src/compiler/generic/early-objdef.lisp

   1 ;;;; type-based constants
   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
  14 ;;; Tags for the main low-level types are stored in the low n (usually three)
  15 ;;; bits to identify the type of a machine word.  Certain constraints
  16 ;;; apply:
  17 ;;;   * EVEN-FIXNUM-LOWTAG and ODD-FIXNUM-LOWTAG must be 0 and 4: code
  18 ;;;     which shifts left two places to convert raw integers to tagged
  19 ;;;     fixnums is ubiquitous.
  20 ;;;   * LIST-POINTER-LOWTAG + N-WORD-BYTES = OTHER-POINTER-LOWTAG: NIL
  21 ;;;     is both a cons and a symbol (at the same address) and depends on this.
  22 ;;;     See the definition of SYMBOL in objdef.lisp
  23 ;;;   * OTHER-POINTER-LOWTAG > 4: Some code in the SPARC backend,
  24 ;;;     which uses bit 2 of the ALLOC register to indicate that
  25 ;;;     PSEUDO-ATOMIC is on, doesn't strip the low bits of reg_ALLOC
  26 ;;;     before ORing in OTHER-POINTER-LOWTAG within a PSEUDO-ATOMIC
  27 ;;;     section.
  28 ;;;   * OTHER-IMMEDIATE-0-LOWTAG are spaced 4 apart: various code wants to
  29 ;;;     iterate through these
  30 ;;;   * Allocation code on Alpha wants lowtags for heap-allocated
  31 ;;;     objects to be odd.
  32 ;;; (These are just the ones we know about as of sbcl-0.7.1.22. There
  33 ;;; might easily be more, since these values have stayed highly
  34 ;;; constrained for more than a decade, an inviting target for
  35 ;;; inventive abstraction-phobic maintainers.:-)
  36 (eval-when (:compile-toplevel :load-toplevel :execute)
  37   ;; The EVAL-WHEN is necessary (at least for Lispworks), because the
  38   ;; second DEFENUM uses the value of OTHER-IMMEDIATE-0-LOWTAG, which is
  39   ;; defined in the first DEFENUM. -- AL 20000216
  40   #!+#.(cl:if (cl:= 64 sb!vm:n-word-bits) '(and) '(or))
  41   (defenum ()
  42     even-fixnum-lowtag
  43     instance-pointer-lowtag
  44     other-immediate-0-lowtag
  45     pad0-lowtag
  46     pad1-lowtag pad2-lowtag
  47     other-immediate-1-lowtag
  48     list-pointer-lowtag
  49     odd-fixnum-lowtag
  50     fun-pointer-lowtag
  51     other-immediate-2-lowtag
  52     pad3-lowtag
  53     pad4-lowtag
  54     pad5-lowtag
  55     other-immediate-3-lowtag
  56     other-pointer-lowtag)
  57   #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
  58   (defenum ()
  59     even-fixnum-lowtag
  60     instance-pointer-lowtag
  61     other-immediate-0-lowtag
  62     list-pointer-lowtag
  63     odd-fixnum-lowtag
  64     fun-pointer-lowtag
  65     other-immediate-1-lowtag
  66     other-pointer-lowtag))
  67
  68 (def!constant nil-value
  69     (+ static-space-start n-word-bytes other-pointer-lowtag))
  70
  71 (defconstant-eqx fixnum-lowtags
  72     #.(let ((fixtags nil))
  73         (do-external-symbols (sym "SB!VM")
  74           (let* ((name (symbol-name sym))
  75                  (len (length name)))
  76             (when (and (boundp sym)
  77                        (integerp (symbol-value sym))
  78                        (> len 7)
  79                        (string= name "-LOWTAG" :start1 (- len 7))
  80                        (zerop (logand (symbol-value sym) fixnum-tag-mask)))
  81               (push sym fixtags))))
  82         `',fixtags)
  83   #'equal)
  84
  85 ;;; the heap types, stored in 8 bits of the header of an object on the
  86 ;;; heap, to identify the type of the heap object (which'll be at
  87 ;;; least two machine words, often more)
  88 ;;;
  89 ;;; Note: the order specified here is not critical for correctness,
  90 ;;; but (FIXME) with %TEST-HEADERS as currently defined, BIGNUM must
  91 ;;; be first, and COMPLEX-ARRAY must be last.
  92 ;;;
  93 ;;; However, for efficiency, we prefer contiguous sets of widetags for
  94 ;;; "similar" objects, so that type checking can be done with a range
  95 ;;; check, rather than several individual checks.
  96 ;;;
  97 ;;; * BIGNUM + RATIO (+ FIXNUM) = RATIONAL
  98 ;;;
  99 ;;; * SINGLE-FLOAT + DOUBLE-FLOAT + LONG-FLOAT = FLOAT
 100 ;;;
 101 ;;; * RATIONAL + FLOAT = REAL
 102 ;;;
 103 ;;; * (FIXME: COMPLEX example, which needs fixing anyway -- see
 104 ;;;   UPGRADED-COMPLEX-PART-TYPE)
 105 ;;;
 106 ;;; * SIMPLE-ARRAY-* = (SIMPLE-ARRAY * (*))
 107 ;;;
 108 ;;; * SIMPLE-ARRAY-NIL + SIMPLE-BASE-STRING = SIMPLE-STRING
 109 ;;;
 110 ;;; * SIMPLE-ARRAY + COMPLEX-ARRAYOID = (SATISFIES ARRAY-HEADER-P)
 111 ;;;
 112 ;;; In addition, with
 113 ;;; sufficient care we can cause extra combinations to appear with
 114 ;;; differences in only one bit, permitting a more efficient type
 115 ;;; test.  As an example, if SIMPLE-BASE-STRING = 0xA6 and
 116 ;;; COMPLEX-BASE-STRING = 0xE6, then the type test for BASE-STRING is
 117 ;;;
 118 ;;;   AND   tag, ~0x40, tag
 119 ;;;   ANDcc tag,  0xA6, tag
 120 ;;;   JNE   tag, label
 121 ;;;
 122 ;;; rather than two separate tests and jumps
 123 (defenum (;; The first widetag must be greater than SB!VM:LOWTAG-LIMIT
 124           ;; otherwise code in generic/early-type-vops will suffer
 125           ;; a long, horrible death.  --njf, 2004-08-09
 126           :start (+ (ash 1 n-lowtag-bits) other-immediate-0-lowtag)
 127           :step 4)
 128   ;; NOTE: the binary numbers off to the side are only valid for 32-bit
 129   ;; ports; add #b1000 if you want to know the values for 64-bit ports.
 130   ;; And note that the numbers get a little scrambled further down.
 131   ;;   --njf, 2004-08-09
 132   bignum-widetag                            ; 00001010
 133   ratio-widetag                             ; 00001110
 134   single-float-widetag                      ; 00010010
 135   double-float-widetag                      ; 00010110
 136   complex-widetag                           ; 00011010
 137   complex-single-float-widetag              ; 00011110
 138   complex-double-float-widetag              ; 00100010
 139
 140   code-header-widetag                       ; 00100110
 141
 142   simple-fun-header-widetag                 ; 00101010
 143   closure-header-widetag                    ; 00101110
 144   funcallable-instance-header-widetag       ; 00110010
 145
 146   return-pc-header-widetag                  ; 00110110
 147   value-cell-header-widetag                 ; 00111010
 148   symbol-header-widetag                     ; 00111110
 149   character-widetag                         ; 01000010
 150   sap-widetag                               ; 01000110
 151   unbound-marker-widetag                    ; 01001010
 152   weak-pointer-widetag                      ; 01001110
 153   instance-header-widetag                   ; 01010010
 154   fdefn-widetag                             ; 01010110
 155
 156   no-tls-value-marker-widetag               ; 01011010
 157   #!-(and sb-lutex sb-thread)
 158   unused01-widetag
 159   #!+(and sb-lutex sb-thread)
 160   lutex-widetag                             ; 01011110
 161   unused02-widetag                          ; 01100010
 162   unused03-widetag                          ; 01100110
 163   unused04-widetag                          ; 01101010
 164   unused05-widetag                          ; 01101110
 165   unused06-widetag                          ; 01110010
 166   unused07-widetag                          ; 01110110
 167   #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
 168   unused08-widetag                          ; 01111010
 169   #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
 170   unused09-widetag                          ; 01111110
 171
 172   #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
 173   unused10-widetag                          ; 10000010
 174   #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
 175   unused11-widetag                          ; 10000110
 176
 177   simple-array-unsigned-byte-2-widetag      ; 10001010
 178   simple-array-unsigned-byte-4-widetag      ; 10001110
 179   simple-array-unsigned-byte-7-widetag      ; 10010010
 180   simple-array-unsigned-byte-8-widetag      ; 10010110
 181   simple-array-unsigned-byte-15-widetag     ; 10011010
 182   simple-array-unsigned-byte-16-widetag     ; 10011110
 183   simple-array-nil-widetag                  ; 10100010
 184   simple-base-string-widetag                ; 10100110
 185   #!+sb-unicode simple-character-string-widetag
 186   simple-bit-vector-widetag                 ; 10101010
 187   simple-vector-widetag                     ; 10101110
 188   #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
 189   simple-array-unsigned-byte-29-widetag     ; 10110010
 190   simple-array-unsigned-byte-31-widetag     ; 10110110
 191   simple-array-unsigned-byte-32-widetag     ; 10111010
 192   #!+#.(cl:if (cl:= 64 sb!vm:n-word-bits) '(and) '(or))
 193   simple-array-unsigned-byte-60-widetag
 194   #!+#.(cl:if (cl:= 64 sb!vm:n-word-bits) '(and) '(or))
 195   simple-array-unsigned-byte-63-widetag
 196   #!+#.(cl:if (cl:= 64 sb!vm:n-word-bits) '(and) '(or))
 197   simple-array-unsigned-byte-64-widetag
 198   simple-array-signed-byte-8-widetag        ; 10111110
 199   simple-array-signed-byte-16-widetag       ; 11000010
 200   #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
 201   simple-array-signed-byte-30-widetag       ; 11000110
 202   simple-array-signed-byte-32-widetag       ; 11001010
 203   #!+#.(cl:if (cl:= 64 sb!vm:n-word-bits) '(and) '(or))
 204   simple-array-signed-byte-61-widetag
 205   #!+#.(cl:if (cl:= 64 sb!vm:n-word-bits) '(and) '(or))
 206   simple-array-signed-byte-64-widetag
 207   simple-array-single-float-widetag         ; 11001110
 208   simple-array-double-float-widetag         ; 11010010
 209   simple-array-complex-single-float-widetag ; 11010110
 210   simple-array-complex-double-float-widetag ; 11011010
 211   simple-array-widetag                      ; 11011110
 212   complex-vector-nil-widetag                ; 11100010
 213   complex-base-string-widetag               ; 11100110
 214   #!+sb-unicode complex-character-string-widetag
 215   complex-bit-vector-widetag                ; 11101010
 216   complex-vector-widetag                    ; 11101110
 217   complex-array-widetag                     ; 11110010
 218
 219   #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
 220   unused12-widetag                          ; 11110110
 221   #!+(and #.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
 222           (not sb-unicode))
 223   unused13-widetag                          ; 11111010
 224   #!+(and #.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
 225           (not sb-unicode))
 226   unused14-widetag                          ; 11111110
 227 )
 228
 229 ;;; the different vector subtypes
 230 (defenum ()
 231   vector-normal-subtype
 232   vector-unused-subtype
 233   vector-valid-hashing-subtype)