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.
56 ;; unsafe call may be eliminated if value is unused. The function
57 ;; has no side effects except possibly cons and signalling an error
58 ;; in the safe code. If a function MUST signal errors, then it is
59 ;; not unsafely-flushable even if it is movable or foldable.
61 ;; may be moved with impunity. Has no side effects except possibly
62 ;; consing, and is affected only by its arguments.
64 ;; The function is a true predicate likely to be open-coded. Convert
65 ;; any non-conditional uses into (IF <pred> T NIL). Not usually
66 ;; specified to DEFKNOWN, since this is implementation dependent,
67 ;; and is usually automatically set by the DEFINE-VOP :CONDITIONAL
70 ;; Inhibit any warning for compiling a recursive definition.
71 ;; (Normally the compiler warns when compiling a recursive
72 ;; definition for a known function, since it might be a botched
75 ;; The function does explicit argument type checking, so the
76 ;; declared type should not be asserted when a definition is
80 (defstruct (fun-info #-sb-xc-host (:pure t))
81 ;; boolean attributes of this function.
82 (attributes (missing-arg) :type attributes)
83 ;; TRANSFORM structures describing transforms for this function
84 (transforms () :type list)
85 ;; a function which computes the derived type for a call to this
86 ;; function by examining the arguments. This is null when there is
87 ;; no special method for this function.
88 (derive-type nil :type (or function null))
89 ;; a function that does various unspecified code transformations by
90 ;; directly hacking the IR. Returns true if further optimizations of
91 ;; the call shouldn't be attempted.
93 ;; KLUDGE: This return convention (non-NIL if you shouldn't do
94 ;; further optimiz'ns) is backwards from the return convention for
95 ;; transforms. -- WHN 19990917
96 (optimizer nil :type (or function null))
97 ;; If true, a special-case LTN annotation method that is used in
98 ;; place of the standard type/policy template selection. It may use
99 ;; arbitrary code to choose a template, decide to do a full call, or
100 ;; conspire with the IR2-CONVERT method to do almost anything. The
101 ;; COMBINATION node is passed as the argument.
102 (ltn-annotate nil :type (or function null))
103 ;; If true, the special-case IR2 conversion method for this
104 ;; function. This deals with funny functions, and anything else that
105 ;; can't be handled using the template mechanism. The Combination
106 ;; node and the IR2-BLOCK are passed as arguments.
107 (ir2-convert nil :type (or function null))
108 ;; all the templates that could be used to translate this function
109 ;; into IR2, sorted by increasing cost.
110 (templates nil :type list)
111 ;; If non-null, then this function is a unary type predicate for
113 (predicate-type nil :type (or ctype null)))
115 (defprinter (fun-info)
116 (transforms :test transforms)
117 (derive-type :test derive-type)
118 (optimizer :test optimizer)
119 (ltn-annotate :test ltn-annotate)
120 (ir2-convert :test ir2-convert)
121 (templates :test templates)
122 (predicate-type :test predicate-type))
124 ;;;; interfaces to defining macros
127 (defstruct (transform (:copier nil))
128 ;; the function type which enables this transform.
130 ;; (Note that declaring this :TYPE FUN-TYPE probably wouldn't
131 ;; work because some function types, like (SPECIFIER-TYPE 'FUNCTION0
132 ;; itself, are represented as BUILT-IN-TYPE, and at least as of
133 ;; sbcl-0.pre7.54 or so, that's inconsistent with being a
135 (type (missing-arg) :type ctype)
136 ;; the transformation function. Takes the COMBINATION node and
137 ;; returns a lambda expression, or throws out.
138 (function (missing-arg) :type function)
139 ;; string used in efficiency notes
140 (note (missing-arg) :type string)
141 ;; T if we should emit a failure note even if SPEED=INHIBIT-WARNINGS.
142 (important nil :type (member t nil)))
144 (defprinter (transform) type note important)
146 ;;; Grab the FUN-INFO and enter the function, replacing any old
147 ;;; one with the same type and note.
148 (declaim (ftype (function (t list function &optional (or string null)
152 (defun %deftransform (name type fun &optional note important)
153 (let* ((ctype (specifier-type type))
154 (note (or note "optimize"))
155 (info (fun-info-or-lose name))
156 (old (find-if (lambda (x)
157 (and (type= (transform-type x) ctype)
158 (string-equal (transform-note x) note)
159 (eq (transform-important x) important)))
160 (fun-info-transforms info))))
162 (setf (transform-function old) fun
163 (transform-note old) note)
164 (push (make-transform :type ctype :function fun :note note
165 :important important)
166 (fun-info-transforms info)))
169 ;;; Make a FUN-INFO structure with the specified type, attributes
171 (declaim (ftype (function (list list attributes &key
172 (:derive-type (or function null))
173 (:optimizer (or function null)))
176 (defun %defknown (names type attributes &key derive-type optimizer)
177 (let ((ctype (specifier-type type))
178 (info (make-fun-info :attributes attributes
179 :derive-type derive-type
180 :optimizer optimizer))
181 (target-env *info-environment*))
183 (let ((old-fun-info (info :function :info name)))
185 ;; This is handled as an error because it's generally a bad
186 ;; thing to blow away all the old optimization stuff. It's
187 ;; also a potential source of sneaky bugs:
190 ;; DEFKNOWN FOO ; possibly hidden inside some macroexpansion
191 ;; ; Now the DEFTRANSFORM doesn't exist in the target Lisp.
192 ;; However, it's continuable because it might be useful to do
193 ;; it when testing new optimization stuff interactively.
194 (cerror "Go ahead, overwrite it."
195 "~@<overwriting old FUN-INFO ~2I~_~S ~I~_for ~S~:>"
197 (setf (info :function :type name target-env) ctype)
198 (setf (info :function :where-from name target-env) :declared)
199 (setf (info :function :kind name target-env) :function)
200 (setf (info :function :info name target-env) info)))
203 ;;; Return the FUN-INFO for NAME or die trying. Since this is
204 ;;; used by callers who want to modify the info, and the info may be
205 ;;; shared, we copy it. We don't have to copy the lists, since each
206 ;;; function that has generators or transforms has already been
208 (declaim (ftype (function (t) fun-info) fun-info-or-lose))
209 (defun fun-info-or-lose (name)
210 (let (;; FIXME: Do we need this rebinding here? It's a literal
211 ;; translation of the old CMU CL rebinding to
212 ;; (OR *BACKEND-INFO-ENVIRONMENT* *INFO-ENVIRONMENT*),
213 ;; and it's not obvious whether the rebinding to itself is
214 ;; needed that SBCL doesn't need *BACKEND-INFO-ENVIRONMENT*.
215 (*info-environment* *info-environment*))
216 (let ((old (info :function :info name)))
217 (unless old (error "~S is not a known function." name))
218 (setf (info :function :info name) (copy-fun-info old)))))
220 ;;;; generic type inference methods
222 ;;; Derive the type to be the type of the xxx'th arg. This can normally
223 ;;; only be done when the result value is that argument.
224 (defun result-type-first-arg (call)
225 (declare (type combination call))
226 (let ((cont (first (combination-args call))))
227 (when cont (continuation-type cont))))
228 (defun result-type-last-arg (call)
229 (declare (type combination call))
230 (let ((cont (car (last (combination-args call)))))
231 (when cont (continuation-type cont))))
233 ;;; Derive the result type according to the float contagion rules, but
234 ;;; always return a float. This is used for irrational functions that
235 ;;; preserve realness of their arguments.
236 (defun result-type-float-contagion (call)
237 (declare (type combination call))
238 (reduce #'numeric-contagion (combination-args call)
239 :key #'continuation-type
240 :initial-value (specifier-type 'single-float)))
242 ;;; Return a closure usable as a derive-type method for accessing the
243 ;;; N'th argument. If arg is a list, result is a list. If arg is a
244 ;;; vector, result is a vector with the same element type.
245 (defun sequence-result-nth-arg (n)
247 (declare (type combination call))
248 (let ((cont (nth (1- n) (combination-args call))))
250 (let ((type (continuation-type cont)))
251 (if (array-type-p type)
253 `(vector ,(type-specifier (array-type-element-type type))))
254 (let ((ltype (specifier-type 'list)))
255 (when (csubtypep type ltype)
258 ;;; Derive the type to be the type specifier which is the N'th arg.
259 (defun result-type-specifier-nth-arg (n)
261 (declare (type combination call))
262 (let ((cont (nth (1- n) (combination-args call))))
263 (when (and cont (constant-continuation-p cont))
264 (careful-specifier-type (continuation-value cont))))))
266 (/show0 "knownfun.lisp end of file")