Re: Register keyword necessary anymore?
Re: Register keyword necessary anymore?
- Subject: Re: Register keyword necessary anymore?
- From: "email@hidden" <email@hidden>
- Date: Wed, 18 Apr 2007 12:10:29 -0400
Chris Espinosa wrote:
On Apr 18, 2007, at 7:37 AM, email@hidden
<mailto:email@hidden> wrote:
Back before x86 and on much earlier versions of gcc, I used the
register keyword a lot and got a big speed up in certain parts of my
code.
Now, it's a number of gcc versions later and x86 with less registers
is in the picture. I remember hearing that gcc got a lot better with
register usage a version or two ago, and I'm wondering how useful the
register keyword is -- OR -- if I'm actually hurting performance on
x86 (I only have a PPC to test on.)
Then there's no way of knowing.
The only real answers to questions like these is to run your app on
the machine in question and measure its actual performance with
Sampler or Shark. Anything you theorize is likely to be affected by
so many unexpected conditions that any conclusions you draw will be
unreliable.
Chris
Sure, but my app is run on hundreds of machines across many different
PPC/x86 CPUs. I can tune to anything specific, and I know there's no
real answer and it depends on a lot of factors, but what I'm looking for
is a general idea of how good ggc is at this point. 2 years ago adding
register keywords would show a dramatic speed increase. I will be doing
some more testing on my PPC, but I'm worried about the x86 stuff.
[>] Brian
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