Why there isn't a three foreach loop?

[Gabriel Alves Cunha]

for (int i = 0; i <= isize; ++i)

        foreach (j = 0 ... jsize, k = 0 ... ksize)

            if (foo())

                 bar();

foreach (i = 0 ... isize, j = 0 ... jsize, k = 0 ... ksize)

if (foo())

                bar();

[Dmitry Babokin]

We have it, for example here: https://github.com/ispc/ispc/blob/master/examples/aobench/ao.ispc#L216

Note, that tiled version is not much different. If you remove "_tiled" it will work as well.

If you are asking why writing the former version, not the later, it yields different code sequence. This way you guarantee that outer loops has uniform control flow and it's really outer loop. With foreach you cannot guarantee that. Though I think on practice the code should be the same.

Dmitry.

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[Gabriel Alves Cunha]

Oh, goody. Thanks!!! I went back to the documentation and I see now that I've misread it...

Em sexta-feira, 22 de maio de 2020 15:40:42 UTC-3, Dmitry Babokin escreveu:

We have it, for example here: https://github.com/ispc/ispc/blob/master/examples/aobench/ao.ispc#L216

Note, that tiled version is not much different. If you remove "_tiled" it will work as well.

If you are asking why writing the former version, not the later, it yields different code sequence. This way you guarantee that outer loops has uniform control flow and it's really outer loop. With foreach you cannot guarantee that. Though I think on practice the code should be the same.

Dmitry.

On Fri, May 22, 2020 at 10:44 AM Gabriel Alves Cunha <gabrie...@gmail.com> wrote:

for (int i = 0; i <= isize; ++i)

        foreach (j = 0 ... jsize, k = 0 ... ksize)

            if (foo())

                 bar();

foreach (i = 0 ... isize, j = 0 ... jsize, k = 0 ... ksize)

if (foo())

                bar();

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