nir: add atomic isub

Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37702>

src/compiler/nir/nir.c

@@ -3804,6 +3804,8 @@ nir_atomic_op_to_alu(nir_atomic_op op)
    switch (op) {
    case nir_atomic_op_iadd:
       return nir_op_iadd;
+   case nir_atomic_op_isub:
+      return nir_op_isub;
    case nir_atomic_op_imin:
       return nir_op_imin;
    case nir_atomic_op_umin:

src/compiler/nir/nir.h

@@ -1251,6 +1251,7 @@ nir_op nir_type_conversion_op(nir_alu_type src, nir_alu_type dst,
  */
 typedef enum {
    nir_atomic_op_iadd,
+   nir_atomic_op_isub,
    nir_atomic_op_imin,
    nir_atomic_op_umin,
    nir_atomic_op_imax,
@@ -1284,6 +1285,7 @@ nir_atomic_op_type(nir_atomic_op op)
       return nir_type_float;
 
    case nir_atomic_op_iadd:
+   case nir_atomic_op_isub:
    case nir_atomic_op_iand:
    case nir_atomic_op_ior:
    case nir_atomic_op_ixor:

src/compiler/nir/nir_opt_uniform_atomics.c

@@ -191,6 +191,9 @@ static void
 reduce_data(nir_builder *b, nir_op op, nir_def *data,
             nir_def **reduce, nir_def **scan)
 {
+   if (op == nir_op_isub)
+      op = nir_op_iadd;
+
    if (scan) {
       *scan = nir_exclusive_scan(b, data, .reduction_op = op);
       if (reduce) {

src/compiler/nir/nir_print.c

@@ -1268,6 +1268,9 @@ print_intrinsic_instr(nir_intrinsic_instr *instr, print_state *state)
          case nir_atomic_op_iadd:
             fprintf(fp, "iadd");
             break;
+         case nir_atomic_op_isub:
+            fprintf(fp, "isub");
+            break;
          case nir_atomic_op_imin:
             fprintf(fp, "imin");
             break;