;;;; SAP operations for the x86 VM

;;;; This software is part of the SBCL system. See the README file for
;;;; more information.
;;;;
;;;; This software is derived from the CMU CL system, which was
;;;; written at Carnegie Mellon University and released into the
;;;; public domain. The software is in the public domain and is
;;;; provided with absolutely no warranty. See the COPYING and CREDITS
;;;; files for more information.

(in-package "SB!VM")

;;;; moves and coercions

;;; Move a tagged SAP to an untagged representation.
(define-vop (move-to-sap)
  (:args (x :scs (descriptor-reg)))
  (:results (y :scs (sap-reg)))
  (:note "pointer to SAP coercion")
  (:generator 1
    (loadw y x sap-pointer-slot other-pointer-lowtag)))
(define-move-vop move-to-sap :move
  (descriptor-reg) (sap-reg))

;;; Move an untagged SAP to a tagged representation.
(define-vop (move-from-sap)
  (:args (sap :scs (sap-reg) :to :result))
  (:results (res :scs (descriptor-reg) :from :argument))
  (:note "SAP to pointer coercion")
  (:node-var node)
  (:generator 20
    (fixed-alloc res sap-widetag sap-size node)
    (storew sap res sap-pointer-slot other-pointer-lowtag)))
(define-move-vop move-from-sap :move
  (sap-reg) (descriptor-reg))

;;; Move untagged sap values.
(define-vop (sap-move)
  (:args (x :target y
            :scs (sap-reg)
            :load-if (not (location= x y))))
  (:results (y :scs (sap-reg)
               :load-if (not (location= x y))))
  (:note "SAP move")
  (:generator 0
    (move y x)))
(define-move-vop sap-move :move
  (sap-reg) (sap-reg))

;;; Move untagged sap arguments/return-values.
(define-vop (move-sap-arg)
  (:args (x :target y
            :scs (sap-reg))
         (fp :scs (any-reg)
             :load-if (not (sc-is y sap-reg))))
  (:results (y))
  (:note "SAP argument move")
  (:generator 0
    (sc-case y
      (sap-reg
       (move y x))
      (sap-stack
       (if (= (tn-offset fp) esp-offset)
           (storew x fp (tn-offset y))  ; c-call
           (storew x fp (frame-word-offset (tn-offset y))))))))
(define-move-vop move-sap-arg :move-arg
  (descriptor-reg sap-reg) (sap-reg))

;;; Use standard MOVE-ARG + coercion to move an untagged sap to a
;;; descriptor passing location.
(define-move-vop move-arg :move-arg
  (sap-reg) (descriptor-reg))

;;;; SAP-INT and INT-SAP

;;; The function SAP-INT is used to generate an integer corresponding
;;; to the system area pointer, suitable for passing to the kernel
;;; interfaces (which want all addresses specified as integers). The
;;; function INT-SAP is used to do the opposite conversion. The
;;; integer representation of a SAP is the byte offset of the SAP from
;;; the start of the address space.
(define-vop (sap-int)
  (:args (sap :scs (sap-reg) :target int))
  (:arg-types system-area-pointer)
  (:results (int :scs (unsigned-reg)))
  (:result-types unsigned-num)
  (:translate sap-int)
  (:policy :fast-safe)
  (:generator 1
    (move int sap)))
(define-vop (int-sap)
  (:args (int :scs (unsigned-reg) :target sap))
  (:arg-types unsigned-num)
  (:results (sap :scs (sap-reg)))
  (:result-types system-area-pointer)
  (:translate int-sap)
  (:policy :fast-safe)
  (:generator 1
    (move sap int)))

;;;; POINTER+ and POINTER-

(define-vop (pointer+)
  (:translate sap+)
  (:args (ptr :scs (sap-reg) :target res
              :load-if (not (location= ptr res)))
         (offset :scs (signed-reg immediate)))
  (:arg-types system-area-pointer signed-num)
  (:results (res :scs (sap-reg) :from (:argument 0)
                 :load-if (not (location= ptr res))))
  (:result-types system-area-pointer)
  (:temporary (:sc signed-reg) temp)
  (:policy :fast-safe)
  (:generator 1
    (cond ((and (sc-is ptr sap-reg) (sc-is res sap-reg)
                (not (location= ptr res)))
           (sc-case offset
             (signed-reg
              (inst lea res (make-ea :qword :base ptr :index offset)))
             (immediate
              (let ((value (tn-value offset)))
                (cond ((typep value '(or (signed-byte 32) (unsigned-byte 31)))
                       (inst lea res (make-ea :qword :base ptr :disp value)))
                      (t
                       (inst mov temp value)
                       (inst lea res (make-ea :qword :base ptr :index temp))))))))
          (t
           (move res ptr)
           (sc-case offset
             (signed-reg
              (inst add res offset))
             (immediate
              (let ((value (tn-value offset)))
                (cond ((typep value '(or (signed-byte 32) (unsigned-byte 31)))
                       (inst add res (tn-value offset)))
                      (t
                       (inst mov temp value)
                       (inst add res temp))))))))))

(define-vop (pointer-)
  (:translate sap-)
  (:args (ptr1 :scs (sap-reg) :target res)
         (ptr2 :scs (sap-reg)))
  (:arg-types system-area-pointer system-area-pointer)
  (:policy :fast-safe)
  (:results (res :scs (signed-reg) :from (:argument 0)))
  (:result-types signed-num)
  (:generator 1
    (move res ptr1)
    (inst sub res ptr2)))

;;;; mumble-SYSTEM-REF and mumble-SYSTEM-SET

;; from 'llvm/projects/compiler-rt/lib/msan/msan.h':
;;  "#define MEM_TO_SHADOW(mem) (((uptr)(mem)) ^ 0x500000000000ULL)"
#!+linux ; shadow space differs by OS
(defconstant msan-mem-to-shadow-xor-const #x500000000000)

(defun emit-sap-set (size sap ea-index ea-disp value result)
  #!+linux
  (when sb!c::*msan-unpoison*
    (let ((offset (or ea-index ea-disp)))
      (unless (eql offset 0)
        (inst add sap offset))
      (inst mov temp-reg-tn msan-mem-to-shadow-xor-const)
      (inst xor temp-reg-tn sap)
      (inst mov (make-ea size :base temp-reg-tn) 0)
      (unless (eql offset 0) ; restore SAP as if nothing happened
        (inst sub sap offset))))
  (inst mov
        (make-ea size :base sap :index ea-index :disp ea-disp)
        (reg-in-size value size))
  (move result value))

(macrolet ((def-system-ref-and-set (ref-name
                                    set-name
                                    ref-insn
                                    sc
                                    type
                                    size)
             (let ((ref-name-c (symbolicate ref-name "-C"))
                   (set-name-c (symbolicate set-name "-C")))
               `(progn
                  (define-vop (,ref-name)
                    (:translate ,ref-name)
                    (:policy :fast-safe)
                    (:args (sap :scs (sap-reg))
                           (offset :scs (signed-reg)))
                    (:arg-types system-area-pointer signed-num)
                    (:results (result :scs (,sc)))
                    (:result-types ,type)
                    (:generator 5
                      (inst ,ref-insn result
                            (make-ea ,size :base sap :index offset))))
                  (define-vop (,ref-name-c)
                    (:translate ,ref-name)
                    (:policy :fast-safe)
                    (:args (sap :scs (sap-reg)))
                    (:arg-types system-area-pointer
                                (:constant (signed-byte 32)))
                    (:info offset)
                    (:results (result :scs (,sc)))
                    (:result-types ,type)
                    (:generator 4
                      (inst ,ref-insn result
                            (make-ea ,size :base sap :disp offset))))
                  (define-vop (,set-name)
                    (:translate ,set-name)
                    (:policy :fast-safe)
                    (:args (sap :scs (sap-reg) :to (:eval 0))
                           (offset :scs (signed-reg) :to (:eval 0))
                           (value :scs (,sc) :target result))
                    (:arg-types system-area-pointer signed-num ,type)
                    (:results (result :scs (,sc)))
                    (:result-types ,type)
                    (:generator 5 (emit-sap-set ,size sap offset 0 value result)))
                  (define-vop (,set-name-c)
                    (:translate ,set-name)
                    (:policy :fast-safe)
                    (:args (sap :scs (sap-reg) :to (:eval 0))
                           (value :scs (,sc) :target result))
                    (:arg-types system-area-pointer
                                (:constant (signed-byte 32)) ,type)
                    (:info offset)
                    (:results (result :scs (,sc)))
                    (:result-types ,type)
                    (:generator 4 (emit-sap-set ,size sap nil offset value result)))))))

  (def-system-ref-and-set sap-ref-8 %set-sap-ref-8 movzx
    unsigned-reg positive-fixnum :byte)
  (def-system-ref-and-set signed-sap-ref-8 %set-signed-sap-ref-8 movsx
    signed-reg tagged-num :byte)
  (def-system-ref-and-set sap-ref-16 %set-sap-ref-16 movzx
    unsigned-reg positive-fixnum :word)
  (def-system-ref-and-set signed-sap-ref-16 %set-signed-sap-ref-16 movsx
    signed-reg tagged-num :word)
  (def-system-ref-and-set sap-ref-32 %set-sap-ref-32 movzxd
    unsigned-reg unsigned-num :dword)
  (def-system-ref-and-set signed-sap-ref-32 %set-signed-sap-ref-32 movsxd
    signed-reg signed-num :dword)
  (def-system-ref-and-set sap-ref-64 %set-sap-ref-64 mov
    unsigned-reg unsigned-num :qword)
  (def-system-ref-and-set signed-sap-ref-64 %set-signed-sap-ref-64 mov
    signed-reg signed-num :qword)
  (def-system-ref-and-set sap-ref-sap %set-sap-ref-sap mov
    sap-reg system-area-pointer :qword)
  (def-system-ref-and-set sap-ref-lispobj %set-sap-ref-lispobj mov
    descriptor-reg * :qword))

;;;; SAP-REF-DOUBLE

(define-vop (sap-ref-double)
  (:translate sap-ref-double)
  (:policy :fast-safe)
  (:args (sap :scs (sap-reg))
         (offset :scs (signed-reg)))
  (:arg-types system-area-pointer signed-num)
  (:results (result :scs (double-reg)))
  (:result-types double-float)
  (:generator 5
     (inst movsd result (make-ea :qword :base sap :index offset))))

(define-vop (sap-ref-double-c)
  (:translate sap-ref-double)
  (:policy :fast-safe)
  (:args (sap :scs (sap-reg)))
  (:arg-types system-area-pointer (:constant (signed-byte 32)))
  (:info offset)
  (:results (result :scs (double-reg)))
  (:result-types double-float)
  (:generator 4
     (inst movsd result (make-ea :qword :base sap :disp offset))))

(define-vop (%set-sap-ref-double)
  (:translate %set-sap-ref-double)
  (:policy :fast-safe)
  (:args (sap :scs (sap-reg) :to (:eval 0))
         (offset :scs (signed-reg) :to (:eval 0))
         (value :scs (double-reg)))
  (:arg-types system-area-pointer signed-num double-float)
  (:results (result :scs (double-reg)))
  (:result-types double-float)
  (:generator 5
    (inst movsd (make-ea :qword :base sap :index offset) value)
    (move result value)))

(define-vop (%set-sap-ref-double-c)
  (:translate %set-sap-ref-double)
  (:policy :fast-safe)
  (:args (sap :scs (sap-reg) :to (:eval 0))
         (value :scs (double-reg)))
  (:arg-types system-area-pointer (:constant (signed-byte 32)) double-float)
  (:info offset)
  (:results (result :scs (double-reg)))
  (:result-types double-float)
  (:generator 4
    (inst movsd (make-ea :qword :base sap :disp offset) value)
    (move result value)))

;;;; SAP-REF-SINGLE

(define-vop (sap-ref-single)
  (:translate sap-ref-single)
  (:policy :fast-safe)
  (:args (sap :scs (sap-reg))
         (offset :scs (signed-reg)))
  (:arg-types system-area-pointer signed-num)
  (:results (result :scs (single-reg)))
  (:result-types single-float)
  (:generator 5
     (inst movss result (make-ea :dword :base sap :index offset))))

(define-vop (sap-ref-single-c)
  (:translate sap-ref-single)
  (:policy :fast-safe)
  (:args (sap :scs (sap-reg)))
  (:arg-types system-area-pointer (:constant (signed-byte 32)))
  (:info offset)
  (:results (result :scs (single-reg)))
  (:result-types single-float)
  (:generator 4
     (inst movss result (make-ea :dword :base sap :disp offset))))

(define-vop (%set-sap-ref-single)
  (:translate %set-sap-ref-single)
  (:policy :fast-safe)
  (:args (sap :scs (sap-reg) :to (:eval 0))
         (offset :scs (signed-reg) :to (:eval 0))
         (value :scs (single-reg)))
  (:arg-types system-area-pointer signed-num single-float)
  (:results (result :scs (single-reg)))
  (:result-types single-float)
  (:generator 5
    (inst movss (make-ea :dword :base sap :index offset) value)
    (move result value)))

(define-vop (%set-sap-ref-single-c)
  (:translate %set-sap-ref-single)
  (:policy :fast-safe)
  (:args (sap :scs (sap-reg) :to (:eval 0))
         (value :scs (single-reg)))
  (:arg-types system-area-pointer (:constant (signed-byte 32)) single-float)
  (:info offset)
  (:results (result :scs (single-reg)))
  (:result-types single-float)
  (:generator 4
    (inst movss (make-ea :dword :base sap :disp offset) value)
    (move result value)))


;;; noise to convert normal lisp data objects into SAPs

(define-vop (vector-sap)
  (:translate vector-sap)
  (:policy :fast-safe)
  (:args (vector :scs (descriptor-reg) :target sap))
  (:results (sap :scs (sap-reg)))
  (:result-types system-area-pointer)
  (:generator 2
    (let ((disp (- (* vector-data-offset n-word-bytes) other-pointer-lowtag)))
      (if (location= sap vector)
          (inst add sap disp)
          (inst lea sap (make-ea :qword :base vector :disp disp))))))

;;; Compare and swap
(define-vop (signed-sap-cas-32)
  (:policy :fast-safe)
  (:args (sap :scs (sap-reg) :to (:eval 0))
         (offset :scs (signed-reg) :to (:eval 0))
         (oldval :scs (signed-reg) :target eax)
         (newval :scs (signed-reg) :to (:eval 0)))
  (:temporary (:sc dword-reg :offset eax-offset
                   :from (:argument 2) :to (:result 0)) eax)
  (:arg-types system-area-pointer signed-num signed-num signed-num)
  (:results (result :scs (signed-reg)))
  (:result-types signed-num)
  (:generator 5
    (inst mov eax (reg-in-size oldval :dword))
    (inst cmpxchg (make-ea :dword :base sap :index offset)
          (reg-in-size newval :dword) :lock)
    (inst mov (reg-in-size result :dword) eax)))

