[Mesa-dev] [PATCH] glsl: don't eliminate texcoords that can be set by GL_COORD_REPLACE

[Marek Olšák]

Tested by examining generated TGSI shaders from piglit/glsl-routing.

Cc: mesa-stable at lists.freedesktop.org
---
 src/glsl/ir_optimization.h             |  2 +-
 src/glsl/linker.cpp                    |  6 +++---
 src/glsl/opt_dead_builtin_varyings.cpp | 27 +++++++++++++++++++--------
 3 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/src/glsl/ir_optimization.h b/src/glsl/ir_optimization.h
index a61227b..b79c2b7 100644
--- a/src/glsl/ir_optimization.h
+++ b/src/glsl/ir_optimization.h
@@ -77,7 +77,7 @@ bool do_copy_propagation(exec_list *instructions);
 bool do_copy_propagation_elements(exec_list *instructions);
 bool do_constant_propagation(exec_list *instructions);
 void do_dead_builtin_varyings(struct gl_context *ctx,
-                              exec_list *producer, exec_list *consumer,
+                              gl_shader *producer, gl_shader *consumer,
                               unsigned num_tfeedback_decls,
                               class tfeedback_decl *tfeedback_decls);
 bool do_dead_code(exec_list *instructions, bool uniform_locations_assigned);
diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index d36f627..f87ae0e 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -2091,7 +2091,7 @@ link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
             goto done;
       }
 
-      do_dead_builtin_varyings(ctx, sh->ir, NULL,
+      do_dead_builtin_varyings(ctx, sh, NULL,
                                num_tfeedback_decls, tfeedback_decls);
 
       demote_shader_inputs_and_outputs(sh, ir_var_shader_out);
@@ -2106,7 +2106,7 @@ link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
        */
       gl_shader *const sh = prog->_LinkedShaders[first];
 
-      do_dead_builtin_varyings(ctx, NULL, sh->ir,
+      do_dead_builtin_varyings(ctx, NULL, sh,
                                num_tfeedback_decls, tfeedback_decls);
 
       demote_shader_inputs_and_outputs(sh, ir_var_shader_in);
@@ -2130,7 +2130,7 @@ link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
                 tfeedback_decls, gs_input_vertices))
          goto done;
 
-      do_dead_builtin_varyings(ctx, sh_i->ir, sh_next->ir,
+      do_dead_builtin_varyings(ctx, sh_i, sh_next,
                 next == MESA_SHADER_FRAGMENT ? num_tfeedback_decls : 0,
                 tfeedback_decls);
 
diff --git a/src/glsl/opt_dead_builtin_varyings.cpp b/src/glsl/opt_dead_builtin_varyings.cpp
index 2e813d2..6745d5c 100644
--- a/src/glsl/opt_dead_builtin_varyings.cpp
+++ b/src/glsl/opt_dead_builtin_varyings.cpp
@@ -409,7 +409,7 @@ lower_texcoord_array(exec_list *ir, const varying_info_visitor *info)
 
 void
 do_dead_builtin_varyings(struct gl_context *ctx,
-                         exec_list *producer, exec_list *consumer,
+                         gl_shader *producer, gl_shader *consumer,
                          unsigned num_tfeedback_decls,
                          tfeedback_decl *tfeedback_decls)
 {
@@ -431,44 +431,55 @@ do_dead_builtin_varyings(struct gl_context *ctx,
    varying_info_visitor consumer_info(ir_var_shader_in);
 
    if (producer) {
-      producer_info.get(producer, num_tfeedback_decls, tfeedback_decls);
+      producer_info.get(producer->ir, num_tfeedback_decls, tfeedback_decls);
 
       if (!consumer) {
          /* At least eliminate unused gl_TexCoord elements. */
          if (producer_info.lower_texcoord_array) {
-            lower_texcoord_array(producer, &producer_info);
+            lower_texcoord_array(producer->ir, &producer_info);
          }
          return;
       }
    }
 
    if (consumer) {
-      consumer_info.get(consumer, 0, NULL);
+      consumer_info.get(consumer->ir, 0, NULL);
 
       if (!producer) {
          /* At least eliminate unused gl_TexCoord elements. */
          if (consumer_info.lower_texcoord_array) {
-            lower_texcoord_array(consumer, &consumer_info);
+            lower_texcoord_array(consumer->ir, &consumer_info);
          }
          return;
       }
    }
 
-   /* Eliminate the varyings unused by the other shader. */
+   /* Eliminate the outputs unused by the consumer. */
    if (producer_info.lower_texcoord_array ||
        producer_info.color_usage ||
        producer_info.has_fog) {
-      replace_varyings_visitor(producer,
+      replace_varyings_visitor(producer->ir,
                                &producer_info,
                                consumer_info.texcoord_usage,
                                consumer_info.color_usage,
                                consumer_info.has_fog);
    }
 
+   /* The gl_TexCoord fragment shader inputs can be initialized
+    * by GL_COORD_REPLACE, so we can't eliminate them.
+    *
+    * This doesn't prevent elimination of the gl_TexCoord elements which
+    * are not read by the fragment shader. We want to eliminate those anyway.
+    */
+   if (consumer->Type == GL_FRAGMENT_SHADER) {
+      producer_info.texcoord_usage = (1 << MAX_TEXTURE_COORD_UNITS) - 1;
+   }
+
+   /* Eliminate the inputs uninitialized by the producer. */
    if (consumer_info.lower_texcoord_array ||
        consumer_info.color_usage ||
        consumer_info.has_fog) {
-      replace_varyings_visitor(consumer,
+      replace_varyings_visitor(consumer->ir,
                                &consumer_info,
                                producer_info.texcoord_usage,
                                producer_info.color_usage,
-- 
1.8.1.2