compiler: add SYSTEM_VALUE_VARYING_COORD

Used internally in freedreno/ir3 for the vec2 value that hw passes to
shader to use as coordinate for bary.f (varying fetch) instruction.
This is not the same as SYSTEM_VALUE_FRAG_COORD.

Signed-off-by: Rob Clark <robdclark@gmail.com>

src/compiler/shader_enums.c

@@ -244,6 +244,7 @@ gl_system_value_name(gl_system_value sysval)
      ENUM(SYSTEM_VALUE_DEVICE_INDEX),
      ENUM(SYSTEM_VALUE_VIEW_INDEX),
      ENUM(SYSTEM_VALUE_VERTEX_CNT),
+     ENUM(SYSTEM_VALUE_VARYING_COORD),
    };
    STATIC_ASSERT(ARRAY_SIZE(names) == SYSTEM_VALUE_MAX);
    return NAME(sysval);

src/compiler/shader_enums.h

@@ -601,6 +601,12 @@ typedef enum
     */
    SYSTEM_VALUE_VERTEX_CNT,
 
+   /**
+    * Driver internal varying-coord, used for varying-fetch instructions.
+    * Not externally visible.
+    */
+   SYSTEM_VALUE_VARYING_COORD,
+
    SYSTEM_VALUE_MAX             /**< Number of values */
 } gl_system_value;
 

src/mesa/state_tracker/st_glsl_to_tgsi.cpp

@@ -5792,6 +5792,7 @@ _mesa_sysval_to_semantic(unsigned sysval)
    case SYSTEM_VALUE_LOCAL_INVOCATION_INDEX:
    case SYSTEM_VALUE_GLOBAL_INVOCATION_ID:
    case SYSTEM_VALUE_VERTEX_CNT:
+   case SYSTEM_VALUE_VARYING_COORD:
    default:
       assert(!"Unexpected SYSTEM_VALUE_ enum");
       return TGSI_SEMANTIC_COUNT;