Long live the exception handling!

This patch fills the last necessary bits to enable exceptions
handling in LLVM. Currently only on x86-32/linux.

In fact, this patch adds necessary intrinsics (and their lowering) which
represent really weird target-specific gcc builtins used inside unwinder.

After corresponding llvm-gcc patch will land (easy) exceptions should be
more or less workable. However, exceptions handling support should not be 
thought as 'finished': I expect many small and not so small glitches
everywhere.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@39855 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 65 insertions, 0 deletions

diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index a5146bd..8b82b62 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -640,6 +640,7 @@ SDOperand SelectionDAGLegalize::LegalizeOp(SDOperand Op) {
     break;
   case ISD::FRAMEADDR:
   case ISD::RETURNADDR:
+  case ISD::FRAME_TO_ARGS_OFFSET:
     // The only option for these nodes is to custom lower them.  If the target
     // does not custom lower them, then return zero.
     Tmp1 = TLI.LowerOperation(Op, DAG);
@@ -695,6 +696,21 @@ SDOperand SelectionDAGLegalize::LegalizeOp(SDOperand Op) {
     }
     }
     break;
+  case ISD::EH_RETURN:
+    MVT::ValueType VT = Node->getValueType(0);
+    // The only "good" option for this node is to custom lower it.
+    switch (TLI.getOperationAction(Node->getOpcode(), VT)) {
+    default: assert(0 && "This action is not supported at all!");
+    case TargetLowering::Custom:
+      Result = TLI.LowerOperation(Op, DAG);
+      if (Result.Val) break;
+      // Fall Thru
+    case TargetLowering::Legal:
+      // Target does not know, how to lower this, lower to noop
+      Result = LegalizeOp(Node->getOperand(0));
+      break;
+    }
+    break;
   case ISD::AssertSext:
   case ISD::AssertZext:
     Tmp1 = LegalizeOp(Node->getOperand(0));
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index dc23151..9803ab8 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -3369,8 +3369,10 @@ std::string SDNode::getOperationName(const SelectionDAG *G) const {
   case ISD::GLOBAL_OFFSET_TABLE: return "GLOBAL_OFFSET_TABLE";
   case ISD::RETURNADDR: return "RETURNADDR";
   case ISD::FRAMEADDR: return "FRAMEADDR";
+  case ISD::FRAME_TO_ARGS_OFFSET: return "FRAME_TO_ARGS_OFFSET";
   case ISD::EXCEPTIONADDR: return "EXCEPTIONADDR";
   case ISD::EHSELECTION: return "EHSELECTION";
+  case ISD::EH_RETURN: return "EH_RETURN";
   case ISD::ConstantPool:  return "ConstantPool";
   case ISD::ExternalSymbol: return "ExternalSymbol";
   case ISD::INTRINSIC_WO_CHAIN: {
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 87bf249..8a2f7b1 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -2721,6 +2721,53 @@ SelectionDAGLowering::visitIntrinsicCall(CallInst &I, unsigned Intrinsic) {
     return 0;
   }
 
+  case Intrinsic::eh_return: {
+    MachineModuleInfo *MMI = DAG.getMachineModuleInfo();
+
+    if (MMI && ExceptionHandling) {
+      MMI->setCallsEHReturn(true);
+      DAG.setRoot(DAG.getNode(ISD::EH_RETURN,
+                              MVT::Other,
+                              getRoot(),
+                              getValue(I.getOperand(1)),
+                              getValue(I.getOperand(2))));
+    } else {
+      setValue(&I, DAG.getConstant(0, TLI.getPointerTy()));
+    }
+
+    return 0;
+  }
+
+   case Intrinsic::eh_unwind_init: {    
+     if (MachineModuleInfo *MMI = DAG.getMachineModuleInfo()) {
+       MMI->setCallsUnwindInit(true);
+     }
+
+     return 0;
+   }
+
+   case Intrinsic::eh_dwarf_cfa: {
+     if (ExceptionHandling) {
+       MVT::ValueType VT = getValue(I.getOperand(1)).getValueType();
+       SDOperand Offset = DAG.getNode(ISD::ADD,
+                                      TLI.getPointerTy(),
+                                      DAG.getNode(ISD::FRAME_TO_ARGS_OFFSET,
+                                                  VT),
+                                      getValue(I.getOperand(1)));
+       setValue(&I, DAG.getNode(ISD::ADD,
+                                TLI.getPointerTy(),
+                                DAG.getNode(ISD::FRAMEADDR,
+                                            TLI.getPointerTy(),
+                                            DAG.getConstant(0,
+                                                            TLI.getPointerTy())),
+                                Offset));
+     } else {
+       setValue(&I, DAG.getConstant(0, TLI.getPointerTy()));
+     }
+
+     return 0;
+  }
+
   case Intrinsic::sqrt_f32:
   case Intrinsic::sqrt_f64:
     setValue(&I, DAG.getNode(ISD::FSQRT,