[PATCH vkd3d 2/3] vkd3d-shader/hlsl: Take writemask into account when emitting a SM4 constant.

[Zebediah Figura (she/her)]

On 11/12/21 09:36, Giovanni Mascellani wrote:
> Signed-off-by: Giovanni Mascellani <gmascellani at codeweavers.com>
> ---
>   libs/vkd3d-shader/hlsl_sm4.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/libs/vkd3d-shader/hlsl_sm4.c b/libs/vkd3d-shader/hlsl_sm4.c
> index c56a74d4..18c80774 100644
> --- a/libs/vkd3d-shader/hlsl_sm4.c
> +++ b/libs/vkd3d-shader/hlsl_sm4.c
> @@ -1166,7 +1166,7 @@ static void write_sm4_constant(struct hlsl_ctx *ctx,
>   {
>       const unsigned int dimx = constant->node.data_type->dimx;
>       struct sm4_instruction instr;
> -    unsigned int i;
> +    unsigned int i, j = 0;
>   
>       memset(&instr, 0, sizeof(instr));
>       instr.opcode = VKD3D_SM4_OP_MOV;
> @@ -1177,7 +1177,11 @@ static void write_sm4_constant(struct hlsl_ctx *ctx,
>       instr.srcs[0].reg.dim = (dimx > 1) ? VKD3D_SM4_DIMENSION_VEC4 : VKD3D_SM4_DIMENSION_SCALAR;
>       instr.srcs[0].reg.type = VKD3D_SM4_RT_IMMCONST;
>       for (i = 0; i < dimx; ++i)
> -        instr.srcs[0].reg.immconst_uint[i] = constant->value[i].u;
> +    {
> +        while (dimx != 1 && !(instr.dsts[0].writemask & (1u << j)))
> +            j++;
> +        instr.srcs[0].reg.immconst_uint[j++] = constant->value[i].u;
> +    }
>       instr.src_count = 1,
>   
>       write_sm4_instruction(buffer, &instr);
> 

This is probably quibbling, but how about this?

j = 0;
for (i = 0; i < 4; ++i)
{
     if (instr.dsts[0].writemask & (1u << i))
         instr.srcs[0].reg.immconst_uint[i] = constant->value[j++].u;
}

Feels a bit simpler to me.