Commit c7a8b327 authored by Kenneth Graunke's avatar Kenneth Graunke

nir: Replace vecN(undef, undef, ...) with a single undef.

shader-db statistics on Broadwell:

total instructions in shared programs: 8963409 -> 8962455 (-0.01%)
instructions in affected programs: 60858 -> 59904 (-1.57%)
helped: 318
HURT: 0

total cycles in shared programs: 71408022 -> 71406276 (-0.00%)
cycles in affected programs: 398416 -> 396670 (-0.44%)
helped: 199
HURT: 51

GAINED: 1

The only shaders affected were in Dota 2 Reborn.

It also sets up for the next optimization.
Signed-off-by: Kenneth Graunke's avatarKenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Matt Turner's avatarMatt Turner <mattst88@gmail.com>
parent 49ea7454
......@@ -22,6 +22,7 @@
*/
#include "nir.h"
#include "nir_builder.h"
/** @file nir_opt_undef.c
*
......@@ -70,19 +71,51 @@ opt_undef_csel(nir_alu_instr *instr)
return false;
}
/**
* Replace vecN(undef, undef, ...) with a single undef.
*/
static bool
opt_undef_vecN(nir_builder *b, nir_alu_instr *alu)
{
if (alu->op != nir_op_vec2 &&
alu->op != nir_op_vec3 &&
alu->op != nir_op_vec4)
return false;
assert(alu->dest.dest.is_ssa);
unsigned num_components = nir_op_infos[alu->op].num_inputs;
for (unsigned i = 0; i < num_components; i++) {
if (!alu->src[i].src.is_ssa ||
alu->src[i].src.ssa->parent_instr->type != nir_instr_type_ssa_undef)
return false;
}
b->cursor = nir_before_instr(&alu->instr);
nir_ssa_def *undef =
nir_ssa_undef(b, num_components, nir_dest_bit_size(alu->dest.dest));
nir_ssa_def_rewrite_uses(&alu->dest.dest.ssa, nir_src_for_ssa(undef));
return true;
}
bool
nir_opt_undef(nir_shader *shader)
{
nir_builder b;
bool progress = false;
nir_foreach_function(function, shader) {
if (function->impl) {
nir_builder_init(&b, function->impl);
nir_foreach_block(block, function->impl) {
nir_foreach_instr_safe(instr, block) {
if (instr->type == nir_instr_type_alu) {
nir_alu_instr *alu = nir_instr_as_alu(instr);
progress = opt_undef_csel(alu) || progress;
progress = opt_undef_vecN(&b, alu) || progress;
}
}
}
......
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