[Mesa-dev] [PATCH] i965/fs: Use source's original type in register_coalesce().

[Kenneth Graunke]

On 11/16/2013 03:23 PM, Matt Turner wrote:
> Previously, register_coalesce() would modify
> 
>    mov   vgrf1:f  vgrf2:f
>    cmp   null     vgrf3:d  vgrf1:d
> 
> to be
> 
>    cmp   null     vgrf3:d  vgrf2:f
> 
> and incorrectly use vgrf2's type in the instruction that the mov was
> coalesced into.
> ---
> My in progress value-numbering pass exposes this bug, but without it I
> didn't find anything fixed by the patch in piglit.
> 
>  src/mesa/drivers/dri/i965/brw_fs.cpp | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
> index 795e01e..800a7b4 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
> @@ -2442,6 +2442,7 @@ fs_visitor::register_coalesce()
>  		scan_inst->src[i].reg == inst->dst.reg &&
>  		scan_inst->src[i].reg_offset == inst->dst.reg_offset) {
>  	       fs_reg new_src = inst->src[0];
> +               new_src.type = scan_inst->src[i].type;
>                 if (scan_inst->src[i].abs) {
>                    new_src.negate = 0;
>                    new_src.abs = 1;
> 

Yep, clearly needed.  Nice catch.

Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>