X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;ds=sidebyside;f=BUGS;h=a839434ada46a6e89cad1c5d715ef0b27396cdc7;hb=4cf50b1896b25f5337e7c258b0b560da00d47993;hp=ad30c7b996929c947c9d2499e7cb51ec7b791be7;hpb=f0338f6fa732b21daa4405e19465bd460e0526d9;p=sbcl.git

diff --git a/BUGS b/BUGS
index ad30c7b..a839434 100644
--- a/BUGS
+++ b/BUGS
@@ -890,17 +890,62 @@ Error in function C::GET-LAMBDA-TO-COMPILE:
 
 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