Add a quick and dirty "loop aligner pass". x86 uses it to align its loops to 16-byte boundaries.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47703 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/MachineFrameInfo.h

@@ -204,7 +204,7 @@ public:
   }
 
   /// getObjectAlignment - Return the alignment of the specified stack object...
-  int getObjectAlignment(int ObjectIdx) const {
+  unsigned getObjectAlignment(int ObjectIdx) const {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     return Objects[ObjectIdx+NumFixedObjects].Alignment;