SIMD benchmark

[Iain Buclaw]

On 16 January 2012 21:57, Peter Alexander <peter.alexander.au at gmail.com> wrote:
> On 16/01/12 8:56 PM, Iain Buclaw wrote:
>>
>> On 16 January 2012 19:25, Walter Bright<newshound2 at digitalmars.com>
>>  wrote:
>>>
>>> On 1/16/2012 11:16 AM, Iain Buclaw wrote:
>>>
>>>>>
>>>>> But don't worry, I'm not planning on working on that at the moment :-)
>>>>
>>>>
>>>> Leave that sort of optimisation for the backend to handle please. ;-)
>>>
>>>
>>>
>>> Of course.
>>>
>>> I suspect Intel's compiler does that one, does gcc?
>>>
>>
>> There's auto-vectorisation for for(), foreach(), and foreach_reverse()
>> loops that I have written support for.  I am not aware of GCC
>> vectorising anything else.
>>
>> example:
>>
>> int a[256], b[256], c[256];
>> void foo () {
>>   for (int i=0; i<256; i++)
>>     a[i] = b[i] + c[i];
>> }
>>
>
> Unfortunately, if the function was this:
>
> void foo(int[] a, int[] b, int[] c) {
>
>  for (int i=0; i<256; i++)
>    a[i] = b[i] + c[i];
> }
>
> Then it can't vectorize due to aliasing.

Compile with -fstrict-aliasing then?

I could certainly play about with having this enabled by default, but
I forsee there may be issues (maybe have it on for @safe code?)


Regards
-- 
Iain Buclaw

*(p < e ? p++ : p) = (c & 0x0f) + '0';