[Mesa-dev] [PATCH] r600g: set address of pop instructions to next instruction

[Jerome Glisse]

On Fri, Dec 3, 2010 at 7:03 AM, Fabian Bieler <der.fabe at gmx.net> wrote:
> Hello!
>
> In R700-family_instruction_set_architecture.pdf
> pages 3-18 and 9-34 read that pop instructions never jump.
> The table on page 3-16 however reads that it does jump if the condition test
> fails for all pixels.
>
> On RV710 the attached piglit test indicates that the pop instruction does
> indeed jump sometimes.
>
> In the attached image pop instructions are executed in the lower right half
> including the diagonal. If the pop instruction jumps the pixel should be
> black. I can think of no grouping of four pixels at a time to make sense of
> that pattern. So it would seem pop doesn't always jump even if all pixels
> fail the condition test.
>
> Anyway the patch sets the address of pop instructions to the next instruction
> which fixes the test.
>
> Fabian

So my understanding is that we wrongly translate loop_break. Loop
break shouldn't be followed by a pop, as loop break just disable the
pixel in current loop and it's a loop_end that we either keep looping
or quit loop and pop. It seems removing call to pops in
tgsi_loop_brk_cont is not enough, we might be setting the wrong addr
in loop_break.

Cheers,
Jerome