Mesa (main): nir: always set the exact_trip_count_unknown loop terminator property

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Module: Mesa
Branch: main
Commit: 4c3d138e5d28b391c45f75ad1e3073b8e054782b
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=4c3d138e5d28b391c45f75ad1e3073b8e054782b

Author: Timothy Arceri <tarceri at itsqueeze.com>
Date:   Mon May  9 18:20:34 2022 +1000

nir: always set the exact_trip_count_unknown loop terminator property

Previously we only cared if this was set for the limiting
terminator. However in the following patch we will make use of this
information on other terminators to decide if we can eliminate them.

Reviewed-by: Emma Anholt <emma at anholt.net>
Reviewed-by: Jason Ekstrand <jason.ekstrand at collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16399>

---

 src/compiler/nir/nir_loop_analyze.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/compiler/nir/nir_loop_analyze.c b/src/compiler/nir/nir_loop_analyze.c
index 2c6c1790822..c35a129d428 100644
--- a/src/compiler/nir/nir_loop_analyze.c
+++ b/src/compiler/nir/nir_loop_analyze.c
@@ -1072,6 +1072,7 @@ find_trip_count(loop_info_state *state, unsigned execution_mode)
           * nir_opt_dead_cf pass.
           */
          trip_count_known = false;
+         terminator->exact_trip_count_unknown = true;
          continue;
       }
 
@@ -1105,6 +1106,7 @@ find_trip_count(loop_info_state *state, unsigned execution_mode)
        */
       if (!basic_ind.def) {
          trip_count_known = false;
+         terminator->exact_trip_count_unknown = true;
          continue;
       }
 
@@ -1120,6 +1122,7 @@ find_trip_count(loop_info_state *state, unsigned execution_mode)
          if (!try_find_limit_of_alu(limit, &limit_val, terminator, state)) {
             /* Guess loop limit based on array access */
             if (!guess_loop_limit(state, &limit_val, basic_ind)) {
+               terminator->exact_trip_count_unknown = true;
                continue;
             }
 
@@ -1174,11 +1177,13 @@ find_trip_count(loop_info_state *state, unsigned execution_mode)
       if (iterations == -1) {
          trip_count_known = false;
          guessed_trip_count = false;
+         terminator->exact_trip_count_unknown = true;
          continue;
       }
 
       if (guessed_trip_count) {
          guessed_trip_count = false;
+         terminator->exact_trip_count_unknown = true;
          if (state->loop->info->guessed_trip_count == 0 ||
              state->loop->info->guessed_trip_count > iterations)
             state->loop->info->guessed_trip_count = iterations;