2 files changed, 94 insertions, 2 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 88598a1ddd0..72f18cc1143 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -15506,6 +15506,23 @@ static SDValue LowerINTRINSIC_WO_CHAIN(SDValue Op, const X86Subtarget *Subtarget
         DAG.getTargetExternalSymbol(Name.data(), VT, X86II::MO_NOPREFIX);
     return DAG.getNode(X86ISD::Wrapper, dl, VT, Result);
   }
+
+  case Intrinsic::eh_exceptioninfo: {
+    // Compute the symbol for the LSDA. We know it'll get emitted later.
+    MachineFunction &MF = DAG.getMachineFunction();
+    SDValue Op1 = Op.getOperand(1);
+    auto *Fn = cast<Function>(cast<GlobalAddressSDNode>(Op1)->getGlobal());
+    MCSymbol *LSDASym = MF.getMMI().getContext().getOrCreateLSDASymbol(
+        GlobalValue::getRealLinkageName(Fn->getName()));
+    StringRef Name = LSDASym->getName();
+    assert(Name.data()[Name.size()] == '\0' && "not null terminated");
+
+    // Generate a simple absolute symbol reference. This intrinsic is only
+    // supported on 32-bit Windows, which isn't PIC.
+    SDValue Result =
+        DAG.getTargetExternalSymbol(Name.data(), VT, X86II::MO_NOPREFIX);
+    return DAG.getNode(X86ISD::Wrapper, dl, VT, Result);
+  }
   }
 }
 
diff --git a/llvm/lib/Target/X86/X86WinEHState.cpp b/llvm/lib/Target/X86/X86WinEHState.cpp
index ce69ea72199..0c4aabab880 100644
--- a/llvm/lib/Target/X86/X86WinEHState.cpp
+++ b/llvm/lib/Target/X86/X86WinEHState.cpp
@@ -63,9 +63,12 @@ private:
   void linkExceptionRegistration(IRBuilder<> &Builder, Value *Handler);
   void unlinkExceptionRegistration(IRBuilder<> &Builder);
   void addCXXStateStores(Function &F, MachineModuleInfo &MMI);
+  void addSEHStateStores(Function &F, MachineModuleInfo &MMI);
   void addCXXStateStoresToFunclet(Value *ParentRegNode, WinEHFuncInfo &FuncInfo,
                                   Function &F, int BaseState);
   void insertStateNumberStore(Value *ParentRegNode, Instruction *IP, int State);
+  iplist<Instruction>::iterator
+  rewriteExceptionInfoIntrinsics(IntrinsicInst *Intrin);
 
   Value *emitEHLSDA(IRBuilder<> &Builder, Function *F);
 
@@ -171,8 +174,10 @@ bool WinEHStatePass::runOnFunction(Function &F) {
   auto *MMIPtr = getAnalysisIfAvailable<MachineModuleInfo>();
   assert(MMIPtr && "MachineModuleInfo should always be available");
   MachineModuleInfo &MMI = *MMIPtr;
-  if (Personality == EHPersonality::MSVC_CXX) {
-    addCXXStateStores(F, MMI);
+  switch (Personality) {
+  default: llvm_unreachable("unexpected personality function");
+  case EHPersonality::MSVC_CXX:    addCXXStateStores(F, MMI); break;
+  case EHPersonality::MSVC_X86SEH: addSEHStateStores(F, MMI); break;
   }
 
   // Reset per-function state.
@@ -472,6 +477,76 @@ void WinEHStatePass::addCXXStateStoresToFunclet(Value *ParentRegNode,
   }
 }
 
+/// Assign every distinct landingpad a unique state number for SEH. Unlike C++
+/// EH, we can use this very simple algorithm while C++ EH cannot because catch
+/// handlers aren't outlined and the runtime doesn't have to figure out which
+/// catch handler frame to unwind to.
+/// FIXME: __finally blocks are outlined, so this approach may break down there.
+void WinEHStatePass::addSEHStateStores(Function &F, MachineModuleInfo &MMI) {
+  WinEHFuncInfo &FuncInfo = MMI.getWinEHFuncInfo(&F);
+
+  // Iterate all the instructions and emit state number stores.
+  int CurState = 0;
+  for (BasicBlock &BB : F) {
+    for (auto I = BB.begin(), E = BB.end(); I != E; ++I) {
+      if (auto *CI = dyn_cast<CallInst>(I)) {
+        auto *Intrin = dyn_cast<IntrinsicInst>(CI);
+        if (Intrin) {
+          I = rewriteExceptionInfoIntrinsics(Intrin);
+          // Calls that "don't throw" are considered to be able to throw asynch
+          // exceptions, but intrinsics cannot.
+          continue;
+        }
+        insertStateNumberStore(RegNode, CI, -1);
+      } else if (auto *II = dyn_cast<InvokeInst>(I)) {
+        // Look up the state number of the landingpad this unwinds to.
+        LandingPadInst *LPI = II->getUnwindDest()->getLandingPadInst();
+        auto InsertionPair =
+            FuncInfo.LandingPadStateMap.insert(std::make_pair(LPI, 0));
+        auto Iter = InsertionPair.first;
+        int &State = Iter->second;
+        bool Inserted = InsertionPair.second;
+        if (Inserted) {
+          // Each action consumes a state number.
+          auto *EHActions = cast<IntrinsicInst>(LPI->getNextNode());
+          SmallVector<std::unique_ptr<ActionHandler>, 4> ActionList;
+          parseEHActions(EHActions, ActionList);
+          assert(!ActionList.empty());
+          CurState += ActionList.size();
+          State += ActionList.size() - 1;
+        }
+        insertStateNumberStore(RegNode, II, State);
+      }
+    }
+  }
+}
+
+/// Rewrite llvm.eh.exceptioncode and llvm.eh.exceptioninfo to memory loads in
+/// IR.
+iplist<Instruction>::iterator
+WinEHStatePass::rewriteExceptionInfoIntrinsics(IntrinsicInst *Intrin) {
+  Intrinsic::ID ID = Intrin->getIntrinsicID();
+  if (ID != Intrinsic::eh_exceptioncode && ID != Intrinsic::eh_exceptioninfo)
+    return Intrin;
+
+  // RegNode->ExceptionPointers
+  IRBuilder<> Builder(Intrin);
+  Value *Ptrs =
+      Builder.CreateLoad(Builder.CreateStructGEP(RegNodeTy, RegNode, 1));
+  Value *Res;
+  if (ID == Intrinsic::eh_exceptioncode) {
+    // Ptrs->ExceptionRecord->Code
+    Ptrs = Builder.CreateBitCast(
+        Ptrs, Builder.getInt32Ty()->getPointerTo()->getPointerTo());
+    Value *Rec = Builder.CreateLoad(Ptrs);
+    Res = Builder.CreateLoad(Rec);
+  } else {
+    Res = Ptrs;
+  }
+  Intrin->replaceAllUsesWith(Res);
+  return Intrin->eraseFromParent();
+}
+
 void WinEHStatePass::insertStateNumberStore(Value *ParentRegNode,
                                             Instruction *IP, int State) {
   IRBuilder<> Builder(IP);