src/compiler/fixup.lisp

   1 ;;;; fixups, extracted from codegen.lisp by WHN 19990227 in order
   2 ;;;; to help with cross-compiling bootstrapping
   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!C")
  14
  15 ;;; a fixup of some kind
  16 (defstruct (fixup
  17             (:constructor make-fixup (name flavor &optional offset))
  18             (:copier nil))
  19   ;; the name and flavor of the fixup. The assembler makes no
  20   ;; assumptions about the contents of these fields; their semantics
  21   ;; are imposed by the dumper.
  22   name
  23   flavor
  24   ;; OFFSET is an optional offset from whatever external label this
  25   ;; fixup refers to. Or in the case of the :CODE-OBJECT flavor of
  26   ;; fixups on the :X86 architecture, NAME is always NIL, so this
  27   ;; fixup doesn't refer to an external label, and OFFSET is an offset
  28   ;; from the beginning of the current code block.
  29   offset)
  30
  31 (defstruct (fixup-note
  32              (:constructor make-fixup-note (kind fixup position))
  33              (:copier nil))
  34   kind
  35   fixup
  36   position)
  37
  38 (defvar *fixup-notes*)
  39
  40 ;;; Setting this variable lets you see what's going on as items are
  41 ;;; being pushed onto *FIXUPS*.
  42 #!+sb-show (defvar *show-fixups-being-pushed-p* nil)
  43
  44 ;;; This function is called by assembler instruction emitters when
  45 ;;; they find themselves trying to deal with a fixup.
  46 (defun note-fixup (segment kind fixup)
  47   (sb!assem:emit-back-patch segment
  48                             0
  49                             (lambda (segment posn)
  50                               (declare (ignore segment))
  51                               ;; Why use EMIT-BACK-PATCH to cause this PUSH to
  52                               ;; be done later, instead of just doing it now?
  53                               ;; I'm not sure. Perhaps there's some concern
  54                               ;; that POSN isn't known accurately now? Perhaps
  55                               ;; there's a desire for all fixing up to go
  56                               ;; through EMIT-BACK-PATCH whether it needs to or
  57                               ;; not? -- WHN 19990905
  58                               #!+sb-show
  59                               (when *show-fixups-being-pushed-p*
  60                                 (/show "PUSHING FIXUP" kind fixup posn))
  61                               (push (make-fixup-note kind fixup posn) *fixup-notes*)))
  62   (values))