| 1 |
Florian Philipp wrote: |
| 2 |
> Am Freitag 20 Juli 2007 20:16 schrieb Kenneth Prugh: |
| 3 |
>> Andrew Gaydenko wrote: |
| 4 |
>>> I have noticed, the official portage tree has included gcc 4.2. Now for |
| 5 |
>>> Core 2 Duo CPU (amd64 Gentoo arch) I use in make.conf file: |
| 6 |
>>> |
| 7 |
>>> CFLAGS="-O2 -march=nocona -pipe" |
| 8 |
>>> |
| 9 |
>>> gcc' changelog has this note: |
| 10 |
>>> |
| 11 |
>>> -------------------- |
| 12 |
>>> ... |
| 13 |
>>> IA-32/x86-64 |
| 14 |
>>> |
| 15 |
>>> * -mtune=generic can now be used to generate code running well on |
| 16 |
>>> common x86 chips. This includes AMD Athlon, AMD Opteron, Intel Pentium-M, |
| 17 |
>>> Intel Pentium 4 and Intel Core 2. |
| 18 |
>>> * -mtune=native and -march=native will produce code optimized for the |
| 19 |
>>> host architecture as detected using the cpuid instruction. |
| 20 |
>>> ... |
| 21 |
>>> -------------------- |
| 22 |
>>> |
| 23 |
>>> The question is: must I replace '-march=nocona' with '-mtune=native and |
| 24 |
>>> -march=native'? |
| 25 |
>> I have a Core2 Duo E6600 and use these CFLAGS with GCC 4.2: |
| 26 |
>> |
| 27 |
>> CFLAGS="-Os -march=native -mtune=native -fomit-frame-pointer -pipe -mmmx |
| 28 |
>> -msse2 -msse3" |
| 29 |
>> |
| 30 |
>> Native works fine here. |
| 31 |
> |
| 32 |
> I don't think that you need -msse3 -msse2 and -mmmx because -march takes care |
| 33 |
> of that (refer to "man gcc", one notable exeption: -march=athlon64 does not |
| 34 |
> pull -msse3 in because not all Athlons support it). |
| 35 |
> -fomit-frame-pointer is unneccessary on AMD64 (refer to "man gcc", again). |
| 36 |
|
| 37 |
Yeah I wasn't exactly positive if it did pull everything in, and |
| 38 |
specifying specifically can't really hurt at all as long as you know |
| 39 |
it's supported with your cpu. |
| 40 |
|
| 41 |
-- |
| 42 |
Kenneth Prugh - Ken69267 |
| 43 |
Gentoo AMD64 Arch Tester |
Archives