Replacing min with max without changing any real code always looks a biit
weird but it does make sense. :-)
Reviewed-by: Jason Ekstrand <ja...@jlekstrand.net>
On Thu, Dec 6, 2018 at 9:08 PM Timothy Arceri <tarc...@itsqueeze.com> wrote:
> Following commits will introduce additional fields such as
> guessed_trip_count. Renaming these will help avoid confusion
> as our unrolling feature set grows.
>
> Reviewed-by: Thomas Helland <thomashellan...@gmail.com>
> ---
> src/compiler/nir/nir.h | 8 +++++---
> src/compiler/nir/nir_loop_analyze.c | 14 +++++++-------
> src/compiler/nir/nir_opt_loop_unroll.c | 14 +++++++-------
> 3 files changed, 19 insertions(+), 17 deletions(-)
>
> diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
> index db935c8496..ce4a81fbe1 100644
> --- a/src/compiler/nir/nir.h
> +++ b/src/compiler/nir/nir.h
> @@ -1886,9 +1886,11 @@ typedef struct {
> /* Number of instructions in the loop */
> unsigned num_instructions;
>
> - /* How many times the loop is run (if known) */
> - unsigned trip_count;
> - bool is_trip_count_known;
> + /* Maximum number of times the loop is run (if known) */
> + unsigned max_trip_count;
> +
> + /* Do we know the exact number of times the loop will be run */
> + bool exact_trip_count_known;
>
> /* Unroll the loop regardless of its size */
> bool force_unroll;
> diff --git a/src/compiler/nir/nir_loop_analyze.c
> b/src/compiler/nir/nir_loop_analyze.c
> index c779383b36..700d1fe552 100644
> --- a/src/compiler/nir/nir_loop_analyze.c
> +++ b/src/compiler/nir/nir_loop_analyze.c
> @@ -527,7 +527,7 @@ find_trip_count(loop_info_state *state)
> {
> bool trip_count_known = true;
> nir_loop_terminator *limiting_terminator = NULL;
> - int min_trip_count = -1;
> + int max_trip_count = -1;
>
> list_for_each_entry(nir_loop_terminator, terminator,
> &state->loop->info->loop_terminator_list,
> @@ -606,8 +606,8 @@ find_trip_count(loop_info_state *state)
> * iterations than previously (we have identified a more limiting
> * terminator) set the trip count and limiting terminator.
> */
> - if (min_trip_count == -1 || iterations < min_trip_count) {
> - min_trip_count = iterations;
> + if (max_trip_count == -1 || iterations < max_trip_count) {
> + max_trip_count = iterations;
> limiting_terminator = terminator;
> }
> break;
> @@ -617,9 +617,9 @@ find_trip_count(loop_info_state *state)
> }
> }
>
> - state->loop->info->is_trip_count_known = trip_count_known;
> - if (min_trip_count > -1)
> - state->loop->info->trip_count = min_trip_count;
> + state->loop->info->exact_trip_count_known = trip_count_known;
> + if (max_trip_count > -1)
> + state->loop->info->max_trip_count = max_trip_count;
> state->loop->info->limiting_terminator = limiting_terminator;
> }
>
> @@ -639,7 +639,7 @@ force_unroll_array_access(loop_info_state *state,
> nir_deref_instr *deref)
> nir_deref_instr *parent = nir_deref_instr_parent(d);
> assert(glsl_type_is_array(parent->type) ||
> glsl_type_is_matrix(parent->type));
> - if (glsl_get_length(parent->type) == state->loop->info->trip_count)
> + if (glsl_get_length(parent->type) ==
> state->loop->info->max_trip_count)
> return true;
>
> if (deref->mode & state->indirect_mask)
> diff --git a/src/compiler/nir/nir_opt_loop_unroll.c
> b/src/compiler/nir/nir_opt_loop_unroll.c
> index ea2012e292..0e9966320b 100644
> --- a/src/compiler/nir/nir_opt_loop_unroll.c
> +++ b/src/compiler/nir/nir_opt_loop_unroll.c
> @@ -181,7 +181,7 @@ simple_unroll(nir_loop *loop)
> nir_cf_list unrolled_lp_body;
>
> /* Clone loop header and append to the loop body */
> - for (unsigned i = 0; i < loop->info->trip_count; i++) {
> + for (unsigned i = 0; i < loop->info->max_trip_count; i++) {
> /* Clone loop body */
> nir_cf_list_clone(&unrolled_lp_body, &loop_body,
> loop->cf_node.parent,
> remap_table);
> @@ -340,7 +340,7 @@ complex_unroll(nir_loop *loop, nir_loop_terminator
> *unlimit_term,
> * trip count == 1 we execute the code above the break twice and the
> * code below it once so we need clone things twice and so on.
> */
> - num_times_to_clone = loop->info->trip_count + 1;
> + num_times_to_clone = loop->info->max_trip_count + 1;
> } else {
> /* Pluck out the loop header */
> nir_cf_extract(&lp_header, nir_before_block(header_blk),
> @@ -368,7 +368,7 @@ complex_unroll(nir_loop *loop, nir_loop_terminator
> *unlimit_term,
>
> nir_cf_node_remove(&limiting_term->nif->cf_node);
>
> - num_times_to_clone = loop->info->trip_count;
> + num_times_to_clone = loop->info->max_trip_count;
> }
>
> /* In the terminator that we have no trip count for move everything
> after
> @@ -568,14 +568,14 @@ is_loop_small_enough_to_unroll(nir_shader *shader,
> nir_loop_info *li)
> {
> unsigned max_iter = shader->options->max_unroll_iterations;
>
> - if (li->trip_count > max_iter)
> + if (li->max_trip_count > max_iter)
> return false;
>
> if (li->force_unroll)
> return true;
>
> bool loop_not_too_large =
> - li->num_instructions * li->trip_count <= max_iter *
> LOOP_UNROLL_LIMIT;
> + li->num_instructions * li->max_trip_count <= max_iter *
> LOOP_UNROLL_LIMIT;
>
> return loop_not_too_large;
> }
> @@ -641,7 +641,7 @@ process_loops(nir_shader *sh, nir_cf_node *cf_node,
> bool *has_nested_loop_out)
> if (!is_loop_small_enough_to_unroll(sh, loop->info))
> goto exit;
>
> - if (loop->info->is_trip_count_known) {
> + if (loop->info->exact_trip_count_known) {
> simple_unroll(loop);
> progress = true;
> } else {
> @@ -665,7 +665,7 @@ process_loops(nir_shader *sh, nir_cf_node *cf_node,
> bool *has_nested_loop_out)
> * limiting terminator just do a simple unroll as the second
> * terminator can never be reached.
> */
> - if (loop->info->trip_count == 0 && !limiting_term_second) {
> + if (loop->info->max_trip_count == 0 && !limiting_term_second)
> {
> simple_unroll(loop);
> } else {
> complex_unroll(loop, terminator, limiting_term_second);
> --
> 2.19.2
>
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