glsl: add gl_SubGroup*ARB builtins

Reviewed-by: Marek Olšák <marek.olsak@amd.com>

src/compiler/glsl/builtin_variables.cpp

@@ -365,6 +365,7 @@ public:
                               struct _mesa_glsl_parse_state *state);
    void generate_constants();
    void generate_uniforms();
+   void generate_special_vars();
    void generate_vs_special_vars();
    void generate_tcs_special_vars();
    void generate_tes_special_vars();
@@ -428,6 +429,7 @@ private:
    const glsl_type * const bool_t;
    const glsl_type * const int_t;
    const glsl_type * const uint_t;
+   const glsl_type * const uint64_t;
    const glsl_type * const float_t;
    const glsl_type * const vec2_t;
    const glsl_type * const vec3_t;
@@ -447,6 +449,7 @@ builtin_variable_generator::builtin_variable_generator(
      compatibility(state->compat_shader || !state->is_version(140, 100)),
      bool_t(glsl_type::bool_type), int_t(glsl_type::int_type),
      uint_t(glsl_type::uint_type),
+     uint64_t(glsl_type::uint64_t_type),
      float_t(glsl_type::float_type), vec2_t(glsl_type::vec2_type),
      vec3_t(glsl_type::vec3_type), vec4_t(glsl_type::vec4_type),
      uvec3_t(glsl_type::uvec3_type),
@@ -983,6 +986,24 @@ builtin_variable_generator::generate_uniforms()
 }
 
 
+/**
+ * Generate special variables which exist in all shaders.
+ */
+void
+builtin_variable_generator::generate_special_vars()
+{
+   if (state->ARB_shader_ballot_enable) {
+      add_system_value(SYSTEM_VALUE_SUBGROUP_SIZE, uint_t, "gl_SubGroupSizeARB");
+      add_system_value(SYSTEM_VALUE_SUBGROUP_INVOCATION, uint_t, "gl_SubGroupInvocationARB");
+      add_system_value(SYSTEM_VALUE_SUBGROUP_EQ_MASK, uint64_t, "gl_SubGroupEqMaskARB");
+      add_system_value(SYSTEM_VALUE_SUBGROUP_GE_MASK, uint64_t, "gl_SubGroupGeMaskARB");
+      add_system_value(SYSTEM_VALUE_SUBGROUP_GT_MASK, uint64_t, "gl_SubGroupGtMaskARB");
+      add_system_value(SYSTEM_VALUE_SUBGROUP_LE_MASK, uint64_t, "gl_SubGroupLeMaskARB");
+      add_system_value(SYSTEM_VALUE_SUBGROUP_LT_MASK, uint64_t, "gl_SubGroupLtMaskARB");
+   }
+}
+
+
 /**
  * Generate variables which only exist in vertex shaders.
  */
@@ -1416,6 +1437,7 @@ _mesa_glsl_initialize_variables(exec_list *instructions,
 
    gen.generate_constants();
    gen.generate_uniforms();
+   gen.generate_special_vars();
 
    gen.generate_varyings();
 

src/compiler/shader_enums.c

@@ -203,6 +203,13 @@ const char *
 gl_system_value_name(gl_system_value sysval)
 {
    static const char *names[] = {
+     ENUM(SYSTEM_VALUE_SUBGROUP_SIZE),
+     ENUM(SYSTEM_VALUE_SUBGROUP_INVOCATION),
+     ENUM(SYSTEM_VALUE_SUBGROUP_EQ_MASK),
+     ENUM(SYSTEM_VALUE_SUBGROUP_GE_MASK),
+     ENUM(SYSTEM_VALUE_SUBGROUP_GT_MASK),
+     ENUM(SYSTEM_VALUE_SUBGROUP_LE_MASK),
+     ENUM(SYSTEM_VALUE_SUBGROUP_LT_MASK),
      ENUM(SYSTEM_VALUE_VERTEX_ID),
      ENUM(SYSTEM_VALUE_INSTANCE_ID),
      ENUM(SYSTEM_VALUE_INSTANCE_INDEX),

src/compiler/shader_enums.h

@@ -317,6 +317,65 @@ const char *gl_varying_slot_name(gl_varying_slot slot);
  */
 typedef enum
 {
+   /**
+    * \name System values applicable to all shaders
+    */
+   /*@{*/
+
+   /**
+    * Builtin variables added by GL_ARB_shader_ballot.
+    */
+   /*@{*/
+
+   /**
+    * From the GL_ARB_shader-ballot spec:
+    *
+    *    "A sub-group is a collection of invocations which execute in lockstep.
+    *     The variable <gl_SubGroupSizeARB> is the maximum number of
+    *     invocations in a sub-group. The maximum <gl_SubGroupSizeARB>
+    *     supported in this extension is 64."
+    *
+    * The spec defines this as a uniform. However, it's highly unlikely that
+    * implementations actually treat it as a uniform (which is loaded from a
+    * constant buffer). Most likely, this is an implementation-wide constant,
+    * or perhaps something that depends on the shader stage.
+    */
+   SYSTEM_VALUE_SUBGROUP_SIZE,
+
+   /**
+    * From the GL_ARB_shader_ballot spec:
+    *
+    *    "The variable <gl_SubGroupInvocationARB> holds the index of the
+    *     invocation within sub-group. This variable is in the range 0 to
+    *     <gl_SubGroupSizeARB>-1, where <gl_SubGroupSizeARB> is the total
+    *     number of invocations in a sub-group."
+    */
+   SYSTEM_VALUE_SUBGROUP_INVOCATION,
+
+   /**
+    * From the GL_ARB_shader_ballot spec:
+    *
+    *    "The <gl_SubGroup??MaskARB> variables provide a bitmask for all
+    *     invocations, with one bit per invocation starting with the least
+    *     significant bit, according to the following table,
+    *
+    *       variable               equation for bit values
+    *       --------------------   ------------------------------------
+    *       gl_SubGroupEqMaskARB   bit index == gl_SubGroupInvocationARB
+    *       gl_SubGroupGeMaskARB   bit index >= gl_SubGroupInvocationARB
+    *       gl_SubGroupGtMaskARB   bit index >  gl_SubGroupInvocationARB
+    *       gl_SubGroupLeMaskARB   bit index <= gl_SubGroupInvocationARB
+    *       gl_SubGroupLtMaskARB   bit index <  gl_SubGroupInvocationARB
+    */
+   SYSTEM_VALUE_SUBGROUP_EQ_MASK,
+   SYSTEM_VALUE_SUBGROUP_GE_MASK,
+   SYSTEM_VALUE_SUBGROUP_GT_MASK,
+   SYSTEM_VALUE_SUBGROUP_LE_MASK,
+   SYSTEM_VALUE_SUBGROUP_LT_MASK,
+   /*@}*/
+
+   /*@}*/
+
    /**
     * \name Vertex shader system values
     */