anchor.diff:        (typecase inst
           (terminator-instruction
            (dolist (succ (successors backend-function inst))
  +           (assert (typep succ 'label))
              (pushnew succ targets)
              (pushnew succ (gethash active-bb successors))
              (pushnew active-bb (gethash succ predecessors)))
  
positive.code:                            :values '())
               (incf total))))
          (mezzano.compiler.backend.x86-64::x86-branch-instruction
           (let ((true-target (skip-label backend-function (mezzano.compiler.backend.x86-64::x86-branch-true-target inst)))
                 (false-target (skip-label backend-function (mezzano.compiler.backend.x86-64::x86-branch-false-target inst))))
             (when (and (typep true-target 'jump-instruction)
                        ;; Don't snap if there are phi nodes at the target.
                        (endp (jump-values true-target)))
               (setf (mezzano.compiler.backend.x86-64::x86-branch-true-target inst) (jump-target true-target))
               (incf total))
             (when (and (typep false-target 'jump-instruction)
                         ;; Don't snap if there are phi nodes at the target.
                        (endp (jump-values false-target)))
               (setf (mezzano.compiler.backend.x86-64::x86-branch-false-target inst) (jump-target false-target))
               (incf total))))
          (jump-instruction
           (when (endp (jump-values inst))
             (let ((target (skip-label backend-function (jump-target inst))))
               (cond ((and (typep target 'jump-instruction)
                           ;; Don't snap if there are phi nodes at the target.
                           (endp (jump-values target)))
                      (setf (jump-target inst) (jump-target target))
                      (incf total))
                     ((typep target 'branch-instruction)
                      ;; Convert to branch.
                      (change-class inst
                                    'branch-instruction
                                    :value (branch-value target)
                                    :true-target (branch-true-target target)
                                    :false-target (branch-false-target target))
                      (incf total))))))))
      total))
  
  
negative.code:            (push active-bb basic-blocks)))
          (begin-nlx-instruction
           (dolist (succ (begin-nlx-targets inst))
             (assert (typep succ 'label))
             (pushnew succ targets)
             (pushnew succ (gethash active-bb successors))
             (pushnew active-bb (gethash succ predecessors))))))
  