call.lisp

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                (store-stack-tn tn move-temp)))

            (emit-label defaulting-done)
            (move ocfp-tn csp-tn)

            (let ((defaults (defaults)))
              (aver defaults)
              (assemble (*elsewhere*)
                (emit-label default-stack-vals)
                (do ((remaining defaults (cdr remaining)))
                    ((null remaining))
                  (let ((def (car remaining)))
                    (emit-label (car def))
                    (store-stack-tn (cdr def) null-tn)))
                (inst br zero-tn defaulting-done)))))

        (when lra-label
          (inst compute-code-from-lra code-tn code-tn lra-label temp))))
  (values))

;;;; unknown values receiving

;;; Emit code needed at the return point for an unknown-values call
;;; for an arbitrary number of values.
;;;
;;; We do the single and non-single cases with no shared code: there
;;; doesn't seem to be any potential overlap, and receiving a single
;;; value is more important efficiency-wise.
;;;
;;; When there is a single value, we just push it on the stack,
;;; returning the old SP and 1.
;;;
;;; When there is a variable number of values, we move all of the
;;; argument registers onto the stack, and return Args and Nargs.
;;;
;;; Args and Nargs are TNs wired to the named locations. We must
;;; explicitly allocate these TNs, since their lifetimes overlap with
;;; the results Start and Count (also, it's nice to be able to target
;;; them).
(defun receive-unknown-values (args nargs start count lra-label temp)
  (declare (type tn args nargs start count temp))
  (let ((variable-values (gen-label))
        (done (gen-label)))
    (without-scheduling ()
      (inst br zero-tn variable-values)
      (inst nop))

    (when lra-label
      (inst compute-code-from-lra code-tn code-tn lra-label temp))
    (inst addq csp-tn 4 csp-tn)
    (storew (first *register-arg-tns*) csp-tn -1)
    (inst subq csp-tn 4 start)
    (inst li (fixnumize 1) count)

    (emit-label done)

    (assemble (*elsewhere*)
      (emit-label variable-values)
      (when lra-label
        (inst compute-code-from-lra code-tn code-tn lra-label temp))
      (do ((arg *register-arg-tns* (rest arg))
           (i 0 (1+ i)))
          ((null arg))
        (storew (first arg) args i))
      (move args start)
      (move nargs count)
      (inst br zero-tn done)))
  (values))

;;; a VOP that can be inherited by unknown values receivers. The main
;;; thing this handles is allocation of the result temporaries.
(define-vop (unknown-values-receiver)
  (:results
   (start :scs (any-reg))
   (count :scs (any-reg)))
  (:temporary (:sc descriptor-reg :offset ocfp-offset
                   :from :eval :to (:result 0))
              values-start)
  (:temporary (:sc any-reg :offset nargs-offset
               :from :eval :to (:result 1))
              nvals)
  (:temporary (:scs (non-descriptor-reg)) temp))

;;;; local call with unknown values convention return

;;; Non-TR local call for a fixed number of values passed according to the
;;; unknown values convention.
;;;
;;; Args are the argument passing locations, which are specified only to
;;; terminate their lifetimes in the caller.
;;;
;;; Values are the return value locations (wired to the standard passing
;;; locations).
;;;
;;; Save is the save info, which we can ignore since saving has been
;;; done. Return-PC is the TN that the return PC should be passed in.
;;; Target is a continuation pointing to the start of the called
;;; function. Nvals is the number of values received.
;;;
;;; Note: we can't use normal load-tn allocation for the fixed args,
;;; since all registers may be tied up by the more operand. Instead,
;;; we use MAYBE-LOAD-STACK-TN.
(define-vop (call-local)
  (:args (fp)
         (nfp)
         (args :more t))
  (:results (values :more t))
  (:save-p t)
  (:move-args :local-call)
  (:info arg-locs callee target nvals)
  (:vop-var vop)
  (:temporary (:scs (descriptor-reg) :from :eval) move-temp)
  (:temporary (:scs (non-descriptor-reg)) temp)
  (:temporary (:sc control-stack :offset nfp-save-offset) nfp-save)
  (:temporary (:sc any-reg :offset ocfp-offset :from :eval) ocfp)
  (:ignore arg-locs args ocfp)
  (:generator 5
    (let ((label (gen-label))
          (cur-nfp (current-nfp-tn vop)))
      (when cur-nfp
        (store-stack-tn nfp-save cur-nfp))
      (let ((callee-nfp (callee-nfp-tn callee)))
        (maybe-load-stack-nfp-tn callee-nfp nfp temp))
      (maybe-load-stack-tn cfp-tn fp)
      (trace-table-entry trace-table-call-site)
      (inst compute-lra-from-code
            (callee-return-pc-tn callee) code-tn label temp)
      (note-this-location vop :call-site)
      (inst br zero-tn target)
      (trace-table-entry trace-table-normal)
      (emit-return-pc label)
      (default-unknown-values vop values nvals move-temp temp label)
      (maybe-load-stack-nfp-tn cur-nfp nfp-save temp))))


;;; Non-TR local call for a variable number of return values passed
;;; according to the unknown values convention. The results are the
;;; start of the values glob and the number of values received.
;;;
;;; Note: we can't use normal load-tn allocation for the fixed args,
;;; since all registers may be tied up by the more operand. Instead,
;;; we use MAYBE-LOAD-STACK-TN.
(define-vop (multiple-call-local unknown-values-receiver)
  (:args (fp)
         (nfp)
         (args :more t))
  (:save-p t)
  (:move-args :local-call)
  (:info save callee target)
  (:ignore args save)
  (:vop-var vop)
  (:temporary (:sc control-stack :offset nfp-save-offset) nfp-save)
  (:temporary (:scs (non-descriptor-reg)) temp)
  (:generator 20
    (let ((label (gen-label))
          (cur-nfp (current-nfp-tn vop)))
      (when cur-nfp
        (store-stack-tn nfp-save cur-nfp))
      (let ((callee-nfp (callee-nfp-tn callee)))
        (maybe-load-stack-nfp-tn callee-nfp nfp temp))
      (maybe-load-stack-tn cfp-tn fp)
      (trace-table-entry trace-table-call-site)
      (inst compute-lra-from-code
            (callee-return-pc-tn callee) code-tn label temp)
      (note-this-location vop :call-site)
      (inst bsr zero-tn target)
      (trace-table-entry trace-table-normal)
      (emit-return-pc label)
      (note-this-location vop :unknown-return)
      (receive-unknown-values values-start nvals start count label temp)
      (maybe-load-stack-nfp-tn cur-nfp nfp-save temp))))


;;;; local call with known values return

;;; Non-TR local call with known return locations. Known-value return
;;; works just like argument passing in local call.
;;;
;;; Note: we can't use normal load-tn allocation for the fixed args, since all
;;; registers may be tied up by the more operand.  Instead, we use
;;; MAYBE-LOAD-STACK-TN.
(define-vop (known-call-local)
  (:args (fp)
         (nfp)
         (args :more t))
  (:results (res :more t))
  (:move-args :local-call)
  (:save-p t)
  (:info save callee target)
  (:ignore args res save)
  (:vop-var vop)
  (:temporary (:sc control-stack :offset nfp-save-offset) nfp-save)
  (:temporary (:scs (non-descriptor-reg)) temp)
  (:generator 5
    (let ((label (gen-label))
          (cur-nfp (current-nfp-tn vop)))
      (when cur-nfp
        (store-stack-tn nfp-save cur-nfp))
      (let ((callee-nfp (callee-nfp-tn callee)))
        (maybe-load-stack-nfp-tn callee-nfp nfp temp))
      (maybe-load-stack-tn cfp-tn fp)
      (trace-table-entry trace-table-call-site)
      (inst compute-lra-from-code
            (callee-return-pc-tn callee) code-tn label temp)
      (note-this-location vop :call-site)
      (inst bsr zero-tn target)
      (trace-table-entry trace-table-normal)
      (emit-return-pc label)
      (note-this-location vop :known-return)
      (maybe-load-stack-nfp-tn cur-nfp nfp-save temp))))

;;; Return from known values call. We receive the return locations as
;;; arguments to terminate their lifetimes in the returning function.
;;; We restore FP and CSP and jump to the Return-PC.
;;;
;;; Note: we can't use normal load-tn allocation for the fixed args,
;;; since all registers may be tied up by the more operand. Instead,
;;; we use MAYBE-LOAD-STACK-TN.
(define-vop (known-return)
  (:args (ocfp :target ocfp-temp)
         (return-pc :target return-pc-temp)
         (vals :more t))
  (:temporary (:sc any-reg :from (:argument 0)) ocfp-temp)
  (:temporary (:sc any-reg :from (:argument 1))
              return-pc-temp)
  (:temporary (:scs (interior-reg)) lip)
  (:move-args :known-return)
  (:info val-locs)
  (:ignore val-locs vals)
  (:vop-var vop)
  (:generator 6
    (trace-table-entry trace-table-fun-epilogue)
    (maybe-load-stack-tn ocfp-temp ocfp)
    (maybe-load-stack-tn return-pc-temp return-pc)
    (move cfp-tn csp-tn)
    (let ((cur-nfp (current-nfp-tn vop)))
      (when cur-nfp
        (inst addq cur-nfp (bytes-needed-for-non-descriptor-stack-frame)
              nsp-tn)))
    (inst subq return-pc-temp (- other-pointer-lowtag n-word-bytes) lip)
    (move ocfp-temp cfp-tn)
    (inst ret zero-tn lip 1)
    (trace-table-entry trace-table-normal)))

;;;; full call:
;;;;
;;;; There is something of a cross-product effect with full calls.
;;;; Different versions are used depending on whether we know the
;;;; number of arguments or the name of the called function, and
;;;; whether we want fixed values, unknown values, or a tail call.
;;;;
;;;; In full call, the arguments are passed creating a partial frame on
;;;; the stack top and storing stack arguments into that frame. On
;;;; entry to the callee, this partial frame is pointed to by FP. If
;;;; there are no stack arguments, we don't bother allocating a partial
;;;; frame, and instead set FP to SP just before the call.

;;; This macro helps in the definition of full call VOPs by avoiding
;;; code replication in defining the cross-product VOPs.
;;;
;;; Name is the name of the VOP to define.
;;;
;;; Named is true if the first argument is a symbol whose global
;;; function definition is to be called.
;;;
;;; Return is either :FIXED, :UNKNOWN or :TAIL:
;;; -- If :FIXED, then the call is for a fixed number of values, returned
;;;    in the standard passing locations (passed as result operands).
;;; -- If :UNKNOWN, then the result values are pushed on the stack, and
;;;    the result values are specified by the Start and Count as in the
;;;    unknown-values continuation representation.
;;; -- If :TAIL, then do a tail-recursive call.  No values are returned.
;;;    The Ocfp and Return-PC are passed as the second and third arguments.
;;;
;;; In non-tail calls, the pointer to the stack arguments is passed as
;;; the last fixed argument. If Variable is false, then the passing
;;; locations are passed as a more arg. Variable is true if there are
;;; a variable number of arguments passed on the stack. Variable
;;; cannot be specified with :TAIL return. TR variable argument call
;;; is implemented separately.
;;;
;;; In tail call with fixed arguments, the passing locations are
;;; passed as a more arg, but there is no new-FP, since the arguments
;;; have been set up in the current frame.
(defmacro define-full-call (name named return variable)
  (aver (not (and variable (eq return :tail))))
  `(define-vop (,name
                ,@(when (eq return :unknown)
                    '(unknown-values-receiver)))
     (:args
      ,@(unless (eq return :tail)
          '((new-fp :scs (any-reg) :to :eval)))

      ,(if named
           '(name :target name-pass)
           '(arg-fun :target lexenv))

      ,@(when (eq return :tail)
          '((ocfp :target ocfp-pass)
            (return-pc :target return-pc-pass)))

      ,@(unless variable '((args :more t :scs (descriptor-reg)))))

     ,@(when (eq return :fixed)
         '((:results (values :more t))))

     (:save-p ,(if (eq return :tail) :compute-only t))

     ,@(unless (or (eq return :tail) variable)
         '((:move-args :full-call)))