Array Operations

[Iain Buclaw]

== Quote from Jonathan Crapuchettes (jcrapuchettes at gmail.com)'s article
> Michael Parrott wrote:
> > Jonathan Crapuchettes Wrote:
> >
> >> I followed the example in issue #30:
> >> http://bitbucket.org/goshawk/gdc/issue/30/d_inlineasm-updates
> >>
> >> DFLAGS='-O2 -g -frelease -march=pentium3' ../configure --enable-languages=d
> >> --disable-multilib --disable-shared
> >>
> >> Is this wrong?
> >> JC
> >>
> >> Michael Parrott wrote:
> >>> Jonathan Crapuchettes Wrote:
> >>>
> >>>> I have been trying to add the SSE2 array operation code to the
compilation, but
> >>>> it seems like the DFLAGS variable isn't being used. Can you offer any
suggestions?
> >>>> Thank you,
> >>>> JC
> >>>
> >>> Did you set DFLAGS before running configure? If you didn't, that might be
why.
> >>>
> >>> Example:
> >>>
> >>> DFLAGS="-g"
> >>> export DFLAGS
> >>> ../configure --enable-languages=d .....
> >>> make
> >>> sudo make install
> >>>
> >>> Something like that should work.
> >
> > No, that should be fine.
> >
> > What is wrong when you do that? Are there errors when you build? Does Phobos
not seem to be taking advantage of the SSE operations?
> >
> > In phobos/internal/array{byte, double, float, int, short}.d, you need to
uncomment the sections labelled "version (D_InlineAsm_X86)" to enable the ASM
code.
> I did uncommented the version sections, but thank you for the reminder.
> I can tell that the SSE code is not being used because I compared two pieces
of
> code:
> for (int i = 0; i < a.length; i++)
>      c[i] = a[i] / 1000;
> and
> c[] = a[] / 1000;
> They should produce the same result and they do, but the array operation code
> should be much faster. I base this assumption off of the same speed test using
> DMD. The execution time for the two code segments, produced by GDC, are about
> the same. I also compared the assembly for the objects created by GDC and DMD.
> The GDC code is not using the SSE code as specified in the arrayDouble.d file,
> but the DMD code is.
> If you have suggestions, I am all ears.
> Thank you for taking the time to help me,
> JC

That's because the function called to perform the operation
(_arraySliceExpDivSliceAssign_i) is not implemented in phobos - so a stock
function is generated by the compiler instead.

Regards