nir/linker: remove dead variables

3 files changed, 42 insertions, 1 deletions

diff --git a/src/compiler/glsl/linker.cpp b/src/compiler/glsl/linker.cpp
index e47e6e0958..d1462a2b42 100644
--- a/src/compiler/glsl/linker.cpp
+++ b/src/compiler/glsl/linker.cpp
@@ -5049,7 +5049,7 @@ link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
       }
 
       if (spirv) {
-         fprintf(stderr, "todo: nir_remove_dead_variables\n"); /* see opt_dead_code.cpp */
+         nir_linker_remove_dead_variables(prog, prog->_LinkedShaders[i]);
       } else {
          /* Call opts before lowering const arrays to uniforms so we can const
           * propagate any elements accessed directly.
diff --git a/src/compiler/glsl/nir_linker.cpp b/src/compiler/glsl/nir_linker.cpp
index c197c3c21f..698c71ab37 100644
--- a/src/compiler/glsl/nir_linker.cpp
+++ b/src/compiler/glsl/nir_linker.cpp
@@ -265,6 +265,44 @@ create_linked_nir_shader(void *mem_ctx,
    return linked;
 }
 
+void
+nir_linker_remove_dead_variables(gl_shader_program *prog, gl_linked_shader *sh)
+{
+   /* TODO don't remove if ir_var->data.always_active_io, nor uniforms with
+    * constant initializers
+    */
+   nir_remove_dead_variables(sh->nir, nir_var_all);
+
+   /* Cleanup the IR shadows. */
+   exec_list live;
+
+   nir_foreach_variable(var, &sh->nir->inputs) {
+      ir_variable *ir_var = find_ir_variable(sh, var);
+      if (ir_var) {
+         ir_var->remove();
+         live.push_tail(ir_var);
+      }
+   }
+
+   nir_foreach_variable(var, &sh->nir->outputs) {
+      ir_variable *ir_var = find_ir_variable(sh, var);
+      if (ir_var) {
+         ir_var->remove();
+         live.push_tail(ir_var);
+      }
+   }
+
+   nir_foreach_variable(var, &sh->nir->uniforms) {
+      ir_variable *ir_var = find_ir_variable(sh, var);
+      if (ir_var) {
+         ir_var->remove();
+         live.push_tail(ir_var);
+      }
+   }
+
+   live.move_nodes_to(sh->ir);
+}
+
 /**
  * After linking has completed, update the NIR shader with information from
  * the shadow IR variables.
diff --git a/src/compiler/glsl/nir_linker.h b/src/compiler/glsl/nir_linker.h
index a20095b9c1..2d256b804f 100644
--- a/src/compiler/glsl/nir_linker.h
+++ b/src/compiler/glsl/nir_linker.h
@@ -47,4 +47,7 @@ void
 find_nir_assignments(struct nir_shader *nir, unsigned num_variables,
                      struct find_variable * const *variables);
 
+void
+nir_linker_remove_dead_variables(gl_shader_program *prog, gl_linked_shader *sh);
+
 #endif /* NIR_LINKER_H */