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aco: Skip 2nd read of merged wave info when TCS in/out vertices are equal.

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When TCS has an equal number of input and output, it means that the
number of VS and TCS invocations (LS and HS) are the same; and that
the HS invocations operate on the same vertices as the LS.

When this is the case, this commit removes the else-if between
the merged VS and TCS halves, making it possible to schedule
and optimize the code accross the two halves.

Totals:
SGPRS: 5577367 -> 5581735 (0.08 %)
VGPRS: 3958592 -> 3960752 (0.05 %)
Code Size: 254867144 -> 254838244 (-0.01 %) bytes
Max Waves: 1053887 -> 1053747 (-0.01 %)

Totals from affected shaders:
SGPRS: 29032 -> 33400 (15.05 %)
VGPRS: 35664 -> 37824 (6.06 %)
Code Size: 1979028 -> 1950128 (-1.46 %) bytes
Max Waves: 7310 -> 7170 (-1.92 %)

Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4165>
This commit is contained in:
Timur Kristóf 2020-03-12 19:54:16 +01:00 • committed by Marge Bot
parent 4ec48440a0
commit 17c779ab9e
2 changed files with 18 additions and 6 deletions
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14
src/amd/compiler/aco_instruction_selection.cpp
View file

@ -9752,6 +9752,7 @@ void select_program(Program *program,
struct radv_shader_args *args)
{
isel_context ctx = setup_isel_context(program, shader_count, shaders, config, args, false);
if_context ic_merged_wave_info;
for (unsigned i = 0; i < shader_count; i++) {
nir_shader *nir = shaders[i];
@ -9778,14 +9779,15 @@ void select_program(Program *program,
(nir->info.stage == MESA_SHADER_TESS_EVAL &&
ctx.stage == tess_eval_geometry_gs));
if_context ic;
if (shader_count >= 2 && !empty_shader) {
bool check_merged_wave_info = ctx.tcs_in_out_eq ? i == 0 : (shader_count >= 2 && !empty_shader);
bool endif_merged_wave_info = ctx.tcs_in_out_eq ? i == 1 : check_merged_wave_info;
if (check_merged_wave_info) {
Builder bld(ctx.program, ctx.block);
Temp count = bld.sop2(aco_opcode::s_bfe_u32, bld.def(s1), bld.def(s1, scc), get_arg(&ctx, args->merged_wave_info), Operand((8u << 16) | (i * 8u)));
Temp thread_id = emit_mbcnt(&ctx, bld.def(v1));
Temp cond = bld.vopc(aco_opcode::v_cmp_gt_u32, bld.hint_vcc(bld.def(bld.lm)), count, thread_id);
begin_divergent_if_then(&ctx, &ic, cond);
begin_divergent_if_then(&ctx, &ic_merged_wave_info, cond);
}
if (i) {
@ -9821,9 +9823,9 @@ void select_program(Program *program,
if (ctx.stage == fragment_fs)
create_fs_exports(&ctx);
if (shader_count >= 2 && !empty_shader) {
begin_divergent_if_else(&ctx, &ic);
end_divergent_if(&ctx, &ic);
if (endif_merged_wave_info) {
begin_divergent_if_else(&ctx, &ic_merged_wave_info);
end_divergent_if(&ctx, &ic_merged_wave_info);
}
ralloc_free(ctx.divergent_vals);

10
src/amd/compiler/aco_instruction_selection_setup.cpp
View file

@ -100,6 +100,7 @@ struct isel_context {
unsigned tcs_tess_lvl_in_loc;
uint32_t tcs_num_inputs;
uint32_t tcs_num_patches;
bool tcs_in_out_eq = false;
/* VS, FS or GS output information */
output_state outputs;
@ -899,6 +900,15 @@ setup_tcs_variables(isel_context *ctx, nir_shader *nir)
unreachable("Unsupported TCS shader stage");
}
/* When the number of TCS input and output vertices are the same (typically 3):
* - There is an equal amount of LS and HS invocations
* - In case of merged LSHS shaders, the LS and HS halves of the shader
* always process the exact same vertex. We can use this knowledge to optimize them.
*/
ctx->tcs_in_out_eq =
ctx->stage == vertex_tess_control_hs &&
ctx->args->options->key.tcs.input_vertices == nir->info.tess.tcs_vertices_out;
ctx->tcs_num_patches = get_tcs_num_patches(
ctx->args->options->key.tcs.input_vertices,
nir->info.tess.tcs_vertices_out,