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bug#5754: Bytecomp Arithmetic test failed
From: |
Juri Linkov |
Subject: |
bug#5754: Bytecomp Arithmetic test failed |
Date: |
Tue, 30 Mar 2010 19:08:45 +0300 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.0.50 (x86_64-pc-linux-gnu) |
I see that this was extensively discussed in bug#1334,
so I Cc:ed Shigeru Fukaya. Shigeru, are you interested in
looking at the test failure reported by bytecomp-testsuite.el?
>> I tried to run some tests in the `test' subdir,
>> and `bytecomp-testsuite-run' in `test/bytecomp-testsuite.el' fails
>> on one test: (let ((a (expt 2 -1074)) (b 0.125)) (* a 8 b))
>> returns 5e-324 when evaluated by interpreter,
>> but after byte-compilation returns 0.0
>>
>> In GNU Emacs 24.0.50 (x86_64-pc-linux-gnu) of 2010-03-23
>
> This bug is caused by optimization in byte-compilation
> that changes the order of function arguments.
>
> It byte-compiles
>
> (let ((a (expt 2 -1074)) (b 0.125)) (* a 8 b))
>
> to
>
> 0 constant expt
> 1 constant 2
> 2 constant -1074
> 3 call 2
> 4 constant 0.125
> 5 varbind b
> 6 varbind a
> 7 constant *
> 8 varref a
> 9 varref b
> 10 constant 8
> 11 call 3
> 12 unbind 2
> 13 return
>
> where the order of arguments 8-10 is changed from (* a 8 b) to (* a b 8)
>
> For this test the different order of arguments changes
> the returned value:
>
> (funcall '* 5e-324 8 0.125)
> => 5e-324
>
> (funcall '* 5e-324 0.125 8)
> => 0.0
--
Juri Linkov
http://www.jurta.org/emacs/
- bug#5754: Bytecomp Arithmetic test failed, Juri Linkov, 2010/03/23
- bug#5754: Bytecomp Arithmetic test failed, Lennart Borgman, 2010/03/23
- bug#5754: Bytecomp Arithmetic test failed, Juri Linkov, 2010/03/23
- bug#5754: Bytecomp Arithmetic test failed, Lennart Borgman, 2010/03/23
- bug#5754: Bytecomp Arithmetic test failed, Chong Yidong, 2010/03/24
- bug#5754: Bytecomp Arithmetic test failed, Lennart Borgman, 2010/03/24
- bug#5754: Bytecomp Arithmetic test failed, Stefan Monnier, 2010/03/24
- bug#5754: Bytecomp Arithmetic test failed, Lennart Borgman, 2010/03/24
bug#5754: Bytecomp Arithmetic test failed, Juri Linkov, 2010/03/25
- bug#5754: Bytecomp Arithmetic test failed,
Juri Linkov <=