[WinEH] Add cleanupendpad instruction

Summary:
Add a `cleanupendpad` instruction, used to mark exceptional exits out of
cleanups (for languages/targets that can abort a cleanup with another
exception).  The `cleanupendpad` instruction is similar to the `catchendpad`
instruction in that it is an EH pad which is the target of unwind edges in
the handler and which itself has an unwind edge to the next EH action.
The `cleanupendpad` instruction, similar to `cleanupret` has a `cleanuppad`
argument indicating which cleanup it exits.  The unwind successors of a
`cleanuppad`'s `cleanupendpad`s must agree with each other and with its
`cleanupret`s.

Update WinEHPrepare (and docs/tests) to accomodate `cleanupendpad`.

Reviewers: rnk, andrew.w.kaylor, majnemer

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D12433

llvm-svn: 246751

4 files changed, 33 insertions, 9 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 7c1706f6edc..9aa9755796d 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1205,6 +1205,10 @@ void SelectionDAGBuilder::visitCleanupRet(const CleanupReturnInst &I) {
   report_fatal_error("visitCleanupRet not yet implemented!");
 }
 
+void SelectionDAGBuilder::visitCleanupEndPad(const CleanupEndPadInst &I) {
+  report_fatal_error("visitCleanupEndPad not yet implemented!");
+}
+
 void SelectionDAGBuilder::visitTerminatePad(const TerminatePadInst &TPI) {
   report_fatal_error("visitTerminatePad not yet implemented!");
 }
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index 3b97d469f5e..2331127a966 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -740,6 +740,7 @@ private:
   void visitSwitch(const SwitchInst &I);
   void visitIndirectBr(const IndirectBrInst &I);
   void visitUnreachable(const UnreachableInst &I);
+  void visitCleanupEndPad(const CleanupEndPadInst &I);
   void visitCleanupRet(const CleanupReturnInst &I);
   void visitCatchEndPad(const CatchEndPadInst &I);
   void visitCatchRet(const CatchReturnInst &I);
diff --git a/llvm/lib/CodeGen/TargetLoweringBase.cpp b/llvm/lib/CodeGen/TargetLoweringBase.cpp
index d7a58f9686d..7250fdc9385 100644
--- a/llvm/lib/CodeGen/TargetLoweringBase.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringBase.cpp
@@ -1574,6 +1574,7 @@ int TargetLoweringBase::InstructionOpcodeToISD(unsigned Opcode) const {
   case Invoke:         return 0;
   case Resume:         return 0;
   case Unreachable:    return 0;
+  case CleanupEndPad:  return 0;
   case CleanupRet:     return 0;
   case CatchEndPad:  return 0;
   case CatchRet:       return 0;
diff --git a/llvm/lib/CodeGen/WinEHPrepare.cpp b/llvm/lib/CodeGen/WinEHPrepare.cpp
index 8c15b7e4413..c333c074900 100644
--- a/llvm/lib/CodeGen/WinEHPrepare.cpp
+++ b/llvm/lib/CodeGen/WinEHPrepare.cpp
@@ -403,7 +403,7 @@ bool WinEHPrepare::runOnFunction(Function &Fn) {
     } else if (First->isEHPad()) {
       if (!ForExplicitEH)
         EntryBlocks.push_back(&Fn.getEntryBlock());
-      if (!isa<CatchEndPadInst>(First))
+      if (!isa<CatchEndPadInst>(First) && !isa<CleanupEndPadInst>(First))
         EntryBlocks.push_back(&BB);
       ForExplicitEH = true;
     }
@@ -2965,6 +2965,8 @@ static const BasicBlock *getEHPadFromPredecessor(const BasicBlock *BB) {
   if (isa<CatchPadInst>(TI) || isa<CatchEndPadInst>(TI) ||
       isa<TerminatePadInst>(TI))
     return BB;
+  if (auto *CEPI = dyn_cast<CleanupEndPadInst>(TI))
+    return CEPI->getCleanupPad()->getParent();
   return cast<CleanupReturnInst>(TI)->getCleanupPad()->getParent();
 }
 
@@ -3035,18 +3037,27 @@ void llvm::calculateWinCXXEHStateNumbers(const Function *ParentFn,
   for (const BasicBlock &BB : *ParentFn) {
     if (!BB.isEHPad())
       continue;
+    const Instruction *FirstNonPHI = BB.getFirstNonPHI();
+    // Skip cleanupendpads; they are exits, not entries.
+    if (isa<CleanupEndPadInst>(FirstNonPHI))
+      continue;
     // Check if the EH Pad has no exceptional successors (i.e. it unwinds to
     // caller).  Cleanups are a little bit of a special case because their
     // control flow cannot be determined by looking at the pad but instead by
     // the pad's users.
     bool HasNoSuccessors = false;
-    const Instruction *FirstNonPHI = BB.getFirstNonPHI();
     if (FirstNonPHI->mayThrow()) {
       HasNoSuccessors = true;
     } else if (auto *CPI = dyn_cast<CleanupPadInst>(FirstNonPHI)) {
-      HasNoSuccessors =
-          CPI->use_empty() ||
-          cast<CleanupReturnInst>(CPI->user_back())->unwindsToCaller();
+      if (CPI->use_empty()) {
+        HasNoSuccessors = true;
+      } else {
+        const Instruction *User = CPI->user_back();
+        if (auto *CRI = dyn_cast<CleanupReturnInst>(User))
+          HasNoSuccessors = CRI->unwindsToCaller();
+        else
+          HasNoSuccessors = cast<CleanupEndPadInst>(User)->unwindsToCaller();
+      }
     }
 
     if (!HasNoSuccessors)
@@ -3096,7 +3107,8 @@ void WinEHPrepare::colorFunclets(Function &F,
     BasicBlock *Color;
     std::tie(Visiting, Color) = Worklist.pop_back_val();
     Instruction *VisitingHead = Visiting->getFirstNonPHI();
-    if (VisitingHead->isEHPad() && !isa<CatchEndPadInst>(VisitingHead)) {
+    if (VisitingHead->isEHPad() && !isa<CatchEndPadInst>(VisitingHead) &&
+        !isa<CleanupEndPadInst>(VisitingHead)) {
       // Mark this as a funclet head as a member of itself.
       FuncletBlocks[Visiting].insert(Visiting);
       // Queue exits with the parent color.
@@ -3132,7 +3144,8 @@ void WinEHPrepare::colorFunclets(Function &F,
       FuncletBlocks[Color].insert(Visiting);
       TerminatorInst *Terminator = Visiting->getTerminator();
       if (isa<CleanupReturnInst>(Terminator) ||
-          isa<CatchReturnInst>(Terminator)) {
+          isa<CatchReturnInst>(Terminator) ||
+          isa<CleanupEndPadInst>(Terminator)) {
         // These block's successors have already been queued with the parent
         // color.
         continue;
@@ -3288,11 +3301,16 @@ bool WinEHPrepare::prepareExplicitEH(
       bool IsUnreachableCatchret = false;
       if (auto *CRI = dyn_cast<CatchReturnInst>(TI))
         IsUnreachableCatchret = CRI->getCatchPad() != CatchPad;
-      // The token consumed by a CleanupPadInst must match the funclet token.
+      // The token consumed by a CleanupReturnInst must match the funclet token.
       bool IsUnreachableCleanupret = false;
       if (auto *CRI = dyn_cast<CleanupReturnInst>(TI))
         IsUnreachableCleanupret = CRI->getCleanupPad() != CleanupPad;
-      if (IsUnreachableRet || IsUnreachableCatchret || IsUnreachableCleanupret) {
+      // The token consumed by a CleanupEndPadInst must match the funclet token.
+      bool IsUnreachableCleanupendpad = false;
+      if (auto *CEPI = dyn_cast<CleanupEndPadInst>(TI))
+        IsUnreachableCleanupendpad = CEPI->getCleanupPad() != CleanupPad;
+      if (IsUnreachableRet || IsUnreachableCatchret ||
+          IsUnreachableCleanupret || IsUnreachableCleanupendpad) {
         new UnreachableInst(BB->getContext(), TI);
         TI->eraseFromParent();
       }