Re: GNAT's stack checking in Ubuntu 9.04 (and Shootout regex-dna)

[jonathan <johnscpg@googlemail.com>]

On Aug 12, 10:32 am, Ludovic Brenta <ludo...@ludovic-brenta.org>
wrote:

> If you use the amd64 port of Debian Lenny, your compiler is optimized
> for 64-bit. However, I use the default options for the library. For
> example, the i386 (actually i486) build daemon compiled g-spipat.adb
> thus:
>
> /build/buildd-gnat-4.3_4.3.2-1.1-i386-3dUv7K/gnat-4.3-4.3.2/build/./
> gcc/xgcc -B/build/buildd-gnat-4.3_4.3.2-1.1-i386-3dUv7K/gnat-4.3-4.3.2/
> build/./gcc/ -B/usr/i486-linux-gnu/bin/ -B/usr/i486-linux-gnu/lib/ -
> isystem /usr/i486-linux-gnu/include -isystem /usr/i486-linux-gnu/sys-
> include -c -g -O2      -W -Wall -gnatpg  g-spipat.adb -o g-spipat.o
>
> If anyone is interested, I can try to compile with -O3 -funroll-all-
> loops -gnatpg instead.
>

Using the default options for g-spipat.adb sounds reasonable to me.
The user can recompile with -a and with make-benchmark-happy flags,
if he wants to experiment. I doubt that the benchmarking happy-flags
are the safest way to go. (And -funroll-all-loops hardly matters:
seems like 3% improvement. (I finally got around to checking this;)
The
gnatn helped 8%, which was more than I expected.)

Jonathan