[WinEH] Verify consistent funclet unwind exits

[JosephTremoulet]

Summary

A funclet EH pad may be exited by an unwind edge, which may be a
cleanupret exiting its cleanuppad, an invoke exiting a funclet, or an
unwind out of a nested funclet transitively exiting its parent. Funclet
EH personalities require all such exceptional exits from a given funclet to
have the same unwind destination, and EH preparation / state numbering /
table generation implicitly depends on this. Formalize it as a rule of
the IR in the LangRef and verifier.

[majnemer]

Is there any way to get back the tests we lost in test/CodeGen/WinEH/wineh-no-demotion.ll ? Those tests are nice because they stress instances where we might add another edge to a funclet (those tests show this by cloning an invoke).

[andrew.w.kaylor]

docs/ExceptionHandling.rst

837

Making sure I understand this, you are saying that a catchswitch can say it unwinds to caller but it must, at runtime, handle all exceptions that can actually occur in order to produce defined behavior. Is that right?

I can understand why we would want to allow call instructions with no declared unwind destination, but I'm not sure I see why we wouldn't require the unwind destination of a catchswitch to match its parent's destination. Is it to avoid having the catchswitch block appear to be a predecessor of a block that it can never reach?

It seems to me that it would be better to add a nounwind variant of the catchswitch.

[JosephTremoulet]

restore wineh-no-demotion tests

[JosephTremoulet]

In D15962#321660, @majnemer wrote:

Is there any way to get back the tests we lost in test/CodeGen/WinEH/wineh-no-demotion.ll ? Those tests are nice because they stress instances where we might add another edge to a funclet (those tests show this by cloning an invoke).

Yes, looks like the tests can stay if I just remove the funclet bundles from the to-be-cloned invokes, so I've updated to do that.

docs/ExceptionHandling.rst

837

Yes, you're understanding correctly.

When we have catchswitch A unwinding to pad B and we discover that pad B is immediately unreachable, to me it makes more sense to allow stomping out the edge and leaving catchswitch A as "unwinds to caller" like we do than it does to require that code to snoop around and see if catchswitch A has a parent pad and if an unwind edge which leaves the parent can be found and redirect catchswitch A to that edge's successor for consistency -- in addition to requiring a not-rocket-science but nonetheless nontrivial search for the parent's unwind successor, it also requires suddenly giving that successor a new predecessor and doing who-knows-what updates to maintain SSA etc in the face of that.

I absolutely agree that it would be nicer to have a nounwind variant of catchswitch, not just for this but also to be able to express catch-all over funclet EH in a way that the CFG reflects naturally. I think it's a nontrivial undertaking (though easier now that we have parent tokens and funclet bundles than it would have been before), and not the top of my priority list. Happy to review patches, though :).

[andrew.w.kaylor]

docs/ExceptionHandling.rst

837

OK. That's a reasonable explanation.

Another nice-to-have would be some pass that would insert a cleanup pad with a trap instruction in this situation for debugging/testing purposes.

lib/IR/Verifier.cpp

3117

I haven't taken the time to think through it yet but you may know, is it possible to skip over FPI and/or UnwindParent below while walking the pad-parent chain? I think I could make some IR that would do that for just this function. I just don't know if it would be flagged as invalid somewhere else.

[JosephTremoulet]

lib/IR/Verifier.cpp

3117

I did give it some thought, and yes my goal was that any such cases would be quiet here but would get flagged in visitEHPadPredecessors when looking at the same unwind edge from its successor.

[andrew.w.kaylor]

Looks good.

docs/ExceptionHandling.rst

 the edge from a ``catchswitch`` must exit at least itself, and the edge from
 a ``cleanupret`` must exit at least its ``cleanuppad``), and then must enter
 exactly one pad, which must be distinct from all the exited pads.  The parent
 of the pad that an unwind edge enters must be the most-recently-entered
 not-yet-exited pad (after exiting from any pads that the unwind edge exits),
 or "none" if there is no such pad.  This ensures that the stack of executing
 funclets at run-time always corresponds to some path in the funclet pad tree
 that the parent tokens encode.
+
+All unwind edges which exit any given funclet pad (including ``cleanupret``
+edges exiting their ``cleanuppad`` and ``catchswitch`` edges exiting their
+``catchswitch``) must share the same unwind destination.  Similarly, any
+funclet pad which may be exited by unwind to caller must not be exited by
+any exception edges which unwind anywhere other than the caller.  This
+ensures that each funclet as a whole has only one unwind destination, which
+EH tables for funclet personalities may require.  Note that any unwind edge
+which exits a ``catchpad`` also exits its parent ``catchswitch``, so this
+implies that for any given ``catchswitch``, its unwind destination must also
+be the unwind destination of any unwind edge that exits any of its constituent
+``catchpad``\s.  Because ``catchswitch`` has no ``nounwind`` variant, and
+because IR producers are not *required* to annotate calls which will not
+unwind as ``nounwind``, it is legal to nest a ``call`` or an "``unwind to
+caller``\ " ``catchswitch`` within a funclet pad that has an unwind
+destination other than caller; it is undefined behavior for such a ``call``
+or ``catchswitch`` to unwind.

docs/LangRef.rst

 -  A basic block that is not a cleanup block may not include a
    '``cleanuppad``' instruction.
 
 When a ``cleanuppad`` has been "entered" but not yet "exited" (as
 described in the `EH documentation\ <ExceptionHandling.html#wineh-constraints>`_),
 it is undefined behavior to execute a :ref:`call <i_call>` or :ref:`invoke <i_invoke>`
 that does not carry an appropriate :ref:`"funclet" bundle <ob_funclet>`.
 
-It is undefined behavior for the ``cleanuppad`` to exit via an unwind edge which
-does not transitively unwind to the same destination as a constituent
-``cleanupret``.
-
 Example:
 """"""""
 
 .. code-block:: llvm
 
       %tok = cleanuppad within %cs []
 
 .. _intrinsics:

lib/IR/Verifier.cpp

#include "llvm/IR/Metadata.def"
   void visitAllocaInst(AllocaInst &AI);
   void visitExtractValueInst(ExtractValueInst &EVI);
   void visitInsertValueInst(InsertValueInst &IVI);
   void visitEHPadPredecessors(Instruction &I);
   void visitLandingPadInst(LandingPadInst &LPI);
   void visitCatchPadInst(CatchPadInst &CPI);
   void visitCatchReturnInst(CatchReturnInst &CatchReturn);
   void visitCleanupPadInst(CleanupPadInst &CPI);
+  void visitFuncletPadInst(FuncletPadInst &FPI);
   void visitCatchSwitchInst(CatchSwitchInst &CatchSwitch);
   void visitCleanupReturnInst(CleanupReturnInst &CRI);
 
   void VerifyCallSite(CallSite CS);
   void verifyMustTailCall(CallInst &CI);
   bool PerformTypeCheck(Intrinsic::ID ID, Function *F, Type *Ty, int VT,
                         unsigned ArgNo, std::string &Suffix);
   bool VerifyIntrinsicType(Type *Ty, ArrayRef<Intrinsic::IITDescriptor> &Infos,
Assert(isa<CatchSwitchInst>(CPI.getParentPad()),
          "CatchPadInst needs to be directly nested in a CatchSwitchInst.",
          CPI.getParentPad());
 
   // The catchpad instruction must be the first non-PHI instruction in the
   // block.
   Assert(BB->getFirstNonPHI() == &CPI,
          "CatchPadInst not the first non-PHI instruction in the block.", &CPI);
 
-  visitInstruction(CPI);
+  visitFuncletPadInst(CPI);
 }
 
 void Verifier::visitCatchReturnInst(CatchReturnInst &CatchReturn) {
   Assert(isa<CatchPadInst>(CatchReturn.getOperand(0)),
          "CatchReturnInst needs to be provided a CatchPad", &CatchReturn,
          CatchReturn.getOperand(0));
 
   visitTerminatorInst(CatchReturn);
void Verifier::visitCleanupPadInst(CleanupPadInst &CPI) {
   Assert(BB->getFirstNonPHI() == &CPI,
          "CleanupPadInst not the first non-PHI instruction in the block.",
          &CPI);
 
   auto *ParentPad = CPI.getParentPad();
   Assert(isa<ConstantTokenNone>(ParentPad) || isa<FuncletPadInst>(ParentPad),
          "CleanupPadInst has an invalid parent.", &CPI);
 
+  visitFuncletPadInst(CPI);
+}
+
+void Verifier::visitFuncletPadInst(FuncletPadInst &FPI) {
   User *FirstUser = nullptr;
-  BasicBlock *FirstUnwindDest = nullptr;
-  for (User *U : CPI.users()) {
+  Value *FirstUnwindPad = nullptr;
+  SmallVector<FuncletPadInst *, 8> Worklist({&FPI});
+  while (!Worklist.empty()) {
+    FuncletPadInst *CurrentPad = Worklist.pop_back_val();
+    Value *UnresolvedAncestorPad = nullptr;
+    for (User *U : CurrentPad->users()) {
       BasicBlock *UnwindDest;
-    if (CleanupReturnInst *CRI = dyn_cast<CleanupReturnInst>(U)) {
+      if (auto *CRI = dyn_cast<CleanupReturnInst>(U)) {
         UnwindDest = CRI->getUnwindDest();
-    } else if (isa<CleanupPadInst>(U) || isa<CatchSwitchInst>(U)) {
+      } else if (auto *CSI = dyn_cast<CatchSwitchInst>(U)) {
+        // We allow catchswitch unwind to caller to nest
+        // within an outer pad that unwinds somewhere else,
+        // because catchswitch doesn't have a nounwind variant.
+        // See e.g. SimplifyCFGOpt::SimplifyUnreachable.
+        if (CSI->unwindsToCaller())
           continue;
-    } else if (CallSite(U)) {
+        UnwindDest = CSI->getUnwindDest();
+      } else if (auto *II = dyn_cast<InvokeInst>(U)) {
+        UnwindDest = II->getUnwindDest();
+      } else if (isa<CallInst>(U)) {
+        // Calls which don't unwind may be found inside funclet
+        // pads that unwind somewhere else.  We don't *require*
+        // such calls to be annotated nounwind.
+        continue;
+      } else if (auto *CPI = dyn_cast<CleanupPadInst>(U)) {
+        // The unwind dest for a cleanup can only be found by
+        // recursive search.  Add it to the worklist, and we'll
+        // search for its first use that determines where it unwinds.
+        Worklist.push_back(CPI);
         continue;
       } else {
-      Assert(false, "bogus cleanuppad use", &CPI);
+        Assert(isa<CatchReturnInst>(U), "Bogus funclet pad use", U);
+        continue;
       }
 
-    if (!FirstUser) {
-      FirstUser = U;
-      FirstUnwindDest = UnwindDest;
+      Value *UnwindPad;
+      bool ExitsFPI;
+      if (UnwindDest) {
+        UnwindPad = UnwindDest->getFirstNonPHI();
+        Value *UnwindParent = getParentPad(UnwindPad);
+        // Ignore unwind edges that don't exit CurrentPad.
+        if (UnwindParent == CurrentPad)
+          continue;
+        // Determine whether the original funclet pad is exited,
+        // and if we are scanning nested pads determine how many
+        // of them are exited so we can stop searching their
+        // children.
+        Value *ExitedPad = CurrentPad;
+        ExitsFPI = false;
+        do {
+          if (ExitedPad == &FPI) {
+            ExitsFPI = true;
+            // Now we can resolve any ancestors of CurrentPad up to
+            // FPI, but not including FPI since we need to make sure
+            // to check all direct users of FPI for consistency.
+            UnresolvedAncestorPad = &FPI;
+            break;
+          }
+          Value *ExitedParent = getParentPad(ExitedPad);
+          if (ExitedParent == UnwindParent) {
+            // ExitedPad is the ancestor-most pad which this unwind
+            // edge exits, so we can resolve up to it, meaning that
+            // ExitedParent is the first ancestor still unresolved.
+            UnresolvedAncestorPad = ExitedParent;
+            break;
+          }
+          ExitedPad = ExitedParent;
+        } while (!isa<ConstantTokenNone>(ExitedPad));
       } else {
-      Assert(
-          UnwindDest == FirstUnwindDest,
-          "cleanupret instructions from the same cleanuppad must have the same "
-          "unwind destination",
-          FirstUser, U);
+        // Unwinding to caller exits all pads.
+        UnwindPad = ConstantTokenNone::get(FPI.getContext());
+        ExitsFPI = true;
+        UnresolvedAncestorPad = &FPI;
+      }
+
+      if (ExitsFPI) {
+        // This unwind edge exits FPI.  Make sure it agrees with other
+        // such edges.
+        if (FirstUser) {
+          Assert(UnwindPad == FirstUnwindPad, "Unwind edges out of a funclet "
+                                              "pad must have the same unwind "
+                                              "dest",
+                 &FPI, U, FirstUser);
+        } else {
+          FirstUser = U;
+          FirstUnwindPad = UnwindPad;
+        }
+      }
+      // Make sure we visit all uses of FPI, but for nested pads stop as
+      // soon as we know where they unwind to.
+      if (CurrentPad != &FPI)
+        break;
+    }
+    if (UnresolvedAncestorPad) {
+      if (CurrentPad == UnresolvedAncestorPad) {
+        // When CurrentPad is FPI itself, we don't mark it as resolved even if
+        // we've found an unwind edge that exits it, because we need to verify
+        // all direct uses of FPI.
+        assert(CurrentPad == &FPI);
+        continue;
+      }
+      // Pop off the worklist any nested pads that we've found an unwind
+      // destination for.  The pads on the worklist are the uncles,
+      // great-uncles, etc. of CurrentPad.  We've found an unwind destination
+      // for all ancestors of CurrentPad up to but not including
+      // UnresolvedAncestorPad.
+      Value *ResolvedPad = CurrentPad;
+      while (!Worklist.empty()) {
+        Value *UnclePad = Worklist.back();
+        Value *AncestorPad = getParentPad(UnclePad);
+        // Walk ResolvedPad up the ancestor list until we either find the
+        // uncle's parent or the last resolved ancestor.
+        while (ResolvedPad != AncestorPad) {
+          Value *ResolvedParent = getParentPad(ResolvedPad);
+          if (ResolvedParent == UnresolvedAncestorPad) {
+            break;
+          }
+          ResolvedPad = ResolvedParent;
+        }
+        // If the resolved ancestor search didn't find the uncle's parent,
+        // then the uncle is not yet resolved.
+        if (ResolvedPad != AncestorPad)
+          break;
+        // This uncle is resolved, so pop it from the worklist.
+        Worklist.pop_back();
+      }
+    }
+  }
+
+  if (FirstUnwindPad) {
+    if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(FPI.getParentPad())) {
+      BasicBlock *SwitchUnwindDest = CatchSwitch->getUnwindDest();
+      Value *SwitchUnwindPad;
+      if (SwitchUnwindDest)
+        SwitchUnwindPad = SwitchUnwindDest->getFirstNonPHI();
+      else
+        SwitchUnwindPad = ConstantTokenNone::get(FPI.getContext());
+      Assert(SwitchUnwindPad == FirstUnwindPad,
+             "Unwind edges out of a catch must have the same unwind dest as "
+             "the parent catchswitch",
+             &FPI, FirstUser, CatchSwitch);
     }
   }
 
-  visitInstruction(CPI);
+  visitInstruction(FPI);
 }
 
 void Verifier::visitCatchSwitchInst(CatchSwitchInst &CatchSwitch) {
   visitEHPadPredecessors(CatchSwitch);
 
   BasicBlock *BB = CatchSwitch.getParent();
 
   Function *F = BB->getParent();

test/CodeGen/WinEH/wineh-no-demotion.ll

cleanupret:
   cleanupret from %0 unwind label %right
 
 right:
   %1 = cleanuppad within none []
   br label %shared
 
 shared:
   %x = call i32 @g()
-  invoke void @f() [ "funclet"(token %0) ]
+  invoke void @f()
           to label %shared.cont unwind label %inner
 
 shared.cont:
   unreachable
 
 inner:
   %phi = phi i32 [ %x, %shared ], [ 0, %invoke.cont ]
   %i = cleanuppad within none []
cleanupret:
   cleanupret from %0 unwind label %right
 
 right:
   %1 = cleanuppad within none []
   br label %shared
 
 shared:
   %x = call i32 @g()
-  invoke void @f() [ "funclet"(token %0) ]
+  invoke void @f()
           to label %shared.cont unwind label %inner
 
 shared.cont:
   unreachable
 
 inner:
   %i = cleanuppad within none []
   call void @h(i32 %x)

test/CodeGen/WinEH/wineh-statenumbering.ll

 catch.dispatch:                                   ; preds = %entry
   %cs1 = catchswitch within none [label %catch] unwind to caller
 
 catch:                                            ; preds = %catch.dispatch
   %1 = catchpad within %cs1 [i8* null, i32 u0x40, i8* null]
   ; CHECK: catch:
   ; CHECK:   store i32 2
   ; CHECK:   invoke void @_CxxThrowException(
-  invoke void @_CxxThrowException(i8* null, %eh.ThrowInfo* null) #1
+  invoke void @_CxxThrowException(i8* null, %eh.ThrowInfo* null) [ "funclet"(token %1) ]
           to label %unreachable unwind label %catch.dispatch.1
 
 catch.dispatch.1:                                 ; preds = %catch
   %cs2 = catchswitch within %1 [label %catch.3] unwind to caller
 catch.3:                                          ; preds = %catch.dispatch.1
   %2 = catchpad within %cs2 [i8* null, i32 u0x40, i8* null]
   ; CHECK: catch.3:
   ; CHECK:   store i32 3

test/Verifier/invalid-eh.ll

 ; RUN: sed -e s/.T1:// %s | not llvm-as -disable-output 2>&1 | FileCheck --check-prefix=CHECK1 %s
 ; RUN: sed -e s/.T2:// %s | not llvm-as -disable-output 2>&1 | FileCheck --check-prefix=CHECK2 %s
 ; RUN: sed -e s/.T3:// %s | not llvm-as -disable-output 2>&1 | FileCheck --check-prefix=CHECK3 %s
 ; RUN: sed -e s/.T4:// %s | not llvm-as -disable-output 2>&1 | FileCheck --check-prefix=CHECK4 %s
 ; RUN: sed -e s/.T5:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK5 %s
 ; RUN: sed -e s/.T6:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK6 %s
 ; RUN: sed -e s/.T7:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK7 %s
 ; RUN: sed -e s/.T8:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK8 %s
 ; RUN: sed -e s/.T9:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK9 %s
 ; RUN: sed -e s/.T10:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK10 %s
 ; RUN: sed -e s/.T11:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK11 %s
 ; RUN: sed -e s/.T12:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK12 %s
 ; RUN: sed -e s/.T13:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK13 %s
+; RUN: sed -e s/.T14:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK14 %s
+; RUN: sed -e s/.T15:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK15 %s
+; RUN: sed -e s/.T16:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK16 %s
+; RUN: sed -e s/.T17:// %s | not opt -verify -disable-output 2>&1 | FileCheck --check-prefix=CHECK17 %s
 
 declare void @g()
 
 ;T1: define void @f() {
 ;T1:   entry:
 ;T1:     catchret from undef to label %next
 ;T1:     ; CHECK1: CatchReturnInst needs to be provided a CatchPad
 ;T1:   next:

 ;T13:     %cs = catchswitch within none [label %catch] unwind label %switch
 ;T13:     ; CHECK13: EH pad cannot handle exceptions raised within it
 ;T13:     ; CHECK13-NEXT:  %cs = catchswitch within none [label %catch] unwind label %switch
 ;T13:   catch:
 ;T13:     catchpad within %cs [i32 0]
 ;T13:     unreachable
 ;T13: }
 
+;T14: define void @f() personality void ()* @g {
+;T14:   entry:
+;T14:     ret void
+;T14:   cleanup:
+;T14:     %cp = cleanuppad within none []
+;T14:     unreachable
+;T14:   left:
+;T14:     cleanupret from %cp unwind label %switch
+;T14:   right:
+;T14:     cleanupret from %cp unwind to caller
+;T14:     ; CHECK14: Unwind edges out of a funclet pad must have the same unwind dest
+;T14:     ; CHECK14-NEXT: %cp = cleanuppad within none []
+;T14:     ; CHECK14-NEXT: cleanupret from %cp unwind label %switch
+;T14:     ; CHECK14-NEXT: cleanupret from %cp unwind to caller
+;T14:   switch:
+;T14:     %cs = catchswitch within none [label %catch] unwind to caller
+;T14:   catch:
+;T14:     catchpad within %cs [i32 1]
+;T14:     unreachable
+;T14: }
+
+;T15: define void @f() personality void ()* @g {
+;T15:   entry:
+;T15:     ret void
+;T15:   switch:
+;T15:     %cs = catchswitch within none [label %catch] unwind to caller
+;T15:   catch:
+;T15:     %catch.pad = catchpad within %cs [i32 1]
+;T15:     invoke void @g() [ "funclet"(token %catch.pad) ]
+;T15:       to label %unreachable unwind label %target1
+;T15:   unreachable:
+;T15:     unreachable
+;T15:   target1:
+;T15:     cleanuppad within none []
+;T15:     unreachable
+;T15:   target2:
+;T15:     cleanuppad within none []
+;T15:     unreachable
+;T15:   nested.1:
+;T15:     %nested.pad.1 = cleanuppad within %catch.pad []
+;T15:     unreachable
+;T15:   nested.2:
+;T15:     %nested.pad.2 = cleanuppad within %nested.pad.1 []
+;T15:     cleanupret from %nested.pad.2 unwind label %target2
+;T15:     ; CHECK15: Unwind edges out of a funclet pad must have the same unwind dest
+;T15:     ; CHECK15-NEXT: %catch.pad = catchpad within %cs [i32 1]
+;T15:     ; CHECK15-NEXT: cleanupret from %nested.pad.2 unwind label %target2
+;T15:     ; CHECK15-NEXT: invoke void @g() [ "funclet"(token %catch.pad) ]
+;T15:     ; CHECK15-NEXT:   to label %unreachable unwind label %target1
+;T15: }
+
+;T16: define void @f() personality void ()* @g {
+;T16:   entry:
+;T16:     ret void
+;T16:   switch:
+;T16:     %cs = catchswitch within none [label %catch] unwind to caller
+;T16:   catch:
+;T16:     %catch.pad = catchpad within %cs [i32 1]
+;T16:     invoke void @g() [ "funclet"(token %catch.pad) ]
+;T16:       to label %unreachable unwind label %target1
+;T16:     ; CHECK16: Unwind edges out of a catch must have the same unwind dest as the parent catchswitch
+;T16:     ; CHECK16-NEXT:   %catch.pad = catchpad within %cs [i32 1]
+;T16:     ; CHECK16-NEXT:  invoke void @g() [ "funclet"(token %catch.pad) ]
+;T16:     ; CHECK16-NEXT:          to label %unreachable unwind label %target1
+;T16:     ; CHECK16-NEXT:  %cs = catchswitch within none [label %catch] unwind to caller
+;T16:   unreachable:
+;T16:     unreachable
+;T16:   target1:
+;T16:     cleanuppad within none []
+;T16:     unreachable
+;T16: }
+
+;T17: define void @f() personality void ()* @g {
+;T17:   entry:
+;T17:     ret void
+;T17:   switch:
+;T17:     %cs = catchswitch within none [label %catch] unwind label %target1
+;T17:   catch:
+;T17:     %catch.pad = catchpad within %cs [i32 1]
+;T17:     invoke void @g() [ "funclet"(token %catch.pad) ]
+;T17:       to label %unreachable unwind label %target2
+;T17:     ; CHECK17: Unwind edges out of a catch must have the same unwind dest as the parent catchswitch
+;T17:     ; CHECK17-NEXT:  %catch.pad = catchpad within %cs [i32 1]
+;T17:     ; CHECK17-NEXT:  invoke void @g() [ "funclet"(token %catch.pad) ]
+;T17:     ; CHECK17-NEXT:          to label %unreachable unwind label %target2
+;T17:     ; CHECK17-NEXT:  %cs = catchswitch within none [label %catch] unwind label %target1
+;T17:   unreachable:
+;T17:     unreachable
+;T17:   target1:
+;T17:     cleanuppad within none []
+;T17:     unreachable
+;T17:   target2:
+;T17:     cleanuppad within none []
+;T17:     unreachable
+;T17: }