[Mesa-dev] [PATCH 1/2] nir: add rewrite_phi_predecessor_blocks() helper

[Thomas Helland]

This patch is:

Reviewed-by: Thomas Helland <thomashelland90 at gmail.com>

Den tir. 27. nov. 2018 kl. 06:32 skrev Timothy Arceri <tarceri at itsqueeze.com>:
>
> This will also be used by the if merge pass in the following commit.
> ---
>  src/compiler/nir/nir_opt_if.c | 45 ++++++++++++++++++++++-------------
>  1 file changed, 28 insertions(+), 17 deletions(-)
>
> diff --git a/src/compiler/nir/nir_opt_if.c b/src/compiler/nir/nir_opt_if.c
> index 8a971c43f2..62566eb403 100644
> --- a/src/compiler/nir/nir_opt_if.c
> +++ b/src/compiler/nir/nir_opt_if.c
> @@ -237,6 +237,32 @@ is_block_empty(nir_block *block)
>            exec_list_is_empty(&block->instr_list);
>  }
>
> +static void
> +rewrite_phi_predecessor_blocks(nir_if *nif,
> +                               nir_block *old_then_block,
> +                               nir_block *old_else_block,
> +                               nir_block *new_then_block,
> +                               nir_block *new_else_block)
> +{
> +   nir_block *after_if_block =
> +      nir_cf_node_as_block(nir_cf_node_next(&nif->cf_node));
> +
> +   nir_foreach_instr(instr, after_if_block) {
> +      if (instr->type != nir_instr_type_phi)
> +         continue;
> +
> +      nir_phi_instr *phi = nir_instr_as_phi(instr);
> +
> +      foreach_list_typed(nir_phi_src, src, node, &phi->srcs) {
> +         if (src->pred == old_then_block) {
> +            src->pred = new_then_block;
> +         } else if (src->pred == old_else_block) {
> +            src->pred = new_else_block;
> +         }
> +      }
> +   }
> +}
> +
>  /**
>   * This optimization turns:
>   *
> @@ -284,23 +310,8 @@ opt_if_simplification(nir_builder *b, nir_if *nif)
>     /* Walk all the phis in the block immediately following the if statement and
>      * swap the blocks.
>      */
> -   nir_block *after_if_block =
> -      nir_cf_node_as_block(nir_cf_node_next(&nif->cf_node));
> -
> -   nir_foreach_instr(instr, after_if_block) {
> -      if (instr->type != nir_instr_type_phi)
> -         continue;
> -
> -      nir_phi_instr *phi = nir_instr_as_phi(instr);
> -
> -      foreach_list_typed(nir_phi_src, src, node, &phi->srcs) {
> -         if (src->pred == else_block) {
> -            src->pred = then_block;
> -         } else if (src->pred == then_block) {
> -            src->pred = else_block;
> -         }
> -      }
> -   }
> +   rewrite_phi_predecessor_blocks(nif, then_block, else_block, else_block,
> +                                  then_block);
>
>     /* Finally, move the else block to the then block. */
>     nir_cf_list tmp;
> --
> 2.19.1
>
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