[gentoo-amd64] CFLAGS question from a AMD64 newbie

["Sami Näätänen" <sn.ml@keijukammari.fi>]

So hi from a amd64 newbie. Not so newbie with Gentoo though. :)

My system is an Intel quad core core2 with a 2.4 GHz clock speed coupled with 
a 4GB of memory. No overclocking etc. Want this to be stable. :)

I'm just curious what people use as their stable CFLAGS in amd64 Gentoo?
(Sorry if this has been up lately, but I just switched to 64bit env so...)


Here is mine and some explanation of why (And I use ~arch system with gcc 4.3)

The flags are in order they are used in my CFLAGS and CXXFLAGS.

Gives stable base
-O2

Want to optimize for my system, but don't want "native"
-march=core2

If some ebuilds filter march this will still cache optimize etc for my system
-mtune=core2

Faster floating point math and better chance of vectorization
-mfpmath=sse

These because of the march might get filtered
-mmmx -msse -msse2 -msse3 -mssse3

For loop vectorization
-ftree-vectorize

Just to get some Idea how much vectorized loops there will be.
By the way I surprised the amount of "LOOP VECTORIZED" notes in the compile 
output. And only have seen couple of two versions 
-ftree-vectorizer-verbose=1

Of course I don't want temp files :)
-pipe


I don't use any loop unrolling etc, because it would only add the code size.
I'm not so brave that I would dare to use -Os.

So what's your experiences and reasoning behind what you do?
Any benchmarks or so?


PS. If you see same post without this added postscript. Just ignore it, it's 
the same post, but I forgot to change my default identity for this ML.