;;;; generic error-call operations

;;;; 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")

;;; (ARRAY NIL) stuff looks the same on all platforms
;;;
;;; This is separate from DATA-VECTOR-REF, because it's declared as
;;; unsafely-flushable, and flushing access to nil arrays causes all
;;; sorts of problems.
(define-vop (data-nil-vector-ref)
  (:translate data-nil-vector-ref)
  (:policy :fast-safe)
  (:args (object :scs (descriptor-reg))
         (index :scs (any-reg descriptor-reg) :load-if nil))
  (:ignore index)
  (:arg-types simple-array-nil *)
  (:vop-var vop)
  (:save-p :compute-only)
  (:generator 1
    (error-call vop 'nil-array-accessed-error object)))

;;; It shouldn't be possible to fall through to here in normal user
;;; code, as the system is smart enough to deduce that there must be
;;; an error upstream, as there are no objects of type NIL that can be
;;; stored in this data vector; however, just in case, we provide this
;;; translation, so that
;;;   (LOCALLY
;;;     (DECLARE (TYPE (SIMPLE-ARRAY NIL (*)) X)
;;;              (OPTIMIZE (SPEED 3) (SAFETY 0)))
;;;     (SB-KERNEL:DATA-VECTOR-SET X 3 'FOO))
;;; signals the right kind of error.
(define-vop (data-vector-set/simple-array-nil)
  (:translate data-vector-set)
  (:policy :fast-safe)
  (:args (object :scs (descriptor-reg))
         (index :scs (unsigned-reg))
         (value :scs (descriptor-reg)))
  (:arg-types simple-array-nil positive-fixnum *)
  (:ignore index value)
  (:vop-var vop)
  (:save-p :compute-only)
  (:generator 1
    (error-call vop 'nil-array-accessed-error object)))

(define-vop (type-check-error/c)
  (:policy :fast-safe)
  (:translate sb-c::%type-check-error/c)
  (:args (object :scs (descriptor-reg any-reg unsigned-reg signed-reg
                       character-reg constant)))
  (:arg-types * (:constant symbol) (:constant t))
  (:info errcode *location-context*)
  (:vop-var vop)
  (:save-p :compute-only)
  (:generator 900
    ;; FIXME: this should be in the :elsewhere segment.
    ;; For lack of an architecture-independent way to emit
    ;; a jump, it's in the regular segment which pollutes the
    ;; instruction pipe with undecodable junk (the sc-numbers).
    (error-call vop errcode object)))

#+(or immobile-space permgen) ; i.e. can LAYOUT instance have immediate SC
(defun type-err-type-tn-loadp (thing)
  (cond ((sc-is thing immediate)
         (let ((obj (tn-value thing)))
           (typecase obj
             (layout nil)
             ;; non-static symbols can be referenced as error-break args
             ;; because they appear in the code constants.
             ;; static symbols can't be referenced as error-break args
             ;; because there is no way to refer to an immediate value.
             (symbol (static-symbol-p obj))
             (t t))))
        (t t)))

(macrolet ((def (error-name-prefix translate context &rest args)
             (let* ((error (package-symbolicate "SB-KERNEL" error-name-prefix "-ERROR"))
                    (name (or translate error)))
             `(define-vop (,name)
                ,@(when translate
                    `((:policy :fast-safe)
                      (:translate ,translate)))
                (:args ,@(mapcar (lambda (arg)
                                   `(,arg :scs (descriptor-reg any-reg character-reg
                                                unsigned-reg signed-reg constant
                                                single-reg double-reg
                                                complex-single-reg complex-double-reg)
                                          #+(or immobile-space permgen)
                                          ,@(if (eq name 'sb-c::%type-check-error)
                                                `(:load-if (type-err-type-tn-loadp ,arg)))))
                                 args))
                ,@(and context
                       `((:info *location-context*)
                         (:arg-types ,@(make-list (length args) :initial-element '*)
                                     (:constant t))))
                (:vop-var vop)
                (:save-p :compute-only)
                (:generator 1000
                  (error-call vop ',error ,@args))))))
  (def "INVALID-ARG-COUNT"       sb-c::%arg-count-error       nil nargs)
  (def "LOCAL-INVALID-ARG-COUNT" sb-c::%local-arg-count-error nil nargs fname)
  (def "OBJECT-NOT-TYPE"         sb-c::%type-check-error      t   object ptype)
  (def "ODD-KEY-ARGS"            sb-c::%odd-key-args-error    nil)
  (def "UNKNOWN-KEY-ARG"         sb-c::%unknown-key-arg-error t   key)
  (def "ECASE-FAILURE"           ecase-failure                nil value keys)
  (def "ETYPECASE-FAILURE"       etypecase-failure            nil value keys)
  (def "NIL-FUN-RETURNED"        nil-fun-returned-error       nil fun)
  (def "UNREACHABLE"             sb-impl::unreachable         nil)
  (def "FAILED-AVER"             sb-impl::%failed-aver        nil form))


(defun emit-internal-error (kind code values &key trap-emitter)
  (let ((trap-number (if (eq kind error-trap)
                         (+ kind code)
                         kind)))
    (if trap-emitter
        (funcall trap-emitter trap-number)
        (inst byte trap-number)))
  (unless (eq kind error-trap)
    (inst byte code))
  (encode-internal-error-args values))

(defvar *adjustable-vectors*)

(defmacro with-adjustable-vector ((var) &rest body)
  `(let ((,var (or (pop *adjustable-vectors*)
                   (make-array 16
                               :element-type '(unsigned-byte 8)
                               :fill-pointer 0
                               :adjustable t))))
     ;; Don't declare the length - if it gets adjusted and pushed back
     ;; onto the freelist, it's anyone's guess whether it was expanded.
     ;; This code was wrong for >12 years, so nobody must have needed
     ;; more than 16 elements. Maybe we should make it nonadjustable?
     (declare (type (vector (unsigned-byte 8)) ,var))
     (setf (fill-pointer ,var) 0)
     ;; No UNWIND-PROTECT here - semantics are unaffected by nonlocal exit,
     ;; and this macro is about speeding up the compiler, not slowing it down.
     ;; GC will clean up any debris, and since the vector does not point
     ;; to anything, even an accidental promotion to a higher generation
     ;; will not cause transitive garbage retention.
     (prog1 (progn ,@body)
       (push ,var *adjustable-vectors*))))

(defun encode-internal-error-args (values)
  (with-adjustable-vector (vector)
    (dolist (where values)
      (write-var-integer
       ;; WHERE can be either a TN or a packed SC number + offset
       (cond ((consp where)
              (make-sc+offset immediate-sc-number (car where)))
             ((not (tn-p where))
              where)
             ((and (sc-is where immediate)
                   (fixnump (tn-value where)))
              (make-sc+offset immediate-sc-number (tn-value where)))
             (t
              (make-sc+offset (if (and (sc-is where immediate)
                                       (typep (tn-value where) '(or symbol layout)))
                                  constant-sc-number
                                  (sc-number (tn-sc where)))
                              (or (tn-offset where) 0))))
       vector))
    (loop for octet across vector do (inst byte octet))))
