Swap order of operations in JumpThru.Awake for better performance

Celeste.Mod.mm/Patches/JumpThru.cs

@@ -0,0 +1,57 @@
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+using Monocle;
+using MonoMod;
+using MonoMod.Cil;
+using MonoMod.InlineRT;
+using MonoMod.Utils;
+using System;
+
+namespace Celeste {
+    internal class patch_JumpThru {
+        [MonoModIgnore]
+        [PatchJumpThruAwake]
+        public extern void Awake(Scene scene);
+    }
+}
+
+namespace MonoMod {
+    /*
+     * Patches the JumpThru.Awake method to do:
+     * if (staticMover.Platform == null && staticMover.IsRiding(this))
+     * instead of:
+     * if (staticMover.IsRiding(this) && staticMover.Platform == null),
+     *
+     * resulting in many less pointless calls to IsRiding.
+     */
+    [MonoModCustomMethodAttribute(nameof(MonoModRules.PatchJumpThruAwake))]
+    class PatchJumpThruAwakeAttribute : Attribute { }
+
+    static partial class MonoModRules {
+        public static void PatchJumpThruAwake(ILContext context, CustomAttribute attrib) {
+            TypeDefinition t_StaticMover = MonoModRule.Modder.FindType("Celeste.StaticMover").Resolve();
+            FieldDefinition f_platform = t_StaticMover.FindField("Platform");
+
+            ILCursor cursor = new(context);
+            ILLabel label = null;
+            // find if (staticMover.IsRiding(this))
+            cursor.GotoNext(MoveType.Before,
+                instr => instr.MatchLdloc(1),
+                instr => instr.MatchLdarg(0),
+                instr => instr.MatchCallvirt("Celeste.StaticMover", "IsRiding"),
+                instr => instr.MatchBrfalse(out label)
+            );
+
+            // insert mover.Platform != null
+            cursor.Emit(OpCodes.Ldloc, 1);
+            cursor.Emit(OpCodes.Ldfld, f_platform);
+            cursor.Emit(OpCodes.Brtrue_S, label);
+
+            // go after the 4 instructions we matched
+            cursor.Index += 4;
+            // remove the old mover.Platform != null check, as we now perform it earlier
+            cursor.RemoveRange(3);
+        }
+    }
+}
+