src/compiler/x86-64/pred.lisp

   1 ;;;; predicate VOPs for the x86 VM
   2
   3 ;;;; This software is part of the SBCL system. See the README file for
   4 ;;;; more information.
   5 ;;;;
   6 ;;;; This software is derived from the CMU CL system, which was
   7 ;;;; written at Carnegie Mellon University and released into the
   8 ;;;; public domain. The software is in the public domain and is
   9 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
  10 ;;;; files for more information.
  11
  12 (in-package "SB!VM")
  13 \f
  14 ;;;; the branch VOP
  15
  16 ;;; The unconditional branch, emitted when we can't drop through to the desired
  17 ;;; destination. Dest is the continuation we transfer control to.
  18 (define-vop (branch)
  19   (:info dest)
  20   (:generator 5
  21     (inst jmp dest)))
  22
  23 \f
  24 ;;;; conditional VOPs
  25
  26 ;;; Note: a constant-tn is allowed in CMP; it uses an EA displacement,
  27 ;;; not immediate data.
  28 (define-vop (if-eq)
  29   (:args (x :scs (any-reg descriptor-reg control-stack constant)
  30             :load-if (not (and (sc-is x immediate)
  31                                (sc-is y any-reg descriptor-reg
  32                                       control-stack constant))))
  33          (y :scs (any-reg descriptor-reg immediate)
  34             :load-if (not (and (sc-is x any-reg descriptor-reg immediate)
  35                                (sc-is y control-stack constant)))))
  36   (:temporary (:sc descriptor-reg) temp)
  37   (:conditional)
  38   (:info target not-p)
  39   (:policy :fast-safe)
  40   (:translate eq)
  41   (:generator 3
  42     (cond
  43      ((sc-is y immediate)
  44       (let ((val (tn-value y)))
  45         (etypecase val
  46           (integer
  47            (if (and (zerop val) (sc-is x any-reg descriptor-reg))
  48                (inst test x x) ; smaller
  49              (let ((fixnumized (fixnumize val)))
  50                (if (typep fixnumized
  51                           '(or (signed-byte 32) (unsigned-byte 31)))
  52                    (inst cmp x fixnumized)
  53                  (progn
  54                    (inst mov temp fixnumized)
  55                    (inst cmp x temp))))))
  56           (symbol
  57            (inst cmp x (+ nil-value (static-symbol-offset val))))
  58           (character
  59            (inst cmp x (logior (ash (char-code val) n-widetag-bits)
  60                                character-widetag))))))
  61      ((sc-is x immediate) ; and y not immediate
  62       ;; Swap the order to fit the compare instruction.
  63       (let ((val (tn-value x)))
  64         (etypecase val
  65           (integer
  66            (if (and (zerop val) (sc-is y any-reg descriptor-reg))
  67                (inst test y y) ; smaller
  68              (let ((fixnumized (fixnumize val)))
  69                (if (typep fixnumized
  70                           '(or (signed-byte 32) (unsigned-byte 31)))
  71                    (inst cmp y fixnumized)
  72                  (progn
  73                    (inst mov temp fixnumized)
  74                    (inst cmp y temp))))))
  75           (symbol
  76            (inst cmp y (+ nil-value (static-symbol-offset val))))
  77           (character
  78            (inst cmp y (logior (ash (char-code val) n-widetag-bits)
  79                                character-widetag))))))
  80       (t
  81        (inst cmp x y)))
  82
  83     (inst jmp (if not-p :ne :e) target)))