Language/OS - Multiplatform Resource Library/LANGUAGE OS.iso/pcl/src-16f.lha/compiler/mips/call.lisp

Text File | 1992-05-19 | 40.5 KB | 1,241 lines

;;; -*- Package: MIPS; Log: C.Log -*-
;;;
;;; **********************************************************************
;;; This code was written as part of the CMU Common Lisp project at
;;; Carnegie Mellon University, and has been placed in the public domain.
;;; If you want to use this code or any part of CMU Common Lisp, please contact
;;; Scott Fahlman or [e-mail].
;;;
(ext:file-comment
  "$Header: call.lisp,v 1.41.2.1 92/05/18 18:26:01 ram Exp $")
;;;
;;; **********************************************************************
;;;
;;; $Header: call.lisp,v 1.41.2.1 92/05/18 18:26:01 ram Exp $
;;;
;;;    This file contains the VM definition of function call for the MIPS.
;;;
;;; Written by Rob MacLachlan
;;;
;;; Converted for the MIPS by William Lott.
;;;
(in-package "MIPS")


;;;; Interfaces to IR2 conversion:

;;; Standard-Argument-Location  --  Interface
;;;
;;;    Return a wired TN describing the N'th full call argument passing
;;; location.
;;;
(def-vm-support-routine standard-argument-location (n)
  (declare (type unsigned-byte n))
  (if (< n register-arg-count)
      (make-wired-tn *any-primitive-type*
             register-arg-scn
             (elt register-arg-offsets n))
      (make-wired-tn *any-primitive-type*
             control-stack-arg-scn n)))


;;; Make-Return-PC-Passing-Location  --  Interface
;;;
;;;    Make a passing location TN for a local call return PC.  If standard is
;;; true, then use the standard (full call) location, otherwise use any legal
;;; location.  Even in the non-standard case, this may be restricted by a
;;; desire to use a subroutine call instruction.
;;;
(def-vm-support-routine make-return-pc-passing-location (standard)
  (if standard
      (make-wired-tn *any-primitive-type* register-arg-scn lra-offset)
      (make-restricted-tn *any-primitive-type* register-arg-scn)))

;;; Make-Old-FP-Passing-Location  --  Interface
;;;
;;;    Similar to Make-Return-PC-Passing-Location, but makes a location to pass
;;; Old-FP in.  This is (obviously) wired in the standard convention, but is
;;; totally unrestricted in non-standard conventions, since we can always fetch
;;; it off of the stack using the arg pointer.
;;;
(def-vm-support-routine make-old-fp-passing-location (standard)
  (if standard
      (make-wired-tn *fixnum-primitive-type* immediate-arg-scn old-fp-offset)
      (make-normal-tn *fixnum-primitive-type*)))

;;; Make-Old-FP-Save-Location, Make-Return-PC-Save-Location  --  Interface
;;;
;;;    Make the TNs used to hold Old-FP and Return-PC within the current
;;; function.  We treat these specially so that the debugger can find them at a
;;; known location.
;;;
(def-vm-support-routine make-old-fp-save-location (env)
  (specify-save-tn
   (environment-debug-live-tn (make-normal-tn *fixnum-primitive-type*) env)
   (make-wired-tn *fixnum-primitive-type*
          control-stack-arg-scn
          old-fp-save-offset)))
;;;
(def-vm-support-routine make-return-pc-save-location (env)
  (specify-save-tn
   (environment-debug-live-tn (make-normal-tn *any-primitive-type*) env)
   (make-wired-tn *any-primitive-type*
          control-stack-arg-scn
          lra-save-offset)))

;;; Make-Argument-Count-Location  --  Interface
;;;
;;;    Make a TN for the standard argument count passing location.  We only
;;; need to make the standard location, since a count is never passed when we
;;; are using non-standard conventions.
;;;
(def-vm-support-routine make-argument-count-location ()
  (make-wired-tn *fixnum-primitive-type* immediate-arg-scn nargs-offset))


;;; MAKE-NFP-TN  --  Interface
;;;
;;;    Make a TN to hold the number-stack frame pointer.  This is allocated
;;; once per component, and is component-live.
;;;
(def-vm-support-routine make-nfp-tn ()
  (component-live-tn
   (make-wired-tn *fixnum-primitive-type* immediate-arg-scn nfp-offset)))

;;; MAKE-STACK-POINTER-TN ()
;;;
(def-vm-support-routine make-stack-pointer-tn ()
  (make-normal-tn *fixnum-primitive-type*))

;;; MAKE-NUMBER-STACK-POINTER-TN ()
;;;
(def-vm-support-routine make-number-stack-pointer-tn ()
  (make-normal-tn *fixnum-primitive-type*))

;;; Make-Unknown-Values-Locations  --  Interface
;;;
;;;    Return a list of TNs that can be used to represent an unknown-values
;;; continuation within a function.
;;;
(def-vm-support-routine make-unknown-values-locations ()
  (list (make-stack-pointer-tn)
    (make-normal-tn *fixnum-primitive-type*)))


;;; Select-Component-Format  --  Interface
;;;
;;;    This function is called by the Entry-Analyze phase, allowing
;;; VM-dependent initialization of the IR2-Component structure.  We push
;;; placeholder entries in the Constants to leave room for additional
;;; noise in the code object header.
;;;
(def-vm-support-routine select-component-format (component)
  (declare (type component component))
  (dotimes (i code-constants-offset)
    (vector-push-extend nil
            (ir2-component-constants (component-info component))))
  (undefined-value))


;;;; Frame hackery:

;;; BYTES-NEEDED-FOR-NON-DESCRIPTOR-STACK-FRAME -- internal
;;;
;;; Return the number of bytes needed for the current non-descriptor stack
;;; frame.  Non-descriptor stack frames must be multiples of 8 bytes on
;;; the PMAX.
;;;
(defun bytes-needed-for-non-descriptor-stack-frame ()
  (* (logandc2 (1+ (sb-allocated-size 'non-descriptor-stack)) 1)
     vm:word-bytes))

;;; Used for setting up the Old-FP in local call.
;;;
(define-vop (current-fp)
  (:results (val :scs (any-reg)))
  (:generator 1
    (move val fp-tn)))

;;; Used for computing the caller's NFP for use in known-values return.  Only
;;; works assuming there is no variable size stuff on the nstack.
;;;
(define-vop (compute-old-nfp)
  (:results (val :scs (any-reg)))
  (:vop-var vop)
  (:generator 1
    (let ((nfp (current-nfp-tn vop)))
      (when nfp
    (inst addu val nfp (bytes-needed-for-non-descriptor-stack-frame))))))


(define-vop (xep-allocate-frame)
  (:info start-lab)
  (:vop-var vop)
  (:temporary (:scs (non-descriptor-reg)) temp)
  (:generator 1
    ;; Make sure the function is aligned, and drop a label pointing to this
    ;; function header.
    (align vm:lowtag-bits)
    (trace-table-entry trace-table-function-prologue)
    (emit-label start-lab)
    ;; Allocate function header.
    (inst function-header-word)
    (dotimes (i (1- vm:function-header-code-offset))
      (inst word 0))
    ;; The start of the actual code.
    ;; Fix CODE, cause the function object was passed in.
    (let ((entry-point (gen-label)))
      (emit-label entry-point)
      (inst compute-code-from-fn code-tn lip-tn entry-point temp))
    ;; Build our stack frames.
    (inst addu csp-tn fp-tn
      (* vm:word-bytes (sb-allocated-size 'control-stack)))
    (let ((nfp (current-nfp-tn vop)))
      (when nfp
    (inst addu nsp-tn nsp-tn
          (- (bytes-needed-for-non-descriptor-stack-frame)))
    (move nfp nsp-tn)))
    (trace-table-entry trace-table-normal)))

(define-vop (allocate-frame)
  (:results (res :scs (any-reg))
        (nfp :scs (any-reg)))
  (:info callee)
  (:generator 2
    (trace-table-entry trace-table-function-prologue)
    (move res csp-tn)
    (inst addu csp-tn csp-tn
      (* vm:word-bytes (sb-allocated-size 'control-stack)))
    (when (ir2-environment-number-stack-p callee)
      (inst addu nsp-tn nsp-tn
        (- (bytes-needed-for-non-descriptor-stack-frame)))
      (move nfp nsp-tn))
    (trace-table-entry trace-table-normal)))

;;; Allocate a partial frame for passing stack arguments in a full call.  Nargs
;;; is the number of arguments passed.  If no stack arguments are passed, then
;;; we don't have to do anything.
;;;
(define-vop (allocate-full-call-frame)
  (:info nargs)
  (:results (res :scs (any-reg)))
  (:generator 2
    (when (> nargs register-arg-count)
      (move res csp-tn)
      (inst addu csp-tn csp-tn (* nargs vm:word-bytes)))))




;;; Default-Unknown-Values  --  Internal
;;;
;;;    Emit code needed at the return-point from an unknown-values call for a
;;; fixed number of values.  Values is the head of the TN-Ref list for the
;;; locations that the values are to be received into.  Nvals is the number of
;;; values that are to be received (should equal the length of Values).
;;;
;;;    Move-Temp is a Descriptor-Reg TN used as a temporary.
;;;
;;;    This code exploits the fact that in the unknown-values convention, a
;;; single value return returns at the return PC + 8, whereas a return of other
;;; than one value returns directly at the return PC.
;;;
;;;    If 0 or 1 values are expected, then we just emit an instruction to reset
;;; the SP (which will only be executed when other than 1 value is returned.)
;;;
;;; In the general case, we have to do three things:
;;;  -- Default unsupplied register values.  This need only be done when a
;;;     single value is returned, since register values are defaulted by the
;;;     called in the non-single case.
;;;  -- Default unsupplied stack values.  This needs to be done whenever there
;;;     are stack values.
;;;  -- Reset SP.  This must be done whenever other than 1 value is returned,
;;;     regardless of the number of values desired.
;;;
;;; The general-case code looks like this:
#|
    b regs-defaulted        ; Skip if MVs
    nop

    move a1 null-tn            ; Default register values
    ...
    loadi nargs 1            ; Force defaulting of stack values
    move old-fp csp            ; Set up args for SP resetting

regs-defaulted
    subu temp nargs register-arg-count

    bltz temp default-value-7    ; jump to default code
        addu temp temp -1
    loadw move-temp old-fp-tn 6    ; Move value to correct location.
    store-stack-tn val4-tn move-temp

    bltz temp default-value-8
        addu temp temp -1
    loadw move-temp old-fp-tn 7
    store-stack-tn val5-tn move-temp

    ...

defaulting-done
    move sp old-fp            ; Reset SP.
<end of code>

<elsewhere>
default-value-7
    store-stack-tn val4-tn null-tn    ; Nil out 7'th value. (first on stack)

default-value-8
    store-stack-tn val5-tn null-tn    ; Nil out 8'th value.

    ...

    br defaulting-done
        nop
|#
;;;
(defun default-unknown-values (values nvals move-temp temp lra-label)
  (declare (type (or tn-ref null) values)
       (type unsigned-byte nvals) (type tn move-temp temp))
  (if (<= nvals 1)
      (progn
    (move csp-tn old-fp-tn)
    (inst nop)
    (inst entry-point)
    (inst compute-code-from-lra code-tn code-tn lra-label temp))
      (let ((regs-defaulted (gen-label))
        (defaulting-done (gen-label))
        (default-stack-vals (gen-label)))
    ;; Branch off to the MV case.
    (inst b regs-defaulted)
    ;; If there are no stack results, clear the stack now.
    (if (> nvals register-arg-count)
        (inst addu temp nargs-tn (fixnum (- register-arg-count)))
        (move csp-tn old-fp-tn))
    (inst entry-point)

    ;; Do the single value calse.
    (do ((i 1 (1+ i))
         (val (tn-ref-across values) (tn-ref-across val)))
        ((= i (min nvals register-arg-count)))
      (move (tn-ref-tn val) null-tn))
    (when (> nvals register-arg-count)
      (inst b default-stack-vals)
      (move old-fp-tn csp-tn))

    (emit-label regs-defaulted)

    (when (> nvals register-arg-count)
      ;; If there are stack results, we have to default them
      ;; and clear the stack.
      (collect ((defaults))
        (do ((i register-arg-count (1+ i))
         (val (do ((i 0 (1+ i))
               (val values (tn-ref-across val)))
              ((= i register-arg-count) val))
              (tn-ref-across val)))
        ((null val))

          (let ((default-lab (gen-label))
            (tn (tn-ref-tn val)))
        (defaults (cons default-lab tn))

        (inst bltz temp default-lab)
        (inst lw move-temp old-fp-tn (* i vm:word-bytes))
        (inst addu temp temp (fixnum -1))
        (store-stack-tn tn move-temp)))

        (emit-label defaulting-done)
        (move csp-tn old-fp-tn)

        (let ((defaults (defaults)))
          (assert defaults)
          (assemble (*elsewhere*)
        (trace-table-entry trace-table-call-site)
        (emit-label default-stack-vals)
        (do ((remaining defaults (cdr remaining)))
            ((null remaining))
          (let ((def (car remaining)))
            (emit-label (car def))
            (when (null (cdr remaining))
              (inst b defaulting-done))
            (store-stack-tn (cdr def) null-tn)))
        (trace-table-entry trace-table-normal)))))

    (inst compute-code-from-lra code-tn code-tn lra-label temp)))
  (undefined-value))


;;;; Unknown values receiving:

;;; Receive-Unknown-Values  --  Internal
;;;
;;;    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)))
    (inst b variable-values)
    (inst nop)
    (inst entry-point)

    (inst compute-code-from-lra code-tn code-tn lra-label temp)
    (inst addu csp-tn csp-tn 4)
    (storew (first register-arg-tns) csp-tn -1)
    (inst addu start csp-tn -4)
    (inst li count (fixnum 1))

    (emit-label done)

    (assemble (*elsewhere*)
      (trace-table-entry trace-table-call-site)
      (emit-label variable-values)
      (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 start args)
      (move count nargs)
      (inst b done)
      (inst nop)
      (trace-table-entry trace-table-normal)))
  (undefined-value))


;;; 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 old-fp-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 old-fp-offset :from :eval) ocfp)
  (:ignore arg-locs args ocfp)
  (:generator 5
    (trace-table-entry trace-table-call-site)
    (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)))
    (when callee-nfp
      (move callee-nfp nfp)))
      (maybe-load-stack-tn fp-tn fp)
      (inst compute-lra-from-code
        (callee-return-pc-tn callee) code-tn label temp)
      (inst b target)
      (inst nop)
      (emit-return-pc label)
      (note-this-location vop :unknown-return)
      (default-unknown-values values nvals move-temp temp label)
      (when cur-nfp
    (load-stack-tn cur-nfp nfp-save)))
    (trace-table-entry trace-table-normal)))


;;; 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)
  (:generator 20
    (trace-table-entry trace-table-call-site)
    (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)))
    (when callee-nfp
      (move callee-nfp nfp)))
      (maybe-load-stack-tn fp-tn fp)
      (inst compute-lra-from-code
        (callee-return-pc-tn callee) code-tn label temp)
      (inst b target)
      (inst nop)
      (emit-return-pc label)
      (note-this-location vop :unknown-return)
      (receive-unknown-values values-start nvals start count label temp)
      (when cur-nfp
    (load-stack-tn cur-nfp nfp-save)))
    (trace-table-entry trace-table-normal)))


;;;; 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
    (trace-table-entry trace-table-call-site)
    (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)))
    (when callee-nfp
      (move callee-nfp nfp)))
      (maybe-load-stack-tn fp-tn fp)
      (inst compute-lra-from-code
        (callee-return-pc-tn callee) code-tn label temp)
      (inst b target)
      (inst nop)
      (emit-return-pc label)
      (note-this-location vop :known-return)
      (when cur-nfp
    (load-stack-tn cur-nfp nfp-save)))
    (trace-table-entry trace-table-normal)))

;;; 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 (old-fp :target old-fp-temp)
     (return-pc :target return-pc-temp)
     (vals :more t))
  (:temporary (:sc any-reg :from (:argument 0)) old-fp-temp)
  (:temporary (:sc descriptor-reg :from (:argument 1)) return-pc-temp)
  (:temporary (:scs (interior-reg) :type interior) lip)
  (:move-args :known-return)
  (:info val-locs)
  (:ignore val-locs vals)
  (:vop-var vop)
  (:generator 6
    (trace-table-entry trace-table-function-epilogue)
    (maybe-load-stack-tn old-fp-temp old-fp)
    (maybe-load-stack-tn return-pc-temp return-pc)
    (move csp-tn fp-tn)
    (let ((cur-nfp (current-nfp-tn vop)))
      (when cur-nfp
    (inst addu nsp-tn cur-nfp
          (bytes-needed-for-non-descriptor-stack-frame))))
    (inst addu lip return-pc-temp (- vm:word-bytes vm:other-pointer-type))
    (inst j lip)
    (move fp-tn old-fp-temp)
    (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.

;;; Define-Full-Call  --  Internal
;;;
;;;    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 Old-Fp 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)
  (assert (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)
      '((old-fp :target old-fp-pass)
        (return-pc :target return-pc-pass)))

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

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

     ,@(unless (eq return :tail)
     `((:save-p t)
       ,@(unless variable
           '((:move-args :full-call)))))

     (:vop-var vop)
     (:info ,@(unless (or variable (eq return :tail)) '(arg-locs))
        ,@(unless variable '(nargs))
        ,@(when (eq return :fixed) '(nvals)))

     (:ignore
      ,@(unless (or variable (eq return :tail)) '(arg-locs))
      ,@(unless variable '(args)))

     (:temporary (:sc descriptor-reg
          :offset old-fp-offset
          :from (:argument 1)
          ,@(unless (eq return :fixed)
              '(:to :eval)))
         old-fp-pass)

     (:temporary (:sc descriptor-reg
          :offset lra-offset
          :from (:argument ,(if (eq return :tail) 2 1))
          :to :eval)
         return-pc-pass)

     ,@(if named
     `((:temporary (:sc descriptor-reg :offset cname-offset
            :from (:argument ,(if (eq return :tail) 0 1))
            :to :eval)
               name-pass))

     `((:temporary (:sc descriptor-reg :offset lexenv-offset
            :from (:argument ,(if (eq return :tail) 0 1))
            :to :eval)
               lexenv)
       (:temporary (:scs (descriptor-reg) :from (:argument 0) :to :eval)
               function)))

     (:temporary (:sc any-reg :offset nargs-offset :to :eval)
         nargs-pass)

     ,@(when variable
     (mapcar #'(lambda (name offset)
             `(:temporary (:sc descriptor-reg
                   :offset ,offset
                   :to :eval)
             ,name))
         register-arg-names register-arg-offsets))
     ,@(when (eq return :fixed)
     '((:temporary (:scs (descriptor-reg) :from :eval) move-temp)))

     ,@(unless (eq return :tail)
     '((:temporary (:scs (non-descriptor-reg) :from :eval) temp)
       (:temporary (:sc control-stack :offset nfp-save-offset) nfp-save)))

     (:temporary (:scs (interior-reg) :type interior) lip)

     (:generator ,(+ (if named 5 0)
             (if variable 19 1)
             (if (eq return :tail) 0 10)
             15
             (if (eq return :unknown) 25 0))
       (trace-table-entry trace-table-call-site)
       (let* ((cur-nfp (current-nfp-tn vop))
          ,@(unless (eq return :tail)
          '((lra-label (gen-label))))
          (filler
           (remove nil
               (list :load-nargs
                 ,@(if (eq return :tail)
                   '((unless (location= old-fp old-fp-pass)
                       :load-old-fp)
                     (unless (location= return-pc
                            return-pc-pass)
                       :load-return-pc)
                     (when cur-nfp
                       :frob-nfp))
                   '(:comp-lra
                     (when cur-nfp
                       :frob-nfp)
                     :save-fp
                     :load-fp))))))
     (flet ((do-next-filler ()
          (let* ((next (pop filler))
             (what (if (consp next) (car next) next)))
            (ecase what
              (:load-nargs
               ,@(if variable
                 `((inst subu nargs-pass csp-tn new-fp)
                   ,@(let ((index -1))
                   (mapcar #'(lambda (name)
                           `(inst lw ,name new-fp
                              ,(ash (incf index)
                                vm:word-shift)))
                       register-arg-names)))
                 '((inst li nargs-pass (fixnum nargs)))))
              ,@(if (eq return :tail)
                '((:load-old-fp
                   (sc-case old-fp
                 (any-reg
                  (inst move old-fp-pass old-fp))
                 (control-stack
                  (inst lw old-fp-pass fp-tn
                    (ash (tn-offset old-fp)
                         vm:word-shift)))))
                  (:load-return-pc
                   (sc-case return-pc
                 (descriptor-reg
                  (inst move return-pc-pass return-pc))
                 (control-stack
                  (inst lw return-pc-pass fp-tn
                    (ash (tn-offset return-pc)
                         vm:word-shift)))))
                  (:frob-nfp
                   (inst addu nsp-tn cur-nfp
                     (bytes-needed-for-non-descriptor-stack-frame))))
                `((:comp-lra
                   (inst compute-lra-from-code
                     return-pc-pass code-tn lra-label temp))
                  (:frob-nfp
                   (store-stack-tn nfp-save cur-nfp))
                  (:save-fp
                   (inst move old-fp-pass fp-tn))
                  (:load-fp
                   ,(if variable
                    '(move fp-tn new-fp)
                    '(if (> nargs register-arg-count)
                     (move fp-tn new-fp)
                     (move fp-tn csp-tn))))))
              ((nil)
               (inst nop))))))

       ,@(if named
         `((sc-case name
             (descriptor-reg (move name-pass name))
             (control-stack
              (inst lw name-pass fp-tn
                (ash (tn-offset name) vm:word-shift))
              (do-next-filler))
             (random-immediate
              (load-symbol name-pass (tn-value name)))
             (constant
              (inst lw name-pass code-tn
                (- (ash (tn-offset name) vm:word-shift)
                   vm:other-pointer-type))
              (do-next-filler)))
           (inst lw lip name-pass
             (- (ash vm:symbol-raw-function-addr-slot
                 vm:word-shift)
                vm:other-pointer-type))
           (do-next-filler))
         `((sc-case arg-fun
             (descriptor-reg (move lexenv arg-fun))
             (control-stack
              (inst lw lexenv fp-tn
                (ash (tn-offset arg-fun) vm:word-shift))
              (do-next-filler))
             (constant
              (inst lw lexenv code-tn
                (- (ash (tn-offset arg-fun) vm:word-shift)
                   vm:other-pointer-type))
              (do-next-filler)))
           (inst lw function lexenv
             (- (ash vm:closure-function-slot vm:word-shift)
                vm:function-pointer-type))
           (do-next-filler)
           (inst addu lip function
             (- (ash vm:function-header-code-offset
                 vm:word-shift)
                vm:function-pointer-type))))
       (loop
         (if (cdr filler)
         (do-next-filler)
         (return)))

       (inst j lip)
       (do-next-filler))

     ,@(ecase return
         (:fixed
          '((emit-return-pc lra-label)
        (note-this-location vop :unknown-return)
        (default-unknown-values values nvals move-temp temp lra-label)
        (when cur-nfp
          (load-stack-tn cur-nfp nfp-save))))
         (:unknown
          '((emit-return-pc lra-label)
        (note-this-location vop :unknown-return)
        (receive-unknown-values values-start nvals start count
                    lra-label temp)
        (when cur-nfp
          (load-stack-tn cur-nfp nfp-save))))
         (:tail)))
       (trace-table-entry trace-table-normal))))


(define-full-call call nil :fixed nil)
(define-full-call call-named t :fixed nil)
(define-full-call multiple-call nil :unknown nil)
(define-full-call multiple-call-named t :unknown nil)
(define-full-call tail-call nil :tail nil)
(define-full-call tail-call-named t :tail nil)

(define-full-call call-variable nil :fixed t)
(define-full-call multiple-call-variable nil :unknown t)


;;; Defined separately, since needs special code that BLT's the arguments
;;; down.
;;;
(define-vop (tail-call-variable)
  (:args
   (args-arg :scs (any-reg) :target args)
   (function-arg :scs (descriptor-reg) :target lexenv)
   (old-fp-arg :scs (any-reg) :target old-fp)
   (lra-arg :scs (descriptor-reg) :target lra))

  (:temporary (:sc any-reg :offset nl0-offset :from (:argument 0)) args)
  (:temporary (:sc any-reg :offset lexenv-offset :from (:argument 1)) lexenv)
  (:temporary (:sc any-reg :offset old-fp-offset :from (:argument 2)) old-fp)
  (:temporary (:sc any-reg :offset lra-offset :from (:argument 3)) lra)

  (:vop-var vop)

  (:generator 75

    ;; Move these into the passing locations if they are not already there.
    (move args args-arg)
    (move lexenv function-arg)
    (move old-fp old-fp-arg)
    (move lra lra-arg)

    ;; Clear the number stack if anything is there.
    (let ((cur-nfp (current-nfp-tn vop)))
      (when cur-nfp
    (inst addu nsp-tn cur-nfp
          (bytes-needed-for-non-descriptor-stack-frame))))

    ;; And jump to the assembly-routine that does the bliting.
    (inst j (make-fixup 'tail-call-variable :assembly-routine))
    (inst nop)))


;;;; Unknown values return:


;;; Do unknown-values return of a fixed number of values.  The Values are
;;; required to be set up in the standard passing locations.  Nvals is the
;;; number of values returned.
;;;
;;; If returning a single value, then deallocate the current frame, restore
;;; FP and jump to the single-value entry at Return-PC + 8.
;;;
;;; If returning other than one value, then load the number of values returned,
;;; NIL out unsupplied values registers, restore FP and return at Return-PC.
;;; When there are stack values, we must initialize the argument pointer to
;;; point to the beginning of the values block (which is the beginning of the
;;; current frame.)
;;;
(define-vop (return)
  (:args
   (old-fp :scs (any-reg))
   (return-pc :scs (descriptor-reg) :to (:eval 1))
   (values :more t))
  (:ignore values)
  (:info nvals)
  (:temporary (:sc descriptor-reg :offset a0-offset :from (:eval 0)) a0)
  (:temporary (:sc descriptor-reg :offset a1-offset :from (:eval 0)) a1)
  (:temporary (:sc descriptor-reg :offset a2-offset :from (:eval 0)) a2)
  (:temporary (:sc descriptor-reg :offset a3-offset :from (:eval 0)) a3)
  (:temporary (:sc descriptor-reg :offset a4-offset :from (:eval 0)) a4)
  (:temporary (:sc descriptor-reg :offset a5-offset :from (:eval 0)) a5)
  (:temporary (:sc any-reg :offset nargs-offset) nargs)
  (:temporary (:sc any-reg :offset old-fp-offset) val-ptr)
  (:temporary (:scs (interior-reg) :type interior) lip)
  (:vop-var vop)
  (:generator 6
    ;; Clear the number stack.
    (trace-table-entry trace-table-function-epilogue)
    (let ((cur-nfp (current-nfp-tn vop)))
      (when cur-nfp
    (inst addu nsp-tn cur-nfp
          (bytes-needed-for-non-descriptor-stack-frame))))
    (cond ((= nvals 1)
       ;; Clear the control stack, and restore the frame pointer.
       (move csp-tn fp-tn)
       (move fp-tn old-fp)
       ;; Out of here.
       (lisp-return return-pc lip :offset 2))
      (t
       ;; Establish the values pointer and values count.
       (move val-ptr fp-tn)
       (inst li nargs (fixnum nvals))
       ;; restore the frame pointer and clear as much of the control
       ;; stack as possible.
       (move fp-tn old-fp)
       (inst addu csp-tn val-ptr (* nvals word-bytes))
       ;; pre-default any argument register that need it.
       (when (< nvals register-arg-count)
         (dolist (reg (subseq (list a0 a1 a2 a3 a4 a5) nvals))
           (move reg null-tn)))
       ;; And away we go.
       (lisp-return return-pc lip)))
    (trace-table-entry trace-table-normal)))

;;; Do unknown-values return of an arbitrary number of values (passed on the
;;; stack.)  We check for the common case of a single return value, and do that
;;; inline using the normal single value return convention.  Otherwise, we
;;; branch off to code that calls an assembly-routine.
;;;
(define-vop (return-multiple)
  (:args
   (old-fp-arg :scs (any-reg) :to (:eval 1))
   (lra-arg :scs (descriptor-reg) :to (:eval 1))
   (vals-arg :scs (any-reg) :target vals)
   (nvals-arg :scs (any-reg) :target nvals))

  (:temporary (:sc any-reg :offset nl1-offset :from (:argument 0)) old-fp)
  (:temporary (:sc descriptor-reg :offset lra-offset :from (:argument 1)) lra)
  (:temporary (:sc any-reg :offset nl0-offset :from (:argument 2)) vals)
  (:temporary (:sc any-reg :offset nargs-offset :from (:argument 3)) nvals)
  (:temporary (:sc descriptor-reg :offset a0-offset) a0)
  (:temporary (:scs (interior-reg) :type interior) lip)

  (:vop-var vop)

  (:generator 13
    (trace-table-entry trace-table-function-epilogue)
    (let ((not-single (gen-label)))
      ;; Clear the number stack.
      (let ((cur-nfp (current-nfp-tn vop)))
    (when cur-nfp
      (inst addu nsp-tn cur-nfp
        (bytes-needed-for-non-descriptor-stack-frame))))

      ;; Check for the single case.
      (inst li a0 (fixnum 1))
      (inst bne nvals-arg a0 not-single)
      (inst lw a0 vals-arg)

      ;; Return with one value.
      (move csp-tn fp-tn)
      (move fp-tn old-fp-arg)
      (lisp-return lra-arg lip :offset 2)

      ;; Nope, not the single case.
      (emit-label not-single)
      (move old-fp old-fp-arg)
      (move lra lra-arg)
      (move vals vals-arg)
      (move nvals nvals-arg)
      (inst j (make-fixup 'return-multiple :assembly-routine))
      (inst nop))
    (trace-table-entry trace-table-normal)))



;;;; XEP hackery:


;;; We don't need to do anything special for regular functions.
;;;
(define-vop (setup-environment)
  (:info label)
  (:ignore label)
  (:generator 0
    ;; Don't bother doing anything.
    ))

;;; Get the lexical environment from it's passing location.
;;;
(define-vop (setup-closure-environment)
  (:temporary (:sc descriptor-reg :offset lexenv-offset :target closure
           :to (:result 0))
          lexenv)
  (:results (closure :scs (descriptor-reg)))
  (:info label)
  (:ignore label)
  (:generator 6
    ;; Get result.
    (move closure lexenv)))

;;; Copy a more arg from the argument area to the end of the current frame.
;;; Fixed is the number of non-more arguments.
;;;
(define-vop (copy-more-arg)
  (:temporary (:sc any-reg :offset nl0-offset) result)
  (:temporary (:sc any-reg :offset nl1-offset) count)
  (:temporary (:sc any-reg :offset nl2-offset) src)
  (:temporary (:sc any-reg :offset nl3-offset) dst)
  (:temporary (:sc descriptor-reg :offset l0-offset) temp)
  (:info fixed)
  (:generator 20
    (let ((loop (gen-label))
      (do-regs (gen-label))
      (done (gen-label)))
      (when (< fixed register-arg-count)
    ;; Save a pointer to the results so we can fill in register args.
    ;; We don't need this if there are more fixed args than reg args.
    (move result csp-tn))
      ;; Allocate the space on the stack.
      (cond ((zerop fixed)
         (inst beq nargs-tn done)
         (inst addu csp-tn csp-tn nargs-tn))
        (t
         (inst addu count nargs-tn (fixnum (- fixed)))
         (inst blez count done)
         (inst nop)
         (inst addu csp-tn csp-tn count)))
      (when (< fixed register-arg-count)
    ;; We must stop when we run out of stack args, not when we run out of
    ;; more args.
    (inst addu count nargs-tn (fixnum (- register-arg-count))))
      ;; Everything of interest in registers.
      (inst blez count do-regs)
      ;; Initialize dst to be end of stack.
      (move dst csp-tn)
      ;; Initialize src to be end of args.
      (inst addu src fp-tn nargs-tn)

      (emit-label loop)
      ;; *--dst = *--src, --count
      (inst addu src src (- vm:word-bytes))
      (inst addu count count (fixnum -1))
      (loadw temp src)
      (inst addu dst dst (- vm:word-bytes))
      (inst bgtz count loop)
      (storew temp dst)

      (emit-label do-regs)
      (when (< fixed register-arg-count)
    ;; Now we have to deposit any more args that showed up in registers.
    ;; We know there is at least one more arg, otherwise we would have
    ;; branched to done up at the top.
    (inst subu count nargs-tn (fixnum (1+ fixed)))
    (do ((i fixed (1+ i)))
        ((>= i register-arg-count))
      ;; Is this the last one?
      (inst beq count done)
      ;; Store it relative to the pointer saved at the start.
      (storew (nth i register-arg-tns) result (- i fixed))
      ;; Decrement count.
      (inst subu count (fixnum 1))))
      (emit-label done))))


;;; More args are stored consequtively on the stack, starting immediately at
;;; the context pointer.  The context pointer is not typed, so the lowtag is 0.
;;;
(define-vop (more-arg word-index-ref)
  (:variant 0 0)
  (:translate %more-arg))


;;; Turn more arg (context, count) into a list.
;;;
(define-vop (listify-rest-args)
  (:args (context-arg :target context :scs (descriptor-reg))
     (count-arg :target count :scs (any-reg)))
  (:arg-types * tagged-num)
  (:temporary (:scs (any-reg) :from (:argument 0)) context)
  (:temporary (:scs (any-reg) :from (:argument 1)) count)
  (:temporary (:scs (descriptor-reg) :from :eval) temp)
  (:temporary (:scs (non-descriptor-reg) :from :eval) ndescr dst)
  (:results (result :scs (descriptor-reg)))
  (:translate %listify-rest-args)
  (:policy :safe)
  (:generator 20
    (let ((enter (gen-label))
      (loop (gen-label))
      (done (gen-label)))
      (move context context-arg)
      (move count count-arg)
      ;; Check to see if there are any arguments.
      (inst beq count zero-tn done)
      (move result null-tn)

      ;; We need to do this atomically.
      (pseudo-atomic (ndescr)
    ;; Allocate a cons (2 words) for each item.
    (inst addu result alloc-tn vm:list-pointer-type)
    (move dst result)
    (inst addu alloc-tn alloc-tn count)
    (inst b enter)
    (inst addu alloc-tn alloc-tn count)

    ;; Store the current cons in the cdr of the previous cons.
    (emit-label loop)
    (storew dst dst -1 vm:list-pointer-type)

    ;; Grab one value and stash it in the car of this cons.
    (emit-label enter)
    (loadw temp context)
    (inst addu context context vm:word-bytes)
    (storew temp dst 0 vm:list-pointer-type)

    ;; Dec count, and if != zero, go back for more.
    (inst addu count count (fixnum -1))
    (inst bne count zero-tn loop)
    (inst addu dst dst (* 2 vm:word-bytes))

    ;; NIL out the last cons.
    (storew null-tn dst -1 vm:list-pointer-type))
      (emit-label done))))



;;; Return the location and size of the more arg glob created by Copy-More-Arg.
;;; Supplied is the total number of arguments supplied (originally passed in
;;; NARGS.)  Fixed is the number of non-rest arguments.
;;;
;;; We must duplicate some of the work done by Copy-More-Arg, since at that
;;; time the environment is in a pretty brain-damaged state, preventing this
;;; info from being returned as values.  What we do is compute
;;; supplied - fixed, and return a pointer that many words below the current
;;; stack top.
;;;
(define-vop (more-arg-context)
  (:args (supplied :scs (any-reg)))
  (:arg-types positive-fixnum)
  (:info fixed)
  (:results
   (context :scs (descriptor-reg))
   (count :scs (any-reg)))
  (:generator 5
    (inst addu count supplied (fixnum (- fixed)))
    (inst subu context csp-tn count)))


;;; Signal wrong argument count error if Nargs isn't = to Count.
;;;
(define-vop (verify-argument-count)
  (:args (nargs :scs (any-reg)))
  (:arg-types positive-fixnum)
  (:temporary (:scs (any-reg) :type fixnum) temp)
  (:info count)
  (:vop-var vop)
  (:save-p :compute-only)
  (:generator 3
    (let ((err-lab
       (generate-error-code vop invalid-argument-count-error nargs)))
      (cond ((zerop count)
         (inst bne nargs zero-tn err-lab)
         (inst nop))
        (t
         (inst li temp (fixnum count))
         (inst bne nargs temp err-lab)
         (inst nop))))))

;;; Signal an argument count error.
;;;
(macrolet ((frob (name error &rest args)
         `(define-vop (,name)
        (:args ,@(mapcar #'(lambda (arg)
                     `(,arg :scs (any-reg descriptor-reg)))
                 args))
        (:vop-var vop)
        (:save-p :compute-only)
        (:generator 1000
          (error-call vop ,error ,@args)))))
  (frob argument-count-error invalid-argument-count-error nargs)
  (frob type-check-error object-not-type-error object type)
  (frob odd-keyword-arguments-error odd-keyword-arguments-error)
  (frob unknown-keyword-argument-error unknown-keyword-argument-error key)
  (frob nil-function-returned-error nil-function-returned-error fun))