1.0.18.2: more conservative interval artihmetic

[sbcl.git] / BUGS

diff --git a/BUGS b/BUGS
index 7f62d6c..e467f8b 100644 (file)
--- a/BUGS
+++ b/BUGS
@@ -1827,53 +1827,6 @@ WORKAROUND:
   storing the relevant LAMBDA-VARs in a :DYNAMIC-EXTENT cleanup, and
   teaching stack analysis how to deal with them.
 
-420: The MISC.556 test from gcl/ansi-tests/misc.lsp fails hard.
-
-In sbcl-1.0.13 on Linux/x86, executing 
-       (FUNCALL
-        (COMPILE NIL
-                 '(LAMBDA (P1 P2)
-                    (DECLARE
-                     (OPTIMIZE (SPEED 1) (SAFETY 0) (DEBUG 0) (SPACE 0))
-                     (TYPE (MEMBER 8174.8604) P1) (TYPE (MEMBER -95195347) P2))
-                    (FLOOR P1 P2)))
-        8174.8604 -95195347)
-interactively causes
-  SB-SYS:MEMORY-FAULT-ERROR: Unhandled memory fault at #x8.
-The gcl/ansi-tests/doit.lisp program terminates prematurely shortly after
-MISC.556 by falling into gdb with
-  fatal error encountered in SBCL pid 2827: Unhandled SIGILL
-unless the MISC.556 test is commented out.
-
-Analysis: + and a number of other arithmetic functions exhibit the
-same behaviour. Here's the underlying problem: On x86 we perform
-single-float + integer normally using double-precision, and then
-coerce the result back to single-float. (The FILD instruction always
-gives us a double-float, and unless we do MOVE-FROM-SINGLE it remains
-one. Or so it seems to me, and that would also explain the observed
-behaviour below.)
-
-During IR1 we derive the types for both
-
- (+ <single> <integer>)                   ; uses double-precision
- (+ <single> (FLOAT <integer> <single>))  ; uses single-precision
-
-and get a mismatch for a number of unlucky arguments. This leads to
-derived result type NIL, and ends up flushing the whole whole
-operation -- and finally we generate code without a return sequence,
-and fall through to whatever.
-
-The use of double-precision in the first case appears to be an
-(un)happy accident -- interval arithmetic gives us the
-double-precision result because that's what the backend does.
-
- (+ 8172.0 (coerce -95195347 'single-float)) ; => -9.518717e7
- (+ 8172.0 -95195347)                        ; => -9.5187176e7
- (coerce (+ 8172.0 (coerce -95195347 'double-float)) 'single-float)
-                                             ; => -9.5187176e7
-
-Which should be fixed, the IR1, or the backend?
-
 421: READ-CHAR-NO-HANG misbehaviour on Windows Console:
 
   It seems that on Windows READ-CHAR-NO-HANG hangs if the user