src/compiler/x86/subprim.lisp

   1 ;;;; linkage information for standard static functions, and
   2 ;;;; miscellaneous VOPs
   3
   4 ;;;; This software is part of the SBCL system. See the README file for
   5 ;;;; more information.
   6 ;;;;
   7 ;;;; This software is derived from the CMU CL system, which was
   8 ;;;; written at Carnegie Mellon University and released into the
   9 ;;;; public domain. The software is in the public domain and is
  10 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
  11 ;;;; files for more information.
  12
  13 (in-package "SB!VM")
  14 \f
  15 ;;;; LENGTH
  16
  17 (define-vop (length/list)
  18   (:translate length)
  19   (:args (object :scs (descriptor-reg control-stack) :target ptr))
  20   (:arg-types list)
  21   (:temporary (:sc unsigned-reg :offset eax-offset) eax)
  22   (:temporary (:sc descriptor-reg :from (:argument 0)) ptr)
  23   (:results (count :scs (any-reg)))
  24   (:result-types positive-fixnum)
  25   (:policy :fast-safe)
  26   (:vop-var vop)
  27   (:save-p :compute-only)
  28   (:generator 40
  29     ;; Move OBJECT into a temp we can bash on, and initialize the count.
  30     (move ptr object)
  31     (inst xor count count)
  32     ;; If we are starting with NIL, then it's really easy.
  33     (inst cmp ptr nil-value)
  34     (inst jmp :e done)
  35     ;; Note: we don't have to test to see whether the original argument is a
  36     ;; list, because this is a :fast-safe vop.
  37     LOOP
  38     ;; Get the CDR and boost the count.
  39     (loadw ptr ptr cons-cdr-slot list-pointer-lowtag)
  40     (inst add count (fixnumize 1))
  41     ;; If we hit NIL, then we are done.
  42     (inst cmp ptr nil-value)
  43     (inst jmp :e done)
  44     ;; Otherwise, check to see whether we hit the end of a dotted list. If
  45     ;; not, loop back for more.
  46     (move eax ptr)
  47     (inst and al-tn lowtag-mask)
  48     (inst cmp al-tn list-pointer-lowtag)
  49     (inst jmp :e loop)
  50     ;; It's dotted all right. Flame out.
  51     (error-call vop object-not-list-error ptr)
  52     ;; We be done.
  53     DONE))
  54
  55 (define-vop (fast-length/list)
  56   (:translate length)
  57   (:args (object :scs (descriptor-reg control-stack) :target ptr))
  58   (:arg-types list)
  59   (:temporary (:sc descriptor-reg :from (:argument 0)) ptr)
  60   (:results (count :scs (any-reg)))
  61   (:result-types positive-fixnum)
  62   (:policy :fast)
  63   (:vop-var vop)
  64   (:save-p :compute-only)
  65   (:generator 30
  66     ;; Get a copy of OBJECT in a register we can bash on, and
  67     ;; initialize COUNT.
  68     (move ptr object)
  69     (inst xor count count)
  70     ;; If we are starting with NIL, we be done.
  71     (inst cmp ptr nil-value)
  72     (inst jmp :e done)
  73     ;; Indirect the next cons cell, and boost the count.
  74     LOOP
  75     (loadw ptr ptr cons-cdr-slot list-pointer-lowtag)
  76     (inst add count (fixnumize 1))
  77     ;; If we aren't done, go back for more.
  78     (inst cmp ptr nil-value)
  79     (inst jmp :ne loop)
  80     DONE))
  81
  82 (define-static-fun length (object) :translate length)