[Mesa-dev] [PATCH] prog_to_nir: Make RSQ properly take the absolute value of its argument.

[Francisco Jerez]

Kenneth Graunke <kenneth at whitecape.org> writes:

> I just botched this when writing the original code.
>
> From the ARB_vertex_program specification:
> "The RSQ instruction approximates the reciprocal of the square root of
>  the absolute value of the scalar operand and replicates it to all four
>  components of the result vector."
>
> Fixes a Glean vertProg1 subtest:
> RSQ test 2 (reciprocal square root of negative value)
>
> Cc: mesa-stable at lists.freedesktop.org
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90547
> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>

Reviewed-by: Francisco Jerez <currojerez at riseup.net>

> ---
>  src/mesa/program/prog_to_nir.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/src/mesa/program/prog_to_nir.c b/src/mesa/program/prog_to_nir.c
> index e986e51..d3e3f15 100644
> --- a/src/mesa/program/prog_to_nir.c
> +++ b/src/mesa/program/prog_to_nir.c
> @@ -764,7 +764,8 @@ ptn_emit_instruction(struct ptn_compile *c, struct prog_instruction *prog_inst)
>  
>     switch (op) {
>     case OPCODE_RSQ:
> -      ptn_move_dest(b, dest, nir_frsq(b, ptn_channel(b, src[0], X)));
> +      ptn_move_dest(b, dest,
> +                    nir_frsq(b, nir_fabs(b, ptn_channel(b, src[0], X))));
>        break;
>  
>     case OPCODE_RCP:
> -- 
> 2.4.2
>
> _______________________________________________
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> mesa-dev at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/mesa-dev
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