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 we like
22 ;;; to have in IR1. This information is mostly side effect information of a
23 ;;; sort, but it is different from the kind of information we want in IR2. We
24 ;;; aren't interested in a fine breakdown of side effects, since we do very
25 ;;; little code motion on IR1. We are interested in some deeper semantic
26 ;;; properties such as whether it is safe to pass stack closures to.
27 (def-boolean-attribute ir1
28 ;; May call functions that are passed as arguments. In order to determine
29 ;; what other effects are present, we must find the effects of all arguments
30 ;; that may be functions.
32 ;; May incorporate function or number arguments into the result or somehow
33 ;; pass them upward. Note that this applies to any argument that *might* be
34 ;; a function or number, not just the arguments that always are.
36 ;; May fail to return during correct execution. Errors are O.K.
38 ;; The (default) worst case. Includes all the other bad things, plus any
39 ;; other possible bad thing. If this is present, the above bad attributes
40 ;; will be explicitly present as well.
42 ;; May be constant-folded. The function has no side effects, but may be
43 ;; affected by side effects on the arguments. e.g. SVREF, MAPC. Functions
44 ;; that side-effect their arguments are not considered to be foldable.
45 ;; Although it would be "legal" to constant fold them (since it "is an error"
46 ;; to modify a constant), we choose not to mark these functions as foldable
49 ;; May be eliminated if value is unused. The function has no side effects
50 ;; except possibly CONS. If a function is defined to signal errors, then it
51 ;; is not flushable even if it is movable or foldable.
53 ;; May be moved with impunity. Has no side effects except possibly CONS, and
54 ;; is affected only by its arguments.
56 ;; Function is a true predicate likely to be open-coded. Convert any
57 ;; non-conditional uses into (IF <pred> T NIL).
59 ;; Inhibit any warning for compiling a recursive definition. (Normally the
60 ;; compiler warns when compiling a recursive definition for a known function,
61 ;; since it might be a botched interpreter stub.)
63 ;; Function does explicit argument type checking, so the declared type should
64 ;; not be asserted when a definition is compiled.
67 (defstruct (function-info #-sb-xc-host (:pure t))
68 ;; Boolean attributes of this function.
69 (attributes (required-argument) :type attributes)
70 ;; A list of Transform structures describing transforms for this function.
71 (transforms () :type list)
72 ;; A function which computes the derived type for a call to this function by
73 ;; examining the arguments. This is null when there is no special method for
75 (derive-type nil :type (or function null))
76 ;; A function that does various unspecified code transformations by directly
77 ;; hacking the IR. Returns true if further optimizations of the call
78 ;; shouldn't be attempted.
80 ;; KLUDGE: This return convention (non-NIL if you shouldn't do further
81 ;; optimiz'ns) is backwards from the return convention for transforms.
83 (optimizer nil :type (or function null))
84 ;; If true, a special-case LTN annotation method that is used in place of the
85 ;; standard type/policy template selection. It may use arbitrary code to
86 ;; choose a template, decide to do a full call, or conspire with the
87 ;; IR2-Convert method to do almost anything. The Combination node is passed
89 (ltn-annotate nil :type (or function null))
90 ;; If true, the special-case IR2 conversion method for this function. This
91 ;; deals with funny functions, and anything else that can't be handled using
92 ;; the template mechanism. The Combination node and the IR2-Block are passed
94 (ir2-convert nil :type (or function null))
95 ;; A list of all the templates that could be used to translate this function
96 ;; into IR2, sorted by increasing cost.
97 (templates nil :type list)
98 ;; If non-null, then this function is a unary type predicate for this type.
99 (predicate-type nil :type (or ctype null))
100 ;; If non-null, use this function to annotate the known call for the byte
101 ;; compiler. If it returns NIL, then change the call to :full.
102 (byte-annotate nil :type (or function null)))
104 (defprinter (function-info)
105 (transforms :test transforms)
106 (derive-type :test derive-type)
107 (optimizer :test optimizer)
108 (ltn-annotate :test ltn-annotate)
109 (ir2-convert :test ir2-convert)
110 (templates :test templates)
111 (predicate-type :test predicate-type)
112 (byte-annotate :test byte-annotate))
114 ;;;; interfaces to defining macros
117 (defstruct (transform (:copier nil))
118 ;; the function-type which enables this transform
119 (type (required-argument) :type ctype)
120 ;; the transformation function. Takes the COMBINATION node and returns a
121 ;; lambda, or throws out.
122 (function (required-argument) :type function)
123 ;; string used in efficiency notes
124 (note (required-argument) :type string)
125 ;; T if we should emit a failure note even if SPEED=INHIBIT-WARNINGS.
126 (important nil :type (member t nil))
127 ;; usable for byte code, native code, or both?
129 ;; FIXME: Now that there's no byte compiler, this is stale and could
131 (when :native :type (member :byte :native :both)))
133 (defprinter (transform) type note important when)
135 ;;; Grab the FUNCTION-INFO and enter the function, replacing any old
136 ;;; one with the same type and note.
137 (declaim (ftype (function (t list function &optional (or string null)
138 (member t nil) (member :native :byte :both))
141 (defun %deftransform (name type fun &optional note important (when :native))
142 (let* ((ctype (specifier-type type))
143 (note (or note "optimize"))
144 (info (function-info-or-lose name))
145 (old (find-if (lambda (x)
146 (and (type= (transform-type x) ctype)
147 (string-equal (transform-note x) note)
148 (eq (transform-important x) important)
149 (eq (transform-when x) when)))
150 (function-info-transforms info))))
152 (setf (transform-function old) fun (transform-note old) note)
153 (push (make-transform :type ctype :function fun :note note
154 :important important :when when)
155 (function-info-transforms info)))
158 ;;; Make a FUNCTION-INFO structure with the specified type, attributes
160 (declaim (ftype (function (list list attributes &key
161 (:derive-type (or function null))
162 (:optimizer (or function null)))
165 (defun %defknown (names type attributes &key derive-type optimizer)
166 (let ((ctype (specifier-type type))
167 (info (make-function-info :attributes attributes
168 :derive-type derive-type
169 :optimizer optimizer))
170 (target-env *info-environment*))
172 (let ((old-function-info (info :function :info name)))
173 (when old-function-info
174 ;; This is handled as an error because it's generally a bad
175 ;; thing to blow away all the old optimization stuff. It's
176 ;; also a potential source of sneaky bugs:
179 ;; DEFKNOWN FOO ; possibly hidden inside some macroexpansion
180 ;; ; Now the DEFTRANSFORM doesn't exist in the target Lisp.
181 ;; However, it's continuable because it might be useful to do
182 ;; it when testing new optimization stuff interactively.
183 (cerror "Go ahead, overwrite it."
184 "~@<overwriting old FUNCTION-INFO ~2I~_~S ~I~_for ~S~:>"
185 old-function-info name)))
186 (setf (info :function :type name target-env) ctype)
187 (setf (info :function :where-from name target-env) :declared)
188 (setf (info :function :kind name target-env) :function)
189 (setf (info :function :info name target-env) info)))
192 ;;; Return the FUNCTION-INFO for NAME or die trying. Since this is
193 ;;; used by callers who want to modify the info, and the info may be
194 ;;; shared, we copy it. We don't have to copy the lists, since each
195 ;;; function that has generators or transforms has already been
197 (declaim (ftype (function (t) function-info) function-info-or-lose))
198 (defun function-info-or-lose (name)
199 (let (;; FIXME: Do we need this rebinding here? It's a literal
200 ;; translation of the old CMU CL rebinding to
201 ;; (OR *BACKEND-INFO-ENVIRONMENT* *INFO-ENVIRONMENT*),
202 ;; and it's not obvious whether the rebinding to itself is
203 ;; needed that SBCL doesn't need *BACKEND-INFO-ENVIRONMENT*.
204 (*info-environment* *info-environment*))
205 (let ((old (info :function :info name)))
206 (unless old (error "~S is not a known function." name))
207 (setf (info :function :info name) (copy-function-info old)))))
209 ;;;; generic type inference methods
211 ;;; Derive the type to be the type of the xxx'th arg. This can normally
212 ;;; only be done when the result value is that argument.
213 (defun result-type-first-arg (call)
214 (declare (type combination call))
215 (let ((cont (first (combination-args call))))
216 (when cont (continuation-type cont))))
217 (defun result-type-last-arg (call)
218 (declare (type combination call))
219 (let ((cont (car (last (combination-args call)))))
220 (when cont (continuation-type cont))))
222 ;;; Derive the result type according to the float contagion rules, but
223 ;;; always return a float. This is used for irrational functions that preserve
224 ;;; realness of their arguments.
225 (defun result-type-float-contagion (call)
226 (declare (type combination call))
227 (reduce #'numeric-contagion (combination-args call)
228 :key #'continuation-type
229 :initial-value (specifier-type 'single-float)))
231 ;;; Return a closure usable as a derive-type method for accessing the N'th
232 ;;; argument. If arg is a list, result is a list. If arg is a vector, result
233 ;;; is a vector with the same element type.
234 (defun sequence-result-nth-arg (n)
236 (declare (type combination call))
237 (let ((cont (nth (1- n) (combination-args call))))
239 (let ((type (continuation-type cont)))
240 (if (array-type-p type)
242 `(vector ,(type-specifier (array-type-element-type type))))
243 (let ((ltype (specifier-type 'list)))
244 (when (csubtypep type ltype)
247 ;;; Derive the type to be the type specifier which is the N'th arg.
248 (defun result-type-specifier-nth-arg (n)
250 (declare (type combination call))
251 (let ((cont (nth (1- n) (combination-args call))))
252 (when (and cont (constant-continuation-p cont))
253 (specifier-type (continuation-value cont))))))
255 (/show0 "knownfun.lisp end of file")