Recent bake entry fast path

- Facade reads reuse the thread's last chunk entry instead of probing the bake map
- Stores and full-chunk fills refresh that entry from the map
- Surface lattice lookups reuse the previous point's cell indices

core/src/main/java/art/arcane/iris/generation/bake/ChunkBakeCache.java

@@ -10,6 +10,7 @@ public final class ChunkBakeCache implements BakeCache {
     private static final ThreadLocal<int[]> SPARSE = ThreadLocal.withInitial(() -> new int[1]);
 
     private final PlaneSource source;
+    private final ThreadLocal<Recent> recent = ThreadLocal.withInitial(Recent::new);
     private volatile ConcurrentClockCache<ChunkPlanes> entries;
 
     public ChunkBakeCache(PlaneSource source, int capacityChunks) {
@@ -43,7 +44,9 @@ public final class ChunkBakeCache implements BakeCache {
     }
 
     public void clear() {
-        entries.clear();
+        ConcurrentClockCache<ChunkPlanes> current = entries;
+        entries = new ConcurrentClockCache<>(current.capacity());
+        current.clear();
     }
 
     public long[] census() {
@@ -71,8 +74,22 @@ public final class ChunkBakeCache implements BakeCache {
     }
 
     public ChunkPlanes.Plane planeIfPresent(BakePlane plane, int chunkX, int chunkZ) {
-        ChunkPlanes planes = entries.get(key(chunkX, chunkZ));
+        long key = key(chunkX, chunkZ);
-        return planes == null ? null : planes.planeIfPresent(plane);
+        Recent last = recent.get();
+        ConcurrentClockCache<ChunkPlanes> current = entries;
+        ChunkPlanes planes;
+        if (last.key == key && last.entries == current) {
+            planes = last.planes;
+        } else {
+            planes = current.get(key);
+            if (planes == null) {
+                return null;
+            }
+            last.key = key;
+            last.planes = planes;
+            last.entries = current;
+        }
+        return planes.planeIfPresent(plane);
     }
 
     public ChunkPlanes.Plane plane(BakePlane plane, int chunkX, int chunkZ) {
@@ -80,7 +97,7 @@ public final class ChunkBakeCache implements BakeCache {
     }
 
     public Object complete(BakePlane plane, int chunkX, int chunkZ) {
-        return planes(chunkX, chunkZ).complete(plane, source);
+        return remembered(chunkX, chunkZ).complete(plane, source);
     }
 
     public boolean memoAllowed() {
@@ -91,14 +108,26 @@ public final class ChunkBakeCache implements BakeCache {
         if (revision != ProvisionalSampling.revision()) {
             return;
         }
-        planes(blockX >> 4, blockZ >> 4).plane(plane).storeDouble(((blockZ & 15) << 4) | (blockX & 15), value);
+        remembered(blockX >> 4, blockZ >> 4).plane(plane).storeDouble(((blockZ & 15) << 4) | (blockX & 15), value);
     }
 
     public void storeObject(BakePlane plane, int blockX, int blockZ, Object value, long revision) {
         if (revision != ProvisionalSampling.revision()) {
             return;
         }
-        planes(blockX >> 4, blockZ >> 4).plane(plane).storeObject(((blockZ & 15) << 4) | (blockX & 15), value);
+        remembered(blockX >> 4, blockZ >> 4).plane(plane).storeObject(((blockZ & 15) << 4) | (blockX & 15), value);
+    }
+
+    private ChunkPlanes remembered(int chunkX, int chunkZ) {
+        ConcurrentClockCache<ChunkPlanes> current = entries;
+        long key = key(chunkX, chunkZ);
+        ChunkPlanes existing = current.get(key);
+        ChunkPlanes planes = existing != null ? existing : current.putIfAbsent(key, new ChunkPlanes(chunkX, chunkZ));
+        Recent last = recent.get();
+        last.key = key;
+        last.planes = planes;
+        last.entries = current;
+        return planes;
     }
 
     public static <T> T sparse(Supplier<T> action) {
@@ -125,4 +154,10 @@ public final class ChunkBakeCache implements BakeCache {
     public static long key(int chunkX, int chunkZ) {
         return ((long) chunkX << 32) ^ (chunkZ & 0xffffffffL);
     }
+
+    private static final class Recent {
+        private long key;
+        private ChunkPlanes planes;
+        private ConcurrentClockCache<ChunkPlanes> entries;
+    }
 }

core/src/main/java/art/arcane/iris/generation/noise/GeneratorProgram.java

@@ -69,6 +69,12 @@ public final class GeneratorProgram {
         double[] fractionZ = scratch.buffer(count);
         scratch.clearLattice(count * 4);
         int detailed = 0;
+        double previousX = Double.NaN;
+        double previousZ = Double.NaN;
+        int cellNorthWest = -1;
+        int cellNorthEast = -1;
+        int cellSouthWest = -1;
+        int cellSouthEast = -1;
         for (int index = 0; index < count; index++) {
             double lowerX = Math.floor(xs[index] / SURFACE_GRID) * SURFACE_GRID;
             double lowerZ = Math.floor(zs[index] / SURFACE_GRID) * SURFACE_GRID;
@@ -76,10 +82,28 @@ public final class GeneratorProgram {
             double dz = (zs[index] - lowerZ) / SURFACE_GRID;
             fractionX[index] = dx;
             fractionZ[index] = dz;
-            northWest[index] = scratch.lattice(lowerX, lowerZ);
+            if (Double.doubleToRawLongBits(lowerX) != Double.doubleToRawLongBits(previousX)
-            northEast[index] = dx == 0D ? -1 : scratch.lattice(lowerX + SURFACE_GRID, lowerZ);
+                    || Double.doubleToRawLongBits(lowerZ) != Double.doubleToRawLongBits(previousZ)) {
-            southWest[index] = dz == 0D ? -1 : scratch.lattice(lowerX, lowerZ + SURFACE_GRID);
+                previousX = lowerX;
-            southEast[index] = dx == 0D || dz == 0D ? -1 : scratch.lattice(lowerX + SURFACE_GRID, lowerZ + SURFACE_GRID);
+                previousZ = lowerZ;
+                cellNorthWest = scratch.lattice(lowerX, lowerZ);
+                cellNorthEast = -1;
+                cellSouthWest = -1;
+                cellSouthEast = -1;
+            }
+            if (dx != 0D && cellNorthEast < 0) {
+                cellNorthEast = scratch.lattice(lowerX + SURFACE_GRID, lowerZ);
+            }
+            if (dz != 0D && cellSouthWest < 0) {
+                cellSouthWest = scratch.lattice(lowerX, lowerZ + SURFACE_GRID);
+            }
+            if (dx != 0D && dz != 0D && cellSouthEast < 0) {
+                cellSouthEast = scratch.lattice(lowerX + SURFACE_GRID, lowerZ + SURFACE_GRID);
+            }
+            northWest[index] = cellNorthWest;
+            northEast[index] = dx == 0D ? -1 : cellNorthEast;
+            southWest[index] = dz == 0D ? -1 : cellSouthWest;
+            southEast[index] = dx == 0D || dz == 0D ? -1 : cellSouthEast;
             if (dx != 0D || dz != 0D) {
                 detailed++;
             }