This will allow dead components of varyings to be removed.
BDW shader-db results:
total instructions in shared programs: 13190730 -> 13108459 (-0.62%)
instructions in affected programs: 2110903 -> 2028632 (-3.90%)
helped: 14043
HURT: 486
total cycles in shared programs: 541148990 -> 540544072 (-0.11%)
cycles in affected programs: 290344296 -> 289739378 (-0.21%)
helped: 23418
HURT: 11623
total loops in shared programs: 3923 -> 3920 (-0.08%)
loops in affected programs: 3 -> 0
helped: 3
HURT: 0
total spills in shared programs: 85784 -> 85853 (0.08%)
spills in affected programs: 1374 -> 1443 (5.02%)
helped: 6
HURT: 15
total fills in shared programs: 88717 -> 88801 (0.09%)
fills in affected programs: 1719 -> 1803 (4.89%)
helped: 15
HURT: 9
LOST: 3
GAINED: 0
The fills/spills changes were all in the dolphin uber shaders.
I tested enabling this on IVB but the results went in the other
direction.
---
src/mesa/drivers/dri/i965/brw_link.cpp | 35 ++++++++++++++++++++++++----------
1 file changed, 25 insertions(+), 10 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_link.cpp
b/src/mesa/drivers/dri/i965/brw_link.cpp
index 1a28e63fca..e4b642f49d 100644
--- a/src/mesa/drivers/dri/i965/brw_link.cpp
+++ b/src/mesa/drivers/dri/i965/brw_link.cpp
@@ -217,20 +217,31 @@ update_xfb_info(struct gl_transform_feedback_info
*xfb_info,
}
extern "C" GLboolean
brw_link_shader(struct gl_context *ctx, struct gl_shader_program *shProg)
{
struct brw_context *brw = brw_context(ctx);
const struct brw_compiler *compiler = brw->screen->compiler;
unsigned int stage;
struct shader_info *infos[MESA_SHADER_STAGES] = { 0, };
+ /* Determine first and last stage. */
+ unsigned first = MESA_SHADER_STAGES;
+ unsigned last = 0;
+ for (unsigned i = 0; i < MESA_SHADER_STAGES; i++) {
+ if (!shProg->_LinkedShaders[i])
+ continue;
+ if (first == MESA_SHADER_STAGES)
+ first = i;
+ last = i;
+ }
+
for (stage = 0; stage < ARRAY_SIZE(shProg->_LinkedShaders); stage++) {
struct gl_linked_shader *shader = shProg->_LinkedShaders[stage];
if (!shader)
continue;
struct gl_program *prog = shader->Program;
prog->Parameters = _mesa_new_parameter_list();
process_glsl_ir(brw, shProg, shader);
@@ -244,31 +255,35 @@ brw_link_shader(struct gl_context *ctx, struct
gl_shader_program *shProg)
if (debug_enabled && shader->ir) {
fprintf(stderr, "GLSL IR for native %s shader %d:\n",
_mesa_shader_stage_to_string(shader->Stage), shProg->Name);
_mesa_print_ir(stderr, shader->ir, NULL);
fprintf(stderr, "\n\n");
}
prog->nir = brw_create_nir(brw, shProg, prog, (gl_shader_stage) stage,
compiler->scalar_stage[stage]);
- }
- /* Determine first and last stage. */
- unsigned first = MESA_SHADER_STAGES;
- unsigned last = 0;
- for (unsigned i = 0; i < MESA_SHADER_STAGES; i++) {
- if (!shProg->_LinkedShaders[i])
- continue;
- if (first == MESA_SHADER_STAGES)
- first = i;
- last = i;
+ if (brw->screen->devinfo.gen >= 8) {
+ nir_variable_mode mask = (nir_variable_mode) 0;
+
+ if (stage != first)
+ mask = (nir_variable_mode)(mask | nir_var_shader_in);
+
+ if (stage != last)
+ mask = (nir_variable_mode)(mask | nir_var_shader_out);
+
+ nir_lower_io_to_scalar_early(prog->nir, mask);
+
+ prog->nir = brw_nir_optimize(prog->nir, compiler,
+ compiler->scalar_stage[stage]);
+ }
}
/* Linking the stages in the opposite order (from fragment to vertex)
* ensures that inter-shader outputs written to in an earlier stage
* are eliminated if they are (transitively) not used in a later
* stage.
*/
if (first != last) {
int next = last;
for (int i = next - 1; i >= 0; i--) {
--
2.13.6
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