[Mesa-dev] [PATCH 2/5] i965: Explicitly maintain a count of SO_DECL structures emitted.

[Ian Romanick]

On 10/26/2013 01:33 PM, Kenneth Graunke wrote:
> Currently, we emit one SO_DECL structure per output, so we use the index
> in the Outputs[] array as the index into the so_decl[] array as well.
> 
> In order to support the fake "gl_SkipComponents[1234]" varyings from
> ARB_transform_feedback3, we'll need to emit SO_DECLs to fill in the
> holes between successive outputs.  This means we'll likely emit more
> SO_DECLs than there are outputs, so we need to count it explicitly.
> 
> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>

Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>

> ---
>  src/mesa/drivers/dri/i965/gen7_sol_state.c | 15 +++++++--------
>  1 file changed, 7 insertions(+), 8 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/gen7_sol_state.c b/src/mesa/drivers/dri/i965/gen7_sol_state.c
> index 3e02bdf..b9debdb 100644
> --- a/src/mesa/drivers/dri/i965/gen7_sol_state.c
> +++ b/src/mesa/drivers/dri/i965/gen7_sol_state.c
> @@ -108,17 +108,17 @@ gen7_upload_3dstate_so_decl_list(struct brw_context *brw,
>     /* BRW_NEW_TRANSFORM_FEEDBACK */
>     const struct gl_transform_feedback_info *linked_xfb_info =
>        &vs_prog->LinkedTransformFeedback;
> -   int i;
>     uint16_t so_decl[128];
>     int buffer_mask = 0;
>     int next_offset[4] = {0, 0, 0, 0};
> +   int decls = 0;
>  
>     STATIC_ASSERT(ARRAY_SIZE(so_decl) >= MAX_PROGRAM_OUTPUTS);
>  
>     /* Construct the list of SO_DECLs to be emitted.  The formatting of the
>      * command is feels strange -- each dword pair contains a SO_DECL per stream.
>      */
> -   for (i = 0; i < linked_xfb_info->NumOutputs; i++) {
> +   for (int i = 0; i < linked_xfb_info->NumOutputs; i++) {

This is "only" C code, but I strongly approve.

>        int buffer = linked_xfb_info->Outputs[i].OutputBuffer;
>        uint16_t decl = 0;
>        int varying = linked_xfb_info->Outputs[i].OutputRegister;
> @@ -147,24 +147,23 @@ gen7_upload_3dstate_so_decl_list(struct brw_context *brw,
>  
>        next_offset[buffer] += components;
>  
> -      so_decl[i] = decl;
> +      so_decl[decls++] = decl;
>     }
>  
> -   BEGIN_BATCH(linked_xfb_info->NumOutputs * 2 + 3);
> -   OUT_BATCH(_3DSTATE_SO_DECL_LIST << 16 |
> -	     (linked_xfb_info->NumOutputs * 2 + 1));
> +   BEGIN_BATCH(decls * 2 + 3);
> +   OUT_BATCH(_3DSTATE_SO_DECL_LIST << 16 | (decls * 2 + 1));
>  
>     OUT_BATCH((buffer_mask << SO_STREAM_TO_BUFFER_SELECTS_0_SHIFT) |
>  	     (0 << SO_STREAM_TO_BUFFER_SELECTS_1_SHIFT) |
>  	     (0 << SO_STREAM_TO_BUFFER_SELECTS_2_SHIFT) |
>  	     (0 << SO_STREAM_TO_BUFFER_SELECTS_3_SHIFT));
>  
> -   OUT_BATCH((linked_xfb_info->NumOutputs << SO_NUM_ENTRIES_0_SHIFT) |
> +   OUT_BATCH((decls << SO_NUM_ENTRIES_0_SHIFT) |
>  	     (0 << SO_NUM_ENTRIES_1_SHIFT) |
>  	     (0 << SO_NUM_ENTRIES_2_SHIFT) |
>  	     (0 << SO_NUM_ENTRIES_3_SHIFT));
>  
> -   for (i = 0; i < linked_xfb_info->NumOutputs; i++) {
> +   for (int i = 0; i < decls; i++) {
>        OUT_BATCH(so_decl[i]);
>        OUT_BATCH(0);
>     }
>