CFLAGS

**the0r3tic** · 10-26-2005

What you guys make of these optimizations? I know -ffast-math can be dodgy but it's supposed to be stable enough for a ~x86 desktop box, plus from what I hear there's a noticable performance increase. I omitted -funroll-loops because of the problems I've heard it can cause with the kernel (Im building the kernel and bootstrapping with very basic flags anyway), and the amount of bloat it creats.

Code:

CFLAGS="-O3 -pipe -finline-functions -fgcse -fmove-all-movables -fomit-frame-pointer
-falign-functions=4 -falign-jumps=4 -fvisibility-inlines-hidden -fweb -fmerge-all-constants
-ffast-math -ftracer -fprefetch-loop-arrays -march=pentium4 -mtune=pentium4"

My cpu is a Intel Celeron (Northwood P4 core), so it's basically a pentium 4 with a **** cache.

**dylunio** · 10-26-2005

Code:

CFLAGS="-O3 -march=pentium2 -fforce-addr -momit-leaf-frame-pointer -fomit-frame-pointer -ftracer -pipe"

is what I have for my PII 300MHz machine.

**jaboua** · 10-28-2005

Something like this:

Code:

CFLAGS="-Os -march=atlhon-tbird -fomit-frame-pointer -pipe -mmmx -m3dnow -fforce-addr

I don't think I've compiled an entire system with -O3 before, but I've used -O2 and -Os.

I used to use -ffast-math, but I removed it after seing the warning in the GCC manual. Can you notice a huge performance gain?

**borromini** · 10-28-2005

Code:

CFLAGS="-O2 -march=i486 -mcpu=i686"

Just regular stuff, since what I compile must be usable on other boxes too.

**josolanes** · 10-29-2005

mine's pretty simple:

Code:

CFLAGS="-march=athlon-mp -mfpmath=sse -m3dnow -m32 -pipe -O3 -fomit-frame-pointer"

it's a dual-cpu machine...

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