message: skip scalable vectors in alloca; we dont support them ATM
diff: @@ -457,8 +457,11 @@ public:
  return error(i);
  }
  - // FIXME: size bits shouldn't be a constant
  - auto size = make_intconst(DL().getTypeAllocSize(i.getAllocatedType()), 64);
  + auto typesz = DL().getTypeAllocSize(i.getAllocatedType());
  + if (typesz.isScalable()) // TODO: scalable vectors not supported
  + return error(i);
  +
  + auto size = make_intconst(typesz, 64);
  auto alloc = make_unique<Alloc>(*ty, value_name(i), *size, mul,
  pref_alignment(i, i.getAllocatedType()));
  allocs.emplace(&i, make_pair(alloc.get(), /*has lifetime.start?*/ false));
  