WinEH: Create an unwind help alloca for __CxxFrameHandler3 xdata tables

We don't have any logic to emit those tables yet, so the sdag lowering
of this intrinsic is just a stub. We can see the intrinsic in the
prepared IR, though.

llvm-svn: 233209

2 files changed, 23 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 6f5ea7c7469..6c14e7969c5 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -5446,6 +5446,16 @@ SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
   case Intrinsic::eh_begincatch:
   case Intrinsic::eh_endcatch:
     llvm_unreachable("begin/end catch intrinsics not lowered in codegen");
+  case Intrinsic::eh_unwindhelp: {
+    AllocaInst *Slot =
+        cast<AllocaInst>(I.getArgOperand(0)->stripPointerCasts());
+    assert(FuncInfo.StaticAllocaMap.count(Slot) &&
+           "can only use static allocas with llvm.eh.unwindhelp");
+    int FI = FuncInfo.StaticAllocaMap[Slot];
+    // TODO: Save this in the not-yet-existant WinEHFuncInfo struct.
+    (void)FI;
+    return nullptr;
+  }
   }
 }
 
diff --git a/llvm/lib/CodeGen/WinEHPrepare.cpp b/llvm/lib/CodeGen/WinEHPrepare.cpp
index d1b385579b9..ab0f96ef05f 100644
--- a/llvm/lib/CodeGen/WinEHPrepare.cpp
+++ b/llvm/lib/CodeGen/WinEHPrepare.cpp
@@ -601,6 +601,19 @@ bool WinEHPrepare::prepareExceptionHandlers(
   Builder.SetInsertPoint(&F.getEntryBlock().back());
   Builder.CreateCall(FrameEscapeFn, AllocasToEscape);
 
+  // Insert an alloca for the EH state in the entry block. On x86, we will also
+  // insert stores to update the EH state, but on other ISAs, the runtime does
+  // it for us.
+  // FIXME: This record is different on x86.
+  Type *UnwindHelpTy = Type::getInt64Ty(Context);
+  AllocaInst *UnwindHelp =
+      new AllocaInst(UnwindHelpTy, "unwindhelp", &F.getEntryBlock().front());
+  Builder.CreateStore(llvm::ConstantInt::get(UnwindHelpTy, -2), UnwindHelp);
+  Function *UnwindHelpFn =
+      Intrinsic::getDeclaration(M, Intrinsic::eh_unwindhelp);
+  Builder.CreateCall(UnwindHelpFn,
+                     Builder.CreateBitCast(UnwindHelp, Int8PtrType));
+
   // Clean up the handler action maps we created for this function
   DeleteContainerSeconds(CatchHandlerMap);
   CatchHandlerMap.clear();