1 ;;;; This file contains stuff for maintaining a database of special
2 ;;;; information about functions known to the compiler. This includes
3 ;;;; semantic information such as side effects and type inference
4 ;;;; functions as well as transforms and IR2 translators.
6 ;;;; This software is part of the SBCL system. See the README file for
9 ;;;; This software is derived from the CMU CL system, which was
10 ;;;; written at Carnegie Mellon University and released into the
11 ;;;; public domain. The software is in the public domain and is
12 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
13 ;;;; files for more information.
17 (/show0
"knownfun.lisp 17")
19 ;;; IR1 boolean function attributes
21 ;;; There are a number of boolean attributes of known functions which
22 ;;; we like to have in IR1. This information is mostly side effect
23 ;;; information of a sort, but it is different from the kind of
24 ;;; information we want in IR2. We aren't interested in a fine
25 ;;; breakdown of side effects, since we do very little code motion on
26 ;;; IR1. We are interested in some deeper semantic properties such as
27 ;;; whether it is safe to pass stack closures to.
28 (!def-boolean-attribute ir1
29 ;; may call functions that are passed as arguments. In order to
30 ;; determine what other effects are present, we must find the
31 ;; effects of all arguments that may be functions.
33 ;; may incorporate function or number arguments into the result or
34 ;; somehow pass them upward. Note that this applies to any argument
35 ;; that *might* be a function or number, not just the arguments that
38 ;; may fail to return during correct execution. Errors are O.K.
40 ;; the (default) worst case. Includes all the other bad things, plus
41 ;; any other possible bad thing. If this is present, the above bad
42 ;; attributes will be explicitly present as well.
44 ;; may be constant-folded. The function has no side effects, but may
45 ;; be affected by side effects on the arguments. e.g. SVREF, MAPC.
46 ;; Functions that side-effect their arguments are not considered to
47 ;; be foldable. Although it would be "legal" to constant fold them
48 ;; (since it "is an error" to modify a constant), we choose not to
49 ;; mark these functions as foldable in this database.
51 ;; may be eliminated if value is unused. The function has no side
52 ;; effects except possibly cons. If a function might signal errors,
53 ;; then it is not flushable even if it is movable, foldable or
54 ;; unsafely-flushable. Implies UNSAFELY-FLUSHABLE. (In safe code
55 ;; type checking of arguments is always performed by the caller, so
56 ;; a function which SHOULD signal an error if arguments are not of
57 ;; declared types may be FLUSHABLE.)
59 ;; unsafe call may be eliminated if value is unused. The function
60 ;; has no side effects except possibly cons and signalling an error
61 ;; in the safe code. If a function MUST signal errors, then it is
62 ;; not unsafely-flushable even if it is movable or foldable.
64 ;; may be moved with impunity. Has no side effects except possibly
65 ;; consing, and is affected only by its arguments.
67 ;; The function is a true predicate likely to be open-coded. Convert
68 ;; any non-conditional uses into (IF <pred> T NIL). Not usually
69 ;; specified to DEFKNOWN, since this is implementation dependent,
70 ;; and is usually automatically set by the DEFINE-VOP :CONDITIONAL
73 ;; Inhibit any warning for compiling a recursive definition.
74 ;; (Normally the compiler warns when compiling a recursive
75 ;; definition for a known function, since it might be a botched
78 ;; The function does explicit argument type checking, so the
79 ;; declared type should not be asserted when a definition is
83 (defstruct (fun-info #-sb-xc-host
(:pure t
))
84 ;; boolean attributes of this function.
85 (attributes (missing-arg) :type attributes
)
86 ;; TRANSFORM structures describing transforms for this function
87 (transforms () :type list
)
88 ;; a function which computes the derived type for a call to this
89 ;; function by examining the arguments. This is null when there is
90 ;; no special method for this function.
91 (derive-type nil
:type
(or function null
))
92 ;; a function that does various unspecified code transformations by
93 ;; directly hacking the IR. Returns true if further optimizations of
94 ;; the call shouldn't be attempted.
96 ;; KLUDGE: This return convention (non-NIL if you shouldn't do
97 ;; further optimiz'ns) is backwards from the return convention for
98 ;; transforms. -- WHN 19990917
99 (optimizer nil
:type
(or function null
))
100 ;; If true, a special-case LTN annotation method that is used in
101 ;; place of the standard type/policy template selection. It may use
102 ;; arbitrary code to choose a template, decide to do a full call, or
103 ;; conspire with the IR2-CONVERT method to do almost anything. The
104 ;; COMBINATION node is passed as the argument.
105 (ltn-annotate nil
:type
(or function null
))
106 ;; If true, the special-case IR2 conversion method for this
107 ;; function. This deals with funny functions, and anything else that
108 ;; can't be handled using the template mechanism. The Combination
109 ;; node and the IR2-BLOCK are passed as arguments.
110 (ir2-convert nil
:type
(or function null
))
111 ;; all the templates that could be used to translate this function
112 ;; into IR2, sorted by increasing cost.
113 (templates nil
:type list
)
114 ;; If non-null, then this function is a unary type predicate for
116 (predicate-type nil
:type
(or ctype null
)))
118 (defprinter (fun-info)
119 (transforms :test transforms
)
120 (derive-type :test derive-type
)
121 (optimizer :test optimizer
)
122 (ltn-annotate :test ltn-annotate
)
123 (ir2-convert :test ir2-convert
)
124 (templates :test templates
)
125 (predicate-type :test predicate-type
))
127 ;;;; interfaces to defining macros
130 (defstruct (transform (:copier nil
))
131 ;; the function type which enables this transform.
133 ;; (Note that declaring this :TYPE FUN-TYPE probably wouldn't
134 ;; work because some function types, like (SPECIFIER-TYPE 'FUNCTION0
135 ;; itself, are represented as BUILT-IN-TYPE, and at least as of
136 ;; sbcl-0.pre7.54 or so, that's inconsistent with being a
138 (type (missing-arg) :type ctype
)
139 ;; the transformation function. Takes the COMBINATION node and
140 ;; returns a lambda expression, or throws out.
141 (function (missing-arg) :type function
)
142 ;; string used in efficiency notes
143 (note (missing-arg) :type string
)
144 ;; T if we should emit a failure note even if SPEED=INHIBIT-WARNINGS.
145 (important nil
:type
(member t nil
)))
147 (defprinter (transform) type note important
)
149 ;;; Grab the FUN-INFO and enter the function, replacing any old
150 ;;; one with the same type and note.
151 (declaim (ftype (function (t list function
&optional
(or string null
)
155 (defun %deftransform
(name type fun
&optional note important
)
156 (let* ((ctype (specifier-type type
))
157 (note (or note
"optimize"))
158 (info (fun-info-or-lose name
))
159 (old (find-if (lambda (x)
160 (and (type= (transform-type x
) ctype
)
161 (string-equal (transform-note x
) note
)
162 (eq (transform-important x
) important
)))
163 (fun-info-transforms info
))))
165 (setf (transform-function old
) fun
166 (transform-note old
) note
)
167 (push (make-transform :type ctype
:function fun
:note note
168 :important important
)
169 (fun-info-transforms info
)))
172 ;;; Make a FUN-INFO structure with the specified type, attributes
174 (declaim (ftype (function (list list attributes
&key
175 (:derive-type
(or function null
))
176 (:optimizer
(or function null
)))
179 (defun %defknown
(names type attributes
&key derive-type optimizer
)
180 (let ((ctype (specifier-type type
))
181 (info (make-fun-info :attributes attributes
182 :derive-type derive-type
183 :optimizer optimizer
))
184 (target-env *info-environment
*))
186 (let ((old-fun-info (info :function
:info name
)))
188 ;; This is handled as an error because it's generally a bad
189 ;; thing to blow away all the old optimization stuff. It's
190 ;; also a potential source of sneaky bugs:
193 ;; DEFKNOWN FOO ; possibly hidden inside some macroexpansion
194 ;; ; Now the DEFTRANSFORM doesn't exist in the target Lisp.
195 ;; However, it's continuable because it might be useful to do
196 ;; it when testing new optimization stuff interactively.
197 (cerror "Go ahead, overwrite it."
198 "~@<overwriting old FUN-INFO ~2I~_~S ~I~_for ~S~:>"
200 (setf (info :function
:type name target-env
) ctype
)
201 (setf (info :function
:where-from name target-env
) :declared
)
202 (setf (info :function
:kind name target-env
) :function
)
203 (setf (info :function
:info name target-env
) info
)))
206 ;;; Return the FUN-INFO for NAME or die trying. Since this is
207 ;;; used by callers who want to modify the info, and the info may be
208 ;;; shared, we copy it. We don't have to copy the lists, since each
209 ;;; function that has generators or transforms has already been
211 (declaim (ftype (function (t) fun-info
) fun-info-or-lose
))
212 (defun fun-info-or-lose (name)
213 (let (;; FIXME: Do we need this rebinding here? It's a literal
214 ;; translation of the old CMU CL rebinding to
215 ;; (OR *BACKEND-INFO-ENVIRONMENT* *INFO-ENVIRONMENT*),
216 ;; and it's not obvious whether the rebinding to itself is
217 ;; needed that SBCL doesn't need *BACKEND-INFO-ENVIRONMENT*.
218 (*info-environment
* *info-environment
*))
219 (let ((old (info :function
:info name
)))
220 (unless old
(error "~S is not a known function." name
))
221 (setf (info :function
:info name
) (copy-fun-info old
)))))
223 ;;;; generic type inference methods
225 ;;; Derive the type to be the type of the xxx'th arg. This can normally
226 ;;; only be done when the result value is that argument.
227 (defun result-type-first-arg (call)
228 (declare (type combination call
))
229 (let ((cont (first (combination-args call
))))
230 (when cont
(continuation-type cont
))))
231 (defun result-type-last-arg (call)
232 (declare (type combination call
))
233 (let ((cont (car (last (combination-args call
)))))
234 (when cont
(continuation-type cont
))))
236 ;;; Derive the result type according to the float contagion rules, but
237 ;;; always return a float. This is used for irrational functions that
238 ;;; preserve realness of their arguments.
239 (defun result-type-float-contagion (call)
240 (declare (type combination call
))
241 (reduce #'numeric-contagion
(combination-args call
)
242 :key
#'continuation-type
243 :initial-value
(specifier-type 'single-float
)))
245 ;;; Return a closure usable as a derive-type method for accessing the
246 ;;; N'th argument. If arg is a list, result is a list. If arg is a
247 ;;; vector, result is a vector with the same element type.
248 (defun sequence-result-nth-arg (n)
250 (declare (type combination call
))
251 (let ((cont (nth (1- n
) (combination-args call
))))
253 (let ((type (continuation-type cont
)))
254 (if (array-type-p type
)
256 `(vector ,(type-specifier (array-type-element-type type
))))
257 (let ((ltype (specifier-type 'list
)))
258 (when (csubtypep type ltype
)
261 ;;; Derive the type to be the type specifier which is the N'th arg.
262 (defun result-type-specifier-nth-arg (n)
264 (declare (type combination call
))
265 (let ((cont (nth (1- n
) (combination-args call
))))
266 (when (and cont
(constant-continuation-p cont
))
267 (careful-specifier-type (continuation-value cont
))))))
269 (/show0
"knownfun.lisp end of file")