Fix Simplified Rhythm mod breaking diffcalc when applied to some maps

osu.Game.Rulesets.Taiko/Mods/TaikoModSimplifiedRhythm.cs

@@ -122,6 +122,8 @@ void processPattern(int patternEndIndex)
                     }
                 }
             }
+
+            taikoBeatmap.HitObjects.Sort((a, b) => a.StartTime.CompareTo(b.StartTime));
         }
 
         private int getSnapBetweenNotes(ControlPointInfo controlPointInfo, Hit currentNote, Hit nextNote)

osu.Game.Tests/NonVisual/ClosestBeatDivisorTest.cs

@@ -66,6 +66,18 @@ public void TestApproximateDivisors()
             assertClosestDivisors(divisors, closestDivisors, cpi);
         }
 
+        [Test]
+        public void TestNegativeTimingPointOffset()
+        {
+            var cpi = new ControlPointInfo();
+            cpi.Add(-300000, new TimingControlPoint { BeatLength = 1000 });
+
+            double[] divisors = { 3.03d, 0.97d, 14, 13, 7.94d, 6.08d, 3.93d, 2.96d, 2.02d, 64 };
+            double[] closestDivisors = { 3, 1, 16, 12, 8, 6, 4, 3, 2, 1 };
+
+            assertClosestDivisors(divisors, closestDivisors, cpi);
+        }
+
         private static void assertClosestDivisors(IReadOnlyList<double> divisors, IReadOnlyList<double> closestDivisors, ControlPointInfo cpi, double step = 1)
         {
             List<HitObject> hitobjects = new List<HitObject>();

osu.Game/Beatmaps/ControlPoints/ControlPointInfo.cs

@@ -169,7 +169,7 @@ public void RemoveGroup(ControlPointGroup group)
         public double GetClosestSnappedTime(double time, int beatDivisor, double? referenceTime = null)
         {
             var timingPoint = TimingPointAt(referenceTime ?? time);
-            double snappedTime = getClosestSnappedTime(timingPoint, time, beatDivisor);
+            double snappedTime = getClosestPositiveSnappedTime(timingPoint, time, beatDivisor);
 
             if (referenceTime.HasValue)
                 return snappedTime;
@@ -197,9 +197,19 @@ public int GetClosestBeatDivisor(double time, double? referenceTime = null)
             int closestDivisor = 0;
             double closestTime = double.MaxValue;
 
+            // `getClosestSnappedTime()` only returns positive time values.
+            // due to that, if `time` is allowed to be negative, the loop lower below could return bogus results
+            // as the "snapped time" will not necessarily be "closest" at that point.
+            // compensate for this by moving `time` by enough beat lengths to go back to the positives.
+            if (time < 0)
+            {
+                int offsetBeats = (int)Math.Ceiling(-time / timingPoint.BeatLength);
+                time += offsetBeats * timingPoint.BeatLength;
+            }
+
             foreach (int divisor in BindableBeatDivisor.PREDEFINED_DIVISORS)
             {
-                double distanceFromSnap = Math.Abs(time - getClosestSnappedTime(timingPoint, time, divisor));
+                double distanceFromSnap = Math.Abs(time - getClosestPositiveSnappedTime(timingPoint, time, divisor));
 
                 if (Precision.DefinitelyBigger(closestTime, distanceFromSnap))
                 {
@@ -211,7 +221,7 @@ public int GetClosestBeatDivisor(double time, double? referenceTime = null)
             return closestDivisor;
         }
 
-        private static double getClosestSnappedTime(TimingControlPoint timingPoint, double time, int beatDivisor)
+        private static double getClosestPositiveSnappedTime(TimingControlPoint timingPoint, double time, int beatDivisor)
         {
             double beatLength = timingPoint.BeatLength / beatDivisor;
             double beats = (Math.Max(time, 0) - timingPoint.Time) / beatLength;