nir: add frag_coord_xy

to strengthen and simplify pixel_coord lowering

Reviewed-by: Georg Lehmann <dadschoorse@gmail.com>
Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Reviewed-by: Emma Anholt <emma@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/41227>

src/compiler/nir/nir.c

@@ -2435,6 +2435,12 @@ nir_intrinsic_from_system_value(gl_system_value val)
       return nir_intrinsic_load_invocation_id;
    case SYSTEM_VALUE_FRAG_COORD:
       return nir_intrinsic_load_frag_coord;
+   case SYSTEM_VALUE_FRAG_COORD_XY:
+      return nir_intrinsic_load_frag_coord_xy;
+   case SYSTEM_VALUE_FRAG_COORD_Z:
+      return nir_intrinsic_load_frag_coord_z;
+   case SYSTEM_VALUE_FRAG_COORD_W:
+      return nir_intrinsic_load_frag_coord_w;
    case SYSTEM_VALUE_PIXEL_COORD:
       return nir_intrinsic_load_pixel_coord;
    case SYSTEM_VALUE_POINT_COORD:
@@ -2615,9 +2621,13 @@ nir_system_value_from_intrinsic(nir_intrinsic_op intrin)
    case nir_intrinsic_load_invocation_id:
       return SYSTEM_VALUE_INVOCATION_ID;
    case nir_intrinsic_load_frag_coord:
-   case nir_intrinsic_load_frag_coord_z:
-   case nir_intrinsic_load_frag_coord_w:
       return SYSTEM_VALUE_FRAG_COORD;
+   case nir_intrinsic_load_frag_coord_xy:
+      return SYSTEM_VALUE_FRAG_COORD_XY;
+   case nir_intrinsic_load_frag_coord_z:
+      return SYSTEM_VALUE_FRAG_COORD_Z;
+   case nir_intrinsic_load_frag_coord_w:
+      return SYSTEM_VALUE_FRAG_COORD_W;
    case nir_intrinsic_load_pixel_coord:
       return SYSTEM_VALUE_PIXEL_COORD;
    case nir_intrinsic_load_point_coord:

src/compiler/nir/nir_divergence_analysis.c

@@ -867,6 +867,7 @@ visit_intrinsic(nir_intrinsic_instr *instr, struct divergence_state *state)
    case nir_intrinsic_load_point_coord:
    case nir_intrinsic_load_line_coord:
    case nir_intrinsic_load_frag_coord:
+   case nir_intrinsic_load_frag_coord_xy:
    case nir_intrinsic_load_frag_coord_z:
    case nir_intrinsic_load_frag_coord_w:
    case nir_intrinsic_load_frag_coord_w_rcp:

src/compiler/nir/nir_gather_info.c

@@ -724,6 +724,7 @@ gather_intrinsic_info(nir_intrinsic_instr *instr, nir_shader *shader)
    case nir_intrinsic_load_invocation_id:
    case nir_intrinsic_load_frag_coord:
    case nir_intrinsic_load_pixel_coord:
+   case nir_intrinsic_load_frag_coord_xy:
    case nir_intrinsic_load_frag_coord_z:
    case nir_intrinsic_load_frag_coord_w:
    case nir_intrinsic_load_frag_coord_w_rcp:

src/compiler/nir/nir_intrinsics.py

@@ -978,6 +978,8 @@ def system_value(name, dest_comp, indices=[], bit_sizes=[32], can_reorder=True):
               bit_sizes=bit_sizes)
 
 system_value("frag_coord", 4)
+# vec2 load of frag_coord.xy (float fragment coordinates, as opposed to load_pixel_coord).
+system_value("frag_coord_xy", 2)
 # 16-bit integer vec2 of the pixel X/Y in the framebuffer.
 system_value("pixel_coord", 2, bit_sizes=[16])
 # Scalar load of frag_coord Z/W component. Backends can lower frag_coord to

src/compiler/nir/nir_opt_peephole_select.c

@@ -166,6 +166,7 @@ block_check_for_allowed_instrs(nir_block *block, unsigned *count,
          case nir_intrinsic_load_layer_id:
          case nir_intrinsic_load_frag_coord:
          case nir_intrinsic_load_pixel_coord:
+         case nir_intrinsic_load_frag_coord_xy:
          case nir_intrinsic_load_frag_coord_z:
          case nir_intrinsic_load_frag_coord_w:
          case nir_intrinsic_load_sample_pos:

src/compiler/nir/nir_opt_sink.c

@@ -257,6 +257,7 @@ can_sink_instr(nir_instr *instr, nir_move_options options, bool *can_mov_out_of_
          return options & nir_move_load_buffer_amd;
 
       case nir_intrinsic_load_frag_coord:
+      case nir_intrinsic_load_frag_coord_xy:
       case nir_intrinsic_load_frag_coord_z:
       case nir_intrinsic_load_frag_coord_w:
       case nir_intrinsic_load_var_special_pan:

src/compiler/shader_enums.c

@@ -384,6 +384,7 @@ gl_system_value_name(gl_system_value sysval)
      ENUM(SYSTEM_VALUE_INVOCATION_ID),
      ENUM(SYSTEM_VALUE_FRAG_COORD),
      ENUM(SYSTEM_VALUE_PIXEL_COORD),
+     ENUM(SYSTEM_VALUE_FRAG_COORD_XY),
      ENUM(SYSTEM_VALUE_FRAG_COORD_Z),
      ENUM(SYSTEM_VALUE_FRAG_COORD_W),
      ENUM(SYSTEM_VALUE_POINT_COORD),

src/compiler/shader_enums.h

@@ -805,6 +805,7 @@ typedef enum
    /*@{*/
    SYSTEM_VALUE_FRAG_COORD,
    SYSTEM_VALUE_PIXEL_COORD,
+   SYSTEM_VALUE_FRAG_COORD_XY,
    SYSTEM_VALUE_FRAG_COORD_Z,
    SYSTEM_VALUE_FRAG_COORD_W,
    SYSTEM_VALUE_POINT_COORD,