Remove UseThumbBacktraces. Just check if subtarget is darwin.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73734 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index 975eb23..943a420 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -1483,7 +1483,7 @@
   MVT VT = Op.getValueType();
   DebugLoc dl = Op.getDebugLoc();  // FIXME probably not meaningful
   unsigned Depth = cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue();
-  unsigned FrameReg = (Subtarget->isThumb() || Subtarget->useThumbBacktraces())
+  unsigned FrameReg = (Subtarget->isThumb() || Subtarget->isTargetDarwin())
     ? ARM::R7 : ARM::R11;
   SDValue FrameAddr = DAG.getCopyFromReg(DAG.getEntryNode(), dl, FrameReg, VT);
   while (Depth--)