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 ;;; the heap types, stored in 8 bits of the header of an object on the
  72 ;;; heap, to identify the type of the heap object (which'll be at
  73 ;;; least two machine words, often more)
  74 ;;;
  75 ;;; Note: the order specified here is not critical for correctness,
  76 ;;; but (FIXME) with %TEST-HEADERS as currently defined, BIGNUM must
  77 ;;; be first, and COMPLEX-ARRAY must be last.
  78 ;;;
  79 ;;; However, for efficiency, we prefer contiguous sets of widetags for
  80 ;;; "similar" objects, so that type checking can be done with a range
  81 ;;; check, rather than several individual checks.
  82 ;;;
  83 ;;; * BIGNUM + RATIO (+ FIXNUM) = RATIONAL
  84 ;;;
  85 ;;; * SINGLE-FLOAT + DOUBLE-FLOAT + LONG-FLOAT = FLOAT
  86 ;;;
  87 ;;; * RATIONAL + FLOAT = REAL
  88 ;;;
  89 ;;; * (FIXME: COMPLEX example, which needs fixing anyway -- see
  90 ;;;   UPGRADED-COMPLEX-PART-TYPE)
  91 ;;;
  92 ;;; * SIMPLE-ARRAY-* = (SIMPLE-ARRAY * (*))
  93 ;;;
  94 ;;; * SIMPLE-ARRAY-NIL + SIMPLE-BASE-STRING = SIMPLE-STRING
  95 ;;;
  96 ;;; * SIMPLE-ARRAY + COMPLEX-ARRAYOID = (SATISFIES ARRAY-HEADER-P)
  97 ;;;
  98 ;;; In addition, with
  99 ;;; sufficient care we can cause extra combinations to appear with
 100 ;;; differences in only one bit, permitting a more efficient type
 101 ;;; test.  As an example, if SIMPLE-BASE-STRING = 0xA6 and
 102 ;;; COMPLEX-BASE-STRING = 0xE6, then the type test for BASE-STRING is
 103 ;;;
 104 ;;;   AND   tag, ~0x40, tag
 105 ;;;   ANDcc tag,  0xA6, tag
 106 ;;;   JNE   tag, label
 107 ;;;
 108 ;;; rather than two separate tests and jumps
 109 (defenum (;; The first widetag must be greater than SB!VM:LOWTAG-LIMIT
 110           ;; otherwise code in generic/early-type-vops will suffer
 111           ;; a long, horrible death.  --njf, 2004-08-09
 112           :start (+ (ash 1 n-lowtag-bits) other-immediate-0-lowtag)
 113           :step 4)
 114   ;; NOTE: the binary numbers off to the side are only valid for 32-bit
 115   ;; ports; add #b1000 if you want to know the values for 64-bit ports.
 116   ;; And note that the numbers get a little scrambled further down.
 117   ;;   --njf, 2004-08-09
 118   bignum-widetag                            ; 00001010
 119   ratio-widetag                             ; 00001110
 120   single-float-widetag                      ; 00010010
 121   double-float-widetag                      ; 00010110
 122   complex-widetag                           ; 00011010
 123   complex-single-float-widetag              ; 00011110
 124   complex-double-float-widetag              ; 00100010
 125
 126   code-header-widetag                       ; 00100110
 127
 128   simple-fun-header-widetag                 ; 00101010
 129   closure-header-widetag                    ; 00101110
 130   funcallable-instance-header-widetag       ; 00110010
 131
 132   return-pc-header-widetag                  ; 00110110
 133   value-cell-header-widetag                 ; 00111010
 134   symbol-header-widetag                     ; 00111110
 135   character-widetag                         ; 01000010
 136   sap-widetag                               ; 01000110
 137   unbound-marker-widetag                    ; 01001010
 138   weak-pointer-widetag                      ; 01001110
 139   instance-header-widetag                   ; 01010010
 140   fdefn-widetag                             ; 01010110
 141
 142   no-tls-value-marker-widetag               ; 01011010
 143   #!-(and sb-lutex sb-thread)
 144   unused01-widetag
 145   #!+(and sb-lutex sb-thread)
 146   lutex-widetag                             ; 01011110
 147   unused02-widetag                          ; 01100010
 148   unused03-widetag                          ; 01100110
 149   unused04-widetag                          ; 01101010
 150   unused05-widetag                          ; 01101110
 151   unused06-widetag                          ; 01110010
 152   unused07-widetag                          ; 01110110
 153   #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
 154   unused08-widetag                          ; 01111010
 155   #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
 156   unused09-widetag                          ; 01111110
 157
 158   #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
 159   unused10-widetag                          ; 10000010
 160   #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
 161   unused11-widetag                          ; 10000110
 162
 163   simple-array-unsigned-byte-2-widetag      ; 10001010
 164   simple-array-unsigned-byte-4-widetag      ; 10001110
 165   simple-array-unsigned-byte-7-widetag      ; 10010010
 166   simple-array-unsigned-byte-8-widetag      ; 10010110
 167   simple-array-unsigned-byte-15-widetag     ; 10011010
 168   simple-array-unsigned-byte-16-widetag     ; 10011110
 169   simple-array-nil-widetag                  ; 10100010
 170   simple-base-string-widetag                ; 10100110
 171   #!+sb-unicode simple-character-string-widetag
 172   simple-bit-vector-widetag                 ; 10101010
 173   simple-vector-widetag                     ; 10101110
 174   #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
 175   simple-array-unsigned-byte-29-widetag     ; 10110010
 176   simple-array-unsigned-byte-31-widetag     ; 10110110
 177   simple-array-unsigned-byte-32-widetag     ; 10111010
 178   #!+#.(cl:if (cl:= 64 sb!vm:n-word-bits) '(and) '(or))
 179   simple-array-unsigned-byte-60-widetag
 180   #!+#.(cl:if (cl:= 64 sb!vm:n-word-bits) '(and) '(or))
 181   simple-array-unsigned-byte-63-widetag
 182   #!+#.(cl:if (cl:= 64 sb!vm:n-word-bits) '(and) '(or))
 183   simple-array-unsigned-byte-64-widetag
 184   simple-array-signed-byte-8-widetag        ; 10111110
 185   simple-array-signed-byte-16-widetag       ; 11000010
 186   #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
 187   simple-array-signed-byte-30-widetag       ; 11000110
 188   simple-array-signed-byte-32-widetag       ; 11001010
 189   #!+#.(cl:if (cl:= 64 sb!vm:n-word-bits) '(and) '(or))
 190   simple-array-signed-byte-61-widetag
 191   #!+#.(cl:if (cl:= 64 sb!vm:n-word-bits) '(and) '(or))
 192   simple-array-signed-byte-64-widetag
 193   simple-array-single-float-widetag         ; 11001110
 194   simple-array-double-float-widetag         ; 11010010
 195   simple-array-complex-single-float-widetag ; 11010110
 196   simple-array-complex-double-float-widetag ; 11011010
 197   simple-array-widetag                      ; 11011110
 198   complex-vector-nil-widetag                ; 11100010
 199   complex-base-string-widetag               ; 11100110
 200   #!+sb-unicode complex-character-string-widetag
 201   complex-bit-vector-widetag                ; 11101010
 202   complex-vector-widetag                    ; 11101110
 203   complex-array-widetag                     ; 11110010
 204
 205   #!+#.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
 206   unused12-widetag                          ; 11110110
 207   #!+(and #.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
 208           (not sb-unicode))
 209   unused13-widetag                          ; 11111010
 210   #!+(and #.(cl:if (cl:= 32 sb!vm:n-word-bits) '(and) '(or))
 211           (not sb-unicode))
 212   unused14-widetag                          ; 11111110
 213 )
 214
 215 ;;; the different vector subtypes
 216 (defenum ()
 217   vector-normal-subtype
 218   vector-unused-subtype
 219   vector-valid-hashing-subtype)