[Mesa-dev] [PATCH 02/10] nir: Properly clean up CF nodes when we remove them

[Connor Abbott]

While we're cleaning this up, we should go a little farther - we
should also see if anything is using the SSA result of any of these
instructions, and if so make it point to an undef_instr instead to
avoid dangling pointers. This doesn't come up yet but it will when we
start cleaning up constant control flow.

On Thu, Feb 5, 2015 at 5:28 PM, Jason Ekstrand <jason at jlekstrand.net> wrote:
> Previously, if you remved a CF node that still had instructions in it, none
> of the use/def information from those instructions would get cleaned up.
> Also, we weren't removing if statements from the if_uses of the
> corresponding register or SSA def.  This commit fixes both of these
> problems
> ---
>  src/glsl/nir/nir.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 54 insertions(+)
>
> diff --git a/src/glsl/nir/nir.c b/src/glsl/nir/nir.c
> index 9a88bd3..8ea7bb5 100644
> --- a/src/glsl/nir/nir.c
> +++ b/src/glsl/nir/nir.c
> @@ -1148,6 +1148,58 @@ stitch_blocks(nir_block *before, nir_block *after)
>     exec_node_remove(&after->cf_node.node);
>  }
>
> +static void
> +remove_defs_uses(nir_instr *instr);
> +
> +static void
> +cleanup_cf_node(nir_cf_node *node)
> +{
> +   switch (node->type) {
> +   case nir_cf_node_block: {
> +      nir_block *block = nir_cf_node_as_block(node);
> +      /* We need to walk the instructions and clean up defs/uses */
> +      nir_foreach_instr(block, instr)
> +         remove_defs_uses(instr);
> +      break;
> +   }
> +
> +   case nir_cf_node_if: {
> +      nir_if *if_stmt = nir_cf_node_as_if(node);
> +      foreach_list_typed(nir_cf_node, child, node, &if_stmt->then_list)
> +         cleanup_cf_node(child);
> +      foreach_list_typed(nir_cf_node, child, node, &if_stmt->else_list)
> +         cleanup_cf_node(child);
> +
> +      struct set *if_uses;
> +      if (if_stmt->condition.is_ssa) {
> +         if_uses = if_stmt->condition.ssa->if_uses;
> +      } else {
> +         if_uses = if_stmt->condition.reg.reg->if_uses;
> +      }
> +
> +      struct set_entry *entry = _mesa_set_search(if_uses, if_stmt);
> +      assert(entry);
> +      _mesa_set_remove(if_uses, entry);
> +      break;
> +   }
> +
> +   case nir_cf_node_loop: {
> +      nir_loop *loop = nir_cf_node_as_loop(node);
> +      foreach_list_typed(nir_cf_node, child, node, &loop->body)
> +         cleanup_cf_node(child);
> +      break;
> +   }
> +   case nir_cf_node_function: {
> +      nir_function_impl *impl = nir_cf_node_as_function(node);
> +      foreach_list_typed(nir_cf_node, child, node, &impl->body)
> +         cleanup_cf_node(child);
> +      break;
> +   }
> +   default:
> +      unreachable("Invalid CF node type");
> +   }
> +}
> +
>  void
>  nir_cf_node_remove(nir_cf_node *node)
>  {
> @@ -1175,6 +1227,8 @@ nir_cf_node_remove(nir_cf_node *node)
>        exec_node_remove(&node->node);
>        stitch_blocks(before_block, after_block);
>     }
> +
> +   cleanup_cf_node(node);
>  }
>
>  static bool
> --
> 2.2.2
>
> _______________________________________________
> mesa-dev mailing list
> mesa-dev at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/mesa-dev