Use default lowering of DYNAMIC_STACKALLOC. As far as I can tell, ARM isle is doing the right thing and codegen looks correct for both Thumb and Thumb2.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101410 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index 08e8010..f2d8175 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -384,10 +384,7 @@
   // FIXME: Shouldn't need this, since no register is used, but the legalizer
   // doesn't yet know how to not do that for SjLj.
   setExceptionSelectorRegister(ARM::R0);
-  if (Subtarget->isThumb())
-    setOperationAction(ISD::DYNAMIC_STACKALLOC, MVT::i32, Custom);
-  else
-    setOperationAction(ISD::DYNAMIC_STACKALLOC, MVT::i32, Expand);
+  setOperationAction(ISD::DYNAMIC_STACKALLOC, MVT::i32, Expand);
   setOperationAction(ISD::MEMBARRIER,         MVT::Other, Custom);
 
   if (!Subtarget->hasV6Ops() && !Subtarget->isThumb2()) {