[PATCH vkd3d 3.5/5] vkd3d-shader: Consider previous last_read value when computing liveness.

[Zebediah Figura (she/her)]

On 3/21/21 3:40 PM, Matteo Bruni wrote:
> Otherwise we end up overwriting UINT_MAX last_read for output variables.
> 
> Signed-off-by: Matteo Bruni <mbruni at codeweavers.com>
> ---
>   libs/vkd3d-shader/hlsl_codegen.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libs/vkd3d-shader/hlsl_codegen.c b/libs/vkd3d-shader/hlsl_codegen.c
> index b6b9ded..b9f753a 100644
> --- a/libs/vkd3d-shader/hlsl_codegen.c
> +++ b/libs/vkd3d-shader/hlsl_codegen.c
> @@ -355,7 +355,7 @@ static void compute_liveness_recurse(struct list *instrs, unsigned int loop_firs
>               struct hlsl_ir_load *load = hlsl_ir_load(instr);
>   
>               var = load->src.var;
> -            var->last_read = loop_last ? max(instr->index, loop_last) : instr->index;
> +            var->last_read = max(var->last_read, loop_last ? max(instr->index, loop_last) : instr->index);
>               if (load->src.offset.node)
>                   load->src.offset.node->last_read = instr->index;
>               break;
> 

This works, though I guess the other option is to assign UINT_MAX after 
calling compute_liveness_recurse().