Add ResourceLocation deduplication from Hydrogen

src/main/java/org/embeddedt/modernfix/core/config/ModernFixEarlyConfig.java

@@ -32,6 +32,7 @@ public class ModernFixEarlyConfig {
         this.addMixinRule("perf.preload_block_classes", false);
         this.addMixinRule("perf.parallel_potentially_unsafe", false);
         this.addMixinRule("perf.parallel_blockstate_cache_rebuild", true);
+        this.addMixinRule("perf.deduplicate_location", true);
         this.addMixinRule("safety", true);
         this.addMixinRule("launch.transformer_cache", false);
         this.addMixinRule("launch.class_search_cache", false);

src/main/java/org/embeddedt/modernfix/dedup/DeduplicationCache.java

@@ -0,0 +1,56 @@
+package org.embeddedt.modernfix.dedup;
+
+import it.unimi.dsi.fastutil.Hash;
+import it.unimi.dsi.fastutil.objects.ObjectOpenCustomHashSet;
+
+import java.util.Objects;
+
+public class DeduplicationCache<T> {
+    private final ObjectOpenCustomHashSet<T> pool;
+
+    private int attemptedInsertions = 0;
+    private int deduplicated = 0;
+
+    public DeduplicationCache(Hash.Strategy<T> strategy) {
+        this.pool = new ObjectOpenCustomHashSet<>(strategy);
+    }
+
+    public DeduplicationCache() {
+        this.pool = new ObjectOpenCustomHashSet<>(new Hash.Strategy<T>() {
+            @Override
+            public int hashCode(T o) {
+                return Objects.hashCode(o);
+            }
+
+            @Override
+            public boolean equals(T a, T b) {
+                return Objects.equals(a, b);
+            }
+        });
+    }
+
+    public synchronized T deduplicate(T item) {
+        this.attemptedInsertions++;
+
+        T result = this.pool.addOrGet(item);
+
+        if (result != item) {
+            this.deduplicated++;
+        }
+
+        return result;
+    }
+
+    public synchronized void clearCache() {
+        this.attemptedInsertions = 0;
+        this.deduplicated = 0;
+
+        this.pool.clear();
+    }
+
+    @Override
+    public synchronized String toString() {
+        return String.format("DeduplicationCache ( %d/%d de-duplicated, %d pooled )",
+                this.deduplicated, this.attemptedInsertions, this.pool.size());
+    }
+}

src/main/java/org/embeddedt/modernfix/dedup/IdentifierCaches.java

@@ -0,0 +1,15 @@
+package org.embeddedt.modernfix.dedup;
+
+
+import org.embeddedt.modernfix.ModernFix;
+
+public class IdentifierCaches {
+    public static final DeduplicationCache<String> NAMESPACES = new DeduplicationCache<>();
+    public static final DeduplicationCache<String> PATH = new DeduplicationCache<>();
+
+    public static void printDebug() {
+        ModernFix.LOGGER.info("[[[ Identifier de-duplication statistics ]]]");
+        ModernFix.LOGGER.info("Namespace cache: {}", NAMESPACES);
+        ModernFix.LOGGER.info("Path cache: {}", PATH);
+    }
+}

src/main/java/org/embeddedt/modernfix/mixin/perf/deduplicate_location/MixinResourceLocation.java

@@ -0,0 +1,30 @@
+package org.embeddedt.modernfix.mixin.perf.deduplicate_location;
+
+import net.minecraft.util.ResourceLocation;
+import org.embeddedt.modernfix.dedup.IdentifierCaches;
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Mutable;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+@Mixin(ResourceLocation.class)
+public class MixinResourceLocation {
+    @Mutable
+    @Shadow
+    @Final
+    protected String namespace;
+
+    @Mutable
+    @Shadow
+    @Final
+    protected String path;
+
+    @Inject(method = "<init>([Ljava/lang/String;)V", at = @At("RETURN"))
+    private void reinit(String[] id, CallbackInfo ci) {
+        this.namespace = IdentifierCaches.NAMESPACES.deduplicate(this.namespace);
+        this.path = IdentifierCaches.PATH.deduplicate(this.path);
+    }
+}

src/main/resources/modernfix.mixins.json

@@ -24,7 +24,8 @@
     "perf.parallel_blockstate_cache_rebuild.BlocksMixin",
     "perf.parallel_blockstate_cache_rebuild.BlockCallbacksMixin",
     "perf.parallel_blockstate_cache_rebuild.ShapeCacheMixin",
-    "perf.parallel_potentially_unsafe.parallel_deferred_suppliers.DispenserBlockMixin"
+    "perf.parallel_potentially_unsafe.parallel_deferred_suppliers.DispenserBlockMixin",
+    "perf.deduplicate_location.MixinResourceLocation"
   ],
   "client": [
     "perf.skip_first_datapack_reload.MinecraftMixin",