anchor.diff:    (%object-tag function))
   
   (defun function-pool-size (function)
  -  (%type-check function +object-tag-function+ function)
  +  (%type-check function +object-tag-function+ 'compiled-function)
     (ldb +function-header-pool-size+ (%object-header-data function)))
   
   (defun function-code-size (function)
  -  (%type-check function +object-tag-function+ function)
  +  (%type-check function +object-tag-function+ 'compiled-function)
     (* (ldb +function-header-code-size+ (%object-header-data function)) 16))
   
   (defun function-gc-metadata-size (function)
  -  (%type-check function +object-tag-function+ function)
  +  (%type-check function +object-tag-function+ 'compiled-function)
     (ldb +function-header-metadata-size+ (%object-header-data function)))
   
   (defun function-pool-object (function offset)
  -  (%type-check function +object-tag-function+ function)
  +  (%type-check function +object-tag-function+ 'compiled-function)
     (check-type offset (integer 0))
     (assert (< offset (function-pool-size function)))
     (let ((address (logand (lisp-object-address function) -16))
  
positive.code:     (memref-t address (+ mc-size offset))))
  
  (defun function-code-byte (function offset)
    (%type-check function +object-tag-function+ function)
    (check-type offset (integer 0))
    (assert (< offset (function-code-size function)))
    (let ((address (logand (lisp-object-address function) -16)))
      (memref-unsigned-byte-8 address offset)))
  
  (defun function-gc-metadata-byte (function offset)
    (%type-check function +object-tag-function+ function)
    (check-type offset (integer 0))
    (assert (< offset (function-gc-metadata-size function)))
    (let* ((address (logand (lisp-object-address function) -16))
  
negative.code: 
  (defun function-gc-info (function)
    "Return the address of and the number of bytes in FUNCTION's GC info."
    (%type-check function +object-tag-function+ 'compiled-function)
    (let* ((address (logand (lisp-object-address function) -16))
           (gc-length (ldb +function-header-metadata-size+
                           (%object-header-data function)))
  