;;;; array-specific optimizers and transforms

;;;; 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!C")

;;;; Derive-Type Optimizers

;;; Array operations that use a specific number of indices implicitly assert
;;; that the array is of that rank.
(defun assert-array-rank (array rank)
  (assert-continuation-type
   array
   (specifier-type `(array * ,(make-list rank :initial-element '*)))))

;;; Array access functions return an object from the array, hence its
;;; type will be asserted to be array element type.
(defun extract-element-type (array)
  (let ((type (continuation-type array)))
    (if (array-type-p type)
	(array-type-element-type type)
	*universal-type*)))

;;; Array access functions return an object from the array, hence its
;;; type is going to be the array upgraded element type.
(defun extract-upgraded-element-type (array)
  (let ((type (continuation-type array)))
    (if (array-type-p type)
	(array-type-specialized-element-type type)
	*universal-type*)))

;;; The ``new-value'' for array setters must fit in the array, and the
;;; return type is going to be the same as the new-value for SETF
;;; functions.
(defun assert-new-value-type (new-value array)
  (let ((type (continuation-type array)))
    (when (array-type-p type)
      (assert-continuation-type new-value (array-type-element-type type))))
  (continuation-type new-value))

;;; Return true if Arg is NIL, or is a constant-continuation whose value is
;;; NIL, false otherwise.
(defun unsupplied-or-nil (arg)
  (declare (type (or continuation null) arg))
  (or (not arg)
      (and (constant-continuation-p arg)
	   (not (continuation-value arg)))))

(defoptimizer (array-in-bounds-p derive-type) ((array &rest indices))
  (assert-array-rank array (length indices))
  *universal-type*)

(defoptimizer (aref derive-type) ((array &rest indices) node)
  (assert-array-rank array (length indices))
  ;; If the node continuation has a single use then assert its type.
  (let ((cont (node-cont node)))
    (when (= (length (find-uses cont)) 1)
      (assert-continuation-type cont (extract-element-type array))))
  (extract-upgraded-element-type array))

(defoptimizer (%aset derive-type) ((array &rest stuff))
  (assert-array-rank array (1- (length stuff)))
  (assert-new-value-type (car (last stuff)) array))

(defoptimizer (hairy-data-vector-ref derive-type) ((array index))
  (extract-upgraded-element-type array))
(defoptimizer (data-vector-ref derive-type) ((array index))
  (extract-upgraded-element-type array))

(defoptimizer (data-vector-set derive-type) ((array index new-value))
  (assert-new-value-type new-value array))
(defoptimizer (hairy-data-vector-set derive-type) ((array index new-value))
  (assert-new-value-type new-value array))

;;; Figure out the type of the data vector if we know the argument element
;;; type.
(defoptimizer (%with-array-data derive-type) ((array start end))
  (let ((atype (continuation-type array)))
    (when (array-type-p atype)
      (values-specifier-type
       `(values (simple-array ,(type-specifier
				(array-type-element-type atype))
			      (*))
		index index index)))))

(defoptimizer (array-row-major-index derive-type) ((array &rest indices))
  (assert-array-rank array (length indices))
  *universal-type*)

(defoptimizer (row-major-aref derive-type) ((array index))
  (extract-upgraded-element-type array))

(defoptimizer (%set-row-major-aref derive-type) ((array index new-value))
  (assert-new-value-type new-value array))

(defoptimizer (make-array derive-type)
	      ((dims &key initial-element element-type initial-contents
		adjustable fill-pointer displaced-index-offset displaced-to))
  (let ((simple (and (unsupplied-or-nil adjustable)
		     (unsupplied-or-nil displaced-to)
		     (unsupplied-or-nil fill-pointer))))
    (specifier-type
     `(,(if simple 'simple-array 'array)
       ,(cond ((not element-type) 't)
	      ((constant-continuation-p element-type)
	       (continuation-value element-type))
	      (t
	       '*))
       ,(cond ((not simple)
	       '*)
	      ((constant-continuation-p dims)
	       (let ((val (continuation-value dims)))
		 (if (listp val) val (list val))))
	      ((csubtypep (continuation-type dims)
			  (specifier-type 'integer))
	       '(*))
	      (t
	       '*))))))

;;;; constructors

;;; Convert VECTOR into a MAKE-ARRAY followed by SETFs of all the
;;; elements.
(def-source-transform vector (&rest elements)
  (if (byte-compiling)
      (values nil t)
      (let ((len (length elements))
	    (n -1))
	(once-only ((n-vec `(make-array ,len)))
	  `(progn
	     ,@(mapcar #'(lambda (el)
			   (once-only ((n-val el))
			     `(locally (declare (optimize (safety 0)))
				       (setf (svref ,n-vec ,(incf n))
					     ,n-val))))
		       elements)
	     ,n-vec)))))

;;; Just convert it into a MAKE-ARRAY.
(def-source-transform make-string (length &key
					  (element-type ''base-char)
					  (initial-element default-init-char))
  (if (byte-compiling)
      (values nil t)
      `(make-array (the index ,length)
		   :element-type ,element-type
		   :initial-element ,initial-element)))

(defparameter *array-info*
  #((base-char #.default-init-char 8 sb!vm:simple-string-type)
    (single-float 0.0s0 32 sb!vm:simple-array-single-float-type)
    (double-float 0.0d0 64 sb!vm:simple-array-double-float-type)
    #!+long-float (long-float 0.0l0 #!+x86 96 #!+sparc 128
			      sb!vm:simple-array-long-float-type)
    (bit 0 1 sb!vm:simple-bit-vector-type)
    ((unsigned-byte 2) 0 2 sb!vm:simple-array-unsigned-byte-2-type)
    ((unsigned-byte 4) 0 4 sb!vm:simple-array-unsigned-byte-4-type)
    ((unsigned-byte 8) 0 8 sb!vm:simple-array-unsigned-byte-8-type)
    ((unsigned-byte 16) 0 16 sb!vm:simple-array-unsigned-byte-16-type)
    ((unsigned-byte 32) 0 32 sb!vm:simple-array-unsigned-byte-32-type)
    ((signed-byte 8) 0 8 sb!vm:simple-array-signed-byte-8-type)
    ((signed-byte 16) 0 16 sb!vm:simple-array-signed-byte-16-type)
    ((signed-byte 30) 0 32 sb!vm:simple-array-signed-byte-30-type)
    ((signed-byte 32) 0 32 sb!vm:simple-array-signed-byte-32-type)
    ((complex single-float) #C(0.0s0 0.0s0) 64
     sb!vm:simple-array-complex-single-float-type)
    ((complex double-float) #C(0.0d0 0.0d0) 128
     sb!vm:simple-array-complex-double-float-type)
    #!+long-float
    ((complex long-float) #C(0.0l0 0.0l0) #!+x86 192 #!+sparc 256
     sb!vm:simple-array-complex-long-float-type)
    (t 0 32 sb!vm:simple-vector-type)))

;;; The integer type restriction on the length ensures that it will be
;;; a vector. The lack of adjustable, fill-pointer, and displaced-to
;;; keywords ensures that it will be simple.
(deftransform make-array ((length &key initial-element element-type)
			  (integer &rest *))
  (let* ((eltype (cond ((not element-type) t)
		       ((not (constant-continuation-p element-type))
			(give-up-ir1-transform
			 "ELEMENT-TYPE is not constant."))
		       (t
			(continuation-value element-type))))
	 (len (if (constant-continuation-p length)
		  (continuation-value length)
		  '*))
	 (spec `(simple-array ,eltype (,len)))
	 (eltype-type (specifier-type eltype)))
    (multiple-value-bind (default-initial-element element-size typecode)
	(dovector (info *array-info*
			(give-up-ir1-transform
			 "cannot open-code creation of ~S" spec))
	  (when (csubtypep eltype-type (specifier-type (car info)))
	    (return (values-list (cdr info)))))
      (let* ((nwords-form
	      (if (>= element-size sb!vm:word-bits)
		  `(* length ,(/ element-size sb!vm:word-bits))
		  (let ((elements-per-word (/ 32 element-size)))
		    `(truncate (+ length
				  ,(if (eq 'sb!vm:simple-string-type typecode)
				     ;; (Simple strings are stored with an
				     ;; extra trailing null for convenience
				     ;; in calling out to C.)
				     elements-per-word
				     (1- elements-per-word)))
			       ,elements-per-word))))
	     (constructor
	      `(truly-the ,spec
			  (allocate-vector ,typecode length ,nwords-form))))
	(values
	 (cond ((and default-initial-element
		     (or (null initial-element)
			 (and (constant-continuation-p initial-element)
			      (eql (continuation-value initial-element)
				   default-initial-element))))
		(unless (csubtypep (ctype-of default-initial-element)
				   eltype-type)
		  ;; This situation arises e.g. in
		  ;;   (MAKE-ARRAY 4 :ELEMENT-TYPE '(INTEGER 1 5))
		  ;; ANSI's definition of MAKE-ARRAY says "If
		  ;; INITIAL-ELEMENT is not supplied, the consequences
		  ;; of later reading an uninitialized element of
		  ;; new-array are undefined," so this could be legal
		  ;; code as long as the user plans to write before he
		  ;; reads, and if he doesn't we're free to do
		  ;; anything we like. But in case the user doesn't
		  ;; know to write before he reads, we'll signal a
		  ;; STYLE-WARNING in case he didn't realize this.
		  ;;
		  ;; FIXME: should be STYLE-WARNING, not note
		  (compiler-note "The default initial element ~S is not a ~S."
				 default-initial-element
				 eltype))
		constructor)
	       (t
		`(truly-the ,spec (fill ,constructor initial-element))))
	 '((declare (type index length))))))))

;;; The list type restriction does not ensure that the result will be a
;;; multi-dimensional array. But the lack of adjustable, fill-pointer,
;;; and displaced-to keywords ensures that it will be simple.
(deftransform make-array ((dims &key initial-element element-type)
			  (list &rest *))
  (unless (or (null element-type) (constant-continuation-p element-type))
    (give-up-ir1-transform
     "The element-type is not constant; cannot open code array creation."))
  (unless (constant-continuation-p dims)
    (give-up-ir1-transform
     "The dimension list is not constant; cannot open code array creation."))
  (let ((dims (continuation-value dims)))
    (unless (every #'integerp dims)
      (give-up-ir1-transform
       "The dimension list contains something other than an integer: ~S"
       dims))
    (if (= (length dims) 1)
	`(make-array ',(car dims)
		     ,@(when initial-element
			 '(:initial-element initial-element))
		     ,@(when element-type
			 '(:element-type element-type)))
	(let* ((total-size (reduce #'* dims))
	       (rank (length dims))
	       (spec `(simple-array
		       ,(cond ((null element-type) t)
			      ((constant-continuation-p element-type)
			       (continuation-value element-type))
			      (t '*))
			   ,(make-list rank :initial-element '*))))
	  `(let ((header (make-array-header sb!vm:simple-array-type ,rank)))
	     (setf (%array-fill-pointer header) ,total-size)
	     (setf (%array-fill-pointer-p header) nil)
	     (setf (%array-available-elements header) ,total-size)
	     (setf (%array-data-vector header)
		   (make-array ,total-size
			       ,@(when element-type
				   '(:element-type element-type))
			       ,@(when initial-element
				   '(:initial-element initial-element))))
	     (setf (%array-displaced-p header) nil)
	     ,@(let ((axis -1))
		 (mapcar #'(lambda (dim)
			     `(setf (%array-dimension header ,(incf axis))
				    ,dim))
			 dims))
	     (truly-the ,spec header))))))

;;;; miscellaneous properties of arrays

;;; Transforms for various array properties. If the property is know
;;; at compile time because of a type spec, use that constant value.

;;; If we can tell the rank from the type info, use it instead.
(deftransform array-rank ((array))
  (let ((array-type (continuation-type array)))
    (unless (array-type-p array-type)
      (give-up-ir1-transform))
    (let ((dims (array-type-dimensions array-type)))
      (if (not (listp dims))
	  (give-up-ir1-transform
	   "The array rank is not known at compile time: ~S"
	   dims)
	  (length dims)))))

;;; If we know the dimensions at compile time, just use it. Otherwise,
;;; if we can tell that the axis is in bounds, convert to
;;; %ARRAY-DIMENSION (which just indirects the array header) or length
;;; (if it's simple and a vector).
(deftransform array-dimension ((array axis)
			       (array index))
  (unless (constant-continuation-p axis)
    (give-up-ir1-transform "The axis is not constant."))
  (let ((array-type (continuation-type array))
	(axis (continuation-value axis)))
    (unless (array-type-p array-type)
      (give-up-ir1-transform))
    (let ((dims (array-type-dimensions array-type)))
      (unless (listp dims)
	(give-up-ir1-transform
	 "The array dimensions are unknown; must call ARRAY-DIMENSION at runtime."))
      (unless (> (length dims) axis)
	(abort-ir1-transform "The array has dimensions ~S, ~D is too large."
			     dims
			     axis))
      (let ((dim (nth axis dims)))
	(cond ((integerp dim)
	       dim)
	      ((= (length dims) 1)
	       (ecase (array-type-complexp array-type)
		 ((t)
		  '(%array-dimension array 0))
		 ((nil)
		  '(length array))
		 ((:maybe)
		  (give-up-ir1-transform
		   "can't tell whether array is simple"))))
	      (t
	       '(%array-dimension array axis)))))))

;;; If the length has been declared and it's simple, just return it.
(deftransform length ((vector)
		      ((simple-array * (*))))
  (let ((type (continuation-type vector)))
    (unless (array-type-p type)
      (give-up-ir1-transform))
    (let ((dims (array-type-dimensions type)))
      (unless (and (listp dims) (integerp (car dims)))
	(give-up-ir1-transform
	 "Vector length is unknown, must call LENGTH at runtime."))
      (car dims))))

;;; All vectors can get their length by using VECTOR-LENGTH. If it's
;;; simple, it will extract the length slot from the vector. It it's
;;; complex, it will extract the fill pointer slot from the array
;;; header.
(deftransform length ((vector) (vector))
  '(vector-length vector))

;;; If a simple array with known dimensions, then VECTOR-LENGTH is a
;;; compile-time constant.
(deftransform vector-length ((vector) ((simple-array * (*))))
  (let ((vtype (continuation-type vector)))
    (if (array-type-p vtype)
	(let ((dim (first (array-type-dimensions vtype))))
	  (when (eq dim '*) (give-up-ir1-transform))
	  dim)
	(give-up-ir1-transform))))

;;; Again, if we can tell the results from the type, just use it.
;;; Otherwise, if we know the rank, convert into a computation based
;;; on array-dimension. We can wrap a TRULY-THE INDEX around the
;;; multiplications because we know that the total size must be an
;;; INDEX.
(deftransform array-total-size ((array)
				(array))
  (let ((array-type (continuation-type array)))
    (unless (array-type-p array-type)
      (give-up-ir1-transform))
    (let ((dims (array-type-dimensions array-type)))
      (unless (listp dims)
	(give-up-ir1-transform "can't tell the rank at compile time"))
      (if (member '* dims)
	  (do ((form 1 `(truly-the index
				   (* (array-dimension array ,i) ,form)))
	       (i 0 (1+ i)))
	      ((= i (length dims)) form))
	  (reduce #'* dims)))))

;;; Only complex vectors have fill pointers.
(deftransform array-has-fill-pointer-p ((array))
  (let ((array-type (continuation-type array)))
    (unless (array-type-p array-type)
      (give-up-ir1-transform))
    (let ((dims (array-type-dimensions array-type)))
      (if (and (listp dims) (not (= (length dims) 1)))
	  nil
	  (ecase (array-type-complexp array-type)
	    ((t)
	     t)
	    ((nil)
	     nil)
	    ((:maybe)
	     (give-up-ir1-transform
	      "The array type is ambiguous; must call ~
	      array-has-fill-pointer-p at runtime.")))))))

;;; Primitive used to verify indices into arrays. If we can tell at
;;; compile-time or we are generating unsafe code, don't bother with
;;; the VOP.
(deftransform %check-bound ((array dimension index))
  (unless (constant-continuation-p dimension)
    (give-up-ir1-transform))
  (let ((dim (continuation-value dimension)))
    `(the (integer 0 ,dim) index)))
(deftransform %check-bound ((array dimension index) * *
			    :policy (and (> speed safety) (= safety 0)))
  'index)

;;;; array accessors

;;; SVREF, %SVSET, SCHAR, %SCHARSET, CHAR,
;;; %CHARSET, SBIT, %SBITSET, BIT, %BITSET
;;;   --  source transforms.
;;;
;;; We convert all typed array accessors into aref and %aset with type
;;; assertions on the array.
(macrolet ((define-frob (reffer setter type)
	     `(progn
		(def-source-transform ,reffer (a &rest i)
		  (if (byte-compiling)
		      (values nil t)
		      `(aref (the ,',type ,a) ,@i)))
		(def-source-transform ,setter (a &rest i)
		  (if (byte-compiling)
		      (values nil t)
		      `(%aset (the ,',type ,a) ,@i))))))
  (define-frob svref %svset simple-vector)
  (define-frob schar %scharset simple-string)
  (define-frob char %charset string)
  (define-frob sbit %sbitset (simple-array bit))
  (define-frob bit %bitset (array bit)))

(macrolet (;; This is a handy macro for computing the row-major index
	   ;; given a set of indices. We wrap each index with a call
	   ;; to %CHECK-BOUND to ensure that everything works out
	   ;; correctly. We can wrap all the interior arithmetic with
	   ;; TRULY-THE INDEX because we know the the resultant
	   ;; row-major index must be an index.
	   (with-row-major-index ((array indices index &optional new-value)
				  &rest body)
	     `(let (n-indices dims)
		(dotimes (i (length ,indices))
		  (push (make-symbol (format nil "INDEX-~D" i)) n-indices)
		  (push (make-symbol (format nil "DIM-~D" i)) dims))
		(setf n-indices (nreverse n-indices))
		(setf dims (nreverse dims))
		`(lambda (,',array ,@n-indices
				   ,@',(when new-value (list new-value)))
		   (let* (,@(let ((,index -1))
			      (mapcar #'(lambda (name)
					  `(,name (array-dimension
						   ,',array
						   ,(incf ,index))))
				      dims))
			    (,',index
			     ,(if (null dims)
				  0
				(do* ((dims dims (cdr dims))
				      (indices n-indices (cdr indices))
				      (last-dim nil (car dims))
				      (form `(%check-bound ,',array
							   ,(car dims)
							   ,(car indices))
					    `(truly-the
					      index
					      (+ (truly-the index
							    (* ,form
							       ,last-dim))
						 (%check-bound
						  ,',array
						  ,(car dims)
						  ,(car indices))))))
				    ((null (cdr dims)) form)))))
		     ,',@body)))))

  ;; Just return the index after computing it.
  (deftransform array-row-major-index ((array &rest indices))
    (with-row-major-index (array indices index)
      index))

  ;; Convert AREF and %ASET into a HAIRY-DATA-VECTOR-REF (or
  ;; HAIRY-DATA-VECTOR-SET) with the set of indices replaced with the an
  ;; expression for the row major index.
  (deftransform aref ((array &rest indices))
    (with-row-major-index (array indices index)
      (hairy-data-vector-ref array index)))
  (deftransform %aset ((array &rest stuff))
    (let ((indices (butlast stuff)))
      (with-row-major-index (array indices index new-value)
	(hairy-data-vector-set array index new-value)))))

;;; Just convert into a HAIRY-DATA-VECTOR-REF (or
;;; HAIRY-DATA-VECTOR-SET) after checking that the index is inside the
;;; array total size.
(deftransform row-major-aref ((array index))
  `(hairy-data-vector-ref array
			  (%check-bound array (array-total-size array) index)))
(deftransform %set-row-major-aref ((array index new-value))
  `(hairy-data-vector-set array
			  (%check-bound array (array-total-size array) index)
			  new-value))

;;;; bit-vector array operation canonicalization
;;;;
;;;; We convert all bit-vector operations to have the result array
;;;; specified. This allows any result allocation to be open-coded,
;;;; and eliminates the need for any VM-dependent transforms to handle
;;;; these cases.

(dolist (fun '(bit-and bit-ior bit-xor bit-eqv bit-nand bit-nor bit-andc1
		       bit-andc2 bit-orc1 bit-orc2))
  ;; Make a result array if result is NIL or unsupplied.
  (deftransform fun ((bit-array-1 bit-array-2 &optional result-bit-array)
		     '(bit-vector bit-vector &optional null) '*
		     :eval-name t
		     :policy (>= speed space))
    `(,fun bit-array-1 bit-array-2
	   (make-array (length bit-array-1) :element-type 'bit)))
  ;; If result is T, make it the first arg.
  (deftransform fun ((bit-array-1 bit-array-2 result-bit-array)
		     '(bit-vector bit-vector (member t)) '*
		     :eval-name t)
    `(,fun bit-array-1 bit-array-2 bit-array-1)))

;;; Similar for BIT-NOT, but there is only one arg...
(deftransform bit-not ((bit-array-1 &optional result-bit-array)
		       (bit-vector &optional null) *
		       :policy (>= speed space))
  '(bit-not bit-array-1
	    (make-array (length bit-array-1) :element-type 'bit)))
(deftransform bit-not ((bit-array-1 result-bit-array)
		       (bit-vector (constant-argument t)))
  '(bit-not bit-array-1 bit-array-1))
;;; FIXME: What does (CONSTANT-ARGUMENT T) mean? Is it the same thing
;;; as (CONSTANT-ARGUMENT (MEMBER T)), or does it mean any constant
;;; value?

;;; Pick off some constant cases.
(deftransform array-header-p ((array) (array))
  (let ((type (continuation-type array)))
    (declare (optimize (safety 3)))
    (unless (array-type-p type)
      (give-up-ir1-transform))
    (let ((dims (array-type-dimensions type)))
      (cond ((csubtypep type (specifier-type '(simple-array * (*))))
	     ;; No array header.
	     nil)
	    ((and (listp dims) (> (length dims) 1))
	     ;; Multi-dimensional array, will have a header.
	     t)
	    (t
	     (give-up-ir1-transform))))))