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))
103 ;; If non-null, use this function to generate the byte code for this known
104 ;; call. This function can only give up if there is a byte-annotate function
105 ;; that arranged for the functional to be pushed onto the stack.
106 (byte-compile nil :type (or function null)))
108 (defprinter (function-info)
109 (transforms :test transforms)
110 (derive-type :test derive-type)
111 (optimizer :test optimizer)
112 (ltn-annotate :test ltn-annotate)
113 (ir2-convert :test ir2-convert)
114 (templates :test templates)
115 (predicate-type :test predicate-type)
116 (byte-annotate :test byte-annotate)
117 (byte-compile :test byte-compile))
119 ;;;; interfaces to defining macros
122 (defstruct (transform (:copier nil))
123 ;; the function-type which enables this transform
124 (type (required-argument) :type ctype)
125 ;; the transformation function. Takes the COMBINATION node and returns a
126 ;; lambda, or throws out.
127 (function (required-argument) :type function)
128 ;; string used in efficency notes
129 (note (required-argument) :type string)
130 ;; T if we should emit a failure note even if SPEED=INHIBIT-WARNINGS.
131 (important nil :type (member t nil))
132 ;; usable for byte code, native code, or both
133 (when :native :type (member :byte :native :both)))
135 (defprinter (transform) type note important when)
137 ;;; Grab the FUNCTION-INFO and enter the function, replacing any old
138 ;;; one with the same type and note.
139 (declaim (ftype (function (t list function &optional (or string null)
140 (member t nil) (member :native :byte :both))
143 (defun %deftransform (name type fun &optional note important (when :native))
144 (let* ((ctype (specifier-type type))
145 (note (or note "optimize"))
146 (info (function-info-or-lose name))
147 (old (find-if (lambda (x)
148 (and (type= (transform-type x) ctype)
149 (string-equal (transform-note x) note)
150 (eq (transform-important x) important)
151 (eq (transform-when x) when)))
152 (function-info-transforms info))))
154 (setf (transform-function old) fun (transform-note old) note)
155 (push (make-transform :type ctype :function fun :note note
156 :important important :when when)
157 (function-info-transforms info)))
160 ;;; Make a FUNCTION-INFO structure with the specified type, attributes
162 (declaim (ftype (function (list list attributes &key
163 (:derive-type (or function null))
164 (:optimizer (or function null)))
167 (defun %defknown (names type attributes &key derive-type optimizer)
168 (let ((ctype (specifier-type type))
169 (info (make-function-info :attributes attributes
170 :derive-type derive-type
171 :optimizer optimizer))
172 (target-env (or *backend-info-environment* *info-environment*)))
174 (let ((old-function-info (info :function :info name)))
175 (when old-function-info
176 ;; This is handled as an error because it's generally a bad
177 ;; thing to blow away all the old optimization stuff. It's
178 ;; also a potential source of sneaky bugs:
181 ;; DEFKNOWN FOO ; possibly hidden inside some macroexpansion
182 ;; ; Now the DEFTRANSFORM doesn't exist in the target Lisp.
183 ;; However, it's continuable because it might be useful to do
184 ;; it when testing new optimization stuff interactively.
185 (cerror "Go ahead, overwrite it."
186 "~@<overwriting old FUNCTION-INFO ~2I~_~S ~I~_for ~S~:>"
187 old-function-info name)))
188 (setf (info :function :type name target-env) ctype)
189 (setf (info :function :where-from name target-env) :declared)
190 (setf (info :function :kind name target-env) :function)
191 (setf (info :function :info name target-env) info)))
194 ;;; Return the FUNCTION-INFO for NAME or die trying. Since this is
195 ;;; used by callers who want to modify the info, and the info may be
196 ;;; shared, we copy it. We don't have to copy the lists, since each
197 ;;; function that has generators or transforms has already been
199 (declaim (ftype (function (t) function-info) function-info-or-lose))
200 (defun function-info-or-lose (name)
201 (let ((*info-environment* (or *backend-info-environment*
202 *info-environment*)))
203 (let ((old (info :function :info name)))
204 (unless old (error "~S is not a known function." name))
205 (setf (info :function :info name) (copy-function-info old)))))
207 ;;;; generic type inference methods
209 ;;; Derive the type to be the type of the xxx'th arg. This can normally
210 ;;; only be done when the result value is that argument.
211 (defun result-type-first-arg (call)
212 (declare (type combination call))
213 (let ((cont (first (combination-args call))))
214 (when cont (continuation-type cont))))
215 (defun result-type-last-arg (call)
216 (declare (type combination call))
217 (let ((cont (car (last (combination-args call)))))
218 (when cont (continuation-type cont))))
220 ;;; Derive the result type according to the float contagion rules, but
221 ;;; always return a float. This is used for irrational functions that preserve
222 ;;; realness of their arguments.
223 (defun result-type-float-contagion (call)
224 (declare (type combination call))
225 (reduce #'numeric-contagion (combination-args call)
226 :key #'continuation-type
227 :initial-value (specifier-type 'single-float)))
229 ;;; Return a closure usable as a derive-type method for accessing the N'th
230 ;;; argument. If arg is a list, result is a list. If arg is a vector, result
231 ;;; is a vector with the same element type.
232 (defun sequence-result-nth-arg (n)
234 (declare (type combination call))
235 (let ((cont (nth (1- n) (combination-args call))))
237 (let ((type (continuation-type cont)))
238 (if (array-type-p type)
240 `(vector ,(type-specifier (array-type-element-type type))))
241 (let ((ltype (specifier-type 'list)))
242 (when (csubtypep type ltype)
245 ;;; Derive the type to be the type specifier which is the N'th arg.
246 (defun result-type-specifier-nth-arg (n)
248 (declare (type combination call))
249 (let ((cont (nth (1- n) (combination-args call))))
250 (when (and cont (constant-continuation-p cont))
251 (specifier-type (continuation-value cont))))))
253 (/show0 "knownfun.lisp end of file")