On Fri, May 27, 2016 at 7:06 PM, Francisco Jerez <curroje...@riseup.net>
wrote:
> We know that there cannot be any destination dependency race if we
> reach the beginning or end of the program without having found any
> other instruction the send could possibly race with. This avoids
> emitting a pile of useless moves at the beginning or end of the
> program in the most common case in which the program has a single
> basic block only.
>
> On the original i965 I get the following shader-db results:
>
> total instructions in shared programs: 3354165 -> 3215637 (-4.13%)
> instructions in affected programs: 3183065 -> 3044537 (-4.35%)
> helped: 13498
> HURT: 0
>
Nice!
>
> ---
> src/mesa/drivers/dri/i965/brw_fs.cpp | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp
> b/src/mesa/drivers/dri/i965/brw_fs.cpp
> index 660a8db..bfde69c 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
> @@ -3210,7 +3210,7 @@
> fs_visitor::insert_gen4_pre_send_dependency_workarounds(bblock_t *block,
> /* If we hit control flow, assume that there *are* outstanding
> * dependencies, and force their cleanup before our instruction.
> */
> - if (block->start() == scan_inst) {
> + if (block->start() == scan_inst && block->num != 0) {
>
Yes, hitting the top of the program does *not* count as control flow. Good
work us!
Reviewed-by: Jason Ekstrand <ja...@jlekstrand.net>
--Jason
> for (int i = 0; i < write_len; i++) {
> if (needs_dep[i])
> DEP_RESOLVE_MOV(fs_builder(this, block, inst),
> @@ -3274,7 +3274,7 @@
> fs_visitor::insert_gen4_post_send_dependency_workarounds(bblock_t *block,
> fs_ins
> */
> foreach_inst_in_block_starting_from(fs_inst, scan_inst, inst) {
> /* If we hit control flow, force resolve all remaining
> dependencies. */
> - if (block->end() == scan_inst) {
> + if (block->end() == scan_inst && block->num != cfg->num_blocks - 1)
> {
> for (int i = 0; i < write_len; i++) {
> if (needs_dep[i])
> DEP_RESOLVE_MOV(fs_builder(this, block, scan_inst),
> --
> 2.7.3
>
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