Re: Xcode/gcc iPhone Autovectorization?
Re: Xcode/gcc iPhone Autovectorization?
- Subject: Re: Xcode/gcc iPhone Autovectorization?
- From: lbland <email@hidden>
- Date: Tue, 29 Jun 2010 17:06:59 -0400
hi-
On Jun 29, 2010, at 4:54 PM, Jonas Maebe wrote:
> Even the iPod Touch 2G already had VFPv2. Possibly even the first generation iPod Touch and iPhone also supported VFP, I don't know.
>
>> (ie: I have to hand code VFP - noh!)?
>
> The current iOS nee iPhone SDK agreement does not allow you to do that.
Ah, thanks! So, I guess the questions are:
- How good is gcc autovectorization for tight loops like:
double *a, *b, *c;
// assign a, b, c
for(i = 0; i < 100; i++)
{
a[i] = b[i] * c[i];
}
for the arm? I read that VFP does double as well as float.
and:
Does LLVM-GCC-4.2 really not do autovectorization?
I guess I'll have to do some timing/experimentation but knowing some basic information (like what has a VFP and what compiler takes advantage of it) is a good thing to know beforehand.
thanks!-
-lance
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