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0.0 is negative with CogVM

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Levente Uzonyi-2

0.0 is negative with CogVM

Hi!

I downloaded the prebuilt CogVM from
http://www.mirandabanda.org/files/Cog/VM/VM.r2310/ for Windows and found
that 0.0 has strange behavior:

0.0 negative. "true"
0.0 < 0. "true"
0.0 as: WordArray. "a WordArray(0 0)"

while in SqueakVM

0.0 negative. " false"
0.0 < 0. "false"
0.0 as: WordArray. "a WordArray(0 0)"

Levente

Eliot Miranda-2

Re: 0.0 is negative with CogVM

Hi Levente,

On Mon, Sep 20, 2010 at 7:56 AM, Levente Uzonyi <[hidden email]> wrote:

Hi!

I downloaded the prebuilt CogVM from http://www.mirandabanda.org/files/Cog/VM/VM.r2310/ for Windows and found that 0.0 has strange behavior:

0.0 negative. "true"
0.0 < 0. "true"
0.0 as: WordArray. "a WordArray(0 0)"

while in SqueakVM

0.0 negative. " false"
0.0 < 0. "false"
0.0 as: WordArray. "a WordArray(0 0)"

Thank you! I have been looking superficially at Nicholas' NaN tests and have fixed two of the problems (comparisons of NaNs are ordered as in the interpreter and division by 0.0 now fails). But in doing that was seeing some strange results in closeTo: et al. This symptom looks to be related but it could underlie a lot of problems. At least it's an easily debuggable case.

self assert: (Compiler evaluate: '0.0') negative not

Levente

Eliot Miranda-2

Re: 0.0 is negative with CogVM

In reply to this post by Levente Uzonyi-2

On Mon, Sep 20, 2010 at 7:56 AM, Levente Uzonyi <[hidden email]> wrote:

Hi!

I downloaded the prebuilt CogVM from http://www.mirandabanda.org/files/Cog/VM/VM.r2310/ for Windows and found that 0.0 has strange behavior:

0.0 negative. "true"
0.0 < 0. "true"
0.0 as: WordArray. "a WordArray(0 0)"

while in SqueakVM

0.0 negative. " false"
0.0 < 0. "false"
0.0 as: WordArray. "a WordArray(0 0)"

Fixed in r2312. I had misread the code generated by gcc and instead of transforming a < b into !(b > a) and a <= b into (!b >= a) I had transformed a < b into !(b >= a) and a <= b into !(b > a). Tricky.

Eliot

Levente

Levente Uzonyi-2

Re: 0.0 is negative with CogVM

On Tue, 21 Sep 2010, Eliot Miranda wrote:

> Fixed in r2312. I had misread the code generated by gcc and instead of
> transforming a < b into !(b > a) and a <= b into (!b >= a) I had
transformed
> a < b into !(b >= a) and a <= b into !(b > a). Tricky.

Thanks, it works well now, also all Float-related tests pass.

Levente