[Mesa-dev] [PATCH] util/primconvert: Avoid point arithmetic; apply offset on all cases.

[Ilia Mirkin]

On Fri, Dec 5, 2014 at 9:18 AM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
> On Fri, Dec 5, 2014 at 9:16 AM, Jose Fonseca <jfonseca at vmware.com> wrote:
>> From: José Fonseca <jfonseca at vmware.com>
>>
>> Matches what u_vbuf_get_minmax_index() does.
>
> Hm, nouveau nv50 (and probably nvc0) does:
>
>       if (ib->buffer) {
>          nv50->idxbuf.offset = ib->offset;
>          BCTX_REFN(nv50->bufctx_3d, INDEX, nv04_resource(ib->buffer), RD);
>       } else {
>          nv50->idxbuf.user_buffer = ib->user_buffer;
>       }
>
> Is the offset really supposed to be applied to the user buffer? I
> figured the point of the offset was that you couldn't provide an
> offset into a pipe_resource otherwise, while with a user ptr, you can
> just add it in yourself...

But you're right, u_vbuf seems to add it in. Do a lot of drivers use
u_vbuf? The logic for whether it gets used or not does not lend itself
to easy checking.

>
>> ---
>>  src/gallium/auxiliary/indices/u_primconvert.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/gallium/auxiliary/indices/u_primconvert.c b/src/gallium/auxiliary/indices/u_primconvert.c
>> index 4632781..eba1f9e 100644
>> --- a/src/gallium/auxiliary/indices/u_primconvert.c
>> +++ b/src/gallium/auxiliary/indices/u_primconvert.c
>> @@ -137,8 +137,9 @@ util_primconvert_draw_vbo(struct primconvert_context *pc,
>>        src = ib->user_buffer;
>>        if (!src) {
>>           src = pipe_buffer_map(pc->pipe, ib->buffer,
>> -                               PIPE_TRANSFER_READ, &src_transfer) + ib->offset;
>> +                               PIPE_TRANSFER_READ, &src_transfer);
>>        }
>> +      src = (const uint8_t *)src + ib->offset;
>>     }
>>     else {
>>        u_index_generator(pc->primtypes_mask,
>> --
>> 2.1.0
>>