lima: ppir: assign actual index to discard block

Discard block is always added to the block list after translation from NIR,
so we can just assign it an index that equals to block list size.

Reviewed-by: Erico Nunes <nunes.erico@gmail.com>
Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33754>

src/gallium/drivers/lima/ir/pp/nir.c

@@ -293,7 +293,6 @@ static bool ppir_emit_discard_block(ppir_compiler *comp)
 
    comp->discard_block = block;
    block->comp  = comp;
-   block->index = INT_MAX;
 
    discard = ppir_node_create(block, ppir_op_discard, -1, 0);
    if (discard)
@@ -1062,8 +1061,10 @@ bool ppir_compile_nir(struct lima_fs_compiled_shader *prog, struct nir_shader *n
       goto err_out0;
 
    /* If we have discard block add it to the very end */
-   if (comp->discard_block)
+   if (comp->discard_block) {
+      comp->discard_block->index = list_length(&comp->block_list);
       list_addtail(&comp->discard_block->list, &comp->block_list);
+   }
 
    ppir_node_print_prog(comp);