[WinEH] Move WinEHFuncInfo from MachineModuleInfo to MachineFunction

Summary:
Now that there is a one-to-one mapping from MachineFunction to
WinEHFuncInfo, we don't need to use a DenseMap to select the right
WinEHFuncInfo for the current funclet.

The main challenge here is that X86WinEHStatePass is an IR pass that
doesn't have access to the MachineFunction. I gave it its own
WinEHFuncInfo object that it uses to calculate state numbers, which it
then throws away. As long as nobody creates or removes EH pads between
this pass and SDAG construction, we will get the same state numbers.

The other thing X86WinEHStatePass does is to mark the EH registration
node. Instead of communicating which alloca was the registration through
WinEHFuncInfo, I added the llvm.x86.seh.ehregnode intrinsic.  This
intrinsic generates no code and simply marks the alloca in use.

Reviewers: JCTremoulet

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D14668

llvm-svn: 253378

1 files changed, 24 insertions, 86 deletions

diff --git a/llvm/lib/Target/X86/X86WinEHState.cpp b/llvm/lib/Target/X86/X86WinEHState.cpp
index db71738..8a5aa40 100644
--- a/llvm/lib/Target/X86/X86WinEHState.cpp
+++ b/llvm/lib/Target/X86/X86WinEHState.cpp
@@ -66,18 +66,13 @@ private:
 
   void linkExceptionRegistration(IRBuilder<> &Builder, Function *Handler);
   void unlinkExceptionRegistration(IRBuilder<> &Builder);
-  void addCXXStateStores(Function &F, WinEHFuncInfo &FuncInfo);
-  void addSEHStateStores(Function &F, WinEHFuncInfo &FuncInfo);
-  void addStateStoresToFunclet(Value *ParentRegNode, WinEHFuncInfo &FuncInfo,
-                               Function &F, int BaseState);
+  void addStateStores(Function &F, WinEHFuncInfo &FuncInfo);
   void insertStateNumberStore(Value *ParentRegNode, Instruction *IP, int State);
 
   Value *emitEHLSDA(IRBuilder<> &Builder, Function *F);
 
   Function *generateLSDAInEAXThunk(Function *ParentFunc);
 
-  int escapeRegNode(Function &F);
-
   // Module-level type getters.
   Type *getEHLinkRegistrationType();
   Type *getSEHRegistrationType();
@@ -178,26 +173,13 @@ bool WinEHStatePass::runOnFunction(Function &F) {
 
   emitExceptionRegistrationRecord(&F);
 
-  auto *MMI = getAnalysisIfAvailable<MachineModuleInfo>();
-  // If MMI is null, create our own WinEHFuncInfo.  This only happens in opt
-  // tests.
-  std::unique_ptr<WinEHFuncInfo> FuncInfoPtr;
-  if (!MMI)
-    FuncInfoPtr.reset(new WinEHFuncInfo());
-  WinEHFuncInfo &FuncInfo =
-      *(MMI ? &MMI->getWinEHFuncInfo(&F) : FuncInfoPtr.get());
-
-  FuncInfo.EHRegNode = RegNode;
-
-  switch (Personality) {
-  default: llvm_unreachable("unexpected personality function");
-  case EHPersonality::MSVC_CXX:
-    addCXXStateStores(F, FuncInfo);
-    break;
-  case EHPersonality::MSVC_X86SEH:
-    addSEHStateStores(F, FuncInfo);
-    break;
-  }
+  // The state numbers calculated here in IR must agree with what we calculate
+  // later on for the MachineFunction. In particular, if an IR pass deletes an
+  // unreachable EH pad after this point before machine CFG construction, we
+  // will be in trouble. If this assumption is ever broken, we should turn the
+  // numbers into an immutable analysis pass.
+  WinEHFuncInfo FuncInfo;
+  addStateStores(F, FuncInfo);
 
   // Reset per-function state.
   PersonalityFn = nullptr;
@@ -418,65 +400,21 @@ void WinEHStatePass::unlinkExceptionRegistration(IRBuilder<> &Builder) {
   Builder.CreateStore(Next, FSZero);
 }
 
-void WinEHStatePass::addCXXStateStores(Function &F, WinEHFuncInfo &FuncInfo) {
-  // Set up RegNodeEscapeIndex
-  int RegNodeEscapeIndex = escapeRegNode(F);
-  FuncInfo.EHRegNodeEscapeIndex = RegNodeEscapeIndex;
-
-  calculateWinCXXEHStateNumbers(&F, FuncInfo);
-  addStateStoresToFunclet(RegNode, FuncInfo, F, -1);
-}
-
-/// 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.
-void WinEHStatePass::addSEHStateStores(Function &F, WinEHFuncInfo &FuncInfo) {
-  // Remember and return the index that we used. We save it in WinEHFuncInfo so
-  // that we can lower llvm.x86.seh.recoverfp later in filter functions without
-  // too much trouble.
-  int RegNodeEscapeIndex = escapeRegNode(F);
-  FuncInfo.EHRegNodeEscapeIndex = RegNodeEscapeIndex;
-
-  calculateSEHStateNumbers(&F, FuncInfo);
-  addStateStoresToFunclet(RegNode, FuncInfo, F, -1);
-}
-
-/// Escape RegNode so that we can access it from child handlers. Find the call
-/// to localescape, if any, in the entry block and append RegNode to the list
-/// of arguments.
-int WinEHStatePass::escapeRegNode(Function &F) {
-  // Find the call to localescape and extract its arguments.
-  IntrinsicInst *EscapeCall = nullptr;
-  for (Instruction &I : F.getEntryBlock()) {
-    IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
-    if (II && II->getIntrinsicID() == Intrinsic::localescape) {
-      EscapeCall = II;
-      break;
-    }
-  }
-  SmallVector<Value *, 8> Args;
-  if (EscapeCall) {
-    auto Ops = EscapeCall->arg_operands();
-    Args.append(Ops.begin(), Ops.end());
-  }
-  Args.push_back(RegNode);
-
-  // Replace the call (if it exists) with new one. Otherwise, insert at the end
-  // of the entry block.
-  Instruction *InsertPt = EscapeCall;
-  if (!EscapeCall)
-    InsertPt = F.getEntryBlock().getTerminator();
-  IRBuilder<> Builder(InsertPt);
-  Builder.CreateCall(FrameEscape, Args);
-  if (EscapeCall)
-    EscapeCall->eraseFromParent();
-  return Args.size() - 1;
-}
+void WinEHStatePass::addStateStores(Function &F, WinEHFuncInfo &FuncInfo) {
+  // Mark the registration node. The backend needs to know which alloca it is so
+  // that it can recover the original frame pointer.
+  IRBuilder<> Builder(RegNode->getParent(), std::next(RegNode->getIterator()));
+  Value *RegNodeI8 = Builder.CreateBitCast(RegNode, Builder.getInt8PtrTy());
+  Builder.CreateCall(
+      Intrinsic::getDeclaration(TheModule, Intrinsic::x86_seh_ehregnode),
+      {RegNodeI8});
+
+  // Calculate state numbers.
+  if (isAsynchronousEHPersonality(Personality))
+    calculateSEHStateNumbers(&F, FuncInfo);
+  else
+    calculateWinCXXEHStateNumbers(&F, FuncInfo);
 
-void WinEHStatePass::addStateStoresToFunclet(Value *ParentRegNode,
-                                             WinEHFuncInfo &FuncInfo,
-                                             Function &F, int BaseState) {
   // Iterate all the instructions and emit state number stores.
   for (BasicBlock &BB : F) {
     for (Instruction &I : BB) {
@@ -485,14 +423,14 @@ void WinEHStatePass::addStateStoresToFunclet(Value *ParentRegNode,
         // an unwind. Ensure they are in the -1 state.
         if (CI->doesNotThrow())
           continue;
-        insertStateNumberStore(ParentRegNode, CI, BaseState);
+        insertStateNumberStore(RegNode, CI, -1);
       } else if (auto *II = dyn_cast<InvokeInst>(&I)) {
         // Look up the state number of the landingpad this unwinds to.
         Instruction *PadInst = II->getUnwindDest()->getFirstNonPHI();
         // FIXME: Why does this assertion fail?
         //assert(FuncInfo.EHPadStateMap.count(PadInst) && "EH Pad has no state!");
         int State = FuncInfo.EHPadStateMap[PadInst];
-        insertStateNumberStore(ParentRegNode, II, State);
+        insertStateNumberStore(RegNode, II, State);
       }
     }
   }