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

llvm-svn: 47703
diff --git a/llvm/lib/Target/Alpha/AlphaAsmPrinter.cpp b/llvm/lib/Target/Alpha/AlphaAsmPrinter.cpp
index a46a64c..42e4b78 100644
--- a/llvm/lib/Target/Alpha/AlphaAsmPrinter.cpp
+++ b/llvm/lib/Target/Alpha/AlphaAsmPrinter.cpp
@@ -171,7 +171,7 @@
   for (MachineFunction::const_iterator I = MF.begin(), E = MF.end();
        I != E; ++I) {
     if (I != MF.begin()) {
-      printBasicBlockLabel(I, true);
+      printBasicBlockLabel(I, true, true);
       O << '\n';
     }
     for (MachineBasicBlock::const_iterator II = I->begin(), E = I->end();