#| -*-Scheme-*-

$Id: machin.scm,v 4.32 2003/02/14 18:28:07 cph Exp $

Copyright (c) 1988-1999 Massachusetts Institute of Technology

This file is part of MIT/GNU Scheme.

MIT/GNU Scheme is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at
your option) any later version.

MIT/GNU Scheme is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with MIT/GNU Scheme; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
USA.

|#

;;; Machine Model for Spectrum
;;; package: (compiler)

(declare (usual-integrations))

;;;; Architecture Parameters

(define use-pre/post-increment? true)
(define-integrable endianness 'BIG)
(define-integrable addressing-granularity 8)
(define-integrable scheme-object-width 32)
(define-integrable scheme-type-width 6)	;or 8

;; NOTE: expt is not being constant-folded now.
;; For the time being, some of the parameters below are
;; pre-computed and marked with ***
;; There are similar parameters in lapgen.scm
;; Change them if any of the parameters above do.

(define-integrable scheme-datum-width
  (- scheme-object-width scheme-type-width))

(define-integrable type-scale-factor
  ;; (expt 2 (- 8 scheme-type-width)) ***
  4)

(define-integrable float-width 64)
(define-integrable float-alignment 64)

(define-integrable address-units-per-float
  (quotient float-width addressing-granularity))

;;; It is currently required that both packed characters and objects
;;; be integrable numbers of address units.  Furthermore, the number
;;; of address units per object must be an integral multiple of the
;;; number of address units per character.  This will cause problems
;;; on a machine that is word addressed: we will have to rethink the
;;; character addressing strategy.

(define-integrable address-units-per-object
  (quotient scheme-object-width addressing-granularity))

(define-integrable address-units-per-packed-char 1)

(define-integrable signed-fixnum/upper-limit
  ;; (expt 2 (-1+ scheme-datum-width)) ***
  33554432)

(define-integrable signed-fixnum/lower-limit
  (- signed-fixnum/upper-limit))

(define-integrable unsigned-fixnum/upper-limit
  (* 2 signed-fixnum/upper-limit))

(define-integrable (stack->memory-offset offset) offset)
(define-integrable ic-block-first-parameter-offset 2)
(define-integrable execute-cache-size 3) ; Long words per UUO link slot

;;;; Closures and multi-closures

;; On the 68k, to save space, entries can be at 2 mod 4 addresses,
;; which makes it impossible to use an arbitrary closure entry-point
;; to reference closed-over variables since the compiler only uses
;; long-word offsets.  Instead, all closure entry points are bumped
;; back to the first entry point, which is always long-word aligned.

;; On the HP-PA, and all other RISCs, all the entry points are
;; long-word aligned, so there is no need to bump back to the first
;; entry point.

(define-integrable closure-entry-size
  #|
     Long words in a single closure entry:
       GC offset word
       LDIL	L'target,26
       BLE	R'target(5,26)
       ADDI	-12,31,31
   |#
  4)

;; Given: the number of entry points in a closure, and a particular
;; entry point number, compute the distance from that entry point to
;; the first variable slot in the closure object (in long words).

(define (closure-first-offset nentries entry)
  (if (zero? nentries)
      1					; Strange boundary case
      (- (* closure-entry-size (- nentries entry)) 1)))

;; Like the above, but from the start of the complete closure object,
;; viewed as a vector, and including the header word.

(define (closure-object-first-offset nentries)
  (case nentries
    ((0)
     ;; Vector header only
     1)
    ((1)
     ;; Manifest closure header followed by single entry point
     (+ 1 closure-entry-size))
    (else
     ;; Manifest closure header, number of entries, then entries.
     (+ 1 1 (* closure-entry-size nentries)))))

;; Bump distance in bytes from one entry point to another.
;; Used for invocation purposes.

(define (closure-entry-distance nentries entry entry*)
  nentries				; ignored
  (* (* closure-entry-size 4) (- entry* entry)))

;; Bump distance in bytes from one entry point to the entry point used
;; for variable-reference purposes.
;; On a RISC, this is the entry point itself.

(define (closure-environment-adjustment nentries entry)
  nentries entry			; ignored
  0)

;;;; Machine Registers

(define-integrable g0 0)
(define-integrable g1 1)
(define-integrable g2 2)
(define-integrable g3 3)
(define-integrable g4 4)
(define-integrable g5 5)
(define-integrable g6 6)
(define-integrable g7 7)
(define-integrable g8 8)
(define-integrable g9 9)
(define-integrable g10 10)
(define-integrable g11 11)
(define-integrable g12 12)
(define-integrable g13 13)
(define-integrable g14 14)
(define-integrable g15 15)
(define-integrable g16 16)
(define-integrable g17 17)
(define-integrable g18 18)
(define-integrable g19 19)
(define-integrable g20 20)
(define-integrable g21 21)
(define-integrable g22 22)
(define-integrable g23 23)
(define-integrable g24 24)
(define-integrable g25 25)
(define-integrable g26 26)
(define-integrable g27 27)
(define-integrable g28 28)
(define-integrable g29 29)
(define-integrable g30 30)
(define-integrable g31 31)

;; fp0 - fp3 are status registers.  The rest are real registers
(define-integrable fp0 32)
(define-integrable fp1 33)
(define-integrable fp2 34)
(define-integrable fp3 35)
(define-integrable fp4 36)
(define-integrable fp5 37)
(define-integrable fp6 38)
(define-integrable fp7 39)
(define-integrable fp8 40)
(define-integrable fp9 41)
(define-integrable fp10 42)
(define-integrable fp11 43)
(define-integrable fp12 44)
(define-integrable fp13 45)
(define-integrable fp14 46)
(define-integrable fp15 47)

;; The following registers are available only on the newer processors
(define-integrable fp16 48)
(define-integrable fp17 49)
(define-integrable fp18 50)
(define-integrable fp19 51)
(define-integrable fp20 52)
(define-integrable fp21 53)
(define-integrable fp22 54)
(define-integrable fp23 55)
(define-integrable fp24 56)
(define-integrable fp25 57)
(define-integrable fp26 58)
(define-integrable fp27 59)
(define-integrable fp28 60)
(define-integrable fp29 61)
(define-integrable fp30 62)
(define-integrable fp31 63)

(define-integrable number-of-machine-registers 64)
(define-integrable number-of-temporary-registers 256)

;;; Fixed-use registers for Scheme compiled code.
(define-integrable regnum:return-value g2)
(define-integrable regnum:scheme-to-interface-ble g3)
(define-integrable regnum:regs-pointer g4)
(define-integrable regnum:quad-bitmask g5)
(define-integrable regnum:dynamic-link g19)
(define-integrable regnum:memtop-pointer g20)
(define-integrable regnum:free-pointer g21)
(define-integrable regnum:stack-pointer g22)

;;; Fixed-use registers due to architecture or OS calling conventions.
(define-integrable regnum:zero g0)
(define-integrable regnum:addil-result g1)
(define-integrable regnum:C-global-pointer g27)
(define-integrable regnum:C-return-value g28)
(define-integrable regnum:C-stack-pointer g30)
(define-integrable regnum:ble-return g31)
(define-integrable regnum:fourth-arg g23)
(define-integrable regnum:third-arg g24)
(define-integrable regnum:second-arg g25)
(define-integrable regnum:first-arg g26)

(define (machine-register-value-class register)
  (cond ((or (= register 0)
	     (<= 6 register 18)
	     (<= 23 register 26)
	     (= register 29)
	     (= register 31))
	 value-class=word)
	((or (= register 2) (= register 28))
	 value-class=object)
	((or (= register 1) (= register 3))
	 value-class=unboxed)
	((or (= register 4)
	     (<= 19 register 22)
	     (= register 27)
	     (= register 30))
	 value-class=address)
	((= register 5)
	 value-class=immediate)
	((<= 32 register 63)
	 value-class=float)
	(else
	 (error "illegal machine register" register))))

(define-integrable (machine-register-known-value register)
  register				;ignore
  false)

;;;; Interpreter Registers

(define-integrable (interpreter-free-pointer)
  (rtl:make-machine-register regnum:free-pointer))

(define (interpreter-free-pointer? expression)
  (and (rtl:register? expression)
       (= (rtl:register-number expression) regnum:free-pointer)))

(define-integrable (interpreter-regs-pointer)
  (rtl:make-machine-register regnum:regs-pointer))

(define (interpreter-regs-pointer? expression)
  (and (rtl:register? expression)
       (= (rtl:register-number expression) regnum:regs-pointer)))

(define-integrable (interpreter-value-register)
  (rtl:make-machine-register regnum:return-value))

(define (interpreter-value-register? expression)
  (and (rtl:register? expression)
       (= (rtl:register-number expression) regnum:return-value)))

(define-integrable (interpreter-stack-pointer)
  (rtl:make-machine-register regnum:stack-pointer))

(define (interpreter-stack-pointer? expression)
  (and (rtl:register? expression)
       (= (rtl:register-number expression) regnum:stack-pointer)))

(define-integrable (interpreter-dynamic-link)
  (rtl:make-machine-register regnum:dynamic-link))

(define (interpreter-dynamic-link? expression)
  (and (rtl:register? expression)
       (= (rtl:register-number expression) regnum:dynamic-link)))

(define-integrable (interpreter-environment-register)
  (rtl:make-offset (interpreter-regs-pointer)
		   (rtl:make-machine-constant 3)))

(define (interpreter-environment-register? expression)
  (and (rtl:offset? expression)
       (interpreter-regs-pointer? (rtl:offset-base expression))
       (let ((offset (rtl:offset-offset expression)))
	 (and (rtl:machine-constant? offset)
	      (= 3 (rtl:machine-constant-value offset))))))

(define-integrable (interpreter-register:access)
  (rtl:make-machine-register g28))

(define-integrable (interpreter-register:cache-reference)
  (rtl:make-machine-register g28))

(define-integrable (interpreter-register:cache-unassigned?)
  (rtl:make-machine-register g28))

(define-integrable (interpreter-register:lookup)
  (rtl:make-machine-register g28))

(define-integrable (interpreter-register:unassigned?)
  (rtl:make-machine-register g28))

(define-integrable (interpreter-register:unbound?)
  (rtl:make-machine-register g28))

;;;; RTL Registers, Constants, and Primitives

(define (rtl:machine-register? rtl-register)
  (case rtl-register
    ((STACK-POINTER)
     (interpreter-stack-pointer))
    ((DYNAMIC-LINK)
     (interpreter-dynamic-link))
    ((VALUE)
     (interpreter-value-register))
    ((FREE)
     (interpreter-free-pointer))
    ((MEMORY-TOP)
     (rtl:make-machine-register regnum:memtop-pointer))
    ((INTERPRETER-CALL-RESULT:ACCESS)
     (interpreter-register:access))
    ((INTERPRETER-CALL-RESULT:CACHE-REFERENCE)
     (interpreter-register:cache-reference))
    ((INTERPRETER-CALL-RESULT:CACHE-UNASSIGNED?)
     (interpreter-register:cache-unassigned?))
    ((INTERPRETER-CALL-RESULT:LOOKUP)
     (interpreter-register:lookup))
    ((INTERPRETER-CALL-RESULT:UNASSIGNED?)
     (interpreter-register:unassigned?))
    ((INTERPRETER-CALL-RESULT:UNBOUND?)
     (interpreter-register:unbound?))
    (else false)))

(define (rtl:interpreter-register? rtl-register)
  (case rtl-register
    ((INT-MASK) 1)
    ((ENVIRONMENT) 3)
    ((TEMPORARY) 4)
    (else false)))

(define (rtl:interpreter-register->offset locative)
  (or (rtl:interpreter-register? locative)
      (error "Unknown register type" locative)))

(define (rtl:constant-cost expression)
  ;; Magic numbers.
  (let ((if-integer
	 (lambda (value)
	   (cond ((zero? value) 1)
		 ((fits-in-5-bits-signed? value) 2)
		 (else 3)))))
    (let ((if-synthesized-constant
	   (lambda (type datum)
	     (if-integer (make-non-pointer-literal type datum)))))
      (case (rtl:expression-type expression)
	((CONSTANT)
	 (let ((value (rtl:constant-value expression)))
	   (if (non-pointer-object? value)
	       (if-synthesized-constant (object-type value)
					(object-datum value))
	       3)))
	((MACHINE-CONSTANT)
	 (if-integer (rtl:machine-constant-value expression)))
	((ENTRY:PROCEDURE
	  ENTRY:CONTINUATION
	  ASSIGNMENT-CACHE
	  VARIABLE-CACHE
	  OFFSET-ADDRESS
	  BYTE-OFFSET-ADDRESS
	  FLOAT-OFFSET-ADDRESS)
	 3)
	((CONS-POINTER)
	 (and (rtl:machine-constant? (rtl:cons-pointer-type expression))
	      (rtl:machine-constant? (rtl:cons-pointer-datum expression))
	      (if-synthesized-constant
	       (rtl:machine-constant-value (rtl:cons-pointer-type expression))
	       (rtl:machine-constant-value
		(rtl:cons-pointer-datum expression)))))
	(else false)))))

(define compiler:open-code-floating-point-arithmetic?
  true)

(define compiler:primitives-with-no-open-coding
  '(DIVIDE-FIXNUM GCD-FIXNUM &/))