96:
The TRACE facility can't be used on some kinds of functions.
- Basically, the breakpoint facility wasn incompletely implemented
- in the X86 port of CMU CL, and we haven't fixed it in SBCL.
-
-97:
- FRESH-LINE doesn't seem to work properly within pretty-printed
- output. E.g.
- "~@<unhandled CONDITION (of type ~S): ~2I~_~A~:>~2%"
- called on a CONDITION whose printer does
- "~&~@<error in function ~S: ~3I~:_~?~:>"
- gives two newlines between "unhandled CONDITION" and "error", when
- (it at least seems as though) correct behavior would be to give one.
+ (Basically, the breakpoint facility was incompletely implemented
+ in the X86 port of CMU CL, and hasn't been fixed in SBCL.)
+
+98:
+ In sbcl-0.6.11.41 (and in all earlier SBCL, and in CMU
+ CL), out-of-line structure slot setters are horribly inefficient
+ whenever the type of the slot is declared, because out-of-line
+ structure slot setters are implemented as closures to save space,
+ so the compiler doesn't compile the type test into code, but
+ instead just saves the type in a lexical closure and interprets it
+ at runtime.
+ A proper solution involves deciding whether it's really worth
+ saving space by implementing structure slot accessors as closures.
+ (If it's not worth it, the problem vanishes automatically. If it
+ is worth it, there are hacks we could use to force type tests to
+ be compiled anyway, and even shared. E.g. we could implement
+ an EQUAL hash table mapping from types to compiled type tests,
+ and save the appropriate compiled type test as part of each lexical
+ closure; or we could make the lexical closures be placeholders
+ which overwrite their old definition as a lexical closure with
+ a new compiled definition the first time that they're called.)
+ As a workaround for the problem, #'(SETF FOO) expressions can
+ be replaced with (EFFICIENT-SETF-FUNCTION FOO), where
+(defmacro efficient-setf-function (place-function-name)
+ (or #+sbcl (and (sb-impl::info :function :accessor-for place-function-name)
+ ;; a workaround for the problem, encouraging the
+ ;; inline expansion of the structure accessor, so
+ ;; that the compiler can optimize its type test
+ (let ((new-value (gensym "NEW-VALUE-"))
+ (structure-value (gensym "STRUCTURE-VALUE-")))
+ `(lambda (,new-value ,structure-value)
+ (setf (,place-function-name ,structure-value)
+ ,new-value))))
+ ;; no problem, can just use the ordinary expansion
+ `(function (setf ,place-function-name))))
+
+99:
+ DESCRIBE interacts poorly with *PRINT-CIRCLE*, e.g. the output from
+ (let ((*print-circle* t)) (describe (make-hash-table)))
+ is weird,
+ #<HASH-TABLE :TEST EQL :COUNT 0 {90BBFC5}> is an . (EQL)
+ Its SIZE is 16.
+ Its REHASH-SIZE is 1.5. Its REHASH-THRESHOLD is . (1.0)
+ It holds 0 key/value pairs.
+ where the ". (EQL)" and ". (1.0)" substrings are screwups.
+ (This is likely a pretty-printer problem which happens to
+ be exercised by DESCRIBE, not actually a DESCRIBE problem.)
+
+100:
+ There's apparently a bug in CEILING optimization which caused
+ Douglas Crosher to patch the CMU CL version. Martin Atzmueller
+ applied the patches to SBCL and they didn't seem to cause problems
+ (as reported sbcl-devel 2001-05-04). However, since the patches
+ modify nontrivial code which was apparently written incorrectly
+ the first time around, until regression tests are written I'm not
+ comfortable merging the patches in the CVS version of SBCL.
KNOWN BUGS RELATED TO THE IR1 INTERPRETER
projects / sbcl.git / blobdiff