fix: Fixes sending packets and sidesteps a major issue with stackalloc and PGO in .NET 8 (#1607)

### Summary
- Works around a sneaky edge case bug in the JIT with stackalloc where sometimes the buffer is not zero'd.
- Fixes SendDisplayBoatHS
- Fixes sending health bars in the `SendEverything()` logic.
- Fixes a bug in sizing for some string helper functions.

### Developer Note
We are enabled `SkipLocalsInit` - do not rely on `stackalloc` to be zero'd. To zero the buffer, use `span.Clear();`

Closes #1606

Projects/UOContent/Engines/Party/PartyPackets.cs

@@ -140,15 +140,14 @@ namespace Server.Engines.PartySystem
                 return;
             }
 
-            Span<byte> buffer = stackalloc byte[10];
-            var writer = new SpanWriter(buffer);
+            var writer = new SpanWriter(stackalloc byte[10]);
             writer.Write((byte)0xBF); // Packet ID
             writer.Write((ushort)10);
             writer.Write((ushort)0x06); // Sub-packet
             writer.Write((byte)0x07); // command
             writer.Write(leader);
 
-            ns.Send(buffer);
+            ns.Send(writer.Span);
         }
     }
 }

Projects/UOContent/Engines/Quests/Collector/Items/ImageTypeInfo.cs

@@ -86,6 +86,8 @@ public class ImageTypeInfo
 
         var length = m_Table.Length;
         Span<bool> list = stackalloc bool[length];
+        list.Clear();
+
         var imageTypes = new ImageType[count];
 
         var i = 0;
@@ -100,4 +102,4 @@ public class ImageTypeInfo
 
         return imageTypes;
     }
-}
+}

Projects/UOContent/Items/Bulletin Boards/BulletinBoardPackets.cs

@@ -233,7 +233,7 @@ namespace Server.Network
 
             Span<byte> textBuffer = stackalloc byte[TextEncoding.UTF8.GetMaxByteCount(longestTextLine)];
 
-            var writer = maxLength > 81920 ? new SpanWriter(maxLength) : new SpanWriter(stackalloc byte[maxLength]);
+            var writer = maxLength > 1024 ? new SpanWriter(maxLength) : new SpanWriter(stackalloc byte[maxLength]);
             writer.Write((byte)0x71); // Packet ID
             writer.Seek(2, SeekOrigin.Current);
             writer.Write((byte)(content ? 0x02 : 0x01)); // Command

Projects/UOContent/Module.cs

@@ -0,0 +1,4 @@
+using System.Runtime.CompilerServices;
+
+// Skips initializing stackalloc with zeros.
+[module: SkipLocalsInit]

Projects/UOContent/Multis/Boats/BoatPackets.cs

@@ -106,8 +106,6 @@ public static class BoatPackets
 
         using var builder = new PacketContainerBuilder(stackalloc byte[minLength]);
 
-        Span<byte> buffer = builder.GetSpan(OutgoingEntityPackets.MaxWorldEntityPacketLength);
-
         foreach (var entity in boat.GetMovingEntities(true))
         {
             if (!beholder.CanSee(entity))
@@ -115,7 +113,7 @@ public static class BoatPackets
                 continue;
             }
 
-            buffer.InitializePacket();
+            Span<byte> buffer = builder.GetSpan(OutgoingEntityPackets.MaxWorldEntityPacketLength).InitializePacket();
             var bytesWritten = OutgoingEntityPackets.CreateWorldEntity(buffer, entity, true);
             builder.Advance(bytesWritten);
         }

Projects/UOContent/Multis/Houses/HousePackets.cs

@@ -106,6 +106,8 @@ namespace Server.Multis
             using var planesWriter = new SpanWriter(planeLength * planeCount);
 
             Span<bool> planesUsed = stackalloc bool[9];
+            planesUsed.Clear();
+
             int index;
             var totalPlaneOffsets = 0;
             var totalPlanes = 0;