gallium/tgsi: Define system values used to query the compute grid parameters.

src/gallium/auxiliary/tgsi/tgsi_strings.c

@@ -74,7 +74,11 @@ const char *tgsi_semantic_names[TGSI_SEMANTIC_COUNT] =
    "VERTEXID",
    "STENCIL",
    "CLIPDIST",
-   "CLIPVERTEX"
+   "CLIPVERTEX",
+   "GRID_SIZE",
+   "BLOCK_ID",
+   "BLOCK_SIZE",
+   "THREAD_ID"
 };
 
 const char *tgsi_texture_names[TGSI_TEXTURE_COUNT] =

src/gallium/include/pipe/p_shader_tokens.h

@@ -158,7 +158,11 @@ struct tgsi_declaration_interp
 #define TGSI_SEMANTIC_STENCIL    12
 #define TGSI_SEMANTIC_CLIPDIST   13
 #define TGSI_SEMANTIC_CLIPVERTEX 14
-#define TGSI_SEMANTIC_COUNT      15 /**< number of semantic values */
+#define TGSI_SEMANTIC_GRID_SIZE  15 /**< grid size in blocks */
+#define TGSI_SEMANTIC_BLOCK_ID   16 /**< id of the current block */
+#define TGSI_SEMANTIC_BLOCK_SIZE 17 /**< block size in threads */
+#define TGSI_SEMANTIC_THREAD_ID  18 /**< block-relative id of the current thread */
+#define TGSI_SEMANTIC_COUNT      19 /**< number of semantic values */
 
 struct tgsi_declaration_semantic
 {