Am Montag, den 27.11.2017, 12:14 +0100 schrieb Gert Wollny:
> Am Sonntag, den 26.11.2017, 18:01 -0800 schrieb Eric Anholt:
> >
> >
> > This looks like something that should be done with (at most) a
> > small change to opt_array_splitting.cpp, rather than reimplementing
> > it here.
>
> It seems that the reason the arrays are not split there is that in
> the case of the given piglits, the arrays are accessed in loops, and
> only because the loops are completely unrolled (on r600), the array
> elements are then no longer addressed indirectly and can be split.
>
> Since I have not yet looked at that part of the code I wonder now
> whether it one can simply move the "optimize_split_arrays" step past
> the loop unrolling, or whether one should duplicate that step.
Okay, now I see that the optimization is run various times, so it is
not clear to me why the array is not split in
glsl-1.50/execution/geometry/max-input-components
There the array that doesn't get split is declared like
in blk {
float f[min(gl_MaxGeometryInputComponents,
gl_MaxVertexOutputComponents)];
} ins[];
The typical IR for the element access then looks like this
(if
(expression bool != (array_ref
(record_ref
(array_ref
(var_ref ins)
(constant int (4))
)
f)
(constant int (81)) )
(constant float (4082.000000)) ) (
(assign (x) (var_ref ok) (constant bool (0)) )
)
())
in TGSI this is.
FSNE TEMP[851].x := ARRAY(1)[81].xxxx, IMM[83].xxxx
i.e. direct addressing.
If I understand the comments in opt_array_splitting, arrays of arrays
are not properly handled there. Curretly, I don't see how I can fix
this, because I simply didn't look at any code there before.
Best,
Gert
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