[Mesa-dev] [PATCH 2/4] i965/fs: Wire up control flow correctly in predicated break pass.

[Jason Ekstrand]

On Wed, Nov 5, 2014 at 4:13 PM, Matt Turner <mattst88 at gmail.com> wrote:

> When the earlier block ended with control flow, we'd mistakenly remove
> some of its links to its children. The same happened with the later
> block.
> ---
>  src/mesa/drivers/dri/i965/brw_fs_peephole_predicated_break.cpp | 10
> +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git
> a/src/mesa/drivers/dri/i965/brw_fs_peephole_predicated_break.cpp
> b/src/mesa/drivers/dri/i965/brw_fs_peephole_predicated_break.cpp
> index b7a1d7e..047c2c0 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs_peephole_predicated_break.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs_peephole_predicated_break.cpp
> @@ -107,10 +107,14 @@ fs_visitor::opt_peephole_predicated_break()
>        }
>        endif_inst->remove(endif_block);
>
> -      earlier_block->children.make_empty();
> -      later_block->parents.make_empty();
> +      if (!earlier_block->ends_with_control_flow()) {
> +         earlier_block->children.make_empty();
> +         earlier_block->add_successor(cfg->mem_ctx, jump_block);
> +      }
>
> -      earlier_block->add_successor(cfg->mem_ctx, jump_block);
> +      if (!later_block->starts_with_control_flow()) {
> +         later_block->parents.make_empty();
> +      }
>

I *think* this is correct.  I didn't really understand it before and I
don't 100% now.

Acked-by: Jason Ekstrand <jason.ekstrand at intel.com>


>        jump_block->add_successor(cfg->mem_ctx, later_block);
>
>        if (earlier_block->can_combine_with(jump_block)) {
> --
> 2.0.4
>
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