[Mesa-dev] [PATCH 07/25] i965/fs: Implement opt_sampler_eot() in terms of logical sends.
Jason Ekstrand
jason at jlekstrand.net
Sat May 28 20:31:58 UTC 2016
On Sat, May 28, 2016 at 1:21 PM, Francisco Jerez <currojerez at riseup.net>
wrote:
> Jason Ekstrand <jason at jlekstrand.net> writes:
>
> > On Fri, May 27, 2016 at 7:05 PM, Francisco Jerez <currojerez at riseup.net>
> > wrote:
> >
> >> This makes the whole LOAD_PAYLOAD munging unnecessary which simplifies
> >> the code and will allow the optimization to succeed in more cases
> >> independent of whether the LOAD_PAYLOAD instruction can be found or
> >> not.
> >> ---
> >> src/mesa/drivers/dri/i965/brw_fs.cpp | 79
> >> +++++++++++-------------------------
> >> 1 file changed, 23 insertions(+), 56 deletions(-)
> >>
> >> diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp
> >> b/src/mesa/drivers/dri/i965/brw_fs.cpp
> >> index 45c4753..6abf776 100644
> >> --- a/src/mesa/drivers/dri/i965/brw_fs.cpp
> >> +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
> >> @@ -2612,11 +2612,15 @@ fs_visitor::opt_sampler_eot()
> >> if (key->nr_color_regions != 1)
> >> return false;
> >>
> >> + /* Requires clamping the color payload in the shader. */
> >> + if (key->clamp_fragment_color)
> >> + return false;
> >>
> >
> > This looks new... Is it actually needed? Could we simply do "if
> > (tex_inst->saturate) return false;"? In any case, it should probably be
> > it's own commit.
> >
>
> It is necessary to preserve the current behavior and skip the
> optimization when fragment color clamping is required, because right now
> the MOVs used to saturate the color values are inserted during logical
> send lowering so this pass would have no other way to find out. I can
> make the change in a separate commit just before this one if you like.
>
Right. No need to make it a separate commit. Just update the comment so
it says something about the MOVs inserted during lowering.
Incidentally, I think Rob Clark recently added some stuff to do that
lowering in NIR... In the future, we might want to use that and delete
more back-end code. For now, an udpated comment will do. :-)
> >
> >> +
> >> /* Look for a texturing instruction immediately before the final
> >> FB_WRITE. */
> >> bblock_t *block = cfg->blocks[cfg->num_blocks - 1];
> >> fs_inst *fb_write = (fs_inst *)block->end();
> >> assert(fb_write->eot);
> >> - assert(fb_write->opcode == FS_OPCODE_FB_WRITE);
> >> + assert(fb_write->opcode == FS_OPCODE_FB_WRITE_LOGICAL);
> >>
> >> /* There wasn't one; nothing to do. */
> >> if (unlikely(fb_write->prev->is_head_sentinel()))
> >> @@ -2629,24 +2633,20 @@ fs_visitor::opt_sampler_eot()
> >> * “Response Length of zero is allowed on all SIMD8* and SIMD16*
> >> sampler
> >> * messages except sample+killpix, resinfo, sampleinfo, LOD, and
> >> gather4*”
> >> */
> >> - if (!tex_inst->is_tex() ||
> >> - tex_inst->opcode == SHADER_OPCODE_TXS ||
> >> - tex_inst->opcode == SHADER_OPCODE_SAMPLEINFO ||
> >> - tex_inst->opcode == SHADER_OPCODE_LOD ||
> >> - tex_inst->opcode == SHADER_OPCODE_TG4 ||
> >> - tex_inst->opcode == SHADER_OPCODE_TG4_OFFSET)
> >> + if (tex_inst->opcode != SHADER_OPCODE_TEX_LOGICAL &&
> >> + tex_inst->opcode != SHADER_OPCODE_TXD_LOGICAL &&
> >> + tex_inst->opcode != SHADER_OPCODE_TXF_LOGICAL &&
> >> + tex_inst->opcode != SHADER_OPCODE_TXL_LOGICAL &&
> >> + tex_inst->opcode != FS_OPCODE_TXB_LOGICAL &&
> >> + tex_inst->opcode != SHADER_OPCODE_TXF_CMS_LOGICAL &&
> >> + tex_inst->opcode != SHADER_OPCODE_TXF_CMS_W_LOGICAL &&
> >> + tex_inst->opcode != SHADER_OPCODE_TXF_UMS_LOGICAL)
> >> return false;
> >>
> >
> > Same here. This isn't just a rename, it's a switch from listing invalid
> > cases to explicitly listing valid ones.
> >
>
> The reason is that is_tex() is unaware of the logical messages, I
> considered changing that but a few places expect instructions marked
> is_tex to be send-like (e.g. fs_inst::is_send_from_grf,
> fs_inst::regs_read), so we would have to stop using is_tex() in those
> places if we change it.
>
Right. Makes sense. Seems fine to me. Feel free to leave this patch
as-is apart from a better comment above.
Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>
>
> > Other than those two comments, I really like this. It's a nice cleanup.
> >
> >
> >>
> >> - /* If there's no header present, we need to munge the LOAD_PAYLOAD
> as
> >> well.
> >> - * It's very likely to be the previous instruction.
> >> - */
> >> + /* XXX - This shouldn't be necessary. */
> >> if (tex_inst->prev->is_head_sentinel())
> >> return false;
> >>
> >> - fs_inst *load_payload = (fs_inst *) tex_inst->prev;
> >> - if (load_payload->opcode != SHADER_OPCODE_LOAD_PAYLOAD)
> >> - return false;
> >> -
> >> assert(!tex_inst->eot); /* We can't get here twice */
> >> assert((tex_inst->offset & (0xff << 24)) == 0);
> >>
> >> @@ -2658,46 +2658,10 @@ fs_visitor::opt_sampler_eot()
> >> tex_inst->regs_written = 0;
> >> fb_write->remove(cfg->blocks[cfg->num_blocks - 1]);
> >>
> >> - /* If a header is present, marking the eot is sufficient. Otherwise,
> >> we need
> >> - * to create a new LOAD_PAYLOAD command with the same sources and a
> >> space
> >> - * saved for the header. Using a new destination register not only
> >> makes sure
> >> - * we have enough space, but it will make sure the dead code
> >> eliminator kills
> >> - * the instruction that this will replace.
> >> + /* Marking EOT is sufficient, lower_logical_sends() will notice the
> EOT
> >> + * flag and submit a header together with the sampler message as
> >> required
> >> + * by the hardware.
> >> */
> >> - if (tex_inst->header_size != 0) {
> >> - invalidate_live_intervals();
> >> - return true;
> >> - }
> >> -
> >> - fs_reg send_header = ibld.vgrf(BRW_REGISTER_TYPE_F,
> >> - load_payload->sources + 1);
> >> - fs_reg *new_sources =
> >> - ralloc_array(mem_ctx, fs_reg, load_payload->sources + 1);
> >> -
> >> - new_sources[0] = fs_reg();
> >> - for (int i = 0; i < load_payload->sources; i++)
> >> - new_sources[i+1] = load_payload->src[i];
> >> -
> >> - /* The LOAD_PAYLOAD helper seems like the obvious choice here.
> >> However, it
> >> - * requires a lot of information about the sources to appropriately
> >> figure
> >> - * out the number of registers needed to be used. Given this stage
> in
> >> our
> >> - * optimization, we may not have the appropriate GRFs required by
> >> - * LOAD_PAYLOAD at this point (copy propagation). Therefore, we
> need to
> >> - * manually emit the instruction.
> >> - */
> >> - fs_inst *new_load_payload = new(mem_ctx)
> >> fs_inst(SHADER_OPCODE_LOAD_PAYLOAD,
> >> -
> >> load_payload->exec_size,
> >> - send_header,
> >> - new_sources,
> >> -
> load_payload->sources
> >> + 1);
> >> -
> >> - new_load_payload->regs_written = load_payload->regs_written + 1;
> >> - new_load_payload->header_size = 1;
> >> - tex_inst->mlen++;
> >> - tex_inst->header_size = 1;
> >> - tex_inst->insert_before(cfg->blocks[cfg->num_blocks - 1],
> >> new_load_payload);
> >> - tex_inst->src[0] = send_header;
> >> -
> >> invalidate_live_intervals();
> >> return true;
> >> }
> >> @@ -4153,7 +4117,7 @@ lower_sampler_logical_send_gen7(const fs_builder
> >> &bld, fs_inst *inst, opcode op,
> >> sources[i] = bld.vgrf(BRW_REGISTER_TYPE_F);
> >>
> >> if (op == SHADER_OPCODE_TG4 || op == SHADER_OPCODE_TG4_OFFSET ||
> >> - offset_value.file != BAD_FILE ||
> >> + offset_value.file != BAD_FILE || inst->eot ||
> >> op == SHADER_OPCODE_SAMPLEINFO ||
> >> is_high_sampler(devinfo, sampler)) {
> >> /* For general texture offsets (no txf workaround), we need a
> >> header to
> >> @@ -4174,7 +4138,7 @@ lower_sampler_logical_send_gen7(const fs_builder
> >> &bld, fs_inst *inst, opcode op,
> >> * and we have an explicit header, we need to set up the sampler
> >> * writemask. It's reversed from normal: 1 means "don't write".
> >> */
> >> - if (inst->regs_written != 4 * reg_width) {
> >> + if (!inst->eot && inst->regs_written != 4 * reg_width) {
> >> assert((inst->regs_written % reg_width) == 0);
> >> unsigned mask = ~((1 << (inst->regs_written / reg_width)) -
> 1) &
> >> 0xf;
> >> inst->offset |= mask << 12;
> >> @@ -5738,6 +5702,10 @@ fs_visitor::optimize()
> >> pass_num = 0;
> >>
> >> OPT(lower_simd_width);
> >> +
> >> + /* After SIMD lowering just in case we had to unroll the EOT send.
> */
> >> + OPT(opt_sampler_eot);
> >> +
> >> OPT(lower_logical_sends);
> >>
> >> if (progress) {
> >> @@ -5761,7 +5729,6 @@ fs_visitor::optimize()
> >> }
> >>
> >> OPT(opt_redundant_discard_jumps);
> >> - OPT(opt_sampler_eot);
> >>
> >> if (OPT(lower_load_payload)) {
> >> split_virtual_grfs();
> >> --
> >> 2.7.3
> >>
> >> _______________________________________________
> >> mesa-dev mailing list
> >> mesa-dev at lists.freedesktop.org
> >> https://lists.freedesktop.org/mailman/listinfo/mesa-dev
> >>
>
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