Reland "[Windows SEH]: HARDWARE EXCEPTION HANDLING (MSVC -EHa) - Part 2"

This reverts commit db6a979.

Reland D102817 without any change. The previous revert was a mistake.

Differential Revision: https://reviews.llvm.org/D102817

Author: phoebewang

llvm/include/llvm/CodeGen/SelectionDAGISel.h

@@ -337,6 +337,9 @@ class SelectionDAGISel : public MachineFunctionPass {
   /// instruction selected, false if no code should be emitted for it.
   bool PrepareEHLandingPad();
 
+  // Mark and Report IPToState for each Block under AsynchEH
+  void reportIPToStateForBlocks(MachineFunction *Fn);
+
   /// Perform instruction selection on all basic blocks in the function.
   void SelectAllBasicBlocks(const Function &Fn);
 

llvm/include/llvm/CodeGen/WinEHFuncInfo.h

@@ -92,6 +92,7 @@ struct WinEHFuncInfo {
   DenseMap<const FuncletPadInst *, int> FuncletBaseStateMap;
   DenseMap<const InvokeInst *, int> InvokeStateMap;
   DenseMap<MCSymbol *, std::pair<int, MCSymbol *>> LabelToStateMap;
+  DenseMap<const BasicBlock *, int> BlockToStateMap; // for AsynchEH
   SmallVector<CxxUnwindMapEntry, 4> CxxUnwindMap;
   SmallVector<WinEHTryBlockMapEntry, 4> TryBlockMap;
   SmallVector<SEHUnwindMapEntry, 4> SEHUnwindMap;
@@ -104,6 +105,8 @@ struct WinEHFuncInfo {
   void addIPToStateRange(const InvokeInst *II, MCSymbol *InvokeBegin,
                          MCSymbol *InvokeEnd);
 
+  void addIPToStateRange(int State, MCSymbol *InvokeBegin, MCSymbol *InvokeEnd);
+
   int EHRegNodeFrameIndex = std::numeric_limits<int>::max();
   int EHRegNodeEndOffset = std::numeric_limits<int>::max();
   int EHGuardFrameIndex = std::numeric_limits<int>::max();
@@ -123,6 +126,12 @@ void calculateSEHStateNumbers(const Function *ParentFn,
 
 void calculateClrEHStateNumbers(const Function *Fn, WinEHFuncInfo &FuncInfo);
 
+// For AsynchEH (VC++ option -EHa)
+void calculateCXXStateForAsynchEH(const BasicBlock *BB, int State,
+                                  WinEHFuncInfo &FuncInfo);
+void calculateSEHStateForAsynchEH(const BasicBlock *BB, int State,
+                                  WinEHFuncInfo &FuncInfo);
+
 } // end namespace llvm
 
 #endif // LLVM_CODEGEN_WINEHFUNCINFO_H

llvm/include/llvm/IR/BasicBlock.h

@@ -213,6 +213,15 @@ class BasicBlock final : public Value, // Basic blocks are data objects also
         .getNonConst();
   }
 
+  /// Returns the first potential AsynchEH faulty instruction
+  /// currently it checks for loads/stores (which may dereference a null
+  /// pointer) and calls/invokes (which may propagate exceptions)
+  const Instruction* getFirstMayFaultInst() const;
+  Instruction* getFirstMayFaultInst() {
+      return const_cast<Instruction*>(
+          static_cast<const BasicBlock*>(this)->getFirstMayFaultInst());
+  }
+
   /// Return a const iterator range over the instructions in the block, skipping
   /// any debug instructions. Skip any pseudo operations as well if \c
   /// SkipPseudoOp is true.

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -1627,6 +1627,7 @@ void AsmPrinter::emitFunctionBody() {
   // Print out code for the function.
   bool HasAnyRealCode = false;
   int NumInstsInFunction = 0;
+  bool IsEHa = MMI->getModule()->getModuleFlag("eh-asynch");
 
   bool CanDoExtraAnalysis = ORE->allowExtraAnalysis(DEBUG_TYPE);
   for (auto &MBB : *MF) {
@@ -1665,10 +1666,25 @@ void AsmPrinter::emitFunctionBody() {
         emitFrameAlloc(MI);
         break;
       case TargetOpcode::ANNOTATION_LABEL:
-      case TargetOpcode::EH_LABEL:
       case TargetOpcode::GC_LABEL:
         OutStreamer->emitLabel(MI.getOperand(0).getMCSymbol());
         break;
+      case TargetOpcode::EH_LABEL:
+        OutStreamer->emitLabel(MI.getOperand(0).getMCSymbol());
+        // For AsynchEH, insert a Nop if followed by a trap inst
+        //   Or the exception won't be caught.
+        //   (see MCConstantExpr::create(1,..) in WinException.cpp)
+        //  Ignore SDiv/UDiv because a DIV with Const-0 divisor
+        //    must have being turned into an UndefValue.
+        //  Div with variable opnds won't be the first instruction in
+        //  an EH region as it must be led by at least a Load
+        {
+          auto MI2 = std::next(MI.getIterator());
+          if (IsEHa && MI2 != MBB.end() &&
+              (MI2->mayLoadOrStore() || MI2->mayRaiseFPException()))
+            emitNops(1);
+        }
+        break;
       case TargetOpcode::INLINEASM:
       case TargetOpcode::INLINEASM_BR:
         emitInlineAsm(&MI);

llvm/lib/CodeGen/AsmPrinter/WinException.cpp

@@ -762,7 +762,11 @@ void WinException::emitCXXFrameHandler3Table(const MachineFunction *MF) {
   OS.emitInt32(0);
 
   AddComment("EHFlags");
-  OS.emitInt32(1);
+  if (MMI->getModule()->getModuleFlag("eh-asynch")) {
+    OS.emitInt32(0);
+  } else {
+    OS.emitInt32(1);
+  }
 
   // UnwindMapEntry {
   //   int32_t ToState;

llvm/lib/CodeGen/BranchFolding.cpp

@@ -1207,7 +1207,7 @@ bool BranchFolder::OptimizeBranches(MachineFunction &MF) {
     MadeChange |= OptimizeBlock(&MBB);
 
     // If it is dead, remove it.
-    if (MBB.pred_empty()) {
+    if (MBB.pred_empty() && !MBB.isMachineBlockAddressTaken()) {
       RemoveDeadBlock(&MBB);
       MadeChange = true;
       ++NumDeadBlocks;

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

@@ -2971,6 +2971,7 @@ void SelectionDAGBuilder::visitInvoke(const InvokeInst &I) {
   // catchswitch for successors.
   MachineBasicBlock *Return = FuncInfo.MBBMap[I.getSuccessor(0)];
   const BasicBlock *EHPadBB = I.getSuccessor(1);
+  MachineBasicBlock *EHPadMBB = FuncInfo.MBBMap[EHPadBB];
 
   // Deopt bundles are lowered in LowerCallSiteWithDeoptBundle, and we don't
   // have to do anything here to lower funclet bundles.
@@ -2995,6 +2996,10 @@ void SelectionDAGBuilder::visitInvoke(const InvokeInst &I) {
     case Intrinsic::seh_scope_begin:
     case Intrinsic::seh_try_end:
     case Intrinsic::seh_scope_end:
+      if (EHPadMBB)
+          // a block referenced by EH table
+          // so dtor-funclet not removed by opts
+          EHPadMBB->setMachineBlockAddressTaken();
       break;
     case Intrinsic::experimental_patchpoint_void:
     case Intrinsic::experimental_patchpoint_i64:

llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

@@ -59,6 +59,7 @@
 #include "llvm/CodeGen/TargetRegisterInfo.h"
 #include "llvm/CodeGen/TargetSubtargetInfo.h"
 #include "llvm/CodeGen/ValueTypes.h"
+#include "llvm/CodeGen/WinEHFuncInfo.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DataLayout.h"
@@ -1292,6 +1293,43 @@ bool SelectionDAGISel::PrepareEHLandingPad() {
   return true;
 }
 
+// Mark and Report IPToState for each Block under IsEHa
+void SelectionDAGISel::reportIPToStateForBlocks(MachineFunction *MF) {
+  MachineModuleInfo &MMI = MF->getMMI();
+  llvm::WinEHFuncInfo *EHInfo = MF->getWinEHFuncInfo();
+  if (!EHInfo)
+    return;
+  for (auto MBBI = MF->begin(), E = MF->end(); MBBI != E; ++MBBI) {
+    MachineBasicBlock *MBB = &*MBBI;
+    const BasicBlock *BB = MBB->getBasicBlock();
+    int State = EHInfo->BlockToStateMap[BB];
+    if (BB->getFirstMayFaultInst()) {
+      // Report IP range only for blocks with Faulty inst
+      auto MBBb = MBB->getFirstNonPHI();
+      MachineInstr *MIb = &*MBBb;
+      if (MIb->isTerminator())
+        continue;
+
+      // Insert EH Labels
+      MCSymbol *BeginLabel = MMI.getContext().createTempSymbol();
+      MCSymbol *EndLabel = MMI.getContext().createTempSymbol();
+      EHInfo->addIPToStateRange(State, BeginLabel, EndLabel);
+      BuildMI(*MBB, MBBb, SDB->getCurDebugLoc(),
+              TII->get(TargetOpcode::EH_LABEL))
+          .addSym(BeginLabel);
+      auto MBBe = MBB->instr_end();
+      MachineInstr *MIe = &*(--MBBe);
+      // insert before (possible multiple) terminators
+      while (MIe->isTerminator())
+        MIe = &*(--MBBe);
+      ++MBBe;
+      BuildMI(*MBB, MBBe, SDB->getCurDebugLoc(),
+              TII->get(TargetOpcode::EH_LABEL))
+          .addSym(EndLabel);
+    }
+  }
+}
+
 /// isFoldedOrDeadInstruction - Return true if the specified instruction is
 /// side-effect free and is either dead or folded into a generated instruction.
 /// Return false if it needs to be emitted.
@@ -1649,6 +1687,10 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
     ElidedArgCopyInstrs.clear();
   }
 
+  // AsynchEH: Report Block State under -AsynchEH
+  if (Fn.getParent()->getModuleFlag("eh-asynch"))
+    reportIPToStateForBlocks(MF);
+
   SP.copyToMachineFrameInfo(MF->getFrameInfo());
 
   SwiftError->propagateVRegs();

llvm/lib/CodeGen/WinEHPrepare.cpp

@@ -216,6 +216,127 @@ static void calculateStateNumbersForInvokes(const Function *Fn,
   }
 }
 
+// See comments below for calculateSEHStateForAsynchEH().
+// State - incoming State of normal paths
+struct WorkItem {
+  const BasicBlock *Block;
+  int State;
+  WorkItem(const BasicBlock *BB, int St) {
+    Block = BB;
+    State = St;
+  }
+};
+void llvm::calculateCXXStateForAsynchEH(const BasicBlock *BB, int State,
+                                        WinEHFuncInfo &EHInfo) {
+  SmallVector<struct WorkItem *, 8> WorkList;
+  struct WorkItem *WI = new WorkItem(BB, State);
+  WorkList.push_back(WI);
+
+  while (!WorkList.empty()) {
+    WI = WorkList.pop_back_val();
+    const BasicBlock *BB = WI->Block;
+    int State = WI->State;
+    delete WI;
+    if (EHInfo.BlockToStateMap.count(BB) && EHInfo.BlockToStateMap[BB] <= State)
+      continue; // skip blocks already visited by lower State
+
+    const llvm::Instruction *I = BB->getFirstNonPHI();
+    const llvm::Instruction *TI = BB->getTerminator();
+    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);
+      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)) {
+        // In case of conditional ctor, let's retrieve State from Invoke
+        State = EHInfo.InvokeStateMap[cast<InvokeInst>(TI)];
+        // end of current state, retrive new state from UnwindMap
+        State = EHInfo.CxxUnwindMap[State].ToState;
+      }
+    }
+    // Continue push successors into worklist
+    for (auto *SuccBB : successors(BB)) {
+      WI = new WorkItem(SuccBB, State);
+      WorkList.push_back(WI);
+    }
+  }
+}
+
+// The central theory of this routine is based on the following:
+//   A _try scope is always a SEME (Single Entry Multiple Exits) region
+//     as jumping into a _try is not allowed
+//   The single entry must start with a seh_try_begin() invoke with a
+//     correct State number that is the initial state of the SEME.
+//   Through control-flow, state number is propagated into all blocks.
+//   Side exits marked by seh_try_end() will unwind to parent state via
+//     existing SEHUnwindMap[].
+//   Side exits can ONLY jump into parent scopes (lower state number).
+//   Thus, when a block succeeds various states from its predecessors,
+//     the lowest State trumphs others.
+//   If some exits flow to unreachable, propagation on those paths terminate,
+//     not affecting remaining blocks.
+void llvm::calculateSEHStateForAsynchEH(const BasicBlock *BB, int State,
+                                        WinEHFuncInfo &EHInfo) {
+  SmallVector<struct WorkItem *, 8> WorkList;
+  struct WorkItem *WI = new WorkItem(BB, State);
+  WorkList.push_back(WI);
+
+  while (!WorkList.empty()) {
+    WI = WorkList.pop_back_val();
+    const BasicBlock *BB = WI->Block;
+    int State = WI->State;
+    delete WI;
+    if (EHInfo.BlockToStateMap.count(BB) && EHInfo.BlockToStateMap[BB] <= State)
+      continue; // skip blocks already visited by lower State
+
+    const llvm::Instruction *I = BB->getFirstNonPHI();
+    const llvm::Instruction *TI = BB->getTerminator();
+    if (I->isEHPad())
+      State = EHInfo.EHPadStateMap[I];
+    EHInfo.BlockToStateMap[BB] = State; // Record state
+
+    if (isa<CatchPadInst>(I) && isa<CatchReturnInst>(TI)) {
+      const Constant *FilterOrNull = cast<Constant>(
+          cast<CatchPadInst>(I)->getArgOperand(0)->stripPointerCasts());
+      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);
+      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;
+    }
+    // Continue push successors into worklist
+    for (auto *SuccBB : successors(BB)) {
+      WI = new WorkItem(SuccBB, State);
+      WorkList.push_back(WI);
+    }
+  }
+}
+
 // Given BB which ends in an unwind edge, return the EHPad that this BB belongs
 // to. If the unwind edge came from an invoke, return null.
 static const BasicBlock *getEHPadFromPredecessor(const BasicBlock *BB,
@@ -276,6 +397,7 @@ static void calculateCXXStateNumbers(WinEHFuncInfo &FuncInfo,
 
     for (const auto *CatchPad : Handlers) {
       FuncInfo.FuncletBaseStateMap[CatchPad] = CatchLow;
+      FuncInfo.EHPadStateMap[CatchPad] = CatchLow;
       for (const User *U : CatchPad->users()) {
         const auto *UserI = cast<Instruction>(U);
         if (auto *InnerCatchSwitch = dyn_cast<CatchSwitchInst>(UserI)) {
@@ -384,6 +506,7 @@ static void calculateSEHStateNumbers(WinEHFuncInfo &FuncInfo,
 
     // Everything in the __try block uses TryState as its parent state.
     FuncInfo.EHPadStateMap[CatchSwitch] = TryState;
+    FuncInfo.EHPadStateMap[CatchPad] = TryState;
     LLVM_DEBUG(dbgs() << "Assigning state #" << TryState << " to BB "
                       << CatchPadBB->getName() << '\n');
     for (const BasicBlock *PredBlock : predecessors(BB))
@@ -464,6 +587,12 @@ void llvm::calculateSEHStateNumbers(const Function *Fn,
   }
 
   calculateStateNumbersForInvokes(Fn, FuncInfo);
+
+  bool IsEHa = Fn->getParent()->getModuleFlag("eh-asynch");
+  if (IsEHa) {
+    const BasicBlock *EntryBB = &(Fn->getEntryBlock());
+    calculateSEHStateForAsynchEH(EntryBB, -1, FuncInfo);
+  }
 }
 
 void llvm::calculateWinCXXEHStateNumbers(const Function *Fn,
@@ -482,6 +611,12 @@ void llvm::calculateWinCXXEHStateNumbers(const Function *Fn,
   }
 
   calculateStateNumbersForInvokes(Fn, FuncInfo);
+
+  bool IsEHa = Fn->getParent()->getModuleFlag("eh-asynch");
+  if (IsEHa) {
+    const BasicBlock *EntryBB = &(Fn->getEntryBlock());
+    calculateCXXStateForAsynchEH(EntryBB, -1, FuncInfo);
+  }
 }
 
 static int addClrEHHandler(WinEHFuncInfo &FuncInfo, int HandlerParentState,
@@ -1253,4 +1388,9 @@ void WinEHFuncInfo::addIPToStateRange(const InvokeInst *II,
   LabelToStateMap[InvokeBegin] = std::make_pair(InvokeStateMap[II], InvokeEnd);
 }
 
+void WinEHFuncInfo::addIPToStateRange(int State, MCSymbol* InvokeBegin,
+    MCSymbol* InvokeEnd) {
+    LabelToStateMap[InvokeBegin] = std::make_pair(State, InvokeEnd);
+}
+
 WinEHFuncInfo::WinEHFuncInfo() = default;

llvm/lib/IR/BasicBlock.cpp

@@ -205,6 +205,15 @@ const CallInst *BasicBlock::getPostdominatingDeoptimizeCall() const {
   return BB->getTerminatingDeoptimizeCall();
 }
 
+const Instruction *BasicBlock::getFirstMayFaultInst() const {
+  if (InstList.empty())
+    return nullptr;
+  for (const Instruction &I : *this)
+    if (isa<LoadInst>(I) || isa<StoreInst>(I) || isa<CallBase>(I))
+      return &I;
+  return nullptr;
+}
+
 const Instruction* BasicBlock::getFirstNonPHI() const {
   for (const Instruction &I : *this)
     if (!isa<PHINode>(I))