On Thu, Jan 5, 2017 at 5:07 AM, Samuel Iglesias Gonsálvez
<sigles...@igalia.com> wrote:
> From: "Juan A. Suarez Romero" <jasua...@igalia.com>
>
> When splitting a CMP/MOV instruction with NULL dest, DF sources, and
> conditional modifier; we can't use directly the flag registers, as they will
> have the wrong results in IVB/VLV after the scalarization.
>
> Rather, we need to store the result in a temporary register, and then use
> that register to set proper the flags values.
>
> If a MOV has a null destination register and a conditional modifier, it
> can be replaced with a CMP against zero with the same conditional
> modifier. By doing this replacement, we can do the SIMD lowering
> without any problem.
>
> Signed-off-by: Samuel Iglesias Gonsálvez <sigles...@igalia.com>
> Signed-off-by: Juan A. Suarez Romero <jasua...@igalia.com
> ---
> src/mesa/drivers/dri/i965/brw_vec4.cpp | 80
> +++++++++++++++++++++++++++++++---
> 1 file changed, 74 insertions(+), 6 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp
> b/src/mesa/drivers/dri/i965/brw_vec4.cpp
> index c654c8b..74ab866 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
> @@ -2190,6 +2190,46 @@ vec4_visitor::lower_simd_width()
> * value of the instruction's dst.
> */
> bool needs_temp = dst_src_regions_overlap(inst);
> +
> + /* When splitting instructions with conditional modifiers and NULL
> + * dest we can't rely directly on the flags to store the result.
> Rather,
> + * we need first to enqueue the result in a temporary register, and
> then
> + * move those values into flags.
> + */
> + bool inst_df_dst_null =
> + inst->dst.is_null() && inst->exec_data_size() == 8 &&
> + inst->conditional_mod != BRW_CONDITIONAL_NONE;
> +
> + if (inst_df_dst_null) {
> + /* If there are other DF instructions with NULL destination,
> + * we need to verify if we can use the temporary register or
> + * if we need an extra lowering step.
> + */
> + assert(inst->opcode == BRW_OPCODE_MOV ||
> + inst->opcode == BRW_OPCODE_CMP);
> +
> + /* Replace MOV.XX with null destination with the equivalente CMP.XX
Typo: extra 'e' on equivalent
Otherwise looks fine to me. I do hope that Curro has a chance to look
over the series.
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