Avoid assigning esp (or ebp for framepointer-using frames) in Om1.

src/IceTargetLowering.cpp

Index: src/IceTargetLowering.cpp
diff --git a/src/IceTargetLowering.cpp b/src/IceTargetLowering.cpp
index d29506ee422d19d83e1f2a1004ce5e197e0eab28..a5dd39aa30dcf53061ce3fe339c321c14baa0c6c 100644
--- a/src/IceTargetLowering.cpp
+++ b/src/IceTargetLowering.cpp
@@ -167,7 +167,6 @@ void TargetLowering::regAlloc() {
   RegSetMask RegExclude = RegSet_None;
   RegInclude |= RegSet_CallerSave;
   RegInclude |= RegSet_CalleeSave;
-  RegExclude |= RegSet_StackPointer;
   if (hasFramePointer())
     RegExclude |= RegSet_FramePointer;
   llvm::SmallBitVector RegMask = getRegisterSet(RegInclude, RegExclude);