agx: Don't lower load_local_invocation_index

We have an SR for it, which can save a bit of math. This came up while working
on the spiller.

   total instructions in shared programs: 1778396 -> 1778376 (<.01%)
   instructions in affected programs: 3036 -> 3016 (-0.66%)
   helped: 10
   HURT: 3
   Instructions are helped.

   total bytes in shared programs: 12185182 -> 12185018 (<.01%)
   bytes in affected programs: 38640 -> 38476 (-0.42%)
   helped: 18
   HURT: 2
   Bytes are helped.

   total halfregs in shared programs: 531218 -> 531174 (<.01%)
   halfregs in affected programs: 471 -> 427 (-9.34%)
   helped: 6
   HURT: 0
   Halfregs are helped.

   total threads in shared programs: 18909056 -> 18909184 (<.01%)
   threads in affected programs: 1280 -> 1408 (10.00%)
   helped: 2
   HURT: 0

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24635>

src/asahi/compiler/agx_compile.c

@@ -1066,6 +1066,9 @@ agx_emit_intrinsic(agx_builder *b, nir_intrinsic_instr *instr)
       return agx_load_compute_dimension(
          b, dst, instr, AGX_SR_THREAD_POSITION_IN_THREADGROUP_X);
 
+   case nir_intrinsic_load_local_invocation_index:
+      return agx_get_sr_to(b, dst, AGX_SR_THREAD_INDEX_IN_THREADGROUP);
+
    case nir_intrinsic_barrier: {
       assert(!b->shader->is_preamble && "invalid");
 

src/asahi/compiler/agx_compile.h

@@ -246,7 +246,6 @@ static const nir_shader_compiler_options agx_nir_options = {
    .lower_extract_byte = true,
    .lower_insert_byte = true,
    .lower_insert_word = true,
-   .lower_cs_local_index_to_id = true,
    .has_cs_global_id = true,
    .vectorize_io = true,
    .use_interpolated_input_intrinsics = true,