From: Jonas Amoson <jonas.amoson@gmail.com>
To: 9front@9front.org
Subject: Re: [9front] Weird >>= operator behaviour in 5c/5l
Date: Mon, 18 Jan 2021 18:11:15 +0200 [thread overview]
Message-ID: <CAF46DJ5yKeVXWdWs5rNRds2TdsFVDpnFtYPL0S+ZLnjCRaT3eA@mail.gmail.com> (raw)
In-Reply-To: <756C95B55C2DABF6755FCB63F332F045@eigenstate.org>
Left shifting by 32 instead of 0 does explain my
result, and seam indeed to be the real bug.
Regarding optimising out shifts where the number
of steps is zero: it already does that when using the
pattern x = x >> 0; but it doesn't for x >>= 0;
Thanks,
Jonas
On Mon, 18 Jan 2021 at 07:50, <ori@eigenstate.org> wrote:
>
> Quoth Noam Preil <noam@pixelhero.dev>:
> > It could just be architecture specific behavior.
> >
>
> It's a bug. Two, actually.
>
> 1) a shift of zero should be optimized out by
> the compiler; cinap has a change for this in
> the works already. This fix should hide the
> second bug.
>
> 2) a shift by a literal zero is miscompiled by
> the assembler into a shift by 32, because
> of a missed special case in the instruction.
> encoding. I'm working on fixing the assembler.
next prev parent reply other threads:[~2021-01-18 16:41 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-17 21:36 Jonas Amoson
2021-01-18 4:05 ` Noam Preil
2021-01-18 5:20 ` ori
2021-01-18 16:11 ` Jonas Amoson [this message]
2021-01-20 5:59 ` ori
2021-01-20 6:12 ` ori
2021-01-20 12:06 ` Jonas Amoson
2021-01-20 22:11 ` Anthony Martin
2021-01-20 23:39 ` ori
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