[PrologEpilogInserter] Minor refactoring.

[reames]

LGTM, do yo have commit access or would you like me to land this?

[maksfb]

I don't have commit access. Please land. Thx!

llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp

AdjustStackOffset(MachineFrameInfo *MFI, int FrameIdx,
 
   unsigned Align = MFI->getObjectAlignment(FrameIdx);
 
   // If the alignment of this object is greater than that of the stack, then
   // increase the stack alignment to match.
   MaxAlign = std::max(MaxAlign, Align);
 
   // Adjust to alignment boundary.
-  Offset = (Offset + Align - 1) / Align * Align;
+  Offset = RoundUpToAlignment(Offset, Align);
 
   if (StackGrowsDown) {
     DEBUG(dbgs() << "alloc FI(" << FrameIdx << ") at SP[" << -Offset << "]\n");
     MFI->setObjectOffset(FrameIdx, -Offset); // Set the computed offset
   } else {
     DEBUG(dbgs() << "alloc FI(" << FrameIdx << ") at SP[" << Offset << "]\n");
     MFI->setObjectOffset(FrameIdx, Offset);
     Offset += MFI->getObjectSize(FrameIdx);