driconf: Add allow_glsl_builtin_variable_redeclaration option

This option will allow GLSL builtins to be redeclared verbatim (e.g.
redeclaring "in int gl_VertexID" in a vertex shader). This is not strictly
valid and would normally fail to compile, but some applications (such as
newer Techland ports) do it and need more leniency.

v2 (Samuel Pitoiset):
    - Rename allow_glsl_builtin_redeclaration ->
      allow_glsl_builtin_variable_redeclaration

Signed-off-by: John Brooks <john@fastquake.com>
Reviewed-by: Edward O'Callaghan <funfunctor@folklore1984.net>
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>

src/gallium/include/state_tracker/st_api.h

@@ -246,6 +246,7 @@ struct st_config_options
    unsigned force_glsl_version;
    boolean force_s3tc_enable;
    boolean allow_glsl_extension_directive_midshader;
+   boolean allow_glsl_builtin_variable_redeclaration;
    boolean allow_higher_compat_version;
    boolean glsl_zero_init;
    boolean force_glsl_abs_sqrt;

src/gallium/state_trackers/dri/dri_screen.c

@@ -75,6 +75,7 @@ const __DRIconfigOptionsExtension gallium_config_options = {
          DRI_CONF_DISABLE_SHADER_BIT_ENCODING("false")
          DRI_CONF_FORCE_GLSL_VERSION(0)
          DRI_CONF_ALLOW_GLSL_EXTENSION_DIRECTIVE_MIDSHADER("false")
+         DRI_CONF_ALLOW_GLSL_BUILTIN_VARIABLE_REDECLARATION("false")
          DRI_CONF_ALLOW_HIGHER_COMPAT_VERSION("false")
          DRI_CONF_FORCE_GLSL_ABS_SQRT("false")
       DRI_CONF_SECTION_END
@@ -108,6 +109,8 @@ dri_fill_st_options(struct dri_screen *screen)
       driQueryOptionb(optionCache, "force_s3tc_enable");
    options->allow_glsl_extension_directive_midshader =
       driQueryOptionb(optionCache, "allow_glsl_extension_directive_midshader");
+   options->allow_glsl_builtin_variable_redeclaration =
+      driQueryOptionb(optionCache, "allow_glsl_builtin_variable_redeclaration");
    options->allow_higher_compat_version =
       driQueryOptionb(optionCache, "allow_higher_compat_version");
    options->glsl_zero_init = driQueryOptionb(optionCache, "glsl_zero_init");

src/mesa/drivers/dri/common/xmlpool/t_options.h

@@ -115,6 +115,11 @@ DRI_CONF_OPT_BEGIN_B(allow_glsl_extension_directive_midshader, def) \
         DRI_CONF_DESC(en,gettext("Allow GLSL #extension directives in the middle of shaders")) \
 DRI_CONF_OPT_END
 
+#define DRI_CONF_ALLOW_GLSL_BUILTIN_VARIABLE_REDECLARATION(def) \
+DRI_CONF_OPT_BEGIN_B(allow_glsl_builtin_variable_redeclaration, def) \
+        DRI_CONF_DESC(en,gettext("Allow GLSL built-in variables to be redeclared verbatim")) \
+DRI_CONF_OPT_END
+
 #define DRI_CONF_ALLOW_HIGHER_COMPAT_VERSION(def) \
 DRI_CONF_OPT_BEGIN_B(allow_higher_compat_version, def) \
         DRI_CONF_DESC(en,gettext("Allow a higher compat profile (version 3.1+) for apps that request it")) \

src/mesa/drivers/dri/i965/brw_context.c

@@ -934,6 +934,9 @@ brw_process_driconf_options(struct brw_context *brw)
    ctx->Const.AllowGLSLExtensionDirectiveMidShader =
       driQueryOptionb(options, "allow_glsl_extension_directive_midshader");
 
+   ctx->Const.AllowGLSLBuiltinVariableRedeclaration =
+      driQueryOptionb(options, "allow_glsl_builtin_variable_redeclaration");
+
    ctx->Const.AllowHigherCompatVersion =
       driQueryOptionb(options, "allow_higher_compat_version");
 

src/mesa/drivers/dri/i965/intel_screen.c

@@ -89,6 +89,7 @@ DRI_CONF_BEGIN
       DRI_CONF_DISABLE_BLEND_FUNC_EXTENDED("false")
       DRI_CONF_DUAL_COLOR_BLEND_BY_LOCATION("false")
       DRI_CONF_ALLOW_GLSL_EXTENSION_DIRECTIVE_MIDSHADER("false")
+      DRI_CONF_ALLOW_GLSL_BUILTIN_VARIABLE_REDECLARATION("false")
       DRI_CONF_ALLOW_HIGHER_COMPAT_VERSION("false")
       DRI_CONF_FORCE_GLSL_ABS_SQRT("false")
 

src/mesa/main/mtypes.h

@@ -3637,6 +3637,11 @@ struct gl_constants
     */
    GLboolean AllowGLSLExtensionDirectiveMidShader;
 
+   /**
+    * Allow GLSL built-in variables to be redeclared verbatim
+    */
+   GLboolean AllowGLSLBuiltinVariableRedeclaration;
+
    /**
     * Allow creating a higher compat profile (version 3.1+) for apps that
     * request it. Be careful when adding that driconf option because some

src/mesa/state_tracker/st_extensions.c

@@ -892,6 +892,8 @@ void st_init_extensions(struct pipe_screen *screen,
 
    consts->ForceGLSLAbsSqrt = options->force_glsl_abs_sqrt;
 
+   consts->AllowGLSLBuiltinVariableRedeclaration = options->allow_glsl_builtin_variable_redeclaration;
+
    consts->dri_config_options_sha1 = options->config_options_sha1;
 
    if (consts->GLSLVersion >= 400)