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> Gcc -o4 Flag, Is it different than -O3
ShiroiKuma
post Mar 27 2007, 10:04 AM
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I'm playing around with optimizing compiled packages to run fine on Ångström, but the question isn't really Ångström-specific.

I've seen on Meanie's blog on building Firefox natively that he used the -O4 option in CFLAGS.

I've looked but not found anything substantive on this flag. One Finnish page on the web states that if -On has n higher than 3, then the flag is automatically interpreted as -O3. Is this so? Or is there a difference between these?
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speculatrix
post Mar 27 2007, 01:18 PM
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that's using the Spinal Tap version of the compiler - everyone else's goes up to O3, but the 'tap' version goes up to O4.

smile.gif
---

I wonder whether anyone will understand this joke?
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adf
post Mar 27 2007, 03:16 PM
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QUOTE(speculatrix @ Mar 27 2007, 09:18 PM)
that's using the Spinal Tap version of the compiler - everyone else's goes up to O3, but the 'tap' version goes up to O4.

smile.gif
---

I wonder whether anyone will understand this joke?
*

11
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Meanie
post Mar 27 2007, 11:42 PM
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QUOTE(adf @ Mar 28 2007, 09:16 AM)
QUOTE(speculatrix @ Mar 27 2007, 09:18 PM)
that's using the Spinal Tap version of the compiler - everyone else's goes up to O3, but the 'tap' version goes up to O4.

smile.gif
---

I wonder whether anyone will understand this joke?
*

11
*



oh man, these geek jokes are way over my head. can someone explain it so some dummy like me can understand it?
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speculatrix
post Mar 28 2007, 02:17 AM
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If you haven't seen the film "Spinal Tap", the joke won't make any sense.
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ShiroiKuma
post Mar 28 2007, 04:58 AM
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QUOTE(speculatrix @ Mar 28 2007, 11:17 AM)
If you haven't seen the film "Spinal Tap", the joke won't make any sense.
*

smile.gif Didn't get the joke either...

How about the original issue though, is there really an -O4 flag that furthers optimization, or is it just the same as -O3?
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koen
post Mar 28 2007, 05:00 AM
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QUOTE(ShiroiKuma @ Mar 28 2007, 12:58 PM)
QUOTE(speculatrix @ Mar 28 2007, 11:17 AM)
If you haven't seen the film "Spinal Tap", the joke won't make any sense.
*

smile.gif Didn't get the joke either...

How about the original issue though, is there really an -O4 flag that furthers optimization, or is it just the same as -O3?
*



Just keep in mind that you're reading from *slow* media into a tiny amount of RAM, so 'optimized' binaries will execute slower in the end. I heard the people at nokia use -Os for certain applications because execution time is IO-limited.
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ZDevil
post Mar 31 2007, 11:04 PM
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Well then, i have another curiosity question: how would a Firefox build with -O2 optimization (which seems to be very common for compiling Z apps) compared with the one with -O4?
When do we use which level of optimization?
And how do we know? :?
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Da_Blitz
post Apr 1 2007, 12:11 AM
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just stick with -O2, -O3 or higer dont always produce faster binaries and somtimes will not compile (as i have found out)

if you really need spped -O640K should be good enough for anyone
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ShiroiKuma
post Apr 1 2007, 09:44 AM
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QUOTE(Da_Blitz @ Apr 1 2007, 09:11 AM)
if you really need spped -O640K should be good enough for anyone
*

What does this one do? And how does it compare in terms of speed, subjectively what you feel when using the compiled app, with -O2 or -O3 ?
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adf
post Apr 1 2007, 10:14 AM
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QUOTE(ShiroiKuma @ Apr 1 2007, 05:44 PM)
QUOTE(Da_Blitz @ Apr 1 2007, 09:11 AM)
if you really need spped -O640K should be good enough for anyone
*

What does this one do? And how does it compare in terms of speed, subjectively what you feel when using the compiled app, with -O2 or -O3 ?
*


Wasn't that MS humor?
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