[Verifier] Handle more funclet edge cases

This change makes the verifier a little more paranoid.  It was possible
to trick the verifier into crashing or infinite looping.

llvm-svn: 262268

1 files changed, 9 insertions, 6 deletions

diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index f02879eeb5b..8367a2702eb 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -3119,8 +3119,6 @@ void Verifier::visitLandingPadInst(LandingPadInst &LPI) {
 }
 
 void Verifier::visitCatchPadInst(CatchPadInst &CPI) {
-  visitEHPadPredecessors(CPI);
-
   BasicBlock *BB = CPI.getParent();
 
   Function *F = BB->getParent();
@@ -3136,6 +3134,7 @@ void Verifier::visitCatchPadInst(CatchPadInst &CPI) {
   Assert(BB->getFirstNonPHI() == &CPI,
          "CatchPadInst not the first non-PHI instruction in the block.", &CPI);
 
+  visitEHPadPredecessors(CPI);
   visitFuncletPadInst(CPI);
 }
 
@@ -3148,8 +3147,6 @@ void Verifier::visitCatchReturnInst(CatchReturnInst &CatchReturn) {
 }
 
 void Verifier::visitCleanupPadInst(CleanupPadInst &CPI) {
-  visitEHPadPredecessors(CPI);
-
   BasicBlock *BB = CPI.getParent();
 
   Function *F = BB->getParent();
@@ -3166,6 +3163,7 @@ void Verifier::visitCleanupPadInst(CleanupPadInst &CPI) {
   Assert(isa<ConstantTokenNone>(ParentPad) || isa<FuncletPadInst>(ParentPad),
          "CleanupPadInst has an invalid parent.", &CPI);
 
+  visitEHPadPredecessors(CPI);
   visitFuncletPadInst(CPI);
 }
 
@@ -3173,8 +3171,12 @@ void Verifier::visitFuncletPadInst(FuncletPadInst &FPI) {
   User *FirstUser = nullptr;
   Value *FirstUnwindPad = nullptr;
   SmallVector<FuncletPadInst *, 8> Worklist({&FPI});
+  std::set<FuncletPadInst *> Seen;
+
   while (!Worklist.empty()) {
     FuncletPadInst *CurrentPad = Worklist.pop_back_val();
+    Assert(Seen.insert(CurrentPad).second,
+           "FuncletPadInst must not be nested within itself", CurrentPad);
     Value *UnresolvedAncestorPad = nullptr;
     for (User *U : CurrentPad->users()) {
       BasicBlock *UnwindDest;
@@ -3210,6 +3212,8 @@ void Verifier::visitFuncletPadInst(FuncletPadInst &FPI) {
       bool ExitsFPI;
       if (UnwindDest) {
         UnwindPad = UnwindDest->getFirstNonPHI();
+        if (!cast<Instruction>(UnwindPad)->isEHPad())
+          continue;
         Value *UnwindParent = getParentPad(UnwindPad);
         // Ignore unwind edges that don't exit CurrentPad.
         if (UnwindParent == CurrentPad)
@@ -3323,8 +3327,6 @@ void Verifier::visitFuncletPadInst(FuncletPadInst &FPI) {
 }
 
 void Verifier::visitCatchSwitchInst(CatchSwitchInst &CatchSwitch) {
-  visitEHPadPredecessors(CatchSwitch);
-
   BasicBlock *BB = CatchSwitch.getParent();
 
   Function *F = BB->getParent();
@@ -3362,6 +3364,7 @@ void Verifier::visitCatchSwitchInst(CatchSwitchInst &CatchSwitch) {
            "CatchSwitchInst handlers must be catchpads", &CatchSwitch, Handler);
   }
 
+  visitEHPadPredecessors(CatchSwitch);
   visitTerminatorInst(CatchSwitch);
 }