message: Remove unnecessary fallback
diff: @@ -144,11 +144,9 @@ def lvn_block(block, lookup, canonicalize):
  num2var[newnum] = var
  instr['dest'] = var
  - # Update argument variable names.
  + # Update argument variable names to canonical variables.
  if 'args' in instr:
  - # Numbers not in the table are inputs and left unchanged.
  - new_args = [num2var.get(n, v)
  - for n, v in zip(argnums, argvars)]
  + new_args = [num2var[n] for n in argnums]
  if instr['op'] not in TERMINATORS:
  instr['args'] = new_args
  elif instr['op'] == 'br':
  