src/compiler/arm/system.lisp

   1 ;;;; ARM VM definitions of various system hacking operations
   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 \f
  14 ;;;; Type frobbing VOPs
  15
  16 (define-vop (lowtag-of)
  17   (:translate lowtag-of)
  18   (:policy :fast-safe)
  19   (:args (object :scs (any-reg descriptor-reg)))
  20   (:results (result :scs (unsigned-reg)))
  21   (:result-types positive-fixnum)
  22   (:generator 1
  23     (inst and result object lowtag-mask)))
  24
  25 (define-vop (widetag-of)
  26   (:translate widetag-of)
  27   (:policy :fast-safe)
  28   (:args (object :scs (descriptor-reg) :to (:eval 1)))
  29   (:results (result :scs (unsigned-reg) :from (:eval 0)))
  30   (:result-types positive-fixnum)
  31   (:generator 6
  32     ;; First, pick off the immediate types, starting with FIXNUM.
  33     (inst ands result object fixnum-tag-mask)
  34     ;; If it wasn't a fixnum, start with the full widetag.
  35     (inst and :ne result object widetag-mask)
  36
  37     ;; Now, we have our result for an immediate type, but we might
  38     ;; have a pointer object instead, in which case we need to do more
  39     ;; work.  Check for a pointer type.
  40
  41     ;; KLUDGE: We're a 32-bit port, so all pointer lowtags have the
  42     ;; low bit set, but there's no obvious named constant for this.
  43     ;; On 64-bit ports, all pointer lowtags have the low two bits set,
  44     ;; so this wouldn't work as easily.
  45     (inst tst object 1)
  46
  47     ;; If we have a pointer type, we need to compute a different
  48     ;; answer.  For lists and instances, we just need the lowtag.  For
  49     ;; functions and "other", we need to load the widetag from the
  50     ;; object header.  In both cases, having just the widetag
  51     ;; available is handy.
  52     (inst and :ne result object lowtag-mask)
  53
  54     ;; We now have the correct answer for list-pointer-lowtag and
  55     ;; instance-pointer-lowtag, but need to pick off the case for the
  56     ;; other two pointer types.  KLUDGE: FUN-POINTER-LOWTAG and
  57     ;; OTHER-POINTER-LOWTAG are both in the upper half of the lowtag
  58     ;; space, while LIST-POINTER-LOWTAG and INSTANCE-POINTER-LOWTAG
  59     ;; are in the lower half, so we distinguish with a bit test.
  60     (inst tst :ne object 4)
  61
  62     ;; We can't use both register and immediate offsets in the same
  63     ;; load/store instruction, so we need to bias our register offset
  64     ;; on big-endian systems.
  65     (when (eq *backend-byte-order* :big-endian)
  66       (inst sub :ne result (1- n-word-bytes)))
  67
  68     ;; And, finally, pick out the widetag from the header.
  69     (inst ldrb :ne result (@ object (- result)))))
  70
  71
  72 (define-vop (fun-subtype)
  73   (:translate fun-subtype)
  74   (:policy :fast-safe)
  75   (:args (function :scs (descriptor-reg)))
  76   (:results (result :scs (unsigned-reg)))
  77   (:result-types positive-fixnum)
  78   (:generator 6
  79     (load-type result function (- fun-pointer-lowtag))))
  80
  81 (define-vop (set-fun-subtype)
  82   (:translate (setf fun-subtype))
  83   (:policy :fast-safe)
  84   (:args (type :scs (unsigned-reg) :target result)
  85          (function :scs (descriptor-reg)))
  86   (:arg-types positive-fixnum *)
  87   (:results (result :scs (unsigned-reg)))
  88   (:result-types positive-fixnum)
  89   (:generator 6
  90     (inst strb type (@ function (- (ecase *backend-byte-order*
  91                                      (:little-endian 0)
  92                                      (:big-endian (1- n-word-bytes)))
  93                                    fun-pointer-lowtag)))
  94     (move result type)))
  95
  96 (define-vop (get-header-data)
  97   (:translate get-header-data)
  98   (:policy :fast-safe)
  99   (:args (x :scs (descriptor-reg)))
 100   (:results (res :scs (unsigned-reg)))
 101   (:result-types positive-fixnum)
 102   (:generator 6
 103     (loadw res x 0 other-pointer-lowtag)
 104     (inst mov res (lsr res n-widetag-bits))))
 105
 106 (define-vop (get-closure-length)
 107   (:translate get-closure-length)
 108   (:policy :fast-safe)
 109   (:args (x :scs (descriptor-reg)))
 110   (:results (res :scs (unsigned-reg)))
 111   (:result-types positive-fixnum)
 112   (:generator 6
 113     (loadw res x 0 fun-pointer-lowtag)
 114     (inst mov res (lsr res n-widetag-bits))))
 115
 116 (define-vop (set-header-data)
 117   (:translate set-header-data)
 118   (:policy :fast-safe)
 119   (:args (x :scs (descriptor-reg) :target res)
 120          (data :scs (any-reg immediate)))
 121   (:arg-types * positive-fixnum)
 122   (:results (res :scs (descriptor-reg)))
 123   (:temporary (:scs (non-descriptor-reg)) t1)
 124   (:generator 6
 125     ;; FIXME: Using LDRB here would save us an instruction.
 126     (loadw t1 x 0 other-pointer-lowtag)
 127     (inst and t1 t1 widetag-mask)
 128     (sc-case data
 129       (any-reg
 130        (inst orr t1 t1 (lsl data (- n-widetag-bits n-fixnum-tag-bits))))
 131       (immediate
 132        ;; FIXME: This will break if DATA has bits spread over more
 133        ;; than an eight bit range aligned on an even bit position.
 134        ;; See SYS:SRC;COMPILER;ARM;MOVE.LISP for a partial fix...  And
 135        ;; maybe it should be promoted to an instruction-macro?
 136        (inst orr t1 t1 (ash (tn-value data) n-widetag-bits))))
 137     (storew t1 x 0 other-pointer-lowtag)
 138     (move res x)))
 139
 140
 141 (define-vop (pointer-hash)
 142   (:translate pointer-hash)
 143   (:args (ptr :scs (any-reg descriptor-reg)))
 144   (:results (res :scs (any-reg descriptor-reg)))
 145   (:policy :fast-safe)
 146   (:generator 1
 147     (inst bic res ptr lowtag-mask)
 148     (inst mov res (lsr res 1))))
 149 \f
 150 ;;;; Allocation
 151
 152 (define-vop (dynamic-space-free-pointer)
 153   (:results (int :scs (sap-reg)))
 154   (:result-types system-area-pointer)
 155   (:translate dynamic-space-free-pointer)
 156   (:policy :fast-safe)
 157   (:generator 1
 158     (load-symbol-value int *allocation-pointer*)))
 159
 160 (define-vop (binding-stack-pointer-sap)
 161   (:results (int :scs (sap-reg)))
 162   (:result-types system-area-pointer)
 163   (:translate binding-stack-pointer-sap)
 164   (:policy :fast-safe)
 165   (:generator 1
 166     (load-symbol-value int *binding-stack-pointer*)))
 167
 168 (define-vop (control-stack-pointer-sap)
 169   (:results (int :scs (sap-reg)))
 170   (:result-types system-area-pointer)
 171   (:translate control-stack-pointer-sap)
 172   (:policy :fast-safe)
 173   (:generator 1
 174     (move int csp-tn)))
 175 \f
 176 ;;;; Code object frobbing.
 177
 178 (define-vop (code-instructions)
 179   (:translate code-instructions)
 180   (:policy :fast-safe)
 181   (:args (code :scs (descriptor-reg)))
 182   (:temporary (:scs (non-descriptor-reg)) ndescr)
 183   (:results (sap :scs (sap-reg)))
 184   (:result-types system-area-pointer)
 185   (:generator 10
 186     (loadw ndescr code 0 other-pointer-lowtag)
 187     ;; CODE-HEADER-WIDETAG is #x38, which has the top two bits clear,
 188     ;; so we don't to clear the low bits here.  If we do, use BIC.
 189     (inst mov ndescr (lsr ndescr (- n-widetag-bits word-shift)))
 190     (inst sub ndescr ndescr other-pointer-lowtag)
 191     (inst add sap code ndescr)))
 192
 193 (define-vop (compute-fun)
 194   (:args (code :scs (descriptor-reg))
 195          (offset :scs (signed-reg unsigned-reg)))
 196   (:arg-types * positive-fixnum)
 197   (:results (func :scs (descriptor-reg)))
 198   (:temporary (:scs (non-descriptor-reg)) ndescr)
 199   (:generator 10
 200     (loadw ndescr code 0 other-pointer-lowtag)
 201     ;; CODE-HEADER-WIDETAG is #x38, which has the top two bits clear,
 202     ;; so we don't to clear the low bits here.  If we do, use BIC.
 203     (inst add ndescr offset (lsr ndescr (- n-widetag-bits word-shift)))
 204     (inst sub ndescr ndescr (- other-pointer-lowtag fun-pointer-lowtag))
 205     (inst add func code ndescr)))
 206 \f
 207 ;;;; other miscellaneous VOPs
 208
 209 (define-vop (halt)
 210   (:temporary (:sc non-descriptor-reg :offset ocfp-offset) error-temp)
 211   (:generator 1
 212     ;; See macros.lisp, EMIT-ERROR-BREAK, for an explanation.
 213     (inst mov error-temp #x000f0000)
 214     (inst add error-temp error-temp 1)
 215     (inst swi 0)
 216     (inst byte halt-trap)
 217     ;; Re-align to the next instruction boundary.
 218     (emit-alignment word-shift)))
 219
 220 ;;;; Dummy definition for a spin-loop hint VOP
 221 (define-vop (spin-loop-hint)
 222   (:translate spin-loop-hint)
 223   (:policy :fast-safe)
 224   (:generator 0))