glsl/linker: eliminate unused and set-but-unused built-in varyings
This eliminates built-in varyings such as gl_Color, gl_SecondaryColor,
gl_TexCoord, and gl_FogFragCoord if they are unused by the next stage or
not written at all (e.g. gl_TexCoord elements). The gl_TexCoord array is
broken down into separate vec4s if needed.
v2: - use a switch statement in varying_info_visitor::visit(ir_variable*)
- use snprintf
- disable the optimization for GLES2
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index 6d73578..ba97ade 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -1887,6 +1887,9 @@
goto done;
}
+ do_dead_builtin_varyings(ctx, sh->ir, NULL,
+ num_tfeedback_decls, tfeedback_decls);
+
demote_shader_inputs_and_outputs(sh, ir_var_shader_out);
/* Eliminate code that is now dead due to unused outputs being demoted.
@@ -1895,11 +1898,13 @@
;
}
else if (first == MESA_SHADER_FRAGMENT) {
- /* If the program only contains a fragment shader, just demote
- * user-defined varyings.
+ /* If the program only contains a fragment shader...
*/
gl_shader *const sh = prog->_LinkedShaders[first];
+ do_dead_builtin_varyings(ctx, NULL, sh->ir,
+ num_tfeedback_decls, tfeedback_decls);
+
demote_shader_inputs_and_outputs(sh, ir_var_shader_in);
while (do_dead_code(sh->ir, false))
@@ -1919,6 +1924,10 @@
tfeedback_decls))
goto done;
+ do_dead_builtin_varyings(ctx, sh_i->ir, sh_next->ir,
+ next == MESA_SHADER_FRAGMENT ? num_tfeedback_decls : 0,
+ tfeedback_decls);
+
demote_shader_inputs_and_outputs(sh_i, ir_var_shader_out);
demote_shader_inputs_and_outputs(sh_next, ir_var_shader_in);