i965: Allocate space in the binding table for non-coherent FB fetch.

Unfortunately due to the inconsistent meaning of some surface state
structure fields, we cannot re-use the same binding table entries for
sampling from and rendering into the same set of render buffers, so we
need to allocate a separate binding table block specifically for
render target reads if the non-coherent path is in use.

The slight noise is due to the change of
brw_assign_common_binding_table_offsets to return the next available
binding table index rather than void.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

4 files changed, 16 insertions, 7 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_compiler.h b/src/mesa/drivers/dri/i965/brw_compiler.h
index 0c300e7..933ab11 100644
--- a/src/mesa/drivers/dri/i965/brw_compiler.h
+++ b/src/mesa/drivers/dri/i965/brw_compiler.h
@@ -389,6 +389,7 @@ struct brw_wm_prog_data {
        * surface indices the WM-specific surfaces
        */
       uint32_t render_target_start;
+      uint32_t render_target_read_start;
       /** @} */
    } binding_table;
 
diff --git a/src/mesa/drivers/dri/i965/brw_shader.cpp b/src/mesa/drivers/dri/i965/brw_shader.cpp
index 62bad9b..aa2c9d4 100644
--- a/src/mesa/drivers/dri/i965/brw_shader.cpp
+++ b/src/mesa/drivers/dri/i965/brw_shader.cpp
@@ -1148,7 +1148,7 @@ backend_shader::calculate_cfg()
  * unused but also make sure that addition of small offsets to them will
  * trigger some of our asserts that surface indices are < BRW_MAX_SURFACES.
  */
-void
+uint32_t
 brw_assign_common_binding_table_offsets(gl_shader_stage stage,
                                         const struct brw_device_info *devinfo,
                                         const struct gl_shader_program *shader_prog,
@@ -1224,9 +1224,10 @@ brw_assign_common_binding_table_offsets(gl_shader_stage stage,
    stage_prog_data->binding_table.plane_start[2] = next_binding_table_offset;
    next_binding_table_offset += num_textures;
 
-   assert(next_binding_table_offset <= BRW_MAX_SURFACES);
-
    /* prog_data->base.binding_table.size will be set by brw_mark_surface_used. */
+
+   assert(next_binding_table_offset <= BRW_MAX_SURFACES);
+   return next_binding_table_offset;
 }
 
 static void
diff --git a/src/mesa/drivers/dri/i965/brw_shader.h b/src/mesa/drivers/dri/i965/brw_shader.h
index e61c080..3b3be07 100644
--- a/src/mesa/drivers/dri/i965/brw_shader.h
+++ b/src/mesa/drivers/dri/i965/brw_shader.h
@@ -261,7 +261,7 @@ struct brw_gs_compile
    unsigned control_data_header_size_bits;
 };
 
-void
+uint32_t
 brw_assign_common_binding_table_offsets(gl_shader_stage stage,
                                         const struct brw_device_info *devinfo,
                                         const struct gl_shader_program *shader_prog,
diff --git a/src/mesa/drivers/dri/i965/brw_wm.c b/src/mesa/drivers/dri/i965/brw_wm.c
index c513dbc..3f929c4 100644
--- a/src/mesa/drivers/dri/i965/brw_wm.c
+++ b/src/mesa/drivers/dri/i965/brw_wm.c
@@ -56,9 +56,16 @@ assign_fs_binding_table_offsets(const struct brw_device_info *devinfo,
    prog_data->binding_table.render_target_start = next_binding_table_offset;
    next_binding_table_offset += MAX2(key->nr_color_regions, 1);
 
-   brw_assign_common_binding_table_offsets(MESA_SHADER_FRAGMENT, devinfo,
-                                           shader_prog, prog, &prog_data->base,
-                                           next_binding_table_offset);
+   next_binding_table_offset =
+      brw_assign_common_binding_table_offsets(MESA_SHADER_FRAGMENT, devinfo,
+                                              shader_prog, prog, &prog_data->base,
+                                              next_binding_table_offset);
+
+   if (prog->nir->info.outputs_read && !key->coherent_fb_fetch) {
+      prog_data->binding_table.render_target_read_start =
+         next_binding_table_offset;
+      next_binding_table_offset += key->nr_color_regions;
+   }
 }
 
 /**