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
128 (when :native :type (member :byte :native :both)))
130 (defprinter (transform) type note important when)
132 ;;; Grab the FUNCTION-INFO and enter the function, replacing any old
133 ;;; one with the same type and note.
134 (declaim (ftype (function (t list function &optional (or string null)
135 (member t nil) (member :native :byte :both))
138 (defun %deftransform (name type fun &optional note important (when :native))
139 (let* ((ctype (specifier-type type))
140 (note (or note "optimize"))
141 (info (function-info-or-lose name))
142 (old (find-if (lambda (x)
143 (and (type= (transform-type x) ctype)
144 (string-equal (transform-note x) note)
145 (eq (transform-important x) important)
146 (eq (transform-when x) when)))
147 (function-info-transforms info))))
149 (setf (transform-function old) fun (transform-note old) note)
150 (push (make-transform :type ctype :function fun :note note
151 :important important :when when)
152 (function-info-transforms info)))
155 ;;; Make a FUNCTION-INFO structure with the specified type, attributes
157 (declaim (ftype (function (list list attributes &key
158 (:derive-type (or function null))
159 (:optimizer (or function null)))
162 (defun %defknown (names type attributes &key derive-type optimizer)
163 (let ((ctype (specifier-type type))
164 (info (make-function-info :attributes attributes
165 :derive-type derive-type
166 :optimizer optimizer))
167 (target-env *info-environment*))
169 (let ((old-function-info (info :function :info name)))
170 (when old-function-info
171 ;; This is handled as an error because it's generally a bad
172 ;; thing to blow away all the old optimization stuff. It's
173 ;; also a potential source of sneaky bugs:
176 ;; DEFKNOWN FOO ; possibly hidden inside some macroexpansion
177 ;; ; Now the DEFTRANSFORM doesn't exist in the target Lisp.
178 ;; However, it's continuable because it might be useful to do
179 ;; it when testing new optimization stuff interactively.
180 (cerror "Go ahead, overwrite it."
181 "~@<overwriting old FUNCTION-INFO ~2I~_~S ~I~_for ~S~:>"
182 old-function-info name)))
183 (setf (info :function :type name target-env) ctype)
184 (setf (info :function :where-from name target-env) :declared)
185 (setf (info :function :kind name target-env) :function)
186 (setf (info :function :info name target-env) info)))
189 ;;; Return the FUNCTION-INFO for NAME or die trying. Since this is
190 ;;; used by callers who want to modify the info, and the info may be
191 ;;; shared, we copy it. We don't have to copy the lists, since each
192 ;;; function that has generators or transforms has already been
194 (declaim (ftype (function (t) function-info) function-info-or-lose))
195 (defun function-info-or-lose (name)
196 (let (;; FIXME: Do we need this rebinding here? It's a literal
197 ;; translation of the old CMU CL rebinding to
198 ;; (OR *BACKEND-INFO-ENVIRONMENT* *INFO-ENVIRONMENT*),
199 ;; and it's not obvious whether the rebinding to itself is
200 ;; needed that SBCL doesn't need *BACKEND-INFO-ENVIRONMENT*.
201 (*info-environment* *info-environment*))
202 (let ((old (info :function :info name)))
203 (unless old (error "~S is not a known function." name))
204 (setf (info :function :info name) (copy-function-info old)))))
206 ;;;; generic type inference methods
208 ;;; Derive the type to be the type of the xxx'th arg. This can normally
209 ;;; only be done when the result value is that argument.
210 (defun result-type-first-arg (call)
211 (declare (type combination call))
212 (let ((cont (first (combination-args call))))
213 (when cont (continuation-type cont))))
214 (defun result-type-last-arg (call)
215 (declare (type combination call))
216 (let ((cont (car (last (combination-args call)))))
217 (when cont (continuation-type cont))))
219 ;;; Derive the result type according to the float contagion rules, but
220 ;;; always return a float. This is used for irrational functions that preserve
221 ;;; realness of their arguments.
222 (defun result-type-float-contagion (call)
223 (declare (type combination call))
224 (reduce #'numeric-contagion (combination-args call)
225 :key #'continuation-type
226 :initial-value (specifier-type 'single-float)))
228 ;;; Return a closure usable as a derive-type method for accessing the N'th
229 ;;; argument. If arg is a list, result is a list. If arg is a vector, result
230 ;;; is a vector with the same element type.
231 (defun sequence-result-nth-arg (n)
233 (declare (type combination call))
234 (let ((cont (nth (1- n) (combination-args call))))
236 (let ((type (continuation-type cont)))
237 (if (array-type-p type)
239 `(vector ,(type-specifier (array-type-element-type type))))
240 (let ((ltype (specifier-type 'list)))
241 (when (csubtypep type ltype)
244 ;;; Derive the type to be the type specifier which is the N'th arg.
245 (defun result-type-specifier-nth-arg (n)
247 (declare (type combination call))
248 (let ((cont (nth (1- n) (combination-args call))))
249 (when (and cont (constant-continuation-p cont))
250 (specifier-type (continuation-value cont))))))
252 (/show0 "knownfun.lisp end of file")