[Mesa-dev] [PATCH] i965: fix transform feedback with primitive restart

[Jordan Justen]

On Fri, Jun 29, 2012 at 2:02 PM, Ian Romanick <idr at freedesktop.org> wrote:
> On 06/28/2012 04:12 PM, Jordan Justen wrote:
>>
>> When querying GL_PRIMITIVES_GENERATED, if primitive restart
>> is also used, then take the software primitive restart
>> path so GL_PRIMITIVES_GENERATED is returned correctly.
>>
>> GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN is also updated
>> since it will also affected by the same issue.
>>
>> As noted in brw_primitive_restart.c, with further work we
>> should be able to move this situation back to a hardware
>> handled path.
>>
>> Signed-off-by: Jordan Justen<jordan.l.justen at intel.com>
>
> Do we have piglit tests for this case?

I posted a patch for a piglit test for this issue:
"[PATCH] ext_transform_feedback: Test Tranform Feedback with Primitive Restart"

It is related to:
https://bugs.freedesktop.org/show_bug.cgi?id=50925

> Is it safe to assume that they fail
> without but pass with this patch?

Yep

>> ---
>>  src/mesa/drivers/dri/i965/brw_context.h           |    2 ++
>>  src/mesa/drivers/dri/i965/brw_primitive_restart.c |   12 ++++++++++++
>>  src/mesa/drivers/dri/i965/brw_queryobj.c          |    4 ++++
>>  3 files changed, 18 insertions(+)
>>
>> diff --git a/src/mesa/drivers/dri/i965/brw_context.h
>> b/src/mesa/drivers/dri/i965/brw_context.h
>> index 2c9f5ad..ee860f3 100644
>> --- a/src/mesa/drivers/dri/i965/brw_context.h
>> +++ b/src/mesa/drivers/dri/i965/brw_context.h
>> @@ -1037,7 +1037,9 @@ struct brw_context
>>        uint32_t svbi_0_max_index;
>>        uint32_t offset_0_batch_start;
>>        uint32_t primitives_generated;
>> +      bool counting_primitives_generated;
>>        uint32_t primitives_written;
>> +      bool counting_primitives_written;
>
> These should be grouped together for better packing.

Ok, I'll fix that.

Is this Reviewed-by you with that change?

Thanks,

-Jordan

>>     } sol;
>>
>>     uint32_t render_target_format[MESA_FORMAT_COUNT];
>> diff --git a/src/mesa/drivers/dri/i965/brw_primitive_restart.c
>> b/src/mesa/drivers/dri/i965/brw_primitive_restart.c
>> index 962ff18..02deba4 100644
>> --- a/src/mesa/drivers/dri/i965/brw_primitive_restart.c
>> +++ b/src/mesa/drivers/dri/i965/brw_primitive_restart.c
>> @@ -69,6 +69,18 @@ can_cut_index_handle_prims(struct gl_context *ctx,
>>                             GLuint nr_prims,
>>                             const struct _mesa_index_buffer *ib)
>>  {
>> +   struct brw_context *brw = brw_context(ctx);
>> +
>> +   if (brw->sol.counting_primitives_generated ||
>> +       brw->sol.counting_primitives_written) {
>> +      /* Counting primitives generated in hardware is not currently
>> +       * supported, so take the software path. We need to investigate
>> +       * the *_PRIMITIVES_COUNT registers to allow this to be handled
>> +       * entirely in hardware.
>> +       */
>> +      return false;
>> +   }
>> +
>>     if (!can_cut_index_handle_restart_index(ctx, ib)) {
>>        /* The primitive restart index can't be handled, so take
>>         * the software path
>> diff --git a/src/mesa/drivers/dri/i965/brw_queryobj.c
>> b/src/mesa/drivers/dri/i965/brw_queryobj.c
>> index 72b83f4..240fe32 100644
>> --- a/src/mesa/drivers/dri/i965/brw_queryobj.c
>> +++ b/src/mesa/drivers/dri/i965/brw_queryobj.c
>> @@ -171,6 +171,7 @@ brw_begin_query(struct gl_context *ctx, struct
>> gl_query_object *q)
>>         * it a software counter.  So just reset the counter.
>>         */
>>        brw->sol.primitives_generated = 0;
>> +      brw->sol.counting_primitives_generated = true;
>>        break;
>>
>>     case GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN:
>> @@ -178,6 +179,7 @@ brw_begin_query(struct gl_context *ctx, struct
>> gl_query_object *q)
>>         * it a software counter.  So just reset the counter.
>>         */
>>        brw->sol.primitives_written = 0;
>> +      brw->sol.counting_primitives_written = true;
>>        break;
>>
>>     default:
>> @@ -249,6 +251,7 @@ brw_end_query(struct gl_context *ctx, struct
>> gl_query_object *q)
>>         * the query object.
>>         */
>>        query->Base.Result = brw->sol.primitives_generated;
>> +      brw->sol.counting_primitives_generated = false;
>>
>>        /* And set brw->query.obj to NULL so that this query won't try to
>> wait
>>         * for any rendering to complete.
>> @@ -262,6 +265,7 @@ brw_end_query(struct gl_context *ctx, struct
>> gl_query_object *q)
>>         * the query object.
>>         */
>>        query->Base.Result = brw->sol.primitives_written;
>> +      brw->sol.counting_primitives_written = false;
>>
>>        /* And set brw->query.obj to NULL so that this query won't try to
>> wait
>>         * for any rendering to complete.
>
>
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