Initial commit of the 'landingpad' instruction.

This implements the 'landingpad' instruction. It's used to indicate that a basic
block is a landing pad. There are several restrictions on its use (see
LangRef.html for more detail). These restrictions allow the exception handling
code to gather the information it needs in a much more sane way.

This patch has the definition, implementation, C interface, parsing, and bitcode
support in it.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@137501 91177308-0d34-0410-b5e6-96231b3b80d8

15 files changed, 303 insertions, 10 deletions

diff --git a/lib/AsmParser/LLLexer.cpp b/lib/AsmParser/LLLexer.cpp
index c3a5a4d0db..fdadd1ba93 100644
--- a/lib/AsmParser/LLLexer.cpp
+++ b/lib/AsmParser/LLLexer.cpp
@@ -584,6 +584,11 @@ lltok::Kind LLLexer::LexIdentifier() {
 
   KEYWORD(x);
   KEYWORD(blockaddress);
+
+  KEYWORD(personality);
+  KEYWORD(cleanup);
+  KEYWORD(catch);
+  KEYWORD(filter);
 #undef KEYWORD
 
   // Keywords for types.
@@ -653,6 +658,7 @@ lltok::Kind LLLexer::LexIdentifier() {
   INSTKEYWORD(shufflevector,  ShuffleVector);
   INSTKEYWORD(extractvalue,   ExtractValue);
   INSTKEYWORD(insertvalue,    InsertValue);
+  INSTKEYWORD(landingpad,     LandingPad);
 #undef INSTKEYWORD
 
   // Check for [us]0x[0-9A-Fa-f]+ which are Hexadecimal constant generated by
diff --git a/lib/AsmParser/LLParser.cpp b/lib/AsmParser/LLParser.cpp
index 8b30eef3d5..6a4c2a8fb9 100644
--- a/lib/AsmParser/LLParser.cpp
+++ b/lib/AsmParser/LLParser.cpp
@@ -2945,6 +2945,7 @@ int LLParser::ParseInstruction(Instruction *&Inst, BasicBlock *BB,
   case lltok::kw_insertelement:  return ParseInsertElement(Inst, PFS);
   case lltok::kw_shufflevector:  return ParseShuffleVector(Inst, PFS);
   case lltok::kw_phi:            return ParsePHI(Inst, PFS);
+  case lltok::kw_landingpad:     return ParseLandingPad(Inst, PFS);
   case lltok::kw_call:           return ParseCall(Inst, PFS, false);
   case lltok::kw_tail:           return ParseCall(Inst, PFS, true);
   // Memory.
@@ -3519,6 +3520,47 @@ int LLParser::ParsePHI(Instruction *&Inst, PerFunctionState &PFS) {
   return AteExtraComma ? InstExtraComma : InstNormal;
 }
 
+/// ParseLandingPad
+///   ::= 'landingpad' Type 'personality' TypeAndValue 'cleanup'? Clause+
+/// Clause
+///   ::= 'catch' TypeAndValue
+///   ::= 'filter'
+///   ::= 'filter' TypeAndValue ( ',' TypeAndValue )*
+bool LLParser::ParseLandingPad(Instruction *&Inst, PerFunctionState &PFS) {
+  Type *Ty = 0; LocTy TyLoc;
+  Value *PersFn; LocTy PersFnLoc;
+  LocTy LPLoc = Lex.getLoc();
+
+  if (ParseType(Ty, TyLoc) ||
+      ParseToken(lltok::kw_personality, "expected 'personality'") ||
+      ParseTypeAndValue(PersFn, PersFnLoc, PFS))
+    return true;
+
+  LandingPadInst *LP = LandingPadInst::Create(Ty, PersFn, 0);
+  LP->setCleanup(EatIfPresent(lltok::kw_cleanup));
+
+  while (Lex.getKind() == lltok::kw_catch || Lex.getKind() == lltok::kw_filter){
+    LandingPadInst::ClauseType CT;
+    if (EatIfPresent(lltok::kw_catch))
+      CT = LandingPadInst::Catch;
+    else if (EatIfPresent(lltok::kw_filter))
+      CT = LandingPadInst::Filter;
+    else
+      return TokError("expected 'catch' or 'filter' clause type");
+
+    Value *V; LocTy VLoc;
+    if (ParseTypeAndValue(V, VLoc, PFS)) {
+      delete LP;
+      return true;
+    }
+
+    LP->addClause(V);
+  }
+
+  Inst = LP;
+  return false;
+}
+
 /// ParseCall
 ///   ::= 'tail'? 'call' OptionalCallingConv OptionalAttrs Type Value
 ///       ParameterList OptionalAttrs
diff --git a/lib/AsmParser/LLParser.h b/lib/AsmParser/LLParser.h
index 815f062026..ef4d3dba9e 100644
--- a/lib/AsmParser/LLParser.h
+++ b/lib/AsmParser/LLParser.h
@@ -360,6 +360,7 @@ namespace llvm {
     bool ParseInsertElement(Instruction *&I, PerFunctionState &PFS);
     bool ParseShuffleVector(Instruction *&I, PerFunctionState &PFS);
     int ParsePHI(Instruction *&I, PerFunctionState &PFS);
+    bool ParseLandingPad(Instruction *&I, PerFunctionState &PFS);
     bool ParseCall(Instruction *&I, PerFunctionState &PFS, bool isTail);
     int ParseAlloc(Instruction *&I, PerFunctionState &PFS);
     int ParseLoad(Instruction *&I, PerFunctionState &PFS,
diff --git a/lib/AsmParser/LLToken.h b/lib/AsmParser/LLToken.h
index 3da85ad5d7..d22ecf31bd 100644
--- a/lib/AsmParser/LLToken.h
+++ b/lib/AsmParser/LLToken.h
@@ -124,6 +124,8 @@ namespace lltok {
     kw_fptoui, kw_fptosi, kw_inttoptr, kw_ptrtoint, kw_bitcast,
     kw_select, kw_va_arg,
 
+    kw_landingpad, kw_personality, kw_cleanup, kw_catch, kw_filter,
+
     kw_ret, kw_br, kw_switch, kw_indirectbr, kw_invoke, kw_unwind, kw_resume,
     kw_unreachable,
 
diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index 8f4e8c3e46..a33705d2dd 100644
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -2543,6 +2543,44 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
       break;
     }
 
+    case bitc::FUNC_CODE_INST_LANDINGPAD: {
+      // LANDINGPAD: [ty, val, val, num, (id0,val0 ...)?]
+      unsigned Idx = 0;
+      if (Record.size() < 4)
+        return Error("Invalid LANDINGPAD record");
+      Type *Ty = getTypeByID(Record[Idx++]);
+      if (!Ty) return Error("Invalid LANDINGPAD record");
+      Value *PersFn = 0;
+      if (getValueTypePair(Record, Idx, NextValueNo, PersFn))
+        return Error("Invalid LANDINGPAD record");
+
+      bool IsCleanup = !!Record[Idx++];
+      unsigned NumClauses = Record[Idx++];
+      LandingPadInst *LP = LandingPadInst::Create(Ty, PersFn, NumClauses);
+      LP->setCleanup(IsCleanup);
+      for (unsigned J = 0; J != NumClauses; ++J) {
+        LandingPadInst::ClauseType CT =
+          LandingPadInst::ClauseType(Record[Idx++]); (void)CT;
+        Value *Val;
+
+        if (getValueTypePair(Record, Idx, NextValueNo, Val)) {
+          delete LP;
+          return Error("Invalid LANDINGPAD record");
+        }
+
+        assert((CT != LandingPadInst::Catch ||
+                !isa<ArrayType>(Val->getType())) &&
+               "Catch clause has a invalid type!");
+        assert((CT != LandingPadInst::Filter ||
+                isa<ArrayType>(Val->getType())) &&
+               "Filter clause has invalid type!");
+        LP->addClause(Val);
+      }
+
+      I = LP;
+      break;
+    }
+
     case bitc::FUNC_CODE_INST_ALLOCA: { // ALLOCA: [instty, opty, op, align]
       if (Record.size() != 4)
         return Error("Invalid ALLOCA record");
diff --git a/lib/Bitcode/Writer/BitcodeWriter.cpp b/lib/Bitcode/Writer/BitcodeWriter.cpp
index 12f0715f1a..5b3d96953a 100644
--- a/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -1165,6 +1165,23 @@ static void WriteInstruction(const Instruction &I, unsigned InstID,
     break;
   }
 
+  case Instruction::LandingPad: {
+    const LandingPadInst &LP = cast<LandingPadInst>(I);
+    Code = bitc::FUNC_CODE_INST_LANDINGPAD;
+    Vals.push_back(VE.getTypeID(LP.getType()));
+    PushValueAndType(LP.getPersonalityFn(), InstID, Vals, VE);
+    Vals.push_back(LP.isCleanup());
+    Vals.push_back(LP.getNumClauses());
+    for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
+      if (LP.isCatch(I))
+        Vals.push_back(LandingPadInst::Catch);
+      else
+        Vals.push_back(LandingPadInst::Filter);
+      PushValueAndType(LP.getClause(I), InstID, Vals, VE);
+    }
+    break;
+  }
+
   case Instruction::Alloca:
     Code = bitc::FUNC_CODE_INST_ALLOCA;
     Vals.push_back(VE.getTypeID(I.getType()));
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 438667e005..c1d533582f 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -2985,6 +2985,9 @@ void SelectionDAGBuilder::visitExtractValue(const ExtractValueInst &I) {
                            &Values[0], NumValValues));
 }
 
+void SelectionDAGBuilder::visitLandingPad(const LandingPadInst &I) {
+}
+
 void SelectionDAGBuilder::visitGetElementPtr(const User &I) {
   SDValue N = getValue(I.getOperand(0));
   Type *Ty = I.getOperand(0)->getType();
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index 050b86fb60..776b07072b 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -512,6 +512,7 @@ private:
 
   void visitExtractValue(const ExtractValueInst &I);
   void visitInsertValue(const InsertValueInst &I);
+  void visitLandingPad(const LandingPadInst &I);
 
   void visitGetElementPtr(const User &I);
   void visitSelect(const User &I);
diff --git a/lib/Transforms/Scalar/SCCP.cpp b/lib/Transforms/Scalar/SCCP.cpp
index c84d67b49a..59d96bee1c 100644
--- a/lib/Transforms/Scalar/SCCP.cpp
+++ b/lib/Transforms/Scalar/SCCP.cpp
@@ -515,6 +515,7 @@ private:
   void visitShuffleVectorInst(ShuffleVectorInst &I);
   void visitExtractValueInst(ExtractValueInst &EVI);
   void visitInsertValueInst(InsertValueInst &IVI);
+  void visitLandingPadInst(LandingPadInst &I) { markAnythingOverdefined(&I); }
 
   // Instructions that cannot be folded away.
   void visitStoreInst     (StoreInst &I);
diff --git a/lib/VMCore/AsmWriter.cpp b/lib/VMCore/AsmWriter.cpp
index 62214a1a2e..d166604113 100644
--- a/lib/VMCore/AsmWriter.cpp
+++ b/lib/VMCore/AsmWriter.cpp
@@ -1748,6 +1748,24 @@ void AssemblyWriter::printInstruction(const Instruction &I) {
     writeOperand(I.getOperand(1), true);
     for (const unsigned *i = IVI->idx_begin(), *e = IVI->idx_end(); i != e; ++i)
       Out << ", " << *i;
+  } else if (const LandingPadInst *LPI = dyn_cast<LandingPadInst>(&I)) {
+    Out << ' ';
+    TypePrinter.print(I.getType(), Out);
+    Out << " personality ";
+    writeOperand(I.getOperand(0), true); Out << '\n';
+
+    if (LPI->isCleanup())
+      Out << "          cleanup";
+
+    for (unsigned i = 0, e = LPI->getNumClauses(); i != e; ++i) {
+      if (i != 0 || LPI->isCleanup()) Out << "\n";
+      if (LPI->isCatch(i))
+        Out << "          catch ";
+      else
+        Out << "          filter ";
+
+      writeOperand(LPI->getClause(i), true);
+    }
   } else if (isa<ReturnInst>(I) && !Operand) {
     Out << " void";
   } else if (const CallInst *CI = dyn_cast<CallInst>(&I)) {
diff --git a/lib/VMCore/BasicBlock.cpp b/lib/VMCore/BasicBlock.cpp
index 5fab1d39ae..3e29f05d51 100644
--- a/lib/VMCore/BasicBlock.cpp
+++ b/lib/VMCore/BasicBlock.cpp
@@ -348,3 +348,15 @@ void BasicBlock::replaceSuccessorsPhiUsesWith(BasicBlock *New) {
     }
   }
 }
+
+/// isLandingPad - Return true if this basic block is a landing pad. I.e., it's
+/// the destination of the 'unwind' edge of an invoke instruction.
+bool BasicBlock::isLandingPad() const {
+  return isa<LandingPadInst>(getFirstNonPHI());
+}
+
+/// getLandingPadInst() - Return the landingpad instruction associated with
+/// the landing pad.
+LandingPadInst *BasicBlock::getLandingPadInst() {
+  return dyn_cast<LandingPadInst>(getFirstNonPHI());
+}
diff --git a/lib/VMCore/Core.cpp b/lib/VMCore/Core.cpp
index 883ad91343..7e87103a0d 100644
--- a/lib/VMCore/Core.cpp
+++ b/lib/VMCore/Core.cpp
@@ -1683,6 +1683,14 @@ LLVMValueRef LLVMBuildInvoke(LLVMBuilderRef B, LLVMValueRef Fn,
                                       Name));
 }
 
+LLVMValueRef LLVMBuildLandingPad(LLVMBuilderRef B, LLVMTypeRef Ty,
+                                 LLVMValueRef PersFn, unsigned NumClauses,
+                                 const char *Name) {
+  return wrap(unwrap(B)->CreateLandingPad(unwrap(Ty),
+                                          cast<Function>(unwrap(PersFn)),
+                                          NumClauses, Name));
+}
+
 LLVMValueRef LLVMBuildResume(LLVMBuilderRef B, LLVMValueRef Exn) {
   return wrap(unwrap(B)->CreateResume(unwrap(Exn)));
 }
@@ -1700,6 +1708,15 @@ void LLVMAddDestination(LLVMValueRef IndirectBr, LLVMBasicBlockRef Dest) {
   unwrap<IndirectBrInst>(IndirectBr)->addDestination(unwrap(Dest));
 }
 
+void LLVMAddClause(LLVMValueRef LandingPad, LLVMValueRef ClauseVal) {
+  unwrap<LandingPadInst>(LandingPad)->
+    addClause(cast<Constant>(unwrap(ClauseVal)));
+}
+
+void LLVMSetCleanup(LLVMValueRef LandingPad, LLVMBool Val) {
+  unwrap<LandingPadInst>(LandingPad)->setCleanup(Val);
+}
+
 /*--.. Arithmetic ..........................................................--*/
 
 LLVMValueRef LLVMBuildAdd(LLVMBuilderRef B, LLVMValueRef LHS, LLVMValueRef RHS,
diff --git a/lib/VMCore/Instruction.cpp b/lib/VMCore/Instruction.cpp
index 216bb35d4d..eadcd098b1 100644
--- a/lib/VMCore/Instruction.cpp
+++ b/lib/VMCore/Instruction.cpp
@@ -162,6 +162,7 @@ const char *Instruction::getOpcodeName(unsigned OpCode) {
   case ShuffleVector:  return "shufflevector";
   case ExtractValue:   return "extractvalue";
   case InsertValue:    return "insertvalue";
+  case LandingPad:     return "landingpad";
 
   default: return "<Invalid operator> ";
   }
diff --git a/lib/VMCore/Instructions.cpp b/lib/VMCore/Instructions.cpp
index 8966bbe1dd..2f6c069a2d 100644
--- a/lib/VMCore/Instructions.cpp
+++ b/lib/VMCore/Instructions.cpp
@@ -166,6 +166,88 @@ Value *PHINode::hasConstantValue() const {
   return ConstantValue;
 }
 
+//===----------------------------------------------------------------------===//
+//                       LandingPadInst Implementation
+//===----------------------------------------------------------------------===//
+
+LandingPadInst::LandingPadInst(Type *RetTy, Value *PersonalityFn,
+                               unsigned NumReservedValues, const Twine &NameStr,
+                               Instruction *InsertBefore)
+  : Instruction(RetTy, Instruction::LandingPad, 0, 0, InsertBefore) {
+  init(PersonalityFn, 1 + NumReservedValues, NameStr);
+}
+
+LandingPadInst::LandingPadInst(Type *RetTy, Value *PersonalityFn,
+                               unsigned NumReservedValues, const Twine &NameStr,
+                               BasicBlock *InsertAtEnd)
+  : Instruction(RetTy, Instruction::LandingPad, 0, 0, InsertAtEnd) {
+  init(PersonalityFn, 1 + NumReservedValues, NameStr);
+}
+
+LandingPadInst::LandingPadInst(const LandingPadInst &LP)
+  : Instruction(LP.getType(), Instruction::LandingPad,
+                allocHungoffUses(LP.getNumOperands()), LP.getNumOperands()),
+    ReservedSpace(LP.getNumOperands()) {
+  Use *OL = OperandList, *InOL = LP.OperandList;
+  for (unsigned I = 0, E = ReservedSpace; I != E; ++I)
+    OL[I] = InOL[I];
+
+  setCleanup(LP.isCleanup());
+}
+
+LandingPadInst::~LandingPadInst() {
+  dropHungoffUses();
+}
+
+LandingPadInst *LandingPadInst::Create(Type *RetTy, Value *PersonalityFn,
+                                       unsigned NumReservedClauses,
+                                       const Twine &NameStr,
+                                       Instruction *InsertBefore) {
+  return new LandingPadInst(RetTy, PersonalityFn, NumReservedClauses, NameStr,
+                            InsertBefore);
+}
+
+LandingPadInst *LandingPadInst::Create(Type *RetTy, Value *PersonalityFn,
+                                       unsigned NumReservedClauses,
+                                       const Twine &NameStr,
+                                       BasicBlock *InsertAtEnd) {
+  return new LandingPadInst(RetTy, PersonalityFn, NumReservedClauses, NameStr,
+                            InsertAtEnd);
+}
+
+void LandingPadInst::init(Value *PersFn, unsigned NumReservedValues,
+                          const Twine &NameStr) {
+  ReservedSpace = NumReservedValues;
+  NumOperands = 1;
+  OperandList = allocHungoffUses(ReservedSpace);
+  OperandList[0] = PersFn;
+  setName(NameStr);
+  setCleanup(false);
+}
+
+/// growOperands - grow operands - This grows the operand list in response to a
+/// push_back style of operation. This grows the number of ops by 2 times.
+void LandingPadInst::growOperands(unsigned Size) {
+  unsigned e = getNumOperands();
+  if (ReservedSpace >= e + Size) return;
+  ReservedSpace = (e + Size / 2) * 2;
+
+  Use *NewOps = allocHungoffUses(ReservedSpace);
+  Use *OldOps = OperandList;
+  for (unsigned i = 0; i != e; ++i)
+      NewOps[i] = OldOps[i];
+
+  OperandList = NewOps;
+  Use::zap(OldOps, OldOps + e, true);
+}
+
+void LandingPadInst::addClause(Value *Val) {
+  unsigned OpNo = getNumOperands();
+  growOperands(1);
+  assert(OpNo < ReservedSpace && "Growing didn't work!");
+  ++NumOperands;
+  OperandList[OpNo] = Val;
+}
 
 //===----------------------------------------------------------------------===//
 //                        CallInst Implementation
@@ -494,6 +576,9 @@ void InvokeInst::removeAttribute(unsigned i, Attributes attr) {
   setAttributes(PAL);
 }
 
+LandingPadInst *InvokeInst::getLandingPadInst() const {
+  return cast<LandingPadInst>(getUnwindDest()->getFirstNonPHI());
+}
 
 //===----------------------------------------------------------------------===//
 //                        ReturnInst Implementation
@@ -3344,6 +3429,10 @@ PHINode *PHINode::clone_impl() const {
   return new PHINode(*this);
 }
 
+LandingPadInst *LandingPadInst::clone_impl() const {
+  return new LandingPadInst(*this);
+}
+
 ReturnInst *ReturnInst::clone_impl() const {
   return new(getNumOperands()) ReturnInst(*this);
 }
diff --git a/lib/VMCore/Verifier.cpp b/lib/VMCore/Verifier.cpp
index 415c85e142..7635998a59 100644
--- a/lib/VMCore/Verifier.cpp
+++ b/lib/VMCore/Verifier.cpp
@@ -35,6 +35,12 @@
 //  * It is illegal to have a ret instruction that returns a value that does not
 //    agree with the function return value type.
 //  * Function call argument types match the function prototype
+//  * A landing pad is defined by a landingpad instruction, and can be jumped to
+//    only by the unwind edge of an invoke instruction.
+//  * A landingpad instruction must be the first non-PHI instruction in the
+//    block.
+//  * All landingpad instructions must use the same personality function with
+//    the same function.
 //  * All other things that are tested by asserts spread about the code...
 //
 //===----------------------------------------------------------------------===//
@@ -131,18 +137,22 @@ namespace {
     /// already.
     SmallPtrSet<MDNode *, 32> MDNodes;
 
+    /// PersonalityFn - The personality function referenced by the
+    /// LandingPadInsts. All LandingPadInsts within the same function must use
+    /// the same personality function.
+    const Value *PersonalityFn;
+
     Verifier()
-      : FunctionPass(ID), 
-      Broken(false), RealPass(true), action(AbortProcessAction),
-      Mod(0), Context(0), DT(0), MessagesStr(Messages) {
-        initializeVerifierPass(*PassRegistry::getPassRegistry());
-      }
+      : FunctionPass(ID), Broken(false), RealPass(true),
+        action(AbortProcessAction), Mod(0), Context(0), DT(0),
+        MessagesStr(Messages), PersonalityFn(0) {
+      initializeVerifierPass(*PassRegistry::getPassRegistry());
+    }
     explicit Verifier(VerifierFailureAction ctn)
-      : FunctionPass(ID), 
-      Broken(false), RealPass(true), action(ctn), Mod(0), Context(0), DT(0),
-      MessagesStr(Messages) {
-        initializeVerifierPass(*PassRegistry::getPassRegistry());
-      }
+      : FunctionPass(ID), Broken(false), RealPass(true), action(ctn), Mod(0),
+        Context(0), DT(0), MessagesStr(Messages), PersonalityFn(0) {
+      initializeVerifierPass(*PassRegistry::getPassRegistry());
+    }
 
     bool doInitialization(Module &M) {
       Mod = &M;
@@ -165,6 +175,7 @@ namespace {
 
       visit(F);
       InstsInThisBlock.clear();
+      PersonalityFn = 0;
 
       // If this is a real pass, in a pass manager, we must abort before
       // returning back to the pass manager, or else the pass manager may try to
@@ -284,6 +295,7 @@ namespace {
     void visitAllocaInst(AllocaInst &AI);
     void visitExtractValueInst(ExtractValueInst &EVI);
     void visitInsertValueInst(InsertValueInst &IVI);
+    void visitLandingPadInst(LandingPadInst &LPI);
 
     void VerifyCallSite(CallSite CS);
     bool PerformTypeCheck(Intrinsic::ID ID, Function *F, Type *Ty,
@@ -1401,6 +1413,39 @@ void Verifier::visitInsertValueInst(InsertValueInst &IVI) {
   visitInstruction(IVI);
 }
 
+void Verifier::visitLandingPadInst(LandingPadInst &LPI) {
+  BasicBlock *BB = LPI.getParent();
+
+  // The landingpad instruction is ill-formed if it doesn't have any clauses and
+  // isn't a cleanup.
+  Assert1(LPI.getNumClauses() > 0 || LPI.isCleanup(),
+          "LandingPadInst needs at least one clause or to be a cleanup.", &LPI);
+
+  // The landingpad instruction defines its parent as a landing pad block. The
+  // landing pad block may be branched to only by the unwind edge of an invoke.
+  for (pred_iterator I = pred_begin(BB), E = pred_end(BB); I != E; ++I) {
+    const InvokeInst *II = dyn_cast<InvokeInst>((*I)->getTerminator());
+    Assert1(II && II->getUnwindDest() == BB,
+            "Block containing LandingPadInst must be jumped to "
+            "only by the unwind edge of an invoke.", &LPI);
+  }
+
+  // The landingpad instruction must be the first non-PHI instruction in the
+  // block.
+  Assert1(LPI.getParent()->getLandingPadInst() == &LPI,
+          "LandingPadInst not the first non-PHI instruction in the block.",
+          &LPI);
+
+  // The personality functions for all landingpad instructions within the same
+  // function should match.
+  if (PersonalityFn)
+    Assert1(LPI.getPersonalityFn() == PersonalityFn,
+            "Personality function doesn't match others in function", &LPI);
+  PersonalityFn = LPI.getPersonalityFn();
+
+  visitInstruction(LPI);
+}
+
 /// verifyInstruction - Verify that an instruction is well formed.
 ///
 void Verifier::visitInstruction(Instruction &I) {