From 5e3dbe6f912c62aecb1a07d1f7fa0531dc2b63b4 Mon Sep 17 00:00:00 2001
From: Andreas Buhr <andreas@andreasbuhr.de>
Date: Wed, 10 Apr 2024 18:02:17 +0200
Subject: [PATCH] Move getConflictingAltSubsets calculation, reduce its usage

This patch moves the calculation of conflicting als subsets in
ParserATNSimulator::execATNWithFullContext() to the point where it
is actually needed.
In our benchmark, this saves about 10% of calls to
getConflictingAltSubsets().

Signed-off-by: Andreas Buhr <andreas@andreasbuhr.de>
---
 runtime/Cpp/runtime/src/atn/ParserATNSimulator.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/runtime/Cpp/runtime/src/atn/ParserATNSimulator.cpp b/runtime/Cpp/runtime/src/atn/ParserATNSimulator.cpp
index 3a1537587c..1c031984d4 100755
--- a/runtime/Cpp/runtime/src/atn/ParserATNSimulator.cpp
+++ b/runtime/Cpp/runtime/src/atn/ParserATNSimulator.cpp
@@ -388,13 +388,13 @@ size_t ParserATNSimulator::execATNWithFullContext(dfa::DFA &dfa, dfa::DFAState *
         delete previous;
     previous = nullptr;
 
-    std::vector<BitSet> altSubSets = PredictionModeClass::getConflictingAltSubsets(reach.get());
     reach->uniqueAlt = getUniqueAlt(reach.get());
     // unique prediction?
     if (reach->uniqueAlt != ATN::INVALID_ALT_NUMBER) {
       predictedAlt = reach->uniqueAlt;
       break;
     }
+    std::vector<BitSet> altSubSets = PredictionModeClass::getConflictingAltSubsets(reach.get());
     if (_mode != PredictionMode::LL_EXACT_AMBIG_DETECTION) {
       predictedAlt = PredictionModeClass::resolvesToJustOneViableAlt(altSubSets);
       if (predictedAlt != ATN::INVALID_ALT_NUMBER) {