[Mesa-dev] [PATCH] mesa: deal with vs_inputs as 64-bit unsigned integer

[Iago Toral]

On Mon, 2017-11-27 at 18:37 +0100, Juan A. Suarez Romero wrote:
> Commit 78942e ("mesa: shrink VERT_ATTRIB bitfields to 32 bits") uses
> vs_prog_data->vs_inputs as if it were a 32-bit unsigned integer.
> 
> But actually it is a 64-bit integer, and as such it is used in other
> parts of Mesa code. It is worth to note that bits from the entire
> range
> are used, and not only 32-bits.

For reference, this is because of 64-bit dual-slot input attributes.
Our implementation uses a larger bitfield to handle these.

> This commit reverts the changes done in brw_draw_upload.c, keeping
> the
> rest of the changes.
> 
> This fixes the following tests:
> 
> - KHR-GL45.enhanced_layouts.varying_array_locations
> - KHR-GL45.enhanced_layouts.varying_locations
> 
> Fixes: 78942e ("mesa: shrink VERT_ATTRIB bitfields to 32 bits")
> CC: Marek Olšák <marek.olsak at amd.com>
> CC: Ian Romanick <ian.d.romanick at intel.com>
> Signed-off-by: Juan A. Suarez Romero <jasuarez at igalia.com>

Reviewed-by: Iago Toral Quiroga <itoral at igalia.com>

> ---
>  src/mesa/drivers/dri/i965/brw_draw_upload.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_draw_upload.c
> b/src/mesa/drivers/dri/i965/brw_draw_upload.c
> index 2204bf474bd..9b81999ea05 100644
> --- a/src/mesa/drivers/dri/i965/brw_draw_upload.c
> +++ b/src/mesa/drivers/dri/i965/brw_draw_upload.c
> @@ -458,7 +458,7 @@ brw_prepare_vertices(struct brw_context *brw)
>     /* BRW_NEW_VS_PROG_DATA */
>     const struct brw_vs_prog_data *vs_prog_data =
>        brw_vs_prog_data(brw->vs.base.prog_data);
> -   GLbitfield vs_inputs = vs_prog_data->inputs_read;
> +   GLbitfield64 vs_inputs = vs_prog_data->inputs_read;
>     const unsigned char *ptr = NULL;
>     GLuint interleaved = 0;
>     unsigned int min_index = brw->vb.min_index + brw->basevertex;
> @@ -487,16 +487,16 @@ brw_prepare_vertices(struct brw_context *brw)
>     /* Accumulate the list of enabled arrays. */
>     brw->vb.nr_enabled = 0;
>     while (vs_inputs) {
> -      GLuint first = ffs(vs_inputs) - 1;
> +      GLuint first = ffsll(vs_inputs) - 1;
>        assert (first < 64);
>        GLuint index =
>           first - DIV_ROUND_UP(_mesa_bitcount_64(vs_prog_data-
> >double_inputs_read &
>                                                  BITFIELD64_MASK(firs
> t)), 2);
>        struct brw_vertex_element *input = &brw->vb.inputs[index];
>        input->is_dual_slot = (vs_prog_data->double_inputs_read &
> BITFIELD64_BIT(first)) != 0;
> -      vs_inputs &= ~BITFIELD_BIT(first);
> +      vs_inputs &= ~BITFIELD64_BIT(first);
>        if (input->is_dual_slot)
> -         vs_inputs &= ~BITFIELD_BIT(first + 1);
> +         vs_inputs &= ~BITFIELD64_BIT(first + 1);
>        brw->vb.enabled[brw->vb.nr_enabled++] = input;
>     }
>