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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
7 ;;;; more information.
8 ;;;;
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.
19 ;;; IR1 boolean function attributes
20 ;;;
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.
32 call
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
36 ;; always are.
37 unsafe
38 ;; may fail to return during correct execution. Errors are O.K.
39 unwind
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.
43 any
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.
50 foldable
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.)
58 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.
63 unsafely-flushable
64 ;; may be moved with impunity. Has no side effects except possibly
65 ;; consing, and is affected only by its arguments.
66 ;;
67 ;; Since it is not used now, its distribution in fndb.lisp is
68 ;; mere random; use with caution.
69 movable
70 ;; The function is a true predicate likely to be open-coded. Convert
71 ;; any non-conditional uses into (IF <pred> T NIL). Not usually
72 ;; specified to DEFKNOWN, since this is implementation dependent,
73 ;; and is usually automatically set by the DEFINE-VOP :CONDITIONAL
74 ;; option.
75 predicate
76 ;; Inhibit any warning for compiling a recursive definition.
77 ;; (Normally the compiler warns when compiling a recursive
78 ;; definition for a known function, since it might be a botched
79 ;; interpreter stub.)
80 recursive
81 ;; The function does explicit argument type checking, so the
82 ;; declared type should not be asserted when a definition is
83 ;; compiled.
84 explicit-check)
87 ;; boolean attributes of this function.
89 ;; TRANSFORM structures describing transforms for this function
91 ;; a function which computes the derived type for a call to this
92 ;; function by examining the arguments. This is null when there is
93 ;; no special method for this function.
95 ;; a function that does various unspecified code transformations by
96 ;; directly hacking the IR. Returns true if further optimizations of
97 ;; the call shouldn't be attempted.
98 ;;
99 ;; KLUDGE: This return convention (non-NIL if you shouldn't do
100 ;; further optimiz'ns) is backwards from the return convention for
101 ;; transforms. -- WHN 19990917
103 ;; If true, a special-case LTN annotation method that is used in
104 ;; place of the standard type/policy template selection. It may use
105 ;; arbitrary code to choose a template, decide to do a full call, or
106 ;; conspire with the IR2-CONVERT method to do almost anything. The
107 ;; COMBINATION node is passed as the argument.
109 ;; If true, the special-case IR2 conversion method for this
110 ;; function. This deals with funny functions, and anything else that
111 ;; can't be handled using the template mechanism. The COMBINATION
112 ;; node and the IR2-BLOCK are passed as arguments.
114 ;; If true, the function can stack-allocate the result. The
115 ;; COMBINATION node is passed as an argument.
117 ;; all the templates that could be used to translate this function
118 ;; into IR2, sorted by increasing cost.
120 ;; If non-null, then this function is a unary type predicate for
121 ;; this type.
134 \f
135 ;;;; interfaces to defining macros
137 ;;; an IR1 transform
139 ;; the function type which enables this transform.
140 ;;
141 ;; (Note that declaring this :TYPE FUN-TYPE probably wouldn't
142 ;; work because some function types, like (SPECIFIER-TYPE 'FUNCTION0
143 ;; itself, are represented as BUILT-IN-TYPE, and at least as of
144 ;; sbcl-0.pre7.54 or so, that's inconsistent with being a
145 ;; FUN-TYPE.)
147 ;; the transformation function. Takes the COMBINATION node and
148 ;; returns a lambda expression, or throws out.
150 ;; string used in efficiency notes
152 ;; T if we should emit a failure note even if SPEED=INHIBIT-WARNINGS.
157 ;;; Grab the FUN-INFO and enter the function, replacing any old
158 ;;; one with the same type and note.
161 *)
162 %deftransform))
180 name))
182 ;;; Make a FUN-INFO structure with the specified type, attributes
183 ;;; and optimizers.
187 *)
188 %defknown))
192 :derive-type derive-type
198 ;; This is handled as an error because it's generally a bad
199 ;; thing to blow away all the old optimization stuff. It's
200 ;; also a potential source of sneaky bugs:
201 ;; DEFKNOWN FOO
202 ;; DEFTRANSFORM FOO
203 ;; DEFKNOWN FOO ; possibly hidden inside some macroexpansion
204 ;; ; Now the DEFTRANSFORM doesn't exist in the target Lisp.
205 ;; However, it's continuable because it might be useful to do
206 ;; it when testing new optimization stuff interactively.
208 "~@<overwriting old FUN-INFO ~2I~_~S ~I~_for ~S~:>"
209 old-fun-info name)))
214 names)
216 ;;; Return the FUN-INFO for NAME or die trying. Since this is
217 ;;; used by callers who want to modify the info, and the info may be
218 ;;; shared, we copy it. We don't have to copy the lists, since each
219 ;;; function that has generators or transforms has already been
220 ;;; through here.
224 ;; translation of the old CMU CL rebinding to
225 ;; (OR *BACKEND-INFO-ENVIRONMENT* *INFO-ENVIRONMENT*),
226 ;; and it's not obvious whether the rebinding to itself is
227 ;; needed that SBCL doesn't need *BACKEND-INFO-ENVIRONMENT*.
232 \f
233 ;;;; generic type inference methods
235 ;;; Derive the type to be the type of the xxx'th arg. This can normally
236 ;;; only be done when the result value is that argument.
246 ;;; Derive the result type according to the float contagion rules, but
247 ;;; always return a float. This is used for irrational functions that
248 ;;; preserve realness of their arguments.
255 ;;; Return a closure usable as a derive-type method for accessing the
256 ;;; N'th argument. If arg is a list, result is a list. If arg is a
257 ;;; vector, result is a vector with the same element type.
269 ltype))))))))
271 ;;; Derive the type to be the type specifier which is the Nth arg.
279 ;;; Derive the type to be the type specifier which is the Nth arg,
280 ;;; with the additional restriptions noted in the CLHS for STRING and
281 ;;; SIMPLE-STRING, defined to specialize on CHARACTER, and for VECTOR
282 ;;; (under the page for MAKE-SEQUENCE).
293 lspecifier
299 lspecifier
308 ;; I don't think I'm allowed to modify what I get
309 ;; back from SPECIFIER-TYPE; it is, after all,
310 ;; cached. Better copy it, then.
316 real-ctype)
317 ctype)))))))))