On Sun, Apr 17, 2016 at 11:14 PM, Kenneth Graunke <kenn...@whitecape.org> wrote:
> This reworks opt_vector_float() so that there's only one place that
> flushes out any accumulated state and emits a VF.
>
> Signed-off-by: Kenneth Graunke <kenn...@whitecape.org>
> ---
> src/mesa/drivers/dri/i965/brw_vec4.cpp | 63
> +++++++++++++++++++---------------
> 1 file changed, 35 insertions(+), 28 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp
> b/src/mesa/drivers/dri/i965/brw_vec4.cpp
> index 6433fc5..fa0d80d 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
> @@ -385,48 +385,55 @@ vec4_visitor::opt_vector_float()
> unsigned writemask = 0;
>
> foreach_block_and_inst_safe(block, vec4_instruction, inst, cfg) {
> - if (last_reg != inst->dst.nr ||
> + int vf = -1;
> +
> + /* Look for unconditional MOVs from an immediate with a partial
> + * writemask. See if the immediate can be represented as a VF.
> + */
> + if (inst->opcode == BRW_OPCODE_MOV &&
> + inst->src[0].file == IMM &&
> + inst->predicate == BRW_PREDICATE_NONE &&
> + inst->dst.writemask != WRITEMASK_XYZW) {
> + vf = brw_float_to_vf(inst->src[0].f);
> + }
> +
> + /* If this wasn't a MOV, or the value was non-representable, or
> + * the destination register doesn't match, then this breaks our
> + * sequence. Combine anything we've accumulated so far.
> + */
> + if (vf == -1 ||
Is the value being non-representable an important point? Running
shader-db on the first three patches shows that something hurt 20
programs, and I think it's considering a non-representable value to
break the sequence.
For instance, in metro-last-light/2175 we see:
-mov(8) g16<1>.yD 1033476506D
-mov(8) g16<1>.xzF [0.375F, 0F, 2.5F, 0F]VF
+mov(8) g16<1>.xD 1052770304D
+mov(8) g16<1>.yD 1033476506D
+mov(8) g16<1>.zD 1075838976D
where the .y component isn't representable but x and z are. I suspect
the other 19 cases are the same problem.
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