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i965/cs: Don't use a thread channel ID for small local sizes 

When the local group size is 8 or less, we will execute the program at
most 1 time. Therefore, the local channel ID will always be 0. By
using a constant 0 in this case we can prevent using push constant
data.

This is not expected to be common a occurance in real applications,
but it has been seen in tests.

We could extend this optimization to 16 and 32 for SIMD16 and SIMD32,
but it gets a bit more complicated, because this optimization is
currently being done early on, before we have decided the SIMD size.

Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
This commit is contained in:
Jordan Justen 2016-07-06 15:08:27 -07:00
parent 1fa000a33b
commit 64c3d73535
1 changed files with 11 additions and 2 deletions
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13
src/mesa/drivers/dri/i965/brw_nir_intrinsics.c
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@ -39,12 +39,21 @@ struct lower_intrinsics_state {
static nir_ssa_def *
read_thread_local_id(struct lower_intrinsics_state *state)
{
nir_builder *b = &state->builder;
nir_shader *nir = state->nir;
const unsigned *sizes = nir->info.cs.local_size;
const unsigned group_size = sizes[0] * sizes[1] * sizes[2];
/* Some programs have local_size dimensions so small that the thread local
* ID will always be 0.
*/
if (group_size <= 8)
return nir_imm_int(b, 0);
assert(state->cs_prog_data->thread_local_id_index >= 0);
state->cs_thread_id_used = true;
const int id_index = state->cs_prog_data->thread_local_id_index;
nir_builder *b = &state->builder;
nir_shader *nir = state->nir;
nir_intrinsic_instr *load =
nir_intrinsic_instr_create(nir, nir_intrinsic_load_uniform);
load->num_components = 1;