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[Bug-mit-scheme] [bug #27385] compiler still generates bad code in the g
From: |
Taylor R. Campbell |
Subject: |
[Bug-mit-scheme] [bug #27385] compiler still generates bad code in the general case of FIXNUM-LSH, for negative arguments |
Date: |
Sat, 05 Sep 2009 06:37:03 +0000 |
User-agent: |
Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US) AppleWebKit/525.18 (KHTML, like Gecko, Safari/525.20) OmniWeb/v622.6.1.0.111015 |
URL:
<http://savannah.gnu.org/bugs/?27385>
Summary: compiler still generates bad code in the general
case of FIXNUM-LSH, for negative arguments
Project: MIT/GNU Scheme
Submitted by: riastradh
Submitted on: Sat 05 Sep 2009 06:37:02 GMT
Category: compiler
Severity: 3 - Normal
Priority: 5 - Normal
Item Group: Incorrect behavior
Status: None
Privacy: Public
Assigned to: None
Originator Name:
Originator Email:
Open/Closed: Open
Discussion Lock: Any
Keywords:
_______________________________________________________
Details:
All of the following should yield -1:
(fix:lsh -1 -1)
;Value: 33554431
(fix:lsh -1 -30)
;Value: 0
(fix:lsh -123 -30)
;Value: 0
This should yield -62:
(fix:lsh -123 -1)
;Value: 33554370
The general case is already so complex that it would probably be worthwhile
just to bail and defer to the microcode primitive, but I don't think Liar can
do that only for particular uses of primitives, and obviously we don't want to
do that for every use of the FIXNUM-LSH primitive.
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Taylor R. Campbell <=