Gcc -o4 Flag

[ShiroiKuma]

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?

[speculatrix]

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.


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I wonder whether anyone will understand this joke?

[adf]

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.


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I wonder whether anyone will understand this joke?
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11

[Meanie]

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.


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I wonder whether anyone will understand this joke?
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11
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oh man, these geek jokes are way over my head. can someone explain it so some dummy like me can understand it?

[speculatrix]

If you haven't seen the film "Spinal Tap", the joke won't make any sense.

[ShiroiKuma]

If you haven't seen the film "Spinal Tap", the joke won't make any sense.
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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?

[koen]

If you haven't seen the film "Spinal Tap", the joke won't make any sense.
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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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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.

[ZDevil]

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?  :?

[Da_Blitz]

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

[ShiroiKuma]

if you really need spped -O640K should be good enough for anyone
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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 ?

[adf]

if you really need spped -O640K should be good enough for anyone
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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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Wasn't that MS humor?