Mesa (master): i965/cs: Don' t use a thread channel ID for small local sizes
Jordan Justen
jljusten at kemper.freedesktop.org
Wed Oct 19 23:58:12 UTC 2016
Module: Mesa
Branch: master
Commit: 64c3d735354932c3b14397e9c292f5989a9da710
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=64c3d735354932c3b14397e9c292f5989a9da710
Author: Jordan Justen <jordan.l.justen at intel.com>
Date: Wed Jul 6 15:08:27 2016 -0700
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 at intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>
---
src/mesa/drivers/dri/i965/brw_nir_intrinsics.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_nir_intrinsics.c b/src/mesa/drivers/dri/i965/brw_nir_intrinsics.c
index 9ae161f..d63570f 100644
--- a/src/mesa/drivers/dri/i965/brw_nir_intrinsics.c
+++ b/src/mesa/drivers/dri/i965/brw_nir_intrinsics.c
@@ -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;
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