SIMD benchmark

[Peter Alexander]

On 17/01/12 10:55 PM, Walter Bright wrote:
> On 1/17/2012 1:47 PM, Peter Alexander wrote:
>> On 17/01/12 9:24 PM, Walter Bright wrote:
>>> On 1/17/2012 1:20 PM, Peter Alexander wrote:
>>>> As Manu said, you need something like __restrict (or a linear type
>>>> system) to
>>>> solve this problem.
>>>
>>> No, you don't. It can be done with a runtime check, like array bounds
>>> checking is done.
>>
>> So you'd change it to this, even in release builds?
>
> No. Like array bounds, if they overlap, an exception is thrown.
>
> Remember, the D spec says that overlapping arrays are illegal.

The D spec says that overlapping arrays are illegal for vector ops. The 
foo(int[], int[], int[]) function does not use vector ops.

Or am I missing something really major?

For example, is this legal code?

int[100] a;
int[] b = a[0..100];
int[] c = a[10..90]; // Illegal? b and c overlap...

foreach (i; 0..80)
     c[i] = b[i]; // Illegal?

I know that b[] = c[] would be illegal, but that has nothing to do with 
the prior discussion.