src/compiler/alpha/parms.lisp

   1 ;;;; This software is part of the SBCL system. See the README file for
   2 ;;;; more information.
   3 ;;;;
   4 ;;;; This software is derived from the CMU CL system, which was
   5 ;;;; written at Carnegie Mellon University and released into the
   6 ;;;; public domain. The software is in the public domain and is
   7 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
   8 ;;;; files for more information.
   9
  10 (in-package "SB!VM")
  11
  12 (eval-when  (:compile-toplevel :load-toplevel :execute)
  13
  14 ;;; number of bits per word where a word holds one lisp descriptor
  15 (def!constant n-word-bits 32)
  16
  17 ;;; the natural width of a machine word (as seen in e.g. register width,
  18 ;;; address space)
  19 (def!constant n-machine-word-bits 64)
  20
  21 ;;; number of bits per byte where a byte is the smallest addressable
  22 ;;; object
  23 (def!constant n-byte-bits 8)
  24
  25 (def!constant float-sign-shift 31)
  26
  27 (def!constant single-float-bias 126)
  28 (defconstant-eqx single-float-exponent-byte (byte 8 23) #'equalp)
  29 (defconstant-eqx single-float-significand-byte (byte 23 0) #'equalp)
  30 (def!constant single-float-normal-exponent-min 1)
  31 (def!constant single-float-normal-exponent-max 254)
  32 (def!constant single-float-hidden-bit (ash 1 23))
  33 (def!constant single-float-trapping-nan-bit (ash 1 22))
  34
  35 (def!constant double-float-bias 1022)
  36 (defconstant-eqx double-float-exponent-byte (byte 11 20)   #'equalp)
  37 (defconstant-eqx double-float-significand-byte (byte 20 0) #'equalp)
  38 (def!constant double-float-normal-exponent-min 1)
  39 (def!constant double-float-normal-exponent-max #x7FE)
  40 (def!constant double-float-hidden-bit (ash 1 20))
  41 (def!constant double-float-trapping-nan-bit (ash 1 19))
  42
  43 (def!constant single-float-digits
  44   (+ (byte-size single-float-significand-byte) 1))
  45
  46 (def!constant double-float-digits
  47   (+ (byte-size double-float-significand-byte) n-word-bits 1))
  48
  49 ;;; These values are originally from the DEC Assembly Language
  50 ;;; Programmers guide.  Where possible we read/write the software
  51 ;;; fp_control word, which apparently is necessary for the OS FPU
  52 ;;; completion (OS handler which fixes up non-IEEE answers that the
  53 ;;; hardware occasionally gives us) to work properly.  The rounding
  54 ;;; mode, however, can't be set that way, so we have to deal with that
  55 ;;; directly.  (FIXME: we actually don't suport setting the rounding mode
  56 ;;; at the moment anyway)
  57
  58 ;;; Short guide to floating point trap terminology: an "exception" is
  59 ;;; cheap and can happen at almost any time.  An exception will only
  60 ;;; generate a trap if that trap is enabled, otherwise a default value
  61 ;;; will be substituted.  A "trap" will end up somewhere in the
  62 ;;; kernel, which may play by its own rules,  (on Alpha it allegedly
  63 ;;; actually fixes up some non-IEEE compliant results to get the
  64 ;;; _right_ answer) but if something is really wrong will eventually
  65 ;;; signal SIGFPE and let us sort it out.
  66
  67 ;;; Old comment follows: The active bits are actually in (byte 12 52)
  68 ;;; of the fpcr. (byte 6 52) contain the exception flags. Bit 63 is the
  69 ;;; bitwise logor of all exceptions.  The enable and exception bytes
  70 ;;; are in a software control word manipulated via OS functions and the
  71 ;;; bits in the SCP match those defs. This mapping follows
  72 ;;; <machine/fpu.h>
  73
  74 ;;; trap enables are set in software (fp_control)
  75 (def!constant float-inexact-trap-bit        (ash 1 4)) ; rw
  76 (def!constant float-underflow-trap-bit      (ash 1 3)) ; rw
  77 (def!constant float-overflow-trap-bit       (ash 1 2)) ; ro
  78 (def!constant float-divide-by-zero-trap-bit (ash 1 1)) ; ro
  79 (def!constant float-invalid-trap-bit        (ash 1 0)) ; ro
  80 (defconstant-eqx float-traps-byte          (byte 6  1) #'equalp)
  81
  82 ;;; exceptions are also read/written in software (by syscalls, no less).
  83 ;;; This is kind of dumb, but has to be done
  84 (defconstant-eqx float-sticky-bits     (byte 6 17) #'equalp)    ; fp_control
  85
  86 ;;; (We don't actually _have_ "current exceptions" on Alpha; the
  87 ;;; hardware only ever sets bits.  So, set this the same as accrued
  88 ;;; exceptions)
  89 (defconstant-eqx float-exceptions-byte (byte 6 17)  #'equalp)
  90
  91 ;;; Rounding modes can only be set by frobbing the hardware fpcr directly
  92 (def!constant float-round-to-zero     0)
  93 (def!constant float-round-to-negative 1)
  94 (def!constant float-round-to-nearest  2)
  95 (def!constant float-round-to-positive 3)
  96 (defconstant-eqx float-rounding-mode   (byte 2 58) #'equalp)
  97
  98 ;;; Miscellaneous stuff - I think it's far to say that you deserve
  99 ;;; what you get if you ask for fast mode.
 100 (def!constant float-fast-bit 0)
 101
 102 ); eval-when
 103
 104
 105 \f
 106 ;;;; Description of the target address space.
 107
 108 ;;; Where to put the different spaces.
 109 ;;;
 110
 111 #!+linux
 112 (progn
 113   (def!constant read-only-space-start #x20000000)
 114   (def!constant read-only-space-end   #x24000000))
 115
 116 #!+osf1
 117 (progn
 118   (defconstant read-only-space-start #x10000000)
 119   (defconstant read-only-space-end   #x25000000))
 120
 121
 122 (def!constant static-space-start    #x28000000)
 123 (def!constant static-space-end      #x2c000000)
 124
 125 (def!constant dynamic-0-space-start   #x30000000)
 126 (def!constant dynamic-0-space-end     #x3fff0000)
 127
 128 (def!constant dynamic-1-space-start   #x40000000)
 129 (def!constant dynamic-1-space-end     #x4fff0000)
 130
 131 ;;; FIXME nothing refers to either of these in alpha or x86 cmucl
 132 ;;; backend, so they could probably be removed.
 133
 134 ;; The space-register holding the lisp heap.
 135 (def!constant lisp-heap-space 4)
 136
 137 ;; The space-register holding the C text segment.
 138 (def!constant c-text-space 4)
 139
 140 ;;; the X86 port defines *nil-value* as (+ *target-static-space-start* #xB)
 141 ;;; here, but it seems to be the only port that needs to know the
 142 ;;; location of NIL from lisp.
 143 \f
 144 ;;;; other miscellaneous constants
 145
 146 (defenum (:suffix -trap :start 8)
 147   halt
 148   pending-interrupt
 149   error
 150   cerror
 151   breakpoint
 152   fun-end-breakpoint
 153   single-step-breakpoint
 154   ;; Stepper actually not implemented on Alpha, but these constants
 155   ;; are still needed to avoid undefined variable warnings during sbcl
 156   ;; build.
 157   single-step-around
 158   single-step-before)
 159
 160 (defenum (:prefix trace-table-)
 161   normal
 162   call-site
 163   fun-prologue
 164   fun-epilogue)
 165 \f
 166 ;;;; static symbols
 167
 168 ;;; These symbols are loaded into static space directly after NIL so
 169 ;;; that the system can compute their address by adding a constant
 170 ;;; amount to NIL.
 171 ;;;
 172 ;;; The fdefn objects for the static functions are loaded into static
 173 ;;; space directly after the static symbols.  That way, the raw-addr
 174 ;;; can be loaded directly out of them by indirecting relative to NIL.
 175 ;;;
 176 (defparameter *static-symbols*
 177   (append
 178    *common-static-symbols*
 179    *c-callable-static-symbols*
 180    '()))
 181
 182 (defparameter *static-funs*
 183   '(length
 184     sb!kernel:two-arg-+
 185     sb!kernel:two-arg--
 186     sb!kernel:two-arg-*
 187     sb!kernel:two-arg-/
 188     sb!kernel:two-arg-<
 189     sb!kernel:two-arg->
 190     sb!kernel:two-arg-=
 191     ;; FIXME: Is this
 192     ;;     probably need the following as they are defined in
 193     ;;     arith.lisp: two-arg-<= two-arg->= two-arg-/=
 194     ;; a comment from old CMU CL or old old CMU CL or
 195     ;; the SBCL alpha port or what? Do we need to worry about it,
 196     ;; or can we delete it?
 197     sb!kernel:two-arg-/=
 198     eql
 199     sb!kernel:%negate
 200     sb!kernel:two-arg-and
 201     sb!kernel:two-arg-ior
 202     sb!kernel:two-arg-xor
 203     sb!kernel:two-arg-eqv
 204     sb!kernel:two-arg-gcd
 205     sb!kernel:two-arg-lcm))