Add a pre-dispatch SjLj EH hook on the unwind edge for targets to do any

setup they require. Use this for ARM/Darwin to rematerialize the base
pointer from the frame pointer when required. rdar://8564268

llvm-svn: 116879

4 files changed, 27 insertions, 5 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index c7779495ec1..cd40f640170 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -865,6 +865,7 @@ SDValue SelectionDAGLegalize::LegalizeOp(SDValue Op) {
   case ISD::FRAME_TO_ARGS_OFFSET:
   case ISD::EH_SJLJ_SETJMP:
   case ISD::EH_SJLJ_LONGJMP:
+  case ISD::EH_SJLJ_DISPATCHSETUP:
     // 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));
@@ -2541,9 +2542,14 @@ void SelectionDAGLegalize::ExpandNode(SDNode *Node,
   case ISD::PREFETCH:
   case ISD::VAEND:
   case ISD::EH_SJLJ_LONGJMP:
+  case ISD::EH_SJLJ_DISPATCHSETUP:
+    // If the target didn't expand these, there's nothing to do, so just
+    // preserve the chain and be done.
     Results.push_back(Node->getOperand(0));
     break;
   case ISD::EH_SJLJ_SETJMP:
+    // If the target didn't expand this, just return 'zero' and preserve the
+    // chain.
     Results.push_back(DAG.getConstant(0, MVT::i32));
     Results.push_back(Node->getOperand(0));
     break;
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index c6eb216f633..f52c931a18f 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -5616,6 +5616,7 @@ std::string SDNode::getOperationName(const SelectionDAG *G) const {
   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_DISPATCHSETUP: return "EH_SJLJ_DISPATCHSETUP";
   case ISD::ConstantPool:  return "ConstantPool";
   case ISD::ExternalSymbol: return "ExternalSymbol";
   case ISD::BlockAddress:  return "BlockAddress";
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 04c424f6729..e2b1bb4b751 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -4319,8 +4319,12 @@ SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
   }
   case Intrinsic::eh_sjlj_longjmp: {
     DAG.setRoot(DAG.getNode(ISD::EH_SJLJ_LONGJMP, dl, MVT::Other,
-                            getRoot(),
-                            getValue(I.getArgOperand(0))));
+                            getRoot(), getValue(I.getArgOperand(0))));
+    return 0;
+  }
+  case Intrinsic::eh_sjlj_dispatch_setup: {
+    DAG.setRoot(DAG.getNode(ISD::EH_SJLJ_DISPATCHSETUP, dl, MVT::Other,
+                            getRoot(), getValue(I.getArgOperand(0))));
     return 0;
   }
 
diff --git a/llvm/lib/CodeGen/SjLjEHPrepare.cpp b/llvm/lib/CodeGen/SjLjEHPrepare.cpp
index b637980f885..1f6a5c4ea03 100644
--- a/llvm/lib/CodeGen/SjLjEHPrepare.cpp
+++ b/llvm/lib/CodeGen/SjLjEHPrepare.cpp
@@ -53,6 +53,7 @@ namespace {
     Constant *SelectorFn;
     Constant *ExceptionFn;
     Constant *CallSiteFn;
+    Constant *DispatchSetupFn;
 
     Value *CallSite;
   public:
@@ -116,6 +117,8 @@ bool SjLjEHPass::doInitialization(Module &M) {
   SelectorFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_selector);
   ExceptionFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_exception);
   CallSiteFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_callsite);
+  DispatchSetupFn
+    = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_dispatch_setup);
   PersonalityFn = 0;
 
   return true;
@@ -438,9 +441,17 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) {
     BasicBlock *DispatchBlock =
             BasicBlock::Create(F.getContext(), "eh.sjlj.setjmp.catch", &F);
 
-    // Insert a load in the Catch block, and a switch on its value.  By default,
-    // we go to a block that just does an unwind (which is the correct action
-    // for a standard call).
+    // Add a call to dispatch_setup at the start of the dispatch block. This
+    // is expanded to any target-specific setup that needs to be done.
+    Value *SetupArg =
+      CastInst::Create(Instruction::BitCast, FunctionContext,
+                       Type::getInt8PtrTy(F.getContext()), "",
+                       DispatchBlock);
+    CallInst::Create(DispatchSetupFn, SetupArg, "", DispatchBlock);
+
+    // Insert a load of the callsite in the dispatch block, and a switch on
+    // its value.  By default, we go to a block that just does an unwind
+    // (which is the correct action for a standard call).
     BasicBlock *UnwindBlock =
       BasicBlock::Create(F.getContext(), "unwindbb", &F);
     Unwinds.push_back(new UnwindInst(F.getContext(), UnwindBlock));