Would you like a paste from jitviewer or the source code to run and examine
with jitviewer?
-Roger
________________________________
From: Alex Gaynor <alex.gay...@gmail.com>
To: Roger Flores <aide...@yahoo.com>
Cc: "pypy-dev@python.org" <pypy-dev@python.org>
Sent: Wednesday, February 27, 2013 12:23 PM
Subject: Re: [pypy-dev] Slow int code
In that context large longs means HUNDREDS or THOUSANDS of bits, not 64 :) Can
you show us a full runnable example that illustrates this?
Alex
On Wed, Feb 27, 2013 at 12:10 PM, Roger Flores <aide...@yahoo.com> wrote:
Hi guys. I've been looking at two simple routines using jitviewer to figure
out why they're so much slower than expected.
>
>
>I've also noticed that http://pypy.org/performance.html has the line "Bad
>examples include doing computations with
>large longs – which is performed by unoptimizable support code.". I'm worried
>that my 32 bit int code is falling into this, and I'm wondering what I can do
>to avoid it?
>
>Trivial code like
>
>if (self.low ^ self.high) & 0x80000000 == 0:
>
>
>is expanding into several dozen asm instructions. I'm suspecting that lines
>like
>
>self.low = (self.low << 1) & 0xffffffff
>
>
>with it's shift left are convincing the jit to consider the int to need 64
>bits (large long?) instead of 32.
>
>
>Ideas? The asm is clearly operating on QWORDs and calling routines to do the
>bit arithmetic instead of single instructions. Is this what that line in
>performance.html is warning about?
>
>
>
>-Roger
>
>BTW Fijal's jitviewer is a *must see* for anyone interested in how pypy makes
>their code fast!
>
>_______________________________________________
>pypy-dev mailing list
>pypy-dev@python.org
>http://mail.python.org/mailman/listinfo/pypy-dev
>
--
"I disapprove of what you say, but I will defend to the death your right to say
it." -- Evelyn Beatrice Hall (summarizing Voltaire)
"The people's good is the highest law." -- Cicero
_______________________________________________
pypy-dev mailing list
pypy-dev@python.org
http://mail.python.org/mailman/listinfo/pypy-dev
