;;;; This file contains stuff for maintaining a database of special
;;;; information about functions known to the compiler. This includes
-;;;; semantic information such as side-effects and type inference
+;;;; semantic information such as side effects and type inference
;;;; functions as well as transforms and IR2 translators.
;;;; This software is part of the SBCL system. See the README file for
(in-package "SB!C")
-(file-comment
- "$Header$")
+(/show0 "knownfun.lisp 17")
;;; IR1 boolean function attributes
;;;
-;;; There are a number of boolean attributes of known functions which we like
-;;; to have in IR1. This information is mostly side effect information of a
-;;; sort, but it is different from the kind of information we want in IR2. We
-;;; aren't interested in a fine breakdown of side effects, since we do very
-;;; little code motion on IR1. We are interested in some deeper semantic
-;;; properties such as whether it is safe to pass stack closures to.
-(def-boolean-attribute ir1
- ;; May call functions that are passed as arguments. In order to determine
- ;; what other effects are present, we must find the effects of all arguments
- ;; that may be functions.
+;;; There are a number of boolean attributes of known functions which
+;;; we like to have in IR1. This information is mostly side effect
+;;; information of a sort, but it is different from the kind of
+;;; information we want in IR2. We aren't interested in a fine
+;;; breakdown of side effects, since we do very little code motion on
+;;; IR1. We are interested in some deeper semantic properties such as
+;;; whether it is safe to pass stack closures to.
+;;;
+;;; FIXME: This whole notion of "bad" explicit attributes is bad for
+;;; maintenance. How confident are we that we have no defknowns for functions
+;;; with functional arguments that are missing the CALL attribute? Much better
+;;; to have NO-CALLS, as it is much less likely to break accidentally.
+(!def-boolean-attribute ir1
+ ;; may call functions that are passed as arguments. In order to
+ ;; determine what other effects are present, we must find the
+ ;; effects of all arguments that may be functions.
call
- ;; May incorporate function or number arguments into the result or somehow
- ;; pass them upward. Note that this applies to any argument that *might* be
- ;; a function or number, not just the arguments that always are.
- unsafe
- ;; May fail to return during correct execution. Errors are O.K.
+ ;; may fail to return during correct execution. Errors are O.K.
+ ;; UNUSED, BEWARE OF BITROT.
unwind
- ;; The (default) worst case. Includes all the other bad things, plus any
- ;; other possible bad thing. If this is present, the above bad attributes
- ;; will be explicitly present as well.
+ ;; the (default) worst case. Includes all the other bad things, plus
+ ;; any other possible bad thing. If this is present, the above bad
+ ;; attributes will be explicitly present as well.
any
- ;; May be constant-folded. The function has no side effects, but may be
- ;; affected by side effects on the arguments. e.g. SVREF, MAPC. Functions
- ;; that side-effect their arguments are not considered to be foldable.
- ;; Although it would be "legal" to constant fold them (since it "is an error"
- ;; to modify a constant), we choose not to mark these functions as foldable
- ;; in this database.
+ ;; all arguments are safe for dynamic extent.
+ ;; (We used to have an UNSAFE attribute, which was basically the inverse
+ ;; of this, but it was unused and bitrotted, so when we started making
+ ;; use of the information we flipped the name and meaning the safe way
+ ;; around.)
+ dx-safe
+ ;; may be constant-folded. The function has no side effects, but may
+ ;; be affected by side effects on the arguments. e.g. SVREF, MAPC.
+ ;; Functions that side-effect their arguments are not considered to
+ ;; be foldable. Although it would be "legal" to constant fold them
+ ;; (since it "is an error" to modify a constant), we choose not to
+ ;; mark these functions as foldable in this database.
foldable
- ;; May be eliminated if value is unused. The function has no side effects
- ;; except possibly CONS. If a function is defined to signal errors, then it
- ;; is not flushable even if it is movable or foldable.
+ ;; may be eliminated if value is unused. The function has no side
+ ;; effects except possibly cons. If a function might signal errors,
+ ;; then it is not flushable even if it is movable, foldable or
+ ;; unsafely-flushable. Implies UNSAFELY-FLUSHABLE. (In safe code
+ ;; type checking of arguments is always performed by the caller, so
+ ;; a function which SHOULD signal an error if arguments are not of
+ ;; declared types may be FLUSHABLE.)
flushable
- ;; May be moved with impunity. Has no side effects except possibly CONS, and
- ;; is affected only by its arguments.
+ ;; unsafe call may be eliminated if value is unused. The function
+ ;; has no side effects except possibly cons and signalling an error
+ ;; in the safe code. If a function MUST signal errors, then it is
+ ;; not unsafely-flushable even if it is movable or foldable.
+ unsafely-flushable
+ ;; return value is important, and ignoring it is probably a mistake.
+ ;; Unlike the other attributes, this is used only for style
+ ;; warnings and has no effect on optimization.
+ important-result
+ ;; may be moved with impunity. Has no side effects except possibly
+ ;; consing, and is affected only by its arguments.
+ ;; UNUSED, BEWARE OF BITROT.
movable
- ;; Function is a true predicate likely to be open-coded. Convert any
- ;; non-conditional uses into (IF <pred> T NIL).
+ ;; The function is a true predicate likely to be open-coded. Convert
+ ;; any non-conditional uses into (IF <pred> T NIL). Not usually
+ ;; specified to DEFKNOWN, since this is implementation dependent,
+ ;; and is usually automatically set by the DEFINE-VOP :CONDITIONAL
+ ;; option.
predicate
- ;; Inhibit any warning for compiling a recursive definition. (Normally the
- ;; compiler warns when compiling a recursive definition for a known function,
- ;; since it might be a botched interpreter stub.)
+ ;; Inhibit any warning for compiling a recursive definition.
+ ;; (Normally the compiler warns when compiling a recursive
+ ;; definition for a known function, since it might be a botched
+ ;; interpreter stub.)
recursive
- ;; Function does explicit argument type checking, so the declared type should
- ;; not be asserted when a definition is compiled.
- explicit-check)
-
-(defstruct (function-info #-sb-xc-host (:pure t))
- ;; Boolean attributes of this function.
- (attributes (required-argument) :type attributes)
- ;; A list of Transform structures describing transforms for this function.
+ ;; The function does explicit argument type checking, so the
+ ;; declared type should not be asserted when a definition is
+ ;; compiled.
+ explicit-check
+ ;; The function should always be translated by a VOP (i.e. it should
+ ;; should never be converted into a full call). This is used strictly
+ ;; as a consistency checking mechanism inside the compiler during IR2
+ ;; transformation.
+ always-translatable)
+
+(defstruct (fun-info #-sb-xc-host (:pure t))
+ ;; boolean attributes of this function.
+ (attributes (missing-arg) :type attributes)
+ ;; TRANSFORM structures describing transforms for this function
(transforms () :type list)
- ;; A function which computes the derived type for a call to this function by
- ;; examining the arguments. This is null when there is no special method for
- ;; this function.
+ ;; a function which computes the derived type for a call to this
+ ;; function by examining the arguments. This is null when there is
+ ;; no special method for this function.
(derive-type nil :type (or function null))
- ;; A function that does various unspecified code transformations by directly
- ;; hacking the IR. Returns true if further optimizations of the call
- ;; shouldn't be attempted.
+ ;; a function that does various unspecified code transformations by
+ ;; directly hacking the IR. Returns true if further optimizations of
+ ;; the call shouldn't be attempted.
;;
- ;; KLUDGE: This return convention (non-NIL if you shouldn't do further
- ;; optimiz'ns) is backwards from the return convention for transforms.
- ;; -- WHN 19990917
+ ;; KLUDGE: This return convention (non-NIL if you shouldn't do
+ ;; further optimiz'ns) is backwards from the return convention for
+ ;; transforms. -- WHN 19990917
(optimizer nil :type (or function null))
- ;; If true, a special-case LTN annotation method that is used in place of the
- ;; standard type/policy template selection. It may use arbitrary code to
- ;; choose a template, decide to do a full call, or conspire with the
- ;; IR2-Convert method to do almost anything. The Combination node is passed
- ;; as the argument.
+ ;; a function computing the constant or literal arguments which are
+ ;; destructively modified by the call.
+ (destroyed-constant-args nil :type (or function null))
+ ;; If true, a special-case LTN annotation method that is used in
+ ;; place of the standard type/policy template selection. It may use
+ ;; arbitrary code to choose a template, decide to do a full call, or
+ ;; conspire with the IR2-CONVERT method to do almost anything. The
+ ;; COMBINATION node is passed as the argument.
(ltn-annotate nil :type (or function null))
- ;; If true, the special-case IR2 conversion method for this function. This
- ;; deals with funny functions, and anything else that can't be handled using
- ;; the template mechanism. The Combination node and the IR2-Block are passed
- ;; as arguments.
+ ;; If true, the special-case IR2 conversion method for this
+ ;; function. This deals with funny functions, and anything else that
+ ;; can't be handled using the template mechanism. The COMBINATION
+ ;; node and the IR2-BLOCK are passed as arguments.
(ir2-convert nil :type (or function null))
- ;; A list of all the templates that could be used to translate this function
+ ;; If true, the function can stack-allocate the result. The
+ ;; COMBINATION node is passed as an argument.
+ (stack-allocate-result nil :type (or function null))
+ ;; If true, the function can add flow-sensitive type information
+ ;; about the state of the world after its execution. The COMBINATION
+ ;; node is passed as an argument, along with the current set of
+ ;; active constraints for the block. The function returns a
+ ;; sequence of constraints; a constraint is a triplet of a
+ ;; constraint kind (a symbol, see (defstruct (constraint ...)) in
+ ;; constraint.lisp) and arguments, either LVARs, LAMBDA-VARs, or
+ ;; CTYPEs. If any of these arguments is NIL, the constraint is
+ ;; skipped. This simplifies integration with OK-LVAR-LAMBDA-VAR,
+ ;; which maps LVARs to LAMBDA-VARs. An optional fourth value in
+ ;; each constraint flips the meaning of the constraint if it is
+ ;; non-NIL.
+ (constraint-propagate nil :type (or function null))
+ ;; If true, the function can add flow-sensitive type information
+ ;; depending on the truthiness of its return value. Returns two
+ ;; values, a LVAR and a CTYPE. The LVAR is of that CTYPE iff the
+ ;; function returns true.
+ ;; It may also return additional third and fourth values. Each is
+ ;; a sequence of constraints (see CONSTRAINT-PROPAGATE), for the
+ ;; consequent and alternative branches, respectively.
+ (constraint-propagate-if nil :type (or function null))
+ ;; all the templates that could be used to translate this function
;; into IR2, sorted by increasing cost.
(templates nil :type list)
- ;; If non-null, then this function is a unary type predicate for this type.
+ ;; If non-null, then this function is a unary type predicate for
+ ;; this type.
(predicate-type nil :type (or ctype null))
- ;; If non-null, use this function to annotate the known call for the byte
- ;; compiler. If it returns NIL, then change the call to :full.
- (byte-annotate nil :type (or function null))
- ;; If non-null, use this function to generate the byte code for this known
- ;; call. This function can only give up if there is a byte-annotate function
- ;; that arranged for the functional to be pushed onto the stack.
- (byte-compile nil :type (or function null)))
-
-(defprinter (function-info)
+ ;; If non-null, the index of the argument which becomes the result
+ ;; of the function.
+ (result-arg nil :type (or index null)))
+
+(defprinter (fun-info)
+ (attributes :test (not (zerop attributes))
+ :prin1 (decode-ir1-attributes attributes))
(transforms :test transforms)
(derive-type :test derive-type)
(optimizer :test optimizer)
(ltn-annotate :test ltn-annotate)
(ir2-convert :test ir2-convert)
(templates :test templates)
- (predicate-type :test predicate-type)
- (byte-annotate :test byte-annotate)
- (byte-compile :test byte-compile))
+ (predicate-type :test predicate-type))
\f
;;;; interfaces to defining macros
-;;; The TRANSFORM structure represents an IR1 transform.
-(defstruct transform
- ;; The function-type which enables this transform.
- (type (required-argument) :type ctype)
- ;; The transformation function. Takes the Combination node and Returns a
- ;; lambda, or throws out.
- (function (required-argument) :type function)
- ;; String used in efficency notes.
- (note (required-argument) :type string)
- ;; T if we should spew a failure note even if speed=brevity.
- (important nil :type (member t nil))
- ;; Usable for byte code, native code, or both.
- (when :native :type (member :byte :native :both)))
-
-(defprinter (transform) type note important when)
-
-;;; Grab the FUNCTION-INFO and enter the function, replacing any old
+;;; an IR1 transform
+(defstruct (transform (:copier nil))
+ ;; the function type which enables this transform.
+ ;;
+ ;; (Note that declaring this :TYPE FUN-TYPE probably wouldn't
+ ;; work because some function types, like (SPECIFIER-TYPE 'FUNCTION0
+ ;; itself, are represented as BUILT-IN-TYPE, and at least as of
+ ;; sbcl-0.pre7.54 or so, that's inconsistent with being a
+ ;; FUN-TYPE.)
+ (type (missing-arg) :type ctype)
+ ;; the transformation function. Takes the COMBINATION node and
+ ;; returns a lambda expression, or throws out.
+ (function (missing-arg) :type function)
+ ;; string used in efficiency notes
+ (note (missing-arg) :type string)
+ ;; T if we should emit a failure note even if SPEED=INHIBIT-WARNINGS.
+ (important nil :type (member t nil)))
+
+(defprinter (transform) type note important)
+
+;;; Grab the FUN-INFO and enter the function, replacing any old
;;; one with the same type and note.
(declaim (ftype (function (t list function &optional (or string null)
- (member t nil) (member :native :byte :both))
- *)
- %deftransform))
-(defun %deftransform (name type fun &optional note important (when :native))
+ (member t nil))
+ *)
+ %deftransform))
+(defun %deftransform (name type fun &optional note important)
(let* ((ctype (specifier-type type))
- (note (or note "optimize"))
- (info (function-info-or-lose name))
- (old (find-if (lambda (x)
- (and (type= (transform-type x) ctype)
- (string-equal (transform-note x) note)
- (eq (transform-important x) important)
- (eq (transform-when x) when)))
- (function-info-transforms info))))
- (if old
- (setf (transform-function old) fun (transform-note old) note)
- (push (make-transform :type ctype :function fun :note note
- :important important :when when)
- (function-info-transforms info)))
+ (note (or note "optimize"))
+ (info (fun-info-or-lose name))
+ (old (find-if (lambda (x)
+ (and (type= (transform-type x) ctype)
+ (string-equal (transform-note x) note)
+ (eq (transform-important x) important)))
+ (fun-info-transforms info))))
+ (cond (old
+ (style-warn 'sb!kernel:redefinition-with-deftransform
+ :transform old)
+ (setf (transform-function old) fun
+ (transform-note old) note))
+ (t
+ (push (make-transform :type ctype :function fun :note note
+ :important important)
+ (fun-info-transforms info))))
name))
-;;; Make a FUNCTION-INFO structure with the specified type, attributes
+;;; Make a FUN-INFO structure with the specified type, attributes
;;; and optimizers.
(declaim (ftype (function (list list attributes &key
- (:derive-type (or function null))
- (:optimizer (or function null)))
- *)
- %defknown))
-(defun %defknown (names type attributes &key derive-type optimizer)
+ (:derive-type (or function null))
+ (:optimizer (or function null))
+ (:destroyed-constant-args (or function null))
+ (:result-arg (or index null))
+ (:overwrite-fndb-silently boolean))
+ *)
+ %defknown))
+(defun %defknown (names type attributes
+ &key derive-type optimizer destroyed-constant-args result-arg
+ overwrite-fndb-silently)
(let ((ctype (specifier-type type))
- (info (make-function-info :attributes attributes
- :derive-type derive-type
- :optimizer optimizer))
- (target-env (or *backend-info-environment* *info-environment*)))
+ (info (make-fun-info :attributes attributes
+ :derive-type derive-type
+ :optimizer optimizer
+ :destroyed-constant-args destroyed-constant-args
+ :result-arg result-arg)))
(dolist (name names)
- (setf (info :function :type name target-env) ctype)
- (setf (info :function :where-from name target-env) :declared)
- (setf (info :function :kind name target-env) :function)
- (setf (info :function :info name target-env) info)))
+ (unless overwrite-fndb-silently
+ (let ((old-fun-info (info :function :info name)))
+ (when old-fun-info
+ ;; This is handled as an error because it's generally a bad
+ ;; thing to blow away all the old optimization stuff. It's
+ ;; also a potential source of sneaky bugs:
+ ;; DEFKNOWN FOO
+ ;; DEFTRANSFORM FOO
+ ;; DEFKNOWN FOO ; possibly hidden inside some macroexpansion
+ ;; ; Now the DEFTRANSFORM doesn't exist in the target Lisp.
+ ;; However, it's continuable because it might be useful to do
+ ;; it when testing new optimization stuff interactively.
+ (cerror "Go ahead, overwrite it."
+ "~@<overwriting old FUN-INFO ~2I~_~S ~I~_for ~S~:>"
+ old-fun-info name))))
+ (setf (info :function :type name) ctype)
+ (setf (info :function :where-from name) :declared)
+ (setf (info :function :kind name) :function)
+ (setf (info :function :info name) info)))
names)
-;;; Return the FUNCTION-INFO for NAME or die trying. Since this is
-;;; used by people who want to modify the info, and the info may be
+;;; Return the FUN-INFO for NAME or die trying. Since this is
+;;; used by callers who want to modify the info, and the info may be
;;; shared, we copy it. We don't have to copy the lists, since each
;;; function that has generators or transforms has already been
;;; through here.
-(declaim (ftype (function (t) function-info) function-info-or-lose))
-(defun function-info-or-lose (name)
- (let ((*info-environment* (or *backend-info-environment*
- *info-environment*)))
+(declaim (ftype (sfunction (t) fun-info) fun-info-or-lose))
+(defun fun-info-or-lose (name)
+ (let (;; FIXME: Do we need this rebinding here? It's a literal
+ ;; translation of the old CMU CL rebinding to
+ ;; (OR *BACKEND-INFO-ENVIRONMENT* *INFO-ENVIRONMENT*),
+ ;; and it's not obvious whether the rebinding to itself is
+ ;; needed that SBCL doesn't need *BACKEND-INFO-ENVIRONMENT*.
+ (*info-environment* *info-environment*))
(let ((old (info :function :info name)))
(unless old (error "~S is not a known function." name))
- (setf (info :function :info name) (copy-function-info old)))))
+ (setf (info :function :info name) (copy-fun-info old)))))
\f
;;;; generic type inference methods
;;; only be done when the result value is that argument.
(defun result-type-first-arg (call)
(declare (type combination call))
- (let ((cont (first (combination-args call))))
- (when cont (continuation-type cont))))
+ (let ((lvar (first (combination-args call))))
+ (when lvar (lvar-type lvar))))
(defun result-type-last-arg (call)
(declare (type combination call))
- (let ((cont (car (last (combination-args call)))))
- (when cont (continuation-type cont))))
+ (let ((lvar (car (last (combination-args call)))))
+ (when lvar (lvar-type lvar))))
;;; Derive the result type according to the float contagion rules, but
-;;; always return a float. This is used for irrational functions that preserve
-;;; realness of their arguments.
+;;; always return a float. This is used for irrational functions that
+;;; preserve realness of their arguments.
(defun result-type-float-contagion (call)
(declare (type combination call))
(reduce #'numeric-contagion (combination-args call)
- :key #'continuation-type
- :initial-value (specifier-type 'single-float)))
+ :key #'lvar-type
+ :initial-value (specifier-type 'single-float)))
-;;; Return a closure usable as a derive-type method for accessing the N'th
-;;; argument. If arg is a list, result is a list. If arg is a vector, result
-;;; is a vector with the same element type.
+;;; Return a closure usable as a derive-type method for accessing the
+;;; N'th argument. If arg is a list, result is a list. If arg is a
+;;; vector, result is a vector with the same element type.
(defun sequence-result-nth-arg (n)
- #'(lambda (call)
- (declare (type combination call))
- (let ((cont (nth (1- n) (combination-args call))))
- (when cont
- (let ((type (continuation-type cont)))
- (if (array-type-p type)
- (specifier-type
- `(vector ,(type-specifier (array-type-element-type type))))
- (let ((ltype (specifier-type 'list)))
- (when (csubtypep type ltype)
- ltype))))))))
-
-;;; Derive the type to be the type specifier which is the N'th arg.
+ (lambda (call)
+ (declare (type combination call))
+ (let ((lvar (nth (1- n) (combination-args call))))
+ (when lvar
+ (let ((type (lvar-type lvar)))
+ (if (array-type-p type)
+ (specifier-type
+ `(vector ,(type-specifier (array-type-element-type type))))
+ (let ((ltype (specifier-type 'list)))
+ (when (csubtypep type ltype)
+ ltype))))))))
+
+;;; Derive the type to be the type specifier which is the Nth arg.
(defun result-type-specifier-nth-arg (n)
(lambda (call)
(declare (type combination call))
- (let ((cont (nth (1- n) (combination-args call))))
- (when (and cont (constant-continuation-p cont))
- (specifier-type (continuation-value cont))))))
+ (let ((lvar (nth (1- n) (combination-args call))))
+ (when (and lvar (constant-lvar-p lvar))
+ (careful-specifier-type (lvar-value lvar))))))
+
+;;; Derive the type to be the type specifier which is the Nth arg,
+;;; with the additional restriptions noted in the CLHS for STRING and
+;;; SIMPLE-STRING, defined to specialize on CHARACTER, and for VECTOR
+;;; (under the page for MAKE-SEQUENCE).
+(defun creation-result-type-specifier-nth-arg (n)
+ (lambda (call)
+ (declare (type combination call))
+ (let ((lvar (nth (1- n) (combination-args call))))
+ (when (and lvar (constant-lvar-p lvar))
+ (let* ((specifier (lvar-value lvar))
+ (lspecifier (if (atom specifier) (list specifier) specifier)))
+ (cond
+ ((eq (car lspecifier) 'string)
+ (destructuring-bind (string &rest size)
+ lspecifier
+ (declare (ignore string))
+ (careful-specifier-type
+ `(vector character ,@(when size size)))))
+ ((eq (car lspecifier) 'simple-string)
+ (destructuring-bind (simple-string &rest size)
+ lspecifier
+ (declare (ignore simple-string))
+ (careful-specifier-type
+ `(simple-array character ,@(if size (list size) '((*)))))))
+ (t
+ (let ((ctype (careful-specifier-type specifier)))
+ (if (and (array-type-p ctype)
+ (eq (array-type-specialized-element-type ctype)
+ *wild-type*))
+ ;; I don't think I'm allowed to modify what I get
+ ;; back from SPECIFIER-TYPE; it is, after all,
+ ;; cached. Better copy it, then.
+ (let ((real-ctype (copy-structure ctype)))
+ (setf (array-type-element-type real-ctype)
+ *universal-type*
+ (array-type-specialized-element-type real-ctype)
+ *universal-type*)
+ real-ctype)
+ ctype)))))))))
+
+(defun remove-non-constants-and-nils (fun)
+ (lambda (list)
+ (remove-if-not #'lvar-value
+ (remove-if-not #'constant-lvar-p (funcall fun list)))))
+
+;;; FIXME: bad name (first because it uses 1-based indexing; second
+;;; because it doesn't get the nth constant arguments)
+(defun nth-constant-args (&rest indices)
+ (lambda (list)
+ (let (result)
+ (do ((i 1 (1+ i))
+ (list list (cdr list))
+ (indices indices))
+ ((null indices) (nreverse result))
+ (when (= i (car indices))
+ (when (constant-lvar-p (car list))
+ (push (car list) result))
+ (setf indices (cdr indices)))))))
+
+;;; FIXME: a number of the sequence functions not only do not destroy
+;;; their argument if it is empty, but also leave it alone if :start
+;;; and :end bound a null sequence, or if :count is 0. This test is a
+;;; bit complicated to implement, verging on the impossible, but for
+;;; extra points (fill #\1 "abc" :start 0 :end 0) should not cause a
+;;; warning.
+(defun nth-constant-nonempty-sequence-args (&rest indices)
+ (lambda (list)
+ (let (result)
+ (do ((i 1 (1+ i))
+ (list list (cdr list))
+ (indices indices))
+ ((null indices) (nreverse result))
+ (when (= i (car indices))
+ (when (constant-lvar-p (car list))
+ (let ((value (lvar-value (car list))))
+ (unless (or (typep value 'null)
+ (typep value '(vector * 0)))
+ (push (car list) result))))
+ (setf indices (cdr indices)))))))
+
+(/show0 "knownfun.lisp end of file")
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