need the IMGREL relocations to compute a label difference? You should just need to create an MCSymbolRefExpr like this code from emitCSpecificHandlerTable:

const MCExpr *LabelDiff =
    MCBinaryExpr::createSub(MCSymbolRefExpr::create(TableEnd, Ctx),
                            MCSymbolRefExpr::create(TableBegin, Ctx), Ctx);

I think the assembler will do the same thing either way, but the .s file will look cleaner.

962–965

Hah, I think you actually solved the problem that I avoided solving for __C_specific_handler. :) I might want to share the code at some point so we can get smaller SEH tables.

1028

Can you use or adapt invoke_ranges to work here? The EH_LABEL tracking state machine is pretty subtle, I'd rather write it just once.

1150–1153

I guess using getLabelPlusOne requires keeping the IMGREL stuff inside the label difference.

test/CodeGen/WinEH/wineh-coreclr.ll

130

Interesting. I think these cross-funclet label differences will prohibit us from placing CLR funclets into .text$x, unless we tweak them until they are a perfect match for some relocation.

[JosephTremoulet]

Omit canceling @IMGRELs

[JosephTremoulet]

lib/CodeGen/AsmPrinter/WinException.cpp

906–907

Updated, and yes that looks much nicer, thanks for the suggestion.

1028

I'm not eager to switch to the invoke_ranges API as-is, since it only gets me within-MBB merging (so I still want merging up in this layer), and I find its SawPotentiallyThrowing state awkward to reason about.

I'd be happy to move to an iterator that

• merges ranges across MBBs (I need to *not* merge ranges across funclets, so either the common iterator could take start/end and I could pass the appropriate MBBs, or it could unconditionally split at funclet boundaries and just walk the whole MF)
• reports at each step: + the state entered at the new invoke range (-1 if entering a regions with potentially-throwing calls that aren't invokes, or if closing the final region) + the EH start label that starts the new invoke range (null if the entered state is -1) + the last EH end label that precedes the new range (so the caller can walk its stack of open clauses ending them there)

Would that be useful for generating the SEH tables? I wouldn't mind taking a stab at refactoring both onto a shared iterator like that.

test/CodeGen/WinEH/wineh-coreclr.ll

131

We don't handle splitting out cold code yet in LLILC generally, so I'll cross that bridge when we get there :).

[JosephTremoulet]

lib/CodeGen/AsmPrinter/WinException.cpp

1150–1153

I can (and did) reassociate so the add is on the result of the subtract.

[rnk]

lib/CodeGen/AsmPrinter/WinException.cpp

1028

If you could take a stab at refactoring it, that'd be awesome. The SEH and C++ table emission would be simpler with the interface you described.

I don't think I did a particularly good job writing that adaptor. I think making it cross-MBB will actually fix a bug around SawPotentiallyThrowing that I added when doing that refactor... Oops.

test/CodeGen/WinEH/wineh-coreclr.ll

131

I mentioned this because I want to do this in WinException::endFunclet() as soon as possible. It'll be easy to turn off for the CLR personality for now. :)

[JosephTremoulet]

Refactor to use InvokeStateChangeIterator

[JosephTremoulet]

lib/CodeGen/AsmPrinter/WinException.cpp

1028

Ok, I've submitted the refactoring to the different iterator in D13623, and rebased this diff on top of that.

[JosephTremoulet]

Simplify code to track current funclet state (and stop trying to get a MBB* from MF->end() after the last iteration)

[JosephTremoulet]

rebase

[JosephTremoulet]

rebase

[rnk]

lgtm

lib/CodeGen/AsmPrinter/WinException.cpp

882

nit: blank line between functions.

lib/CodeGen/AsmPrinter/WinException.h

class LLVM_LIBRARY_VISIBILITY WinException : public EHStreamer {
   /// the __CxxFrameHandler3 personality.
   void emitCXXFrameHandler3Table(const MachineFunction *MF);
 
   /// Emit the EH table data for _except_handler3 and _except_handler4
   /// personality functions. These are only used on 32-bit and do not use CFI
   /// tables.
   void emitExceptHandlerTable(const MachineFunction *MF);
 
+  void emitCLRExceptionTable(const MachineFunction *MF);
+
   void computeIP2StateTable(
       const MachineFunction *MF, WinEHFuncInfo &FuncInfo,
       SmallVectorImpl<std::pair<const MCExpr *, int>> &IPToStateTable);
 
   /// Emits the label used with llvm.x86.seh.recoverfp, which is used by
   /// outlined funclets.
   void emitEHRegistrationOffsetLabel(const WinEHFuncInfo &FuncInfo,
                                      StringRef FLinkageName);
 
   const MCExpr *create32bitRef(const MCSymbol *Value);
   const MCExpr *create32bitRef(const Value *V);
   const MCExpr *getLabelPlusOne(const MCSymbol *Label);
+  const MCExpr *getOffset(const MCSymbol *OffsetOf, const MCSymbol *OffsetFrom);
+  const MCExpr *getOffsetPlusOne(const MCSymbol *OffsetOf,
+                                 const MCSymbol *OffsetFrom);
 
   /// Gets the offset that we should use in a table for a stack object with the
   /// given index. For targets using CFI (Win64, etc), this is relative to the
   /// established SP at the end of the prologue. For targets without CFI (Win32
   /// only), it is relative to the frame pointer.
   int getFrameIndexOffset(int FrameIndex);
 
 public:

lib/CodeGen/AsmPrinter/WinException.cpp

if (shouldEmitPersonality || shouldEmitLSDA) {
     // Emit the tables appropriate to the personality function in use. If we
     // don't recognize the personality, assume it uses an Itanium-style LSDA.
     if (Per == EHPersonality::MSVC_Win64SEH)
       emitCSpecificHandlerTable(MF);
     else if (Per == EHPersonality::MSVC_X86SEH)
       emitExceptHandlerTable(MF);
     else if (Per == EHPersonality::MSVC_CXX)
       emitCXXFrameHandler3Table(MF);
+    else if (Per == EHPersonality::CoreCLR)
+      emitCLRExceptionTable(MF);
     else
       emitExceptionTable();
 
     Asm->OutStreamer->PopSection();
   }
 }
 
 /// Retreive the MCSymbol for a GlobalValue or MachineBasicBlock.

 }
 
 const MCExpr *WinException::getLabelPlusOne(const MCSymbol *Label) {
   return MCBinaryExpr::createAdd(create32bitRef(Label),
                                  MCConstantExpr::create(1, Asm->OutContext),
                                  Asm->OutContext);
 }
 
+const MCExpr *WinException::getOffset(const MCSymbol *OffsetOf,
+                                      const MCSymbol *OffsetFrom) {
+  return MCBinaryExpr::createSub(
+      MCSymbolRefExpr::create(OffsetOf, Asm->OutContext),
+      MCSymbolRefExpr::create(OffsetFrom, Asm->OutContext), Asm->OutContext);
+}
+
+const MCExpr *WinException::getOffsetPlusOne(const MCSymbol *OffsetOf,
+                                             const MCSymbol *OffsetFrom) {
+  return MCBinaryExpr::createAdd(getOffset(OffsetOf, OffsetFrom),
+                                 MCConstantExpr::create(1, Asm->OutContext),
+                                 Asm->OutContext);
+}
+
 int WinException::getFrameIndexOffset(int FrameIndex) {
   const TargetFrameLowering &TFI = *Asm->MF->getSubtarget().getFrameLowering();
   unsigned UnusedReg;
   if (Asm->MAI->usesWindowsCFI())
     return TFI.getFrameIndexReferenceFromSP(*Asm->MF, FrameIndex, UnusedReg);
   return TFI.getFrameIndexReference(*Asm->MF, FrameIndex, UnusedReg);
 }
 
void WinException::emitCSpecificHandlerTable(const MachineFunction *MF) {
 
   WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(MF->getFunction());
   // Use the assembler to compute the number of table entries through label
   // difference and division.
   MCSymbol *TableBegin =
       Ctx.createTempSymbol("lsda_begin", /*AlwaysAddSuffix=*/true);
   MCSymbol *TableEnd =
       Ctx.createTempSymbol("lsda_end", /*AlwaysAddSuffix=*/true);
-  const MCExpr *LabelDiff =
-      MCBinaryExpr::createSub(MCSymbolRefExpr::create(TableEnd, Ctx),
-                              MCSymbolRefExpr::create(TableBegin, Ctx), Ctx);
+  const MCExpr *LabelDiff = getOffset(TableEnd, TableBegin);
   const MCExpr *EntrySize = MCConstantExpr::create(16, Ctx);
   const MCExpr *EntryCount = MCBinaryExpr::createDiv(LabelDiff, EntrySize, Ctx);
   OS.EmitValue(EntryCount, 4);
 
   OS.EmitLabel(TableBegin);
 
   // Iterate over all the invoke try ranges. Unlike MSVC, LLVM currently only
   // models exceptions from invokes. LLVM also allows arbitrary reordering of
for (SEHUnwindMapEntry &UME : FuncInfo.SEHUnwindMap) {
     // -1 is usually the base state for "unwind to caller", but for
     // _except_handler4 it's -2. Do that replacement here if necessary.
     int ToState = UME.ToState == -1 ? BaseState : UME.ToState;
     OS.EmitIntValue(ToState, 4);                      // ToState
     OS.EmitValue(create32bitRef(UME.Filter), 4);      // Filter
     OS.EmitValue(create32bitRef(ExceptOrFinally), 4); // Except/Finally
   }
 }
+
+static int getRank(WinEHFuncInfo &FuncInfo, int State) {
+  int Rank = 0;
+  while (State != -1) {
+    ++Rank;
+    State = FuncInfo.ClrEHUnwindMap[State].Parent;
+  }
+  return Rank;
+}
+static int getAncestor(WinEHFuncInfo &FuncInfo, int Left, int Right) {
+  int LeftRank = getRank(FuncInfo, Left);
+  int RightRank = getRank(FuncInfo, Right);
+
+  while (LeftRank < RightRank) {
+    Right = FuncInfo.ClrEHUnwindMap[Right].Parent;
+    --RightRank;
+  }
+
+  while (RightRank < LeftRank) {
+    Left = FuncInfo.ClrEHUnwindMap[Left].Parent;
+    --LeftRank;
+  }
+
+  while (Left != Right) {
+    Left = FuncInfo.ClrEHUnwindMap[Left].Parent;
+    Right = FuncInfo.ClrEHUnwindMap[Right].Parent;
+  }
+
+  return Left;
+}
+
+void WinException::emitCLRExceptionTable(const MachineFunction *MF) {
+  // CLR EH "states" are really just IDs that identify handlers/funclets;
+  // states, handlers, and funclets all have 1:1 mappings between them, and a
+  // handler/funclet's "state" is its index in the ClrEHUnwindMap.
+  MCStreamer &OS = *Asm->OutStreamer;
+  const Function *F = MF->getFunction();
+  WinEHFuncInfo &FuncInfo = MMI->getWinEHFuncInfo(F);
+  MCSymbol *FuncBeginSym = Asm->getFunctionBegin();
+  MCSymbol *FuncEndSym = Asm->getFunctionEnd();
+
+  // A ClrClause describes a protected region.
+  struct ClrClause {
+    const MCSymbol *StartLabel; // Start of protected region
+    const MCSymbol *EndLabel;   // End of protected region
+    int State;          // Index of handler protecting the protected region
+    int EnclosingState; // Index of funclet enclosing the protected region
+  };
+  SmallVector<ClrClause, 8> Clauses;
+
+  // Build a map from handler MBBs to their corresponding states (i.e. their
+  // indices in the ClrEHUnwindMap).
+  int NumStates = FuncInfo.ClrEHUnwindMap.size();
+  assert(NumStates > 0 && "Don't need exception table!");
+  DenseMap<const MachineBasicBlock *, int> HandlerStates;
+  for (int State = 0; State < NumStates; ++State) {
+    MachineBasicBlock *HandlerBlock =
+        FuncInfo.ClrEHUnwindMap[State].Handler.get<MachineBasicBlock *>();
+    HandlerStates[HandlerBlock] = State;
+    // Use this loop through all handlers to verify our assumption (used in
+    // the MinEnclosingState computation) that ancestors have lower state
+    // numbers than their descendants.
+    assert(FuncInfo.ClrEHUnwindMap[State].Parent < State &&
+           "ill-formed state numbering");
+  }
+  // Map the main function to the NullState.
+  HandlerStates[MF->begin()] = NullState;
+
+  // Write out a sentinel indicating the end of the standard (Windows) xdata
+  // and the start of the additional (CLR) info.
+  OS.EmitIntValue(0xffffffff, 4);
+  // Write out the number of funclets
+  OS.EmitIntValue(NumStates, 4);
+
+  // Walk the machine blocks/instrs, computing and emitting a few things:
+  // 1. Emit a list of the offsets to each handler entry, in lexical order.
+  // 2. Compute a map (EndSymbolMap) from each funclet to the symbol at its end.
+  // 3. Compute the list of ClrClauses, in the required order (inner before
+  //    outer, earlier before later; the order by which a forward scan with
+  //    early termination will find the innermost enclosing clause covering
+  //    a given address).
+  // 4. A map (MinClauseMap) from each handler index to the index of the
+  //    outermost funclet/function which contains a try clause targeting the
+  //    key handler.  This will be used to determine IsDuplicate-ness when
+  //    emitting ClrClauses.  The NullState value is used to indicate that the
+  //    top-level function contains a try clause targeting the key handler.
+  // HandlerStack is a stack of (PendingStartLabel, PendingState) pairs for
+  // try regions we entered before entering the PendingState try but which
+  // we haven't yet exited.
+  SmallVector<std::pair<const MCSymbol *, int>, 4> HandlerStack;
+  // EndSymbolMap and MinClauseMap are maps described above.
+  std::unique_ptr<MCSymbol *[]> EndSymbolMap(new MCSymbol *[NumStates]);
+  SmallVector<int, 4> MinClauseMap((size_t)NumStates, NumStates);
+
+  // Visit the root function and each funclet.
+
+  for (MachineFunction::const_iterator FuncletStart = MF->begin(),
+                                       FuncletEnd = MF->begin(),
+                                       End = MF->end();
+       FuncletStart != End; FuncletStart = FuncletEnd) {
+    int FuncletState = HandlerStates[FuncletStart];
+    // Find the end of the funclet
+    MCSymbol *EndSymbol = FuncEndSym;
+    while (++FuncletEnd != End) {
+      if (FuncletEnd->isEHFuncletEntry()) {
+        EndSymbol = getMCSymbolForMBB(Asm, FuncletEnd);
+        break;
+      }
+    }
+    // Emit the function/funclet end and, if this is a funclet (and not the
+    // root function), record it in the EndSymbolMap.
+    OS.EmitValue(getOffset(EndSymbol, FuncBeginSym), 4);
+    if (FuncletState != NullState) {
+      // Record the end of the handler.
+      EndSymbolMap[FuncletState] = EndSymbol;
+    }
+
+    // Walk the state changes in this function/funclet and compute its clauses.
+    // Funclets always start in the null state.
+    const MCSymbol *CurrentStartLabel = nullptr;
+    int CurrentState = NullState;
+    assert(HandlerStack.empty());
+    for (const auto &StateChange :
+         InvokeStateChangeIterator::range(FuncInfo, FuncletStart, FuncletEnd)) {
+      // Close any try regions we're not still under
+      int AncestorState =
+          getAncestor(FuncInfo, CurrentState, StateChange.NewState);
+      while (CurrentState != AncestorState) {
+        assert(CurrentState != NullState && "Failed to find ancestor!");
+        // Close the pending clause
+        Clauses.push_back({CurrentStartLabel, StateChange.PreviousEndLabel,
+                           CurrentState, FuncletState});
+        // Now the parent handler is current
+        CurrentState = FuncInfo.ClrEHUnwindMap[CurrentState].Parent;
+        // Pop the new start label from the handler stack if we've exited all
+        // descendants of the corresponding handler.
+        if (HandlerStack.back().second == CurrentState)
+          CurrentStartLabel = HandlerStack.pop_back_val().first;
+      }
+
+      if (StateChange.NewState != CurrentState) {
+        // For each clause we're starting, update the MinClauseMap so we can
+        // know which is the topmost funclet containing a clause targeting
+        // it.
+        for (int EnteredState = StateChange.NewState;
+             EnteredState != CurrentState;
+             EnteredState = FuncInfo.ClrEHUnwindMap[EnteredState].Parent) {
+          int &MinEnclosingState = MinClauseMap[EnteredState];
+          if (FuncletState < MinEnclosingState)
+            MinEnclosingState = FuncletState;
+        }
+        // Save the previous current start/label on the stack and update to
+        // the newly-current start/state.
+        HandlerStack.emplace_back(CurrentStartLabel, CurrentState);
+        CurrentStartLabel = StateChange.NewStartLabel;
+        CurrentState = StateChange.NewState;
+      }
+    }
+    assert(HandlerStack.empty());
+  }
+
+  // Now emit the clause info, starting with the number of clauses.
+  OS.EmitIntValue(Clauses.size(), 4);
+  for (ClrClause &Clause : Clauses) {
+    // Emit a CORINFO_EH_CLAUSE :
+    /*
+      struct CORINFO_EH_CLAUSE
+      {
+          CORINFO_EH_CLAUSE_FLAGS Flags;         // actually a CorExceptionFlag
+          DWORD                   TryOffset;
+          DWORD                   TryLength;     // actually TryEndOffset
+          DWORD                   HandlerOffset;
+          DWORD                   HandlerLength; // actually HandlerEndOffset
+          union
+          {
+              DWORD               ClassToken;   // use for catch clauses
+              DWORD               FilterOffset; // use for filter clauses
+          };
+      };
+
+      enum CORINFO_EH_CLAUSE_FLAGS
+      {
+          CORINFO_EH_CLAUSE_NONE    = 0,
+          CORINFO_EH_CLAUSE_FILTER  = 0x0001, // This clause is for a filter
+          CORINFO_EH_CLAUSE_FINALLY = 0x0002, // This clause is a finally clause
+          CORINFO_EH_CLAUSE_FAULT   = 0x0004, // This clause is a fault clause
+      };
+      typedef enum CorExceptionFlag
+      {
+          COR_ILEXCEPTION_CLAUSE_NONE,
+          COR_ILEXCEPTION_CLAUSE_FILTER  = 0x0001, // This is a filter clause
+          COR_ILEXCEPTION_CLAUSE_FINALLY = 0x0002, // This is a finally clause
+          COR_ILEXCEPTION_CLAUSE_FAULT = 0x0004,   // This is a fault clause
+          COR_ILEXCEPTION_CLAUSE_DUPLICATED = 0x0008, // duplicated clause. This
+                                                      // clause was duplicated
+                                                      // to a funclet which was
+                                                      // pulled out of line
+      } CorExceptionFlag;
+    */
+    // Add 1 to the start/end of the EH clause; the IP associated with a
+    // call when the runtime does its scan is the IP of the next instruction
+    // (the one to which control will return after the call), so we need
+    // to add 1 to the end of the clause to cover that offset.  We also add
+    // 1 to the start of the clause to make sure that the ranges reported
+    // for all clauses are disjoint.  Note that we'll need some additional
+    // logic when machine traps are supported, since in that case the IP
+    // that the runtime uses is the offset of the faulting instruction
+    // itself; if such an instruction immediately follows a call but the
+    // two belong to different clauses, we'll need to insert a nop between
+    // them so the runtime can distinguish the point to which the call will
+    // return from the point at which the fault occurs.
+
+    const MCExpr *ClauseBegin =
+        getOffsetPlusOne(Clause.StartLabel, FuncBeginSym);
+    const MCExpr *ClauseEnd = getOffsetPlusOne(Clause.EndLabel, FuncBeginSym);
+
+    ClrEHUnwindMapEntry &Entry = FuncInfo.ClrEHUnwindMap[Clause.State];
+    MachineBasicBlock *HandlerBlock = Entry.Handler.get<MachineBasicBlock *>();
+    MCSymbol *BeginSym = getMCSymbolForMBB(Asm, HandlerBlock);
+    const MCExpr *HandlerBegin = getOffset(BeginSym, FuncBeginSym);
+    MCSymbol *EndSym = EndSymbolMap[Clause.State];
+    const MCExpr *HandlerEnd = getOffset(EndSym, FuncBeginSym);
+
+    uint32_t Flags = 0;
+    switch (Entry.HandlerType) {
+    case ClrHandlerType::Catch:
+      // Leaving bits 0-2 clear indicates catch.
+      break;
+    case ClrHandlerType::Filter:
+      Flags |= 1;
+      break;
+    case ClrHandlerType::Finally:
+      Flags |= 2;
+      break;
+    case ClrHandlerType::Fault:
+      Flags |= 4;
+      break;
+    }
+    if (Clause.EnclosingState != MinClauseMap[Clause.State]) {
+      // This is a "duplicate" clause; the handler needs to be entered from a
+      // frame above the one holding the invoke.
+      assert(Clause.EnclosingState > MinClauseMap[Clause.State]);
+      Flags |= 8;
+    }
+    OS.EmitIntValue(Flags, 4);
+
+    // Write the clause start/end
+    OS.EmitValue(ClauseBegin, 4);
+    OS.EmitValue(ClauseEnd, 4);
+
+    // Write out the handler start/end
+    OS.EmitValue(HandlerBegin, 4);
+    OS.EmitValue(HandlerEnd, 4);
+
+    // Write out the type token or filter offset
+    assert(Entry.HandlerType != ClrHandlerType::Filter && "NYI: filters");
+    OS.EmitIntValue(Entry.TypeToken, 4);
+  }
+}

test/CodeGen/WinEH/wineh-coreclr.ll

+; RUN: llc -mtriple=x86_64-pc-windows-coreclr < %s | FileCheck %s
+
+declare void @ProcessCLRException()
+declare void @f(i32)
+
+; Simplified IR for pseudo-C# like the following:
+; void test1() {
+;   try {
+;     f(1);
+;     try {
+;       f(2);
+;     } catch (type1) {
+;       f(3);
+;     } catch (type2) [
+;       f(4);
+;       try {
+;         f(5);
+;       } fault {
+;         f(6);
+;       }
+;     }
+;   } finally {
+;     f(7);
+;   }
+;   f(8);
+; }
+
+; CHECK-LABEL: test1:     # @test1
+; CHECK-NEXT: [[L_begin:.*func_begin.*]]:
+define void @test1() personality i8* bitcast (void ()* @ProcessCLRException to i8*) {
+entry:
+; CHECK: # %entry
+; CHECK: .seh_endprologue
+; CHECK: [[L_before_f1:.+]]:
+; CHECK-NEXT: movl $1, %ecx
+; CHECK-NEXT: callq f
+; CHECK-NEXT: [[L_after_f1:.+]]:
+  invoke void @f(i32 1)
+    to label %inner_try unwind label %finally.pad
+inner_try:
+; CHECK: # %inner_try
+; CHECK: [[L_before_f2:.+]]:
+; CHECK-NEXT: movl $2, %ecx
+; CHECK-NEXT: callq f
+; CHECK-NEXT: [[L_after_f2:.+]]:
+  invoke void @f(i32 2)
+    to label %finally.clone unwind label %catch1.pad
+catch1.pad:
+; CHECK: .seh_proc [[L_catch1:[^ ]+]]
+  %catch1 = catchpad [i32 1]
+    to label %catch1.body unwind label %catch2.pad
+catch1.body:
+; CHECK: .seh_endprologue
+; CHECK: [[L_before_f3:.+]]:
+; CHECK-NEXT: movl $3, %ecx
+; CHECK-NEXT: callq f
+; CHECK-NEXT: [[L_after_f3:.+]]:
+  invoke void @f(i32 3)
+    to label %catch1.ret unwind label %catch.end
+catch1.ret:
+  catchret %catch1 to label %finally.clone
+catch2.pad:
+; CHECK: .seh_proc [[L_catch2:[^ ]+]]
+  %catch2 = catchpad [i32 2]
+    to label %catch2.body unwind label %catch.end
+catch2.body:
+; CHECK: .seh_endprologue
+; CHECK: [[L_before_f4:.+]]:
+; CHECK-NEXT: movl $4, %ecx
+; CHECK-NEXT: callq f
+; CHECK-NEXT: [[L_after_f4:.+]]:
+  invoke void @f(i32 4)
+    to label %try_in_catch unwind label %catch.end
+try_in_catch:
+; CHECK: # %try_in_catch
+; CHECK: [[L_before_f5:.+]]:
+; CHECK-NEXT: movl $5, %ecx
+; CHECK-NEXT: callq f
+; CHECK-NEXT: [[L_after_f5:.+]]:
+  invoke void @f(i32 5)
+    to label %catch2.ret unwind label %fault.pad
+fault.pad:
+; CHECK: .seh_proc [[L_fault:[^ ]+]]
+  %fault = cleanuppad [i32 undef]
+; CHECK: .seh_endprologue
+; CHECK: [[L_before_f6:.+]]:
+; CHECK-NEXT: movl $6, %ecx
+; CHECK-NEXT: callq f
+; CHECK-NEXT: [[L_after_f6:.+]]:
+  invoke void @f(i32 6)
+    to label %fault.ret unwind label %fault.end
+fault.ret:
+  cleanupret %fault unwind label %catch.end
+fault.end:
+  cleanupendpad %fault unwind label %catch.end
+catch2.ret:
+  catchret %catch2 to label %finally.clone
+catch.end:
+  catchendpad unwind label %finally.pad
+finally.clone:
+  call void @f(i32 7)
+  br label %tail
+finally.pad:
+; CHECK: .seh_proc [[L_finally:[^ ]+]]
+  %finally = cleanuppad []
+; CHECK: .seh_endprologue
+; CHECK: [[L_before_f7:.+]]:
+; CHECK-NEXT: movl $7, %ecx
+; CHECK-NEXT: callq f
+; CHECK-NEXT: [[L_after_f7:.+]]:
+  invoke void @f(i32 7)
+    to label %finally.ret unwind label %finally.end
+finally.ret:
+  cleanupret %finally unwind to caller
+finally.end:
+   cleanupendpad %finally unwind to caller
+tail:
+  call void @f(i32 8)
+  ret void
+; CHECK: [[L_end:.*func_end.*]]:
+}
+
+; Now check for EH table in xdata (following standard xdata)
+; CHECK-LABEL: .section .xdata
+; standard xdata comes here
+; CHECK:      .long 4{{$}}
+;                   ^ number of funclets
+; CHECK-NEXT: .long [[L_catch1]]-[[L_begin]]
+;                   ^ offset from L_begin to start of 1st funclet
+; CHECK-NEXT: .long [[L_catch2]]-[[L_begin]]
+;                   ^ offset from L_begin to start of 2nd funclet
+; CHECK-NEXT: .long [[L_fault]]-[[L_begin]]
+;                   ^ offset from L_begin to start of 3rd funclet
+; CHECK-NEXT: .long [[L_finally]]-[[L_begin]]
+;                   ^ offset from L_begin to start of 4th funclet
+; CHECK-NEXT: .long [[L_end]]-[[L_begin]]
+;                   ^ offset from L_begin to end of last funclet
+; CHECK-NEXT: .long 7
+;                   ^ number of EH clauses
+; Clause 1: call f(2) is guarded by catch1
+; CHECK-NEXT: .long 0
+;                   ^ flags (0 => catch handler)
+; CHECK-NEXT: .long ([[L_before_f2]]-[[L_begin]])+1
+;                   ^ offset of start of clause
+; CHECK-NEXT: .long ([[L_after_f2]]-[[L_begin]])+1
+;                   ^ offset of end of clause
+; CHECK-NEXT: .long [[L_catch1]]-[[L_begin]]
+;                   ^ offset of start of handler
+; CHECK-NEXT: .long [[L_catch2]]-[[L_begin]]
+;                   ^ offset of end of handler
+; CHECK-NEXT: .long 1
+;                   ^ type token of catch (from catchpad)
+; Clause 2: call f(2) is also guarded by catch2
+; CHECK-NEXT: .long 0
+;                   ^ flags (0 => catch handler)
+; CHECK-NEXT: .long ([[L_before_f2]]-[[L_begin]])+1
+;                   ^ offset of start of clause
+; CHECK-NEXT: .long ([[L_after_f2]]-[[L_begin]])+1
+;                   ^ offset of end of clause
+; CHECK-NEXT: .long [[L_catch2]]-[[L_begin]]
+;                   ^ offset of start of handler
+; CHECK-NEXT: .long [[L_fault]]-[[L_begin]]
+;                   ^ offset of end of handler
+; CHECK-NEXT: .long 2
+;                   ^ type token of catch (from catchpad)
+; Clause 3: calls f(1) and f(2) are guarded by finally
+; CHECK-NEXT: .long 2
+;                   ^ flags (2 => finally handler)
+; CHECK-NEXT: .long ([[L_before_f1]]-[[L_begin]])+1
+;                   ^ offset of start of clause
+; CHECK-NEXT: .long ([[L_after_f2]]-[[L_begin]])+1
+;                   ^ offset of end of clause
+; CHECK-NEXT: .long [[L_finally]]-[[L_begin]]
+;                   ^ offset of start of handler
+; CHECK-NEXT: .long [[L_end]]-[[L_begin]]
+;                   ^ offset of end of handler
+; CHECK-NEXT: .long 0
+;                   ^ type token slot (null for finally)
+; Clause 4: call f(3) is guarded by finally
+;           This is a "duplicate" because the protected range (f(3))
+;           is in funclet catch1 but the finally's immediate parent
+;           is the main function, not that funclet.
+; CHECK-NEXT: .long 10
+;                   ^ flags (2 => finally handler | 8 => duplicate)
+; CHECK-NEXT: .long ([[L_before_f3]]-[[L_begin]])+1
+;                   ^ offset of start of clause
+; CHECK-NEXT: .long ([[L_after_f3]]-[[L_begin]])+1
+;                   ^ offset of end of clause
+; CHECK-NEXT: .long [[L_finally]]-[[L_begin]]
+;                   ^ offset of start of handler
+; CHECK-NEXT: .long [[L_end]]-[[L_begin]]
+;                   ^ offset of end of handler
+; CHECK-NEXT: .long 0
+;                   ^ type token slot (null for finally)
+; Clause 5: call f(5) is guarded by fault
+; CHECK-NEXT: .long 4
+;                   ^ flags (4 => fault handler)
+; CHECK-NEXT: .long ([[L_before_f5]]-[[L_begin]])+1
+;                   ^ offset of start of clause
+; CHECK-NEXT: .long ([[L_after_f5]]-[[L_begin]])+1
+;                   ^ offset of end of clause
+; CHECK-NEXT: .long [[L_fault]]-[[L_begin]]
+;                   ^ offset of start of handler
+; CHECK-NEXT: .long [[L_finally]]-[[L_begin]]
+;                   ^ offset of end of handler
+; CHECK-NEXT: .long 0
+;                   ^ type token slot (null for fault)
+; Clause 6: calls f(4) and f(5) are guarded by finally
+;           This is a "duplicate" because the protected range (f(4)-f(5))
+;           is in funclet catch2 but the finally's immediate parent
+;           is the main function, not that funclet.
+; CHECK-NEXT: .long 10
+;                   ^ flags (2 => finally handler | 8 => duplicate)
+; CHECK-NEXT: .long ([[L_before_f4]]-[[L_begin]])+1
+;                   ^ offset of start of clause
+; CHECK-NEXT: .long ([[L_after_f5]]-[[L_begin]])+1
+;                   ^ offset of end of clause
+; CHECK-NEXT: .long [[L_finally]]-[[L_begin]]
+;                   ^ offset of start of handler
+; CHECK-NEXT: .long [[L_end]]-[[L_begin]]
+;                   ^ offset of end of handler
+; CHECK-NEXT: .long 0
+;                   ^ type token slot (null for finally)
+; Clause 7: call f(6) is guarded by finally
+;           This is a "duplicate" because the protected range (f(3))
+;           is in funclet catch1 but the finally's immediate parent
+;           is the main function, not that funclet.
+; CHECK-NEXT: .long 10
+;                   ^ flags (2 => finally handler | 8 => duplicate)
+; CHECK-NEXT: .long ([[L_before_f6]]-[[L_begin]])+1
+;                   ^ offset of start of clause
+; CHECK-NEXT: .long ([[L_after_f6]]-[[L_begin]])+1
+;                   ^ offset of end of clause
+; CHECK-NEXT: .long [[L_finally]]-[[L_begin]]
+;                   ^ offset of start of handler
+; CHECK-NEXT: .long [[L_end]]-[[L_begin]]
+;                   ^ offset of end of handler
+; CHECK-NEXT: .long 0
+;                   ^ type token slot (null for finally)