Allow replacing unused params in DynamicLVTPatch

definition/src/main/java/dev/su5ed/sinytra/adapter/patch/transformer/ExtractMixin.java

@@ -199,7 +199,7 @@ private static Patch.Result recreateLocalVariables(ClassNode classNode, MethodNo
             }
         }
         // Find instructions used to initialize each used variable in the target method
-        LocalVariableLookup targetTable = new LocalVariableLookup(capturedLocals.target().methodNode().localVariables);
+        LocalVariableLookup targetTable = new LocalVariableLookup(capturedLocals.target().methodNode());
         Int2ObjectMap<InsnList> varInsnLists = new Int2ObjectOpenHashMap<>();
         Int2IntMap usageCount = new Int2IntOpenHashMap();
         used.forEach(ordinal -> {

definition/src/main/java/dev/su5ed/sinytra/adapter/patch/transformer/ModifyMethodParams.java

@@ -126,7 +126,7 @@ public Result apply(ClassNode classNode, MethodNode methodNode, MethodContext me
             methodNode.localVariables.add(paramOrdinal + (isNonStatic ? 1 : 0), new LocalVariableNode(newParameter.name, type.getDescriptor(), null, self.start, self.end, lvtIndex));
             snapshot.applyDifference(methodNode);
         }
-        LocalVariableLookup lvtLookup = new LocalVariableLookup(methodNode.localVariables);
+        LocalVariableLookup lvtLookup = new LocalVariableLookup(methodNode);
         BytecodeFixerUpper bfu = context.environment().bytecodeFixerUpper();
         this.context.replacements.forEach(pair -> {
             int index = pair.getFirst();

definition/src/main/java/dev/su5ed/sinytra/adapter/patch/transformer/ModifyRedirectToWrapper.java

@@ -26,7 +26,7 @@ public Collection<String> getAcceptedAnnotations() {
 
     @Override
     public Patch.Result apply(ClassNode classNode, MethodNode methodNode, MethodContext methodContext, PatchContext context) {
-        LocalVariableLookup lookup = new LocalVariableLookup(methodNode.localVariables);
+        LocalVariableLookup lookup = new LocalVariableLookup(methodNode);
         Type newOwnerType = Type.getType(this.newTarget.owner());
         boolean sameOwnerType = Type.getType(this.originalTarget.owner()).equals(newOwnerType);
 
@@ -78,7 +78,7 @@ public Patch.Result apply(ClassNode classNode, MethodNode methodNode, MethodCont
             .build();
         addNewParamsPatch.apply(classNode, methodNode, methodContext, context);
 
-        LocalVariableLookup updatedLookup = new LocalVariableLookup(methodNode.localVariables);
+        LocalVariableLookup updatedLookup = new LocalVariableLookup(methodNode);
         LocalVariableNode operationVar = updatedLookup.getForType(OPERATION_TYPE).get(0);
         int operationParamOrdinal = updatedLookup.getOrdinal(operationVar);
         List<LocalVariableNode> localVars = new ArrayList<>();

definition/src/main/java/dev/su5ed/sinytra/adapter/patch/transformer/dynamic/DynamicInjectorOrdinalPatch.java

@@ -209,7 +209,7 @@ public OptionalInt getUpdatedOrdinal(PatchContext context, MethodNode methodNode
                 return OptionalInt.empty();
             }
 
-            LocalVariableLookup dirtyVarLookup = new LocalVariableLookup(dirtyTarget.methodNode().localVariables);
+            LocalVariableLookup dirtyVarLookup = new LocalVariableLookup(dirtyTarget.methodNode());
             List<LocalVariableNode> dirtyLocals = dirtyVarLookup.getForType(targetType);
             if (cleanLocals.size() != dirtyLocals.size() || dirtyLocals.size() <= ordinal) {
                 return findReplacementLocal(cleanTarget.methodNode(), dirtyTarget.methodNode(), cleanLocal)

definition/src/main/java/dev/su5ed/sinytra/adapter/patch/transformer/dynamic/DynamicLVTPatch.java

@@ -6,12 +6,16 @@
 import dev.su5ed.sinytra.adapter.patch.LVTOffsets;
 import dev.su5ed.sinytra.adapter.patch.analysis.EnhancedParamsDiff;
 import dev.su5ed.sinytra.adapter.patch.analysis.ParametersDiff;
-import dev.su5ed.sinytra.adapter.patch.api.*;
+import dev.su5ed.sinytra.adapter.patch.api.MethodContext;
+import dev.su5ed.sinytra.adapter.patch.api.MethodTransform;
+import dev.su5ed.sinytra.adapter.patch.api.MixinConstants;
 import dev.su5ed.sinytra.adapter.patch.api.Patch.Result;
+import dev.su5ed.sinytra.adapter.patch.api.PatchContext;
 import dev.su5ed.sinytra.adapter.patch.selector.AnnotationHandle;
 import dev.su5ed.sinytra.adapter.patch.selector.AnnotationValueHandle;
 import dev.su5ed.sinytra.adapter.patch.transformer.ModifyMethodParams;
 import dev.su5ed.sinytra.adapter.patch.util.AdapterUtil;
+import dev.su5ed.sinytra.adapter.patch.util.LocalVariableLookup;
 import org.jetbrains.annotations.Nullable;
 import org.objectweb.asm.Type;
 import org.objectweb.asm.tree.*;
@@ -20,6 +24,7 @@
 
 import java.util.*;
 import java.util.function.Supplier;
+import java.util.stream.Collectors;
 
 import static dev.su5ed.sinytra.adapter.patch.PatchInstance.MIXINPATCH;
 
@@ -159,8 +164,8 @@ private ParametersDiff compareParameters(ClassNode classNode, MethodNode methodN
             // No changes required
             return null;
         }
-        // Replacements are not supported, as they would require LVT fixups and converters
-        if (!diff.replacements().isEmpty()) {
+        // Replacements are only partially supported, as most would require LVT fixups and converters
+        if (!diff.replacements().isEmpty() && areReplacedParamsUsed(diff.replacements(), methodNode)) {
             // Check if we can rearrange parameters
             ParametersDiff rearrange = ParametersDiff.rearrangeParameters(capturedLocals.expected(), availableTypes);
             if (rearrange == null) {
@@ -198,6 +203,19 @@ private ParametersDiff compareParameters(ClassNode classNode, MethodNode methodN
         return offsetDiff;
     }
 
+    private static boolean areReplacedParamsUsed(List<Pair<Integer, Type>> replacements, MethodNode methodNode) {
+        LocalVariableLookup lookup = new LocalVariableLookup(methodNode);
+        Set<Integer> paramLocals = replacements.stream()
+            .map(p -> lookup.getByParameterOrdinal(p.getFirst()).index)
+            .collect(Collectors.toSet());
+        for (AbstractInsnNode insn : methodNode.instructions) {
+            if (insn instanceof VarInsnNode varInsn && paramLocals.contains(varInsn.var)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     private static int getMaxLocalIndex(List<Type> expected, List<Pair<Integer, Type>> insertions) {
         int maxIndex = expected.size();
         for (Pair<Integer, Type> pair : insertions) {

definition/src/main/java/dev/su5ed/sinytra/adapter/patch/util/AdapterUtil.java

@@ -201,7 +201,7 @@ public static CapturedLocals getCapturedLocals(MethodNode methodNode, MethodCont
         int paramLocalPos = targetParams.length + 1;
         // Get expected local variables from method parameters
         List<Type> expected = AdapterUtil.summariseLocals(params, paramLocalPos);
-        return new CapturedLocals(target, isStatic, paramLocalPos, paramLocalPos + expected.size(), lvtOffset, expected, new LocalVariableLookup(methodNode.localVariables));
+        return new CapturedLocals(target, isStatic, paramLocalPos, paramLocalPos + expected.size(), lvtOffset, expected, new LocalVariableLookup(methodNode));
     }
 
     public record CapturedLocals(MethodContext.TargetPair target, boolean isStatic, int paramLocalStart, int paramLocalEnd, int lvtOffset,

definition/src/main/java/dev/su5ed/sinytra/adapter/patch/util/LocalVariableLookup.java

@@ -2,18 +2,22 @@
 
 import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
 import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;
+import org.objectweb.asm.Opcodes;
 import org.objectweb.asm.Type;
 import org.objectweb.asm.tree.LocalVariableNode;
+import org.objectweb.asm.tree.MethodNode;
 
 import java.util.*;
 
 public class LocalVariableLookup {
     private final List<LocalVariableNode> sortedLocals;
+    private final boolean isNonStatic;
     private final Int2ObjectMap<LocalVariableNode> byIndex = new Int2ObjectOpenHashMap<>();
     private final Map<Type, List<LocalVariableNode>> byType = new HashMap<>();
 
-    public LocalVariableLookup(List<LocalVariableNode> locals) {
-        this.sortedLocals = locals.stream().sorted(Comparator.comparingInt(lvn -> lvn.index)).toList();
+    public LocalVariableLookup(MethodNode methodNode) {
+        this.isNonStatic = (methodNode.access & Opcodes.ACC_STATIC) == 0;
+        this.sortedLocals = methodNode.localVariables.stream().sorted(Comparator.comparingInt(lvn -> lvn.index)).toList();
         for (LocalVariableNode node : this.sortedLocals) {
             this.byIndex.put(node.index, node);
         }
@@ -23,6 +27,10 @@ public LocalVariableNode getByOrdinal(int ordinal) {
         return this.sortedLocals.get(ordinal);
     }
 
+    public LocalVariableNode getByParameterOrdinal(int ordinal) {
+        return this.sortedLocals.get(this.isNonStatic ? ordinal + 1 : ordinal);
+    }
+
     public LocalVariableNode getByIndex(int index) {
         return Objects.requireNonNull(this.byIndex.get(index), "Missing local variable at index " + index);
     }
@@ -34,7 +42,7 @@ public int getOrdinal(LocalVariableNode node) {
     public LocalVariableNode getLast() {
         return this.sortedLocals.get(this.sortedLocals.size() - 1);
     }
-    
+
     public List<LocalVariableNode> getForType(LocalVariableNode node) {
         return getForType(Type.getType(node.desc));
     }