[Mesa-dev] [PATCH 4/5] i965/fs: Make get_timestamp() pass back the MOV rather than emitting it.

[Matt Turner]

On Sun, Mar 8, 2015 at 1:08 AM, Kenneth Graunke <kenneth at whitecape.org> wrote:
> This makes another part of the INTEL_DEBUG=shader_time code emittable
> at arbitrary locations, rather than just at the end of the instruction
> stream.
>
> v2: Don't lose smear!  Caught by Topi Pohjolainen.
> v3: Don't set smear on the destination of the MOV.  Thanks Topi!
>
> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> ---
>  src/mesa/drivers/dri/i965/brw_fs.cpp | 19 +++++++++++++++----
>  src/mesa/drivers/dri/i965/brw_fs.h   |  2 +-
>  2 files changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
> index 682841b..8f11600 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
> @@ -677,8 +677,14 @@ fs_visitor::type_size(const struct glsl_type *type)
>     return 0;
>  }
>
> +/**
> + * Create a MOV to read the timestamp register.
> + *
> + * The caller is responsible for emitting the MOV.  The return value is
> + * the destination of the MOV, with extra parameters set.
> + */
>  fs_reg
> -fs_visitor::get_timestamp()
> +fs_visitor::get_timestamp(fs_inst **out_mov)
>  {
>     assert(brw->gen >= 7);
>
> @@ -689,7 +695,7 @@ fs_visitor::get_timestamp()
>
>     fs_reg dst = fs_reg(GRF, alloc.allocate(1), BRW_REGISTER_TYPE_UD, 4);
>
> -   fs_inst *mov = emit(MOV(dst, ts));
> +   fs_inst *mov = MOV(dst, ts);
>     /* We want to read the 3 fields we care about even if it's not enabled in
>      * the dispatch.
>      */
> @@ -707,6 +713,7 @@ fs_visitor::get_timestamp()
>      */
>     dst.set_smear(0);
>
> +   *out_mov = mov;
>     return dst;
>  }
>
> @@ -714,7 +721,9 @@ void
>  fs_visitor::emit_shader_time_begin()
>  {
>     current_annotation = "shader time start";
> -   shader_start_time = get_timestamp();
> +   fs_inst *mov;
> +   shader_start_time = get_timestamp(&mov);
> +   emit(mov);

What do you think about returning the mov instruction from
get_timestamp, and then just doing shader_start_time = mov->dst?