[Mesa-dev] [PATCH 4/5] i965/fs: Extend SEL peephole to handle only matching MOVs.

[Paul Berry]

On 31 October 2013 18:57, Matt Turner <mattst88 at gmail.com> wrote:

> Before this patch, the following code would not be optimized even though
> the first two instructions were common to the then and else blocks:
>
>    (+f0) IF
>    MOV dst0 ...
>    MOV dst1 ...
>    MOV dst2 ...
>    ELSE
>    MOV dst0 ...
>    MOV dst1 ...
>    MOV dst3 ...
>    ENDIF
>
> This commit extends the peephole to handle this case.
>
> No shader-db changes.
> ---
> This patch made a much bigger difference when pulling instructions from the
> ends of the "then" and "else" blocks, because often we were able to compute
> to MRF.
>

This patch is:

Reviewed-by: Paul Berry <stereotype441 at gmail.com>

I'd be just as happy if you wanted to squash patches 3 and 4 together into
a single patch.


>
>  src/mesa/drivers/dri/i965/brw_fs_sel_peephole.cpp | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_fs_sel_peephole.cpp
> b/src/mesa/drivers/dri/i965/brw_fs_sel_peephole.cpp
> index 9626751..c875487 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs_sel_peephole.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs_sel_peephole.cpp
> @@ -142,7 +142,6 @@ fs_visitor::opt_peephole_sel()
>
>        fs_inst *else_mov[MAX_MOVS] = { NULL };
>        fs_inst *then_mov[MAX_MOVS] = { NULL };
> -      bool malformed_mov_found = false;
>
>        int movs = count_movs_from_if(then_mov, else_mov, if_inst,
> else_inst);
>
> @@ -161,7 +160,7 @@ fs_visitor::opt_peephole_sel()
>           if (!then_mov[i]->dst.equals(else_mov[i]->dst) ||
>               then_mov[i]->is_partial_write() ||
>               else_mov[i]->is_partial_write()) {
> -            malformed_mov_found = true;
> +            movs = i;
>              break;
>           }
>
> @@ -188,7 +187,7 @@ fs_visitor::opt_peephole_sel()
>           }
>        }
>
> -      if (malformed_mov_found)
> +      if (movs == 0)
>           continue;
>
>        /* Emit a CMP if our IF used the embedded comparison */
> --
> 1.8.3.2
>
>
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