;;;; the Alpha definitions of some general purpose memory reference
;;;; VOPs inherited by basic memory reference operations

;;;; This software is part of the SBCL system. See the README file for
;;;; more information.
;;;;
;;;; This software is derived from the CMU CL system, which was
;;;; written at Carnegie Mellon University and released into the
;;;; public domain. The software is in the public domain and is
;;;; provided with absolutely no warranty. See the COPYING and CREDITS
;;;; files for more information.

(in-package "SB!VM")

;;; Cell-Ref and Cell-Set are used to define VOPs like CAR, where the
;;; offset to be read or written is a property of the VOP used.
(define-vop (cell-ref)
  (:args (object :scs (descriptor-reg)))
  (:results (value :scs (descriptor-reg any-reg)))
  (:variant-vars offset lowtag)
  (:policy :fast-safe)
  (:generator 4
    (loadw value object offset lowtag)))
(define-vop (cell-set)
  (:args (object :scs (descriptor-reg))
         (value :scs (descriptor-reg any-reg null zero)))
  (:variant-vars offset lowtag)
  (:policy :fast-safe)
  (:generator 4
    (storew value object offset lowtag)))

;;; Slot-Ref and Slot-Set are used to define VOPs like Closure-Ref,
;;; where the offset is constant at compile time, but varies for
;;; different uses. We add in the stardard g-vector overhead.
(define-vop (slot-ref)
  (:args (object :scs (descriptor-reg)))
  (:results (value :scs (descriptor-reg any-reg)))
  (:variant-vars base lowtag)
  (:info offset)
  (:generator 4
    (loadw value object (+ base offset) lowtag)))
(define-vop (slot-set)
  (:args (object :scs (descriptor-reg))
         (value :scs (descriptor-reg any-reg null zero)))
  (:variant-vars base lowtag)
  (:info offset)
  (:generator 4
    (storew value object (+ base offset) lowtag)))