CodeGen: Reorder MachinePointerInfo fields

This saves a little bit of padding.

Author: arsenm

llvm/include/llvm/CodeGen/MachineMemOperand.h

@@ -43,10 +43,10 @@ struct MachinePointerInfo {
   /// Offset - This is an offset from the base Value*.
   int64_t Offset;
 
-  uint8_t StackID;
-
   unsigned AddrSpace = 0;
 
+  uint8_t StackID;
+
   explicit MachinePointerInfo(const Value *v, int64_t offset = 0,
                               uint8_t ID = 0)
       : V(v), Offset(offset), StackID(ID) {
@@ -60,8 +60,8 @@ struct MachinePointerInfo {
   }
 
   explicit MachinePointerInfo(unsigned AddressSpace = 0, int64_t offset = 0)
-      : V((const Value *)nullptr), Offset(offset), StackID(0),
-        AddrSpace(AddressSpace) {}
+      : V((const Value *)nullptr), Offset(offset), AddrSpace(AddressSpace),
+        StackID(0) {}
 
   explicit MachinePointerInfo(
     PointerUnion<const Value *, const PseudoSourceValue *> v,