[Mesa-dev] [RFC PATCH 30/40] i965/fs: Append ir_binop_ubo_load entries to the gather table

[Abdiel Janulgue]

At the moment, this is only possible if the const block and offset are
immediate values (constants). Otherwise just fall-back to the previous
method of uploading the UBO constant data to GRF using pull constants.

Signed-off-by: Abdiel Janulgue <abdiel.janulgue at linux.intel.com>
---
 src/mesa/drivers/dri/i965/brw_context.h      |  3 +++
 src/mesa/drivers/dri/i965/brw_fs_visitor.cpp | 24 ++++++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/src/mesa/drivers/dri/i965/brw_context.h b/src/mesa/drivers/dri/i965/brw_context.h
index 8eddc54..9877126 100644
--- a/src/mesa/drivers/dri/i965/brw_context.h
+++ b/src/mesa/drivers/dri/i965/brw_context.h
@@ -347,6 +347,7 @@ struct brw_stage_prog_data {
 
    GLuint nr_params;       /**< number of float params/constants */
    GLuint nr_pull_params;
+   GLuint nr_ubo_params;
    GLuint nr_gather_table;
 
    unsigned curb_read_length;
@@ -371,6 +372,8 @@ struct brw_stage_prog_data {
    struct {
       int reg;
       unsigned channel_mask;
+      unsigned const_block;
+      unsigned const_offset;
    } gather_table[128]; /** equal to max_push_components */
 };
 
diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
index 2f592c9..c0499b6 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
@@ -1077,6 +1077,30 @@ fs_visitor::visit(ir_expression *ir)
        */
       ir_constant *const_uniform_block = ir->operands[0]->as_constant();
       ir_constant *const_offset = ir->operands[1]->as_constant();
+
+      /* Use gather push constants if at all possible, otherwise just
+       * fall back to pull constants for UBOs
+       */
+      bool use_gather = (brw->has_resource_streamer && brw->use_gather_constants);
+      int param_index = uniforms + ubo_uniforms;
+      if (use_gather && const_uniform_block && const_offset) {
+
+         fs_reg reg(UNIFORM, param_index);
+         reg.type = brw_type_for_base_type(ir->type);
+
+         result = reg;
+         ubo_uniforms += ir->type->vector_elements;
+
+         int gather = stage_prog_data->nr_gather_table++;
+         stage_prog_data->gather_table[gather].reg = reg.reg;
+         stage_prog_data->gather_table[gather].const_block =
+            const_uniform_block->value.u[0];
+         stage_prog_data->gather_table[gather].const_offset =
+            const_offset->value.u[0];
+
+         break;
+      }
+
       fs_reg surf_index;
 
       if (const_uniform_block) {
-- 
1.9.1