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

lib/CodeGen/MachineBasicBlock.cpp

@@ -166,6 +166,7 @@ void MachineBasicBlock::print(std::ostream &OS) const {
   if (LBB) OS << LBB->getName() << ": ";
   OS << (const void*)this
      << ", LLVM BB @" << (const void*) LBB << ", ID#" << getNumber();
+  if (Alignment) OS << ", Alignment " << Alignment;
   if (isLandingPad()) OS << ", EH LANDING PAD";
   OS << ":\n";