Fix __builtin_setjmp in combination with sjlj exception handling.

llvm.eh.sjlj.setjmp was used as part of the SjLj exception handling
style but is also used in clang to implement __builtin_setjmp.  The ARM
backend needs to output additional dispatch tables for the SjLj
exception handling style, these tables however can't be emitted if
llvm.eh.sjlj.setjmp is simply used for __builtin_setjmp and no actual
landing pad blocks exist.

To solve this issue a new llvm.eh.sjlj.setup_dispatch intrinsic is
introduced which is used instead of llvm.eh.sjlj.setjmp in the SjLj
exception handling lowering, so we can differentiate between the case
where we actually need to setup a dispatch table and the case where we
just need the __builtin_setjmp semantic.

Differential Revision: http://reviews.llvm.org/D9313

llvm-svn: 242481
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index 51057a0..0396736 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -1264,6 +1264,7 @@
   case ISD::FRAME_TO_ARGS_OFFSET:
   case ISD::EH_SJLJ_SETJMP:
   case ISD::EH_SJLJ_LONGJMP:
+  case ISD::EH_SJLJ_SETUP_DISPATCH:
     // These operations lie about being legal: when they claim to be legal,
     // they should actually be expanded.
     Action = TLI.getOperationAction(Node->getOpcode(), Node->getValueType(0));
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 73de6e3..702e14b 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -4410,6 +4410,11 @@
                             getRoot(), getValue(I.getArgOperand(0))));
     return nullptr;
   }
+  case Intrinsic::eh_sjlj_setup_dispatch: {
+    DAG.setRoot(DAG.getNode(ISD::EH_SJLJ_SETUP_DISPATCH, sdl, MVT::Other,
+                            getRoot()));
+    return nullptr;
+  }
 
   case Intrinsic::masked_gather:
     visitMaskedGather(I);
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
index 8dabddc..883cc257 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
@@ -102,6 +102,7 @@
   case ISD::EH_RETURN:                  return "EH_RETURN";
   case ISD::EH_SJLJ_SETJMP:             return "EH_SJLJ_SETJMP";
   case ISD::EH_SJLJ_LONGJMP:            return "EH_SJLJ_LONGJMP";
+  case ISD::EH_SJLJ_SETUP_DISPATCH:     return "EH_SJLJ_SETUP_DISPATCH";
   case ISD::ConstantPool:               return "ConstantPool";
   case ISD::TargetIndex:                return "TargetIndex";
   case ISD::ExternalSymbol:             return "ExternalSymbol";