src/compiler/generic/utils.lisp

   1 ;;;; utility functions and macros needed by the back end to generate
   2 ;;;; code
   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 ;;; Make a fixnum out of NUM. (I.e. shift by two bits if it will fit.)
  16 (defun fixnumize (num)
  17   (if (fixnump num)
  18       (ash num (1- n-lowtag-bits))
  19       (error "~W is too big for a fixnum." num)))
  20
  21 ;;; Determining whether a constant offset fits in an addressing mode.
  22 #!+(or x86 x86-64)
  23 (defun foldable-constant-offset-p (element-size lowtag data-offset offset)
  24   (if (< element-size n-byte-bits)
  25       nil
  26       (multiple-value-bind (min max)
  27           (sb!impl::displacement-bounds lowtag element-size data-offset)
  28         (<= min offset max))))
  29
  30 \f
  31 ;;;; routines for dealing with static symbols
  32
  33 (defun static-symbol-p (symbol)
  34   (or (null symbol)
  35       (and (member symbol *static-symbols*) t)))
  36
  37 ;;; the byte offset of the static symbol SYMBOL
  38 (defun static-symbol-offset (symbol)
  39   (if symbol
  40       (let ((posn (position symbol *static-symbols*)))
  41         (unless posn (error "~S is not a static symbol." symbol))
  42         (+ (* posn (pad-data-block symbol-size))
  43            (pad-data-block (1- symbol-size))
  44            other-pointer-lowtag
  45            (- list-pointer-lowtag)))
  46       0))
  47
  48 ;;; Given a byte offset, OFFSET, return the appropriate static symbol.
  49 (defun offset-static-symbol (offset)
  50   (if (zerop offset)
  51       nil
  52       (multiple-value-bind (n rem)
  53           (truncate (+ offset list-pointer-lowtag (- other-pointer-lowtag)
  54                        (- (pad-data-block (1- symbol-size))))
  55                     (pad-data-block symbol-size))
  56         (unless (and (zerop rem) (<= 0 n (1- (length *static-symbols*))))
  57           (error "The byte offset ~W is not valid." offset))
  58         (elt *static-symbols* n))))
  59
  60 ;;; Return the (byte) offset from NIL to the start of the fdefn object
  61 ;;; for the static function NAME.
  62 (defun static-fun-offset (name)
  63   (let ((static-syms (length *static-symbols*))
  64         (static-fun-index (position name *static-funs*)))
  65     (unless static-fun-index
  66       (error "~S isn't a static function." name))
  67     (+ (* static-syms (pad-data-block symbol-size))
  68        (pad-data-block (1- symbol-size))
  69        (- list-pointer-lowtag)
  70        (* static-fun-index (pad-data-block fdefn-size))
  71        (* fdefn-raw-addr-slot n-word-bytes))))
  72 \f
  73 ;;; Various error-code generating helpers
  74 (defvar *adjustable-vectors* nil)
  75
  76 (defmacro with-adjustable-vector ((var) &rest body)
  77   `(let ((,var (or (pop *adjustable-vectors*)
  78                    (make-array 16
  79                                :element-type '(unsigned-byte 8)
  80                                :fill-pointer 0
  81                                :adjustable t))))
  82      (declare (type (vector (unsigned-byte 8) 16) ,var))
  83      (setf (fill-pointer ,var) 0)
  84      (unwind-protect
  85          (progn
  86            ,@body)
  87        (push ,var *adjustable-vectors*))))