Greg Schafer wrote:

> PS - According to my build logs, GCC-4.2 takes almost *double* the amount
> of time of GCC-4.1 for a 3-stage bootstrap. This doesn't matter much on a
> modern dual-core system (16m 45s vs 8m 41s) but it's very noticeable on an
> older ppc mac mini (91m vs 43m). So maybe there *is* merit in skipping the
> bootstrap after all? :-) But seriously, I suspect the reason is some extra
> checking is switched on in the stage1 4.2 compiler (I managed to hac^H^H^H
> switch it off in the 4.1 series). Will investigate...

Ok, it appears the GCC devs conveniently added a new (undocumented?)
configure switch in 4.2 `--disable-stage1-checking' which does the right
thing. Times for GCC-4.2.1 bootstraps without and with the switch are

real    18m54.421s
user    32m55.131s
sys     1m46.275s

real    13m0.254s
user    22m24.004s
sys     1m47.959s

Amount of time saved will obviously increase the slower the hardware. If
bootstrap times are a concern then I would recommend LFS use this switch
when upgrading to GCC-4.2.x. I'll be adding it to my Refbuild ASAP.


Unsubscribe: See the above information page

Reply via email to