Handle null dereference

[akshaykhadse]

Summary

Add assertes to ensure that we don't derefernce a nullptr

[skan]

llvm/lib/CodeGen/WinEHPrepare.cpp

254

https://llvm.org/docs/CodingStandards.html#assert-liberally

put some kind of error message in the assertion statement,

[craig.topper]

llvm/lib/CodeGen/WinEHPrepare.cpp

254

Use cast instead of dyn_cast. cast has an internal assert

[akshaykhadse]

Use cast instead of dyn_cast

[skan]

LGTM

[LuoYuanke]

llvm/lib/CodeGen/WinEHPrepare.cpp

321–322

Did you use "git commit --amend"?

[skan]

llvm/lib/CodeGen/WinEHPrepare.cpp

321–322

Did you use "git commit --amend"?

Good point. I didn't notice that :-(

[akshaykhadse]

Address review comments

[LuoYuanke]

LGTM

[skan]

This patch is duplicated with D147923

[akshaykhadse]

In D147994#4260037, @skan wrote:

This patch is duplicated with D147923

I think we can abandon the current one in that case

llvm/lib/CodeGen/WinEHPrepare.cpp

while (!WorkList.empty()) {
     if (I->isEHPad())
       State = EHInfo.EHPadStateMap[I];
     EHInfo.BlockToStateMap[BB] = State; // Record state, also flag visiting
 
     if ((isa<CleanupReturnInst>(TI) || isa<CatchReturnInst>(TI)) && State > 0) {
       // Retrive the new State
       State = EHInfo.CxxUnwindMap[State].ToState; // Retrive next State
     } else if (isa<InvokeInst>(TI)) {
-      auto *Call = dyn_cast<CallBase>(TI);
+      auto *Call = cast<CallBase>(TI);
       const Function *Fn = Call->getCalledFunction();
       if (Fn && Fn->isIntrinsic() &&
           (Fn->getIntrinsicID() == Intrinsic::seh_scope_begin ||
            Fn->getIntrinsicID() == Intrinsic::seh_try_begin))
         // Retrive the new State from seh_scope_begin
         State = EHInfo.InvokeStateMap[cast<InvokeInst>(TI)];
       else if (Fn && Fn->isIntrinsic() &&
                (Fn->getIntrinsicID() == Intrinsic::seh_scope_end ||
                 Fn->getIntrinsicID() == Intrinsic::seh_try_end)) {
if (isa<CatchPadInst>(I) && isa<CatchReturnInst>(TI)) {
       const Function *Filter = dyn_cast<Function>(FilterOrNull);
       if (!Filter || !Filter->getName().startswith("__IsLocalUnwind"))
         State = EHInfo.SEHUnwindMap[State].ToState; // Retrive next State
     } else if ((isa<CleanupReturnInst>(TI) || isa<CatchReturnInst>(TI)) &&
                State > 0) {
       // Retrive the new State.
       State = EHInfo.SEHUnwindMap[State].ToState; // Retrive next State
     } else if (isa<InvokeInst>(TI)) {
-      auto *Call = dyn_cast<CallBase>(TI);
+      auto *Call = cast<CallBase>(TI);
       const Function *Fn = Call->getCalledFunction();
       if (Fn && Fn->isIntrinsic() &&
           Fn->getIntrinsicID() == Intrinsic::seh_try_begin)
         // Retrive the new State from seh_try_begin
         State = EHInfo.InvokeStateMap[cast<InvokeInst>(TI)];
       else if (Fn && Fn->isIntrinsic() &&
                Fn->getIntrinsicID() == Intrinsic::seh_try_end)
         // end of current state, retrive new state from UnwindMap
         State = EHInfo.SEHUnwindMap[State].ToState;