[Mesa-dev] [PATCH 1/4] st/glsl_to_nir: gather next_stage in shader_info

[Timothy Arceri]

---
 src/compiler/shader_info.h                |  5 +++++
 src/mesa/state_tracker/st_glsl_to_nir.cpp | 15 +++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/src/compiler/shader_info.h b/src/compiler/shader_info.h
index 0eeb2ca58ea..fcf5cca7b77 100644
--- a/src/compiler/shader_info.h
+++ b/src/compiler/shader_info.h
@@ -63,6 +63,11 @@ typedef struct shader_info {
    /** The shader stage, such as MESA_SHADER_VERTEX. */
    gl_shader_stage stage;
 
+   /** The shader stage in a non SSO linked program that follows this stage,
+     * such as MESA_SHADER_FRAGMENT.
+     */
+   gl_shader_stage next_stage;
+
    /* Number of textures used by this shader */
    unsigned num_textures;
    /* Number of uniform buffers used by this shader */
diff --git a/src/mesa/state_tracker/st_glsl_to_nir.cpp b/src/mesa/state_tracker/st_glsl_to_nir.cpp
index abdb5406a6e..682328b398f 100644
--- a/src/mesa/state_tracker/st_glsl_to_nir.cpp
+++ b/src/mesa/state_tracker/st_glsl_to_nir.cpp
@@ -367,6 +367,21 @@ st_glsl_to_nir(struct st_context *st, struct gl_program *prog,
 
    nir_shader *nir = glsl_to_nir(shader_program, stage, options);
 
+   /* Set the next shader stage hint for VS and TES. */
+   if (!nir->info.separate_shader &&
+       (nir->info.stage == MESA_SHADER_VERTEX ||
+        nir->info.stage == MESA_SHADER_TESS_EVAL)) {
+
+      unsigned prev_stages = (1 << (prog->info.stage + 1)) - 1;
+      unsigned stages_mask =
+         ~prev_stages & shader_program->data->linked_stages;
+
+      nir->info.next_stage = stages_mask ?
+         (gl_shader_stage) ffs(stages_mask) : MESA_SHADER_FRAGMENT;
+   } else {
+      nir->info.next_stage = MESA_SHADER_FRAGMENT;
+   }
+
    nir_variable_mode mask =
       (nir_variable_mode) (nir_var_shader_in | nir_var_shader_out);
    nir_remove_dead_variables(nir, mask);
-- 
2.14.3