Mesa (master): glsl: optionally declare gl_FragCoord & gl_FrontFacing as system values

[Marek Olšák]

Module: Mesa
Branch: master
Commit: 4191c1a57c1e806a078bfc5b074b557ff2b54c35
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=4191c1a57c1e806a078bfc5b074b557ff2b54c35

Author: Marek Olšák <marek.olsak at amd.com>
Date:   Sat Jan  2 20:16:16 2016 +0100

glsl: optionally declare gl_FragCoord & gl_FrontFacing as system values

Reviewed-by: Edward O'Callaghan <eocallaghan at alterapraxis.com
Reviewed-by: Brian Paul <brianp at vmware.com>

---

 src/glsl/ast_to_hir.cpp                    |    2 +-
 src/glsl/builtin_variables.cpp             |   12 ++++++++++--
 src/glsl/nir/shader_enums.h                |    3 ++-
 src/mesa/main/mtypes.h                     |    4 ++++
 src/mesa/state_tracker/st_glsl_to_tgsi.cpp |    1 +
 5 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp
index e6aec36..f3966d7 100644
--- a/src/glsl/ast_to_hir.cpp
+++ b/src/glsl/ast_to_hir.cpp
@@ -3517,7 +3517,7 @@ get_variable_being_redeclared(ir_variable *var, YYLTYPE loc,
               state->is_version(150, 0))
               && strcmp(var->name, "gl_FragCoord") == 0
               && earlier->type == var->type
-              && earlier->data.mode == var->data.mode) {
+              && var->data.mode == ir_var_shader_in) {
       /* Allow redeclaration of gl_FragCoord for ARB_fcc layout
        * qualifiers.
        */
diff --git a/src/glsl/builtin_variables.cpp b/src/glsl/builtin_variables.cpp
index e82c99e..221aab0 100644
--- a/src/glsl/builtin_variables.cpp
+++ b/src/glsl/builtin_variables.cpp
@@ -1057,8 +1057,16 @@ builtin_variable_generator::generate_fs_special_vars()
 {
    ir_variable *var;
 
-   add_input(VARYING_SLOT_POS, vec4_t, "gl_FragCoord");
-   add_input(VARYING_SLOT_FACE, bool_t, "gl_FrontFacing");
+   if (this->state->ctx->Const.GLSLFragCoordIsSysVal)
+      add_system_value(SYSTEM_VALUE_FRAG_COORD, vec4_t, "gl_FragCoord");
+   else
+      add_input(VARYING_SLOT_POS, vec4_t, "gl_FragCoord");
+
+   if (this->state->ctx->Const.GLSLFrontFacingIsSysVal)
+      add_system_value(SYSTEM_VALUE_FRONT_FACE, bool_t, "gl_FrontFacing");
+   else
+      add_input(VARYING_SLOT_FACE, bool_t, "gl_FrontFacing");
+
    if (state->is_version(120, 100))
       add_input(VARYING_SLOT_PNTC, vec2_t, "gl_PointCoord");
 
diff --git a/src/glsl/nir/shader_enums.h b/src/glsl/nir/shader_enums.h
index 0be217c..8a2a81a 100644
--- a/src/glsl/nir/shader_enums.h
+++ b/src/glsl/nir/shader_enums.h
@@ -412,7 +412,8 @@ typedef enum
     * \name Fragment shader system values
     */
    /*@{*/
-   SYSTEM_VALUE_FRONT_FACE,     /**< (not done yet) */
+   SYSTEM_VALUE_FRAG_COORD,
+   SYSTEM_VALUE_FRONT_FACE,
    SYSTEM_VALUE_SAMPLE_ID,
    SYSTEM_VALUE_SAMPLE_POS,
    SYSTEM_VALUE_SAMPLE_MASK_IN,
diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
index dd52368..41f5283 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -3515,6 +3515,10 @@ struct gl_constants
     */
    GLboolean GLSLSkipStrictMaxUniformLimitCheck;
 
+   /** Whether gl_FragCoord and gl_FrontFacing are system values. */
+   bool GLSLFragCoordIsSysVal;
+   bool GLSLFrontFacingIsSysVal;
+
    /**
     * Always use the GetTransformFeedbackVertexCount() driver hook, rather
     * than passing the transform feedback object to the drawing function.
diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
index 6cbc26a..9308eb4 100644
--- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
@@ -4459,6 +4459,7 @@ const unsigned _mesa_sysval_to_semantic[SYSTEM_VALUE_MAX] = {
 
    /* Fragment shader
     */
+   TGSI_SEMANTIC_POSITION,
    TGSI_SEMANTIC_FACE,
    TGSI_SEMANTIC_SAMPLEID,
    TGSI_SEMANTIC_SAMPLEPOS,