agx: Lower nest later

As part of pseudo op lowering. Simpler and will simplify control flow opts.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25052>

src/asahi/compiler/agx_lower_pseudo.c

@@ -28,6 +28,10 @@ lower(agx_builder *b, agx_instr *I)
    case AGX_OPCODE_OR:
       return agx_bitop_to(b, I->dest[0], I->src[0], I->src[1], AGX_BITOP_OR);
 
+   /* Writes to the nesting counter lowered to the real register */
+   case AGX_OPCODE_NEST:
+      return agx_mov_imm_to(b, agx_register(0, AGX_SIZE_16), I->imm);
+
    default:
       return NULL;
    }

src/asahi/compiler/agx_register_allocate.c

@@ -1252,14 +1252,6 @@ agx_ra(agx_context *ctx)
          }
          break;
 
-      /* Writes to the nesting counter lowered to the real register */
-      case AGX_OPCODE_NEST: {
-         agx_builder b = agx_init_builder(ctx, agx_before_instr(I));
-         agx_mov_imm_to(&b, agx_register(0, AGX_SIZE_16), I->imm);
-         agx_remove_instruction(I);
-         break;
-      }
-
       default:
          break;
       }