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