From 2852e1af55b1a2c180e608e62c0a0f0ab18bba10 Mon Sep 17 00:00:00 2001
From: Josh Bleecher Snyder <josharian@gmail.com>
Date: Sat, 9 Mar 2024 08:50:03 -0800
Subject: [PATCH] whisper : make beam candidate sort more stable (#1943)

All else being otherwise equal, this encourages the beam candidate
selection to re-use the same decoder, which slightly
reduces the cache size.

I wouldn't expect it to make much of a performance difference,
but it helps when debug printing the cache and beam.

Added as part of understanding #1941.
---
 whisper.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/whisper.cpp b/whisper.cpp
index 3459dd6efcb..84d292d304c 100644
--- a/whisper.cpp
+++ b/whisper.cpp
@@ -5357,7 +5357,10 @@ int whisper_full_with_state(
                             beam_candidates.begin(),
                             beam_candidates.end(),
                             [](const beam_candidate & a, const beam_candidate & b) {
-                        return a.sequence.sum_logprobs_all > b.sequence.sum_logprobs_all;
+                        if (a.sequence.sum_logprobs_all != b.sequence.sum_logprobs_all) {
+                            return a.sequence.sum_logprobs_all > b.sequence.sum_logprobs_all;
+                        }
+                        return a.decoder_idx < b.decoder_idx;
                     });
 
                     uint32_t cur_c = 0;