Create and use an llvm.eh.sjlj.functioncontext intrinsic.

This intrinsic is used to pass the index of the function context to the back-end
for further processing. The back-end is in charge of filling in the rest of the
entries.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140676 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 9d86c75..b2b93c9 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -4754,6 +4754,14 @@
     MMI.setCurrentCallSite(CI->getZExtValue());
     return 0;
   }
+  case Intrinsic::eh_sjlj_functioncontext: {
+    // Get and store the index of the function context.
+    MachineFrameInfo *MFI = DAG.getMachineFunction().getFrameInfo();
+    AllocaInst *FnCtx = cast<AllocaInst>(I.getArgOperand(0));
+    int FI = FuncInfo.StaticAllocaMap[FnCtx];
+    MFI->setFunctionContextIndex(FI);
+    return 0;
+  }
   case Intrinsic::eh_sjlj_setjmp: {
     setValue(&I, DAG.getNode(ISD::EH_SJLJ_SETJMP, dl, MVT::i32, getRoot(),
                              getValue(I.getArgOperand(0))));