Re: -O3 vs. -Os
Re: -O3 vs. -Os
- Subject: Re: -O3 vs. -Os
- From: Rustam Muginov <email@hidden>
- Date: Tue, 17 Jan 2006 10:30:27 +0300
I believe that -O3 is only useful in the heavily computational tasks.
"Regular" apps would benefit from -Os optimizaiton, and only
manualy-tuned high-performance libraries would work faster with -O3
--
Sincerely,
Rustam Muginov
On Jan 17, 2006, at 10:22 AM, Steve Checkoway wrote:
I've just discovered something a bit surprising. I've been building my
app with -O3 and I'm getting a binary of 8972584 bytes, after striping
(strip -x). I've read numerous times that -Os will lead to better
performance since it will be smaller and thus have more cache hits. I
decided to test (okay, I made a bold proclamation in a cvs commit
message that -Os would reduce the size without testing and somebody
encouraged me to test it, "er, I can guarantee you -Os is not faster
than -O3 for C++"). The result with -Os was 9157124 bytes after
stripping.
The app is roughly 180,000 lines of C++, 10,700 lines of C, 400 lines
of objective-C++ and a 300 lines of Objective-C.
Is this typical?
- Steve _______________________________________________
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| | >-O3 vs. -Os (From: Steve Checkoway <email@hidden>) |