Optimize layer iteration to prevent performance overhead. (#3022)

* Optimize layer iteration to prevent performance overhead.

Adjusted the layer iteration logic in the Region class to use the minimum and maximum Y-values from the chunk. This prevents unnecessary iterations when getMinimumY or getMaximumY returns extreme values, improving performance efficiency.

* Optimize layer iteration logic in Region class.

Refactored the loop to reduce repeated evaluations by storing pre-calculated min and max values for Y coordinates. This change enhances readability and may improve performance by minimizing unnecessary calculations during the iteration process.

* Update variable naming

* Shift bitwise operations to variable initialization

worldedit-core/src/main/java/com/sk89q/worldedit/regions/Region.java

@@ -403,7 +403,9 @@ default IChunkSet processSet(IChunk chunk, IChunkGet get, IChunkSet set) {
         if (tx >= min.x() && bx <= max.x() && tz >= min.z() && bz <= max.z()) {
             // contains some
             boolean processExtra = false;
-            for (int layer = getMinimumY() >> 4; layer <= getMaximumY() >> 4; layer++) {
+            final int minLayer = Math.max(getMinimumY(), chunk.getMinY()) >> 4;
+            final int maxLayer = Math.min(getMaximumY(), chunk.getMaxY()) >> 4;
+            for (int layer = minLayer; layer <= maxLayer; layer++) {
                 if (!set.hasSection(layer)) {
                     continue;
                 }
@@ -457,7 +459,9 @@ default IChunkSet processSet(IChunk chunk, IChunkGet get, IChunkSet set, boolean
         if (tx >= min.x() && bx <= max.x() && tz >= min.z() && bz <= max.z()) {
             // contains some
             boolean processExtra = false;
-            for (int layer = getMinimumY() >> 4; layer <= getMaximumY() >> 4; layer++) {
+            final int minLayer = Math.max(getMinimumY(), chunk.getMinY()) >> 4;
+            final int maxLayer = Math.min(getMaximumY(), chunk.getMaxY()) >> 4;
+            for (int layer = minLayer; layer <= maxLayer; layer++) {
                 int by = layer << 4;
                 int ty = by + 15;
                 if (containsEntireCuboid(bx, tx, by, ty, bz, tz)) {