Merge pull request #1980 from codeflash-ai/cf-java-void-optimization

feat: support void method optimization in Java pipeline

.github/workflows/e2e-java-void-optimization.yaml

@@ -0,0 +1,105 @@
+name: E2E - Java Void Optimization (No Git)
+
+on:
+  pull_request:
+    paths:
+      - 'codeflash/languages/java/**'
+      - 'codeflash/languages/base.py'
+      - 'codeflash/languages/registry.py'
+      - 'codeflash/optimization/**'
+      - 'codeflash/verification/**'
+      - 'code_to_optimize/java/**'
+      - 'codeflash-java-runtime/**'
+      - 'tests/scripts/end_to_end_test_java_void_optimization.py'
+      - '.github/workflows/e2e-java-void-optimization.yaml'
+
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref_name }}
+  cancel-in-progress: true
+
+jobs:
+  java-void-optimization-no-git:
+    environment: ${{ (github.event_name == 'workflow_dispatch' || (contains(toJSON(github.event.pull_request.files.*.filename), '.github/workflows/') && github.event.pull_request.user.login != 'misrasaurabh1' && github.event.pull_request.user.login != 'KRRT7')) && 'external-trusted-contributors' || '' }}
+
+    runs-on: ubuntu-latest
+    env:
+      CODEFLASH_AIS_SERVER: prod
+      POSTHOG_API_KEY: ${{ secrets.POSTHOG_API_KEY }}
+      CODEFLASH_API_KEY: ${{ secrets.CODEFLASH_API_KEY }}
+      COLUMNS: 110
+      MAX_RETRIES: 3
+      RETRY_DELAY: 5
+      EXPECTED_IMPROVEMENT_PCT: 70
+      CODEFLASH_END_TO_END: 1
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.pull_request.head.ref }}
+          repository: ${{ github.event.pull_request.head.repo.full_name }}
+          fetch-depth: 0
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Validate PR
+        env:
+          PR_AUTHOR: ${{ github.event.pull_request.user.login }}
+          PR_STATE: ${{ github.event.pull_request.state }}
+          BASE_SHA: ${{ github.event.pull_request.base.sha }}
+          HEAD_SHA: ${{ github.event.pull_request.head.sha }}
+        run: |
+          if git diff --name-only "$BASE_SHA" "$HEAD_SHA" | grep -q "^.github/workflows/"; then
+            echo "⚠️ Workflow changes detected."
+            echo "PR Author: $PR_AUTHOR"
+            if [[ "$PR_AUTHOR" == "misrasaurabh1" || "$PR_AUTHOR" == "KRRT7" ]]; then
+              echo "✅ Authorized user ($PR_AUTHOR). Proceeding."
+            elif [[ "$PR_STATE" == "open" ]]; then
+              echo "✅ PR is open. Proceeding."
+            else
+              echo "⛔ Unauthorized user ($PR_AUTHOR) attempting to modify workflows. Exiting."
+              exit 1
+            fi
+          else
+            echo "✅ No workflow file changes detected. Proceeding."
+          fi
+
+      - name: Set up JDK 11
+        uses: actions/setup-java@v4
+        with:
+          java-version: '11'
+          distribution: 'temurin'
+          cache: maven
+
+      - name: Set up Python 3.11 for CLI
+        uses: astral-sh/setup-uv@v6
+        with:
+          python-version: 3.11.6
+
+      - name: Install dependencies (CLI)
+        run: uv sync
+
+      - name: Build codeflash-runtime JAR
+        run: |
+          cd codeflash-java-runtime
+          mvn clean package -q -DskipTests
+          mvn install -q -DskipTests
+
+      - name: Verify Java installation
+        run: |
+          java -version
+          mvn --version
+
+      - name: Remove .git
+        run: |
+          if [ -d ".git" ]; then
+            sudo rm -rf .git
+            echo ".git directory removed."
+          else
+            echo ".git directory does not exist."
+            exit 1
+          fi
+
+      - name: Run Codeflash to optimize void function
+        run: |
+          uv run python tests/scripts/end_to_end_test_java_void_optimization.py

code_to_optimize/java/src/main/java/com/example/InPlaceSorter.java

@@ -0,0 +1,21 @@
+package com.example;
+
+public class InPlaceSorter {
+
+    public static void bubbleSortInPlace(int[] arr) {
+        if (arr == null || arr.length <= 1) {
+            return;
+        }
+
+        int n = arr.length;
+        for (int i = 0; i < n; i++) {
+            for (int j = 0; j < n - 1; j++) {
+                if (arr[j] > arr[j + 1]) {
+                    int temp = arr[j];
+                    arr[j] = arr[j + 1];
+                    arr[j + 1] = temp;
+                }
+            }
+        }
+    }
+}

code_to_optimize/java/src/main/java/com/example/InstanceSorter.java

@@ -0,0 +1,21 @@
+package com.example;
+
+public class InstanceSorter {
+
+    public void bubbleSortInPlace(int[] arr) {
+        if (arr == null || arr.length <= 1) {
+            return;
+        }
+
+        int n = arr.length;
+        for (int i = 0; i < n; i++) {
+            for (int j = 0; j < n - 1; j++) {
+                if (arr[j] > arr[j + 1]) {
+                    int temp = arr[j];
+                    arr[j] = arr[j + 1];
+                    arr[j + 1] = temp;
+                }
+            }
+        }
+    }
+}

code_to_optimize/java/src/test/java/com/example/InPlaceSorterTest.java

@@ -0,0 +1,62 @@
+package com.example;
+
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+class InPlaceSorterTest {
+
+    @Test
+    void testBubbleSortInPlace() {
+        int[] arr = {5, 3, 1, 4, 2};
+        InPlaceSorter.bubbleSortInPlace(arr);
+        assertArrayEquals(new int[]{1, 2, 3, 4, 5}, arr);
+    }
+
+    @Test
+    void testBubbleSortInPlaceAlreadySorted() {
+        int[] arr = {1, 2, 3, 4, 5};
+        InPlaceSorter.bubbleSortInPlace(arr);
+        assertArrayEquals(new int[]{1, 2, 3, 4, 5}, arr);
+    }
+
+    @Test
+    void testBubbleSortInPlaceReversed() {
+        int[] arr = {5, 4, 3, 2, 1};
+        InPlaceSorter.bubbleSortInPlace(arr);
+        assertArrayEquals(new int[]{1, 2, 3, 4, 5}, arr);
+    }
+
+    @Test
+    void testBubbleSortInPlaceWithDuplicates() {
+        int[] arr = {3, 2, 4, 1, 3, 2};
+        InPlaceSorter.bubbleSortInPlace(arr);
+        assertArrayEquals(new int[]{1, 2, 2, 3, 3, 4}, arr);
+    }
+
+    @Test
+    void testBubbleSortInPlaceWithNegatives() {
+        int[] arr = {3, -2, 7, 0, -5};
+        InPlaceSorter.bubbleSortInPlace(arr);
+        assertArrayEquals(new int[]{-5, -2, 0, 3, 7}, arr);
+    }
+
+    @Test
+    void testBubbleSortInPlaceSingleElement() {
+        int[] arr = {42};
+        InPlaceSorter.bubbleSortInPlace(arr);
+        assertArrayEquals(new int[]{42}, arr);
+    }
+
+    @Test
+    void testBubbleSortInPlaceEmpty() {
+        int[] arr = {};
+        InPlaceSorter.bubbleSortInPlace(arr);
+        assertArrayEquals(new int[]{}, arr);
+    }
+
+    @Test
+    void testBubbleSortInPlaceNull() {
+        InPlaceSorter.bubbleSortInPlace(null);
+    }
+
+}

code_to_optimize/java/src/test/java/com/example/InstanceSorterTest.java

@@ -0,0 +1,69 @@
+package com.example;
+
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+class InstanceSorterTest {
+
+    @Test
+    void testBubbleSortInPlace() {
+        InstanceSorter sorter = new InstanceSorter();
+        int[] arr = {5, 3, 1, 4, 2};
+        sorter.bubbleSortInPlace(arr);
+        assertArrayEquals(new int[]{1, 2, 3, 4, 5}, arr);
+    }
+
+    @Test
+    void testBubbleSortInPlaceAlreadySorted() {
+        InstanceSorter sorter = new InstanceSorter();
+        int[] arr = {1, 2, 3, 4, 5};
+        sorter.bubbleSortInPlace(arr);
+        assertArrayEquals(new int[]{1, 2, 3, 4, 5}, arr);
+    }
+
+    @Test
+    void testBubbleSortInPlaceReversed() {
+        InstanceSorter sorter = new InstanceSorter();
+        int[] arr = {5, 4, 3, 2, 1};
+        sorter.bubbleSortInPlace(arr);
+        assertArrayEquals(new int[]{1, 2, 3, 4, 5}, arr);
+    }
+
+    @Test
+    void testBubbleSortInPlaceWithDuplicates() {
+        InstanceSorter sorter = new InstanceSorter();
+        int[] arr = {3, 2, 4, 1, 3, 2};
+        sorter.bubbleSortInPlace(arr);
+        assertArrayEquals(new int[]{1, 2, 2, 3, 3, 4}, arr);
+    }
+
+    @Test
+    void testBubbleSortInPlaceWithNegatives() {
+        InstanceSorter sorter = new InstanceSorter();
+        int[] arr = {3, -2, 7, 0, -5};
+        sorter.bubbleSortInPlace(arr);
+        assertArrayEquals(new int[]{-5, -2, 0, 3, 7}, arr);
+    }
+
+    @Test
+    void testBubbleSortInPlaceSingleElement() {
+        InstanceSorter sorter = new InstanceSorter();
+        int[] arr = {42};
+        sorter.bubbleSortInPlace(arr);
+        assertArrayEquals(new int[]{42}, arr);
+    }
+
+    @Test
+    void testBubbleSortInPlaceEmpty() {
+        InstanceSorter sorter = new InstanceSorter();
+        int[] arr = {};
+        sorter.bubbleSortInPlace(arr);
+        assertArrayEquals(new int[]{}, arr);
+    }
+
+    @Test
+    void testBubbleSortInPlaceNull() {
+        InstanceSorter sorter = new InstanceSorter();
+        sorter.bubbleSortInPlace(null);
+    }
+}

codeflash-java-runtime/src/test/java/com/codeflash/ComparatorCorrectnessTest.java

@@ -209,6 +209,87 @@ class ComparatorCorrectnessTest {
         assertFalse(Comparator.isDeserializationError(42));
     }
 
+    // ============================================================
+    // VOID METHOD STATE COMPARISON — proves we actually compare
+    // post-call state for void methods, not just skip them
+    // ============================================================
+
+    @Test
+    @DisplayName("void state: both sides sorted identically → equivalent")
+    void testVoidState_identicalMutation_equivalent() throws Exception {
+        createTestDb(originalDb);
+        createTestDb(candidateDb);
+
+        // Simulate: bubbleSortInPlace(arr) — both original and candidate sort correctly
+        // Post-call state: Object[]{sorted_array}
+        int[] sortedArr = {1, 2, 3, 4, 5};
+        byte[] origState = Serializer.serialize(new Object[]{sortedArr});
+        byte[] candState = Serializer.serialize(new Object[]{new int[]{1, 2, 3, 4, 5}});
+
+        insertRow(originalDb, "L1_1", 1, origState);
+        insertRow(candidateDb, "L1_1", 1, candState);
+
+        String json = Comparator.compareDatabases(originalDb.toString(), candidateDb.toString());
+        Map<String, Object> result = parseJson(json);
+
+        assertTrue((Boolean) result.get("equivalent"),
+            "Both sides produce same sorted array — should be equivalent");
+        assertEquals(1, ((Number) result.get("actualComparisons")).intValue());
+    }
+
+    @Test
+    @DisplayName("void state: candidate mutates array differently → NOT equivalent")
+    void testVoidState_differentMutation_rejected() throws Exception {
+        createTestDb(originalDb);
+        createTestDb(candidateDb);
+
+        // Simulate: original sorts [3,1,2] → [1,2,3]
+        // Bad optimization doesn't sort correctly → [3,1,2] unchanged
+        byte[] origState = Serializer.serialize(new Object[]{new int[]{1, 2, 3}});
+        byte[] candState = Serializer.serialize(new Object[]{new int[]{3, 1, 2}});
+
+        insertRow(originalDb, "L1_1", 1, origState);
+        insertRow(candidateDb, "L1_1", 1, candState);
+
+        String json = Comparator.compareDatabases(originalDb.toString(), candidateDb.toString());
+        Map<String, Object> result = parseJson(json);
+
+        assertFalse((Boolean) result.get("equivalent"),
+            "Candidate produced wrong array — must be rejected");
+        assertEquals(1, ((Number) result.get("actualComparisons")).intValue());
+    }
+
+    @Test
+    @DisplayName("void state: receiver + args both compared — wrong receiver state rejected")
+    void testVoidState_receiverAndArgs_wrongReceiverRejected() throws Exception {
+        createTestDb(originalDb);
+        createTestDb(candidateDb);
+
+        // Simulate: instance method sorter.sort(data)
+        // Post-call state is Object[]{receiver_fields_map, mutated_data}
+        // Original: receiver has size=3, data is [1,2,3]
+        // Candidate: receiver has size=0 (wrong), data is [1,2,3]
+        Map<String, Object> origReceiver = new HashMap<>();
+        origReceiver.put("size", 3);
+        origReceiver.put("sorted", true);
+        Map<String, Object> candReceiver = new HashMap<>();
+        candReceiver.put("size", 0);
+        candReceiver.put("sorted", true);
+
+        byte[] origState = Serializer.serialize(new Object[]{origReceiver, new int[]{1, 2, 3}});
+        byte[] candState = Serializer.serialize(new Object[]{candReceiver, new int[]{1, 2, 3}});
+
+        insertRow(originalDb, "L1_1", 1, origState);
+        insertRow(candidateDb, "L1_1", 1, candState);
+
+        String json = Comparator.compareDatabases(originalDb.toString(), candidateDb.toString());
+        Map<String, Object> result = parseJson(json);
+
+        assertFalse((Boolean) result.get("equivalent"),
+            "Receiver state differs (size 3 vs 0) — must be rejected even though args match");
+        assertEquals(1, ((Number) result.get("actualComparisons")).intValue());
+    }
+
     // --- Helpers ---
 
     private void createTestDb(Path dbPath) throws Exception {

codeflash/discovery/functions_to_optimize.py

@@ -195,7 +195,8 @@ def _find_all_functions_via_language_support(file_path: Path) -> dict[Path, list
 
     try:
         lang_support = get_language_support(file_path)
-        criteria = FunctionFilterCriteria(require_return=True)
+        require_return = lang_support.language != Language.JAVA
+        criteria = FunctionFilterCriteria(require_return=require_return)
         functions[file_path] = lang_support.discover_functions(file_path, criteria)
     except Exception as e:
         logger.debug(f"Failed to discover functions in {file_path}: {e}")
@@ -454,7 +455,8 @@ def find_all_functions_in_file(file_path: Path) -> dict[Path, list[FunctionToOpt
         from codeflash.languages.base import FunctionFilterCriteria
 
         lang_support = get_language_support(file_path)
-        criteria = FunctionFilterCriteria(require_return=True)
+        require_return = lang_support.language != Language.JAVA
+        criteria = FunctionFilterCriteria(require_return=require_return)
         source = file_path.read_text(encoding="utf-8")
         return {file_path: lang_support.discover_functions(source, file_path, criteria)}
     except Exception as e:

codeflash/languages/java/instrumentation.py

@@ -203,6 +203,7 @@ def _generate_sqlite_write_code(
     func_name: str,
     test_method_name: str,
     invocation_id: str = "",
+    verification_type: str = "function_call",
 ) -> list[str]:
     """Generate SQLite write code for a single function call.
 
@@ -249,7 +250,7 @@ def _generate_sqlite_write_code(
         f'{inner_indent}                _cf_pstmt{id_pair}.setString(6, "{inv_id_str}");',
         f"{inner_indent}                _cf_pstmt{id_pair}.setLong(7, _cf_dur{id_pair});",
         f"{inner_indent}                _cf_pstmt{id_pair}.setBytes(8, _cf_serializedResult{id_pair});",
-        f'{inner_indent}                _cf_pstmt{id_pair}.setString(9, "function_call");',
+        f'{inner_indent}                _cf_pstmt{id_pair}.setString(9, "{verification_type}");',
         f"{inner_indent}                _cf_pstmt{id_pair}.executeUpdate();",
         f"{inner_indent}            }}",
         f"{inner_indent}        }}",
@@ -337,22 +338,53 @@ def wrap_target_calls_with_treesitter(
         orig_line = body_lines[line_idx]
         line_indent_str = " " * (len(orig_line) - len(orig_line.lstrip()))
 
+        is_void = target_return_type == "void"
         var_name = f"_cf_result{iter_id}_{call_counter}"
+        receiver = call.get("receiver", "this")
+        arg_texts: list[str] = call.get("arg_texts", [])
         cast_type = _infer_array_cast_type(orig_line)
-        if not cast_type and target_return_type and target_return_type != "void":
+        if not cast_type and target_return_type and not is_void:
             cast_type = target_return_type
         var_with_cast = f"({cast_type}){var_name}" if cast_type else var_name
 
-        capture_stmt_with_decl = f"var {var_name} = {call['full_call']};"
-        capture_stmt_assign = f"{var_name} = {call['full_call']};"
-        if precise_call_timing:
-            serialize_stmt = f"_cf_serializedResult{iter_id}_{call_counter} = com.codeflash.Serializer.serialize((Object) {var_name});"
-            start_stmt = f"_cf_start{iter_id}_{call_counter} = System.nanoTime();"
-            end_stmt = f"_cf_end{iter_id}_{call_counter} = System.nanoTime();"
+        if is_void:
+            bare_call_stmt = f"{call['full_call']};"
+            # For void methods, serialize the post-call state to capture side effects.
+            # We always serialize the arguments (which are mutated in place).
+            # For instance methods, we also include the receiver to capture object state changes.
+            # For static methods, the receiver is a class name (not a value), so args only.
+            is_static_call = receiver != "this" and receiver[:1].isupper()
+            parts: list[str] = []
+            if not is_static_call:
+                parts.append(receiver)
+            parts.extend(arg_texts)
+            if parts:
+                serialize_target = f"new Object[]{{{', '.join(parts)}}}"
+            else:
+                serialize_target = "new Object[]{}"
+            if precise_call_timing:
+                serialize_stmt = f"_cf_serializedResult{iter_id}_{call_counter} = com.codeflash.Serializer.serialize({serialize_target});"
+                start_stmt = f"_cf_start{iter_id}_{call_counter} = System.nanoTime();"
+                end_stmt = f"_cf_end{iter_id}_{call_counter} = System.nanoTime();"
+            else:
+                serialize_stmt = (
+                    f"_cf_serializedResult{iter_id} = com.codeflash.Serializer.serialize({serialize_target});"
+                )
+                start_stmt = f"_cf_start{iter_id} = System.nanoTime();"
+                end_stmt = f"_cf_end{iter_id} = System.nanoTime();"
         else:
-            serialize_stmt = f"_cf_serializedResult{iter_id} = com.codeflash.Serializer.serialize((Object) {var_name});"
-            start_stmt = f"_cf_start{iter_id} = System.nanoTime();"
-            end_stmt = f"_cf_end{iter_id} = System.nanoTime();"
+            capture_stmt_with_decl = f"var {var_name} = {call['full_call']};"
+            capture_stmt_assign = f"{var_name} = {call['full_call']};"
+            if precise_call_timing:
+                serialize_stmt = f"_cf_serializedResult{iter_id}_{call_counter} = com.codeflash.Serializer.serialize((Object) {var_name});"
+                start_stmt = f"_cf_start{iter_id}_{call_counter} = System.nanoTime();"
+                end_stmt = f"_cf_end{iter_id}_{call_counter} = System.nanoTime();"
+            else:
+                serialize_stmt = (
+                    f"_cf_serializedResult{iter_id} = com.codeflash.Serializer.serialize((Object) {var_name});"
+                )
+                start_stmt = f"_cf_start{iter_id} = System.nanoTime();"
+                end_stmt = f"_cf_end{iter_id} = System.nanoTime();"
 
         if call["parent_type"] == "expression_statement":
             es_start = call["_es_start_char"]
@@ -360,31 +392,61 @@ def wrap_target_calls_with_treesitter(
             if precise_call_timing:
                 # No indent on first line — body_text[:es_start] already has leading whitespace.
                 # Subsequent lines get line_indent_str.
-                var_decls = [
-                    f"Object {var_name} = null;",
-                    f"long _cf_end{iter_id}_{call_counter} = -1;",
-                    f"long _cf_start{iter_id}_{call_counter} = 0;",
-                    f"byte[] _cf_serializedResult{iter_id}_{call_counter} = null;",
-                ]
+                if is_void:
+                    var_decls = [
+                        f"long _cf_end{iter_id}_{call_counter} = -1;",
+                        f"long _cf_start{iter_id}_{call_counter} = 0;",
+                        f"byte[] _cf_serializedResult{iter_id}_{call_counter} = null;",
+                    ]
+                else:
+                    var_decls = [
+                        f"Object {var_name} = null;",
+                        f"long _cf_end{iter_id}_{call_counter} = -1;",
+                        f"long _cf_start{iter_id}_{call_counter} = 0;",
+                        f"byte[] _cf_serializedResult{iter_id}_{call_counter} = null;",
+                    ]
                 start_marker = f'System.out.println("!$######" + _cf_mod{iter_id} + ":" + _cf_cls{iter_id} + "." + _cf_test{iter_id} + ":" + _cf_fn{iter_id} + ":" + _cf_loop{iter_id} + ":{inv_id}" + "######$!");'
-                try_block = [
-                    "try {",
-                    f"    {start_stmt}",
-                    f"    {capture_stmt_assign}",
-                    f"    {end_stmt}",
-                    f"    {serialize_stmt}",
-                ]
+                if is_void:
+                    try_block = [
+                        "try {",
+                        f"    {start_stmt}",
+                        f"    {bare_call_stmt}",
+                        f"    {end_stmt}",
+                        f"    {serialize_stmt}",
+                    ]
+                else:
+                    try_block = [
+                        "try {",
+                        f"    {start_stmt}",
+                        f"    {capture_stmt_assign}",
+                        f"    {end_stmt}",
+                        f"    {serialize_stmt}",
+                    ]
                 finally_block = _generate_sqlite_write_code(
-                    iter_id, call_counter, "", class_name, func_name, test_method_name, invocation_id=inv_id
+                    iter_id,
+                    call_counter,
+                    "",
+                    class_name,
+                    func_name,
+                    test_method_name,
+                    invocation_id=inv_id,
+                    verification_type="void_state" if is_void else "function_call",
                 )
                 all_lines = [*var_decls, start_marker, *try_block, *finally_block]
                 replacement = (
                     all_lines[0] + "\n" + "\n".join(f"{line_indent_str}{repl_line}" for repl_line in all_lines[1:])
                 )
+            elif is_void:
+                replacement = f"{bare_call_stmt} {serialize_stmt}"
             else:
                 replacement = f"{capture_stmt_with_decl} {serialize_stmt}"
             body_text = body_text[:es_start] + replacement + body_text[es_end:]
         else:
+            if is_void:
+                # Void calls cannot be embedded in expressions in valid Java — skip instrumentation
+                logger.warning("Skipping instrumentation of embedded void call: %s", call["full_call"])
+                continue
+
             # Embedded call: replace call with variable, then insert capture lines before the line
             call_start = call["_call_start_char"]
             call_end = call["_call_end_char"]
@@ -451,6 +513,15 @@ def _collect_calls(
                 if parent_type == "expression_statement":
                     es_start = parent.start_byte - prefix_len
                     es_end = parent.end_byte - prefix_len
+                object_node = node.child_by_field_name("object")
+                receiver = analyzer.get_node_text(object_node, wrapper_bytes) if object_node else "this"
+                # Extract argument texts for void method serialization
+                args_node = node.child_by_field_name("arguments")
+                arg_texts: list[str] = []
+                if args_node:
+                    for child in args_node.children:
+                        if child.type not in ("(", ")", ","):
+                            arg_texts.append(analyzer.get_node_text(child, wrapper_bytes))
                 out.append(
                     {
                         "start_byte": start,
@@ -461,6 +532,8 @@ def _collect_calls(
                         "in_complex": _is_inside_complex_expression(node),
                         "es_start_byte": es_start,
                         "es_end_byte": es_end,
+                        "receiver": receiver,
+                        "arg_texts": arg_texts,
                     }
                 )
     for child in node.children:

codeflash/languages/java/remove_asserts.py

@@ -189,6 +189,7 @@ class JavaAssertTransformer:
         qualified_name: str | None = None,
         analyzer: JavaAnalyzer | None = None,
         mode: str = "capture",
+        target_return_type: str = "",
     ) -> None:
         self.analyzer = analyzer or get_java_analyzer()
         self.func_name = function_name
@@ -196,6 +197,7 @@ class JavaAssertTransformer:
         self.invocation_counter = 0
         self._detected_framework: str | None = None
         self.mode = mode  # "capture" (default, instrumentation) or "strip" (clean display)
+        self.target_return_type = target_return_type
 
         # Precompile the assignment-detection regex to avoid recompiling on each call.
         self._assign_re = re.compile(r"(\w+(?:<[^>]+>)?)\s+(\w+)\s*=\s*$")
@@ -1062,7 +1064,7 @@ class JavaAssertTransformer:
         if not assertion.target_calls:
             return ""
 
-        if self.mode == "strip":
+        if self.mode == "strip" or self.target_return_type == "void":
             return self._generate_strip_replacement(assertion)
 
         # Infer the return type from assertion context to avoid Object→primitive cast errors
@@ -1244,7 +1246,9 @@ class JavaAssertTransformer:
         return "".join(cur).rstrip()
 
 
-def transform_java_assertions(source: str, function_name: str, qualified_name: str | None = None) -> str:
+def transform_java_assertions(
+    source: str, function_name: str, qualified_name: str | None = None, target_return_type: str = ""
+) -> str:
     """Transform Java test code by removing assertions and capturing function calls.
 
     This is the main entry point for Java assertion transformation.
@@ -1253,12 +1257,15 @@ def transform_java_assertions(source: str, function_name: str, qualified_name: s
         source: The Java test source code.
         function_name: Name of the function being tested.
         qualified_name: Optional fully qualified name of the function.
+        target_return_type: Return type of the target function (e.g., "void", "int").
 
     Returns:
         Transformed source code with assertions replaced by capture statements.
 
     """
-    transformer = JavaAssertTransformer(function_name=function_name, qualified_name=qualified_name)
+    transformer = JavaAssertTransformer(
+        function_name=function_name, qualified_name=qualified_name, target_return_type=target_return_type
+    )
     return transformer.transform(source)
 
 

codeflash/models/models.py

@@ -740,6 +740,7 @@ class VerificationType(str, Enum):
     )
     INIT_STATE_FTO = "init_state_fto"  # Correctness verification for fto class instance attributes after init
     INIT_STATE_HELPER = "init_state_helper"  # Correctness verification for helper class instance attributes after init
+    VOID_STATE = "void_state"  # Correctness verification for void methods (no return value)
 
 
 @dataclass(frozen=True, slots=True)

tests/scripts/end_to_end_test_java_void_optimization.py

@@ -0,0 +1,18 @@
+import os
+import pathlib
+
+from end_to_end_test_utilities import TestConfig, run_codeflash_command, run_with_retries
+
+
+def run_test(expected_improvement_pct: int) -> bool:
+    config = TestConfig(
+        file_path="src/main/java/com/example/InPlaceSorter.java",
+        function_name="bubbleSortInPlace",
+        min_improvement_x=0.70,
+    )
+    cwd = (pathlib.Path(__file__).parent.parent.parent / "code_to_optimize" / "java").resolve()
+    return run_codeflash_command(cwd, config, expected_improvement_pct)
+
+
+if __name__ == "__main__":
+    exit(run_with_retries(run_test, int(os.getenv("EXPECTED_IMPROVEMENT_PCT", 70))))

tests/test_languages/fixtures/java_tracer_e2e/pom.xml

@@ -11,7 +11,18 @@
         <maven.compiler.source>11</maven.compiler.source>
         <maven.compiler.target>11</maven.compiler.target>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-    </properties>
+            <checkstyle.skip>true</checkstyle.skip>
+        <disable.checks>true</disable.checks>
+        <spotbugs.skip>true</spotbugs.skip>
+        <pmd.skip>true</pmd.skip>
+        <rat.skip>true</rat.skip>
+        <enforcer.skip>true</enforcer.skip>
+        <japicmp.skip>true</japicmp.skip>
+        <checkstyle.failOnViolation>false</checkstyle.failOnViolation>
+        <checkstyle.failsOnError>false</checkstyle.failsOnError>
+        <maven-checkstyle-plugin.failsOnError>false</maven-checkstyle-plugin.failsOnError>
+        <maven-checkstyle-plugin.failOnViolation>false</maven-checkstyle-plugin.failOnViolation>
+</properties>
 
     <dependencies>
         <dependency>
@@ -62,6 +73,26 @@
           </execution>
         </executions>
       </plugin>
-    </plugins>
+    <!-- codeflash-validation-skip -->
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-checkstyle-plugin</artifactId>
+                <configuration>
+                    <skip>true</skip>
+                    <failOnViolation>false</failOnViolation>
+                    <failsOnError>false</failsOnError>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>com.github.spotbugs</groupId>
+                <artifactId>spotbugs-maven-plugin</artifactId>
+                <configuration><skip>true</skip></configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-pmd-plugin</artifactId>
+                <configuration><skip>true</skip></configuration>
+            </plugin>
+</plugins>
     </build>
 </project>

tests/test_languages/test_java/test_instrumentation.py

@@ -22,7 +22,6 @@ os.environ["CODEFLASH_API_KEY"] = "cf-test-key"
 from codeflash.discovery.functions_to_optimize import FunctionToOptimize
 from codeflash.languages.base import Language
 from codeflash.languages.current import set_current_language
-from codeflash.languages.java.maven_strategy import MavenStrategy
 from codeflash.languages.java.discovery import discover_functions_from_source
 from codeflash.languages.java.instrumentation import (
     _add_behavior_instrumentation,
@@ -34,6 +33,7 @@ from codeflash.languages.java.instrumentation import (
     instrument_generated_java_test,
     remove_instrumentation,
 )
+from codeflash.languages.java.maven_strategy import MavenStrategy
 
 
 class TestInstrumentForBehavior:
@@ -2177,7 +2177,7 @@ public class AccentTest {
 
 # Skip all E2E tests if Maven is not available
 requires_maven = pytest.mark.skipif(
-    MavenStrategy().find_executable(Path(".")) is None, reason="Maven not found - skipping execution tests"
+    MavenStrategy().find_executable(Path()) is None, reason="Maven not found - skipping execution tests"
 )
 
 
@@ -3485,3 +3485,444 @@ public class SpinWaitTest__perfonlyinstrumented {
             assert math.isclose(duration, 100_000_000, rel_tol=0.15), (
                 f"Long spin measured {duration}ns, expected ~100_000_000ns (15% tolerance)"
             )
+
+
+class TestVoidMethodInstrumentation:
+    """Tests for void method instrumentation — behavior mode captures receiver state."""
+
+    def test_behavior_mode_void_method_serializes_receiver(self, tmp_path: Path):
+        """Void method instrumentation should serialize the receiver, not a return value."""
+        source_file = (tmp_path / "Sorter.java").resolve()
+        source_file.write_text(
+            "public class Sorter {\n"
+            "    public void sort(int[] data) {\n"
+            "        java.util.Arrays.sort(data);\n"
+            "    }\n"
+            "}\n",
+            encoding="utf-8",
+        )
+
+        test_file = (tmp_path / "SorterTest.java").resolve()
+        test_source = (
+            "import org.junit.jupiter.api.Test;\n"
+            "\n"
+            "public class SorterTest {\n"
+            "    @Test\n"
+            "    public void testSort() {\n"
+            "        Sorter sorter = new Sorter();\n"
+            "        int[] data = {3, 1, 2};\n"
+            "        sorter.sort(data);\n"
+            "    }\n"
+            "}\n"
+        )
+        test_file.write_text(test_source, encoding="utf-8")
+
+        func = FunctionToOptimize(
+            function_name="sort",
+            file_path=source_file,
+            starting_line=2,
+            ending_line=4,
+            parents=[],
+            is_method=True,
+            language="java",
+        )
+
+        success, result = instrument_existing_test(
+            test_string=test_source, function_to_optimize=func, mode="behavior", test_path=test_file
+        )
+
+        assert success is True
+        assert result == (
+            "import org.junit.jupiter.api.Test;\n"
+            "import java.sql.Connection;\n"
+            "import java.sql.DriverManager;\n"
+            "import java.sql.PreparedStatement;\n"
+            "\n"
+            '@SuppressWarnings("CheckReturnValue")\n'
+            "public class SorterTest__perfinstrumented {\n"
+            "    @Test\n"
+            "    public void testSort() {\n"
+            "        // Codeflash behavior instrumentation\n"
+            '        int _cf_loop1 = Integer.parseInt(System.getenv("CODEFLASH_LOOP_INDEX"));\n'
+            "        int _cf_iter1 = 1;\n"
+            '        String _cf_mod1 = "SorterTest__perfinstrumented";\n'
+            '        String _cf_cls1 = "SorterTest__perfinstrumented";\n'
+            '        String _cf_fn1 = "sort";\n'
+            '        String _cf_outputFile1 = System.getenv("CODEFLASH_OUTPUT_FILE");\n'
+            '        String _cf_testIteration1 = System.getenv("CODEFLASH_TEST_ITERATION");\n'
+            '        if (_cf_testIteration1 == null) _cf_testIteration1 = "0";\n'
+            '        String _cf_test1 = "testSort";\n'
+            "        Sorter sorter = new Sorter();\n"
+            "        int[] data = {3, 1, 2};\n"
+            "        long _cf_end1_1 = -1;\n"
+            "        long _cf_start1_1 = 0;\n"
+            "        byte[] _cf_serializedResult1_1 = null;\n"
+            '        System.out.println("!$######" + _cf_mod1 + ":" + _cf_cls1 + "." + _cf_test1 + ":" + _cf_fn1 + ":" + _cf_loop1 + ":L12_1" + "######$!");\n'
+            "        try {\n"
+            "            _cf_start1_1 = System.nanoTime();\n"
+            "            sorter.sort(data);\n"
+            "            _cf_end1_1 = System.nanoTime();\n"
+            "            _cf_serializedResult1_1 = com.codeflash.Serializer.serialize(new Object[]{sorter, data});\n"
+            "        } finally {\n"
+            "            long _cf_end1_1_finally = System.nanoTime();\n"
+            "            long _cf_dur1_1 = (_cf_end1_1 != -1 ? _cf_end1_1 : _cf_end1_1_finally) - _cf_start1_1;\n"
+            '            System.out.println("!######" + _cf_mod1 + ":" + _cf_cls1 + "." + _cf_test1 + ":" + _cf_fn1 + ":" + _cf_loop1 + ":" + "L12_1" + "######!");\n'
+            "            // Write to SQLite if output file is set\n"
+            "            if (_cf_outputFile1 != null && !_cf_outputFile1.isEmpty()) {\n"
+            "                try {\n"
+            '                    Class.forName("org.sqlite.JDBC");\n'
+            '                    try (Connection _cf_conn1_1 = DriverManager.getConnection("jdbc:sqlite:" + _cf_outputFile1)) {\n'
+            "                        try (java.sql.Statement _cf_stmt1_1 = _cf_conn1_1.createStatement()) {\n"
+            '                            _cf_stmt1_1.execute("CREATE TABLE IF NOT EXISTS test_results (" +\n'
+            '                                "test_module_path TEXT, test_class_name TEXT, test_function_name TEXT, " +\n'
+            '                                "function_getting_tested TEXT, loop_index INTEGER, iteration_id TEXT, " +\n'
+            '                                "runtime INTEGER, return_value BLOB, verification_type TEXT)");\n'
+            "                        }\n"
+            '                        String _cf_sql1_1 = "INSERT INTO test_results VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)";\n'
+            "                        try (PreparedStatement _cf_pstmt1_1 = _cf_conn1_1.prepareStatement(_cf_sql1_1)) {\n"
+            "                            _cf_pstmt1_1.setString(1, _cf_mod1);\n"
+            "                            _cf_pstmt1_1.setString(2, _cf_cls1);\n"
+            "                            _cf_pstmt1_1.setString(3, _cf_test1);\n"
+            "                            _cf_pstmt1_1.setString(4, _cf_fn1);\n"
+            "                            _cf_pstmt1_1.setInt(5, _cf_loop1);\n"
+            '                            _cf_pstmt1_1.setString(6, "L12_1");\n'
+            "                            _cf_pstmt1_1.setLong(7, _cf_dur1_1);\n"
+            "                            _cf_pstmt1_1.setBytes(8, _cf_serializedResult1_1);\n"
+            '                            _cf_pstmt1_1.setString(9, "void_state");\n'
+            "                            _cf_pstmt1_1.executeUpdate();\n"
+            "                        }\n"
+            "                    }\n"
+            "                } catch (Exception _cf_e1_1) {\n"
+            '                    System.err.println("CodeflashHelper: SQLite error: " + _cf_e1_1.getMessage());\n'
+            "                }\n"
+            "            }\n"
+            "        }\n"
+            "    }\n"
+            "}\n"
+        )
+
+    def test_behavior_mode_void_method_implicit_this_receiver(self, tmp_path: Path):
+        """Void method with no explicit receiver uses 'this' for serialization."""
+        source_file = (tmp_path / "Container.java").resolve()
+        source_file.write_text(
+            "public class Container {\n"
+            "    public void clear() {\n"
+            "        // clears internal state\n"
+            "    }\n"
+            "}\n",
+            encoding="utf-8",
+        )
+
+        test_file = (tmp_path / "ContainerTest.java").resolve()
+        test_source = (
+            "import org.junit.jupiter.api.Test;\n"
+            "\n"
+            "public class ContainerTest {\n"
+            "    @Test\n"
+            "    public void testClear() {\n"
+            "        clear();\n"
+            "    }\n"
+            "}\n"
+        )
+        test_file.write_text(test_source, encoding="utf-8")
+
+        func = FunctionToOptimize(
+            function_name="clear",
+            file_path=source_file,
+            starting_line=2,
+            ending_line=4,
+            parents=[],
+            is_method=True,
+            language="java",
+        )
+
+        success, result = instrument_existing_test(
+            test_string=test_source, function_to_optimize=func, mode="behavior", test_path=test_file
+        )
+
+        assert success is True
+        assert result == (
+            "import org.junit.jupiter.api.Test;\n"
+            "import java.sql.Connection;\n"
+            "import java.sql.DriverManager;\n"
+            "import java.sql.PreparedStatement;\n"
+            "\n"
+            '@SuppressWarnings("CheckReturnValue")\n'
+            "public class ContainerTest__perfinstrumented {\n"
+            "    @Test\n"
+            "    public void testClear() {\n"
+            "        // Codeflash behavior instrumentation\n"
+            '        int _cf_loop1 = Integer.parseInt(System.getenv("CODEFLASH_LOOP_INDEX"));\n'
+            "        int _cf_iter1 = 1;\n"
+            '        String _cf_mod1 = "ContainerTest__perfinstrumented";\n'
+            '        String _cf_cls1 = "ContainerTest__perfinstrumented";\n'
+            '        String _cf_fn1 = "clear";\n'
+            '        String _cf_outputFile1 = System.getenv("CODEFLASH_OUTPUT_FILE");\n'
+            '        String _cf_testIteration1 = System.getenv("CODEFLASH_TEST_ITERATION");\n'
+            '        if (_cf_testIteration1 == null) _cf_testIteration1 = "0";\n'
+            '        String _cf_test1 = "testClear";\n'
+            "        long _cf_end1_1 = -1;\n"
+            "        long _cf_start1_1 = 0;\n"
+            "        byte[] _cf_serializedResult1_1 = null;\n"
+            '        System.out.println("!$######" + _cf_mod1 + ":" + _cf_cls1 + "." + _cf_test1 + ":" + _cf_fn1 + ":" + _cf_loop1 + ":L10_1" + "######$!");\n'
+            "        try {\n"
+            "            _cf_start1_1 = System.nanoTime();\n"
+            "            clear();\n"
+            "            _cf_end1_1 = System.nanoTime();\n"
+            "            _cf_serializedResult1_1 = com.codeflash.Serializer.serialize(new Object[]{this});\n"
+            "        } finally {\n"
+            "            long _cf_end1_1_finally = System.nanoTime();\n"
+            "            long _cf_dur1_1 = (_cf_end1_1 != -1 ? _cf_end1_1 : _cf_end1_1_finally) - _cf_start1_1;\n"
+            '            System.out.println("!######" + _cf_mod1 + ":" + _cf_cls1 + "." + _cf_test1 + ":" + _cf_fn1 + ":" + _cf_loop1 + ":" + "L10_1" + "######!");\n'
+            "            // Write to SQLite if output file is set\n"
+            "            if (_cf_outputFile1 != null && !_cf_outputFile1.isEmpty()) {\n"
+            "                try {\n"
+            '                    Class.forName("org.sqlite.JDBC");\n'
+            '                    try (Connection _cf_conn1_1 = DriverManager.getConnection("jdbc:sqlite:" + _cf_outputFile1)) {\n'
+            "                        try (java.sql.Statement _cf_stmt1_1 = _cf_conn1_1.createStatement()) {\n"
+            '                            _cf_stmt1_1.execute("CREATE TABLE IF NOT EXISTS test_results (" +\n'
+            '                                "test_module_path TEXT, test_class_name TEXT, test_function_name TEXT, " +\n'
+            '                                "function_getting_tested TEXT, loop_index INTEGER, iteration_id TEXT, " +\n'
+            '                                "runtime INTEGER, return_value BLOB, verification_type TEXT)");\n'
+            "                        }\n"
+            '                        String _cf_sql1_1 = "INSERT INTO test_results VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)";\n'
+            "                        try (PreparedStatement _cf_pstmt1_1 = _cf_conn1_1.prepareStatement(_cf_sql1_1)) {\n"
+            "                            _cf_pstmt1_1.setString(1, _cf_mod1);\n"
+            "                            _cf_pstmt1_1.setString(2, _cf_cls1);\n"
+            "                            _cf_pstmt1_1.setString(3, _cf_test1);\n"
+            "                            _cf_pstmt1_1.setString(4, _cf_fn1);\n"
+            "                            _cf_pstmt1_1.setInt(5, _cf_loop1);\n"
+            '                            _cf_pstmt1_1.setString(6, "L10_1");\n'
+            "                            _cf_pstmt1_1.setLong(7, _cf_dur1_1);\n"
+            "                            _cf_pstmt1_1.setBytes(8, _cf_serializedResult1_1);\n"
+            '                            _cf_pstmt1_1.setString(9, "void_state");\n'
+            "                            _cf_pstmt1_1.executeUpdate();\n"
+            "                        }\n"
+            "                    }\n"
+            "                } catch (Exception _cf_e1_1) {\n"
+            '                    System.err.println("CodeflashHelper: SQLite error: " + _cf_e1_1.getMessage());\n'
+            "                }\n"
+            "            }\n"
+            "        }\n"
+            "    }\n"
+            "}\n"
+        )
+
+    def test_behavior_mode_non_void_still_captures_result(self, tmp_path: Path):
+        """Non-void methods should still capture the return value (not the receiver)."""
+        source_file = (tmp_path / "Calculator.java").resolve()
+        source_file.write_text(
+            "public class Calculator {\n"
+            "    public int add(int a, int b) {\n"
+            "        return a + b;\n"
+            "    }\n"
+            "}\n",
+            encoding="utf-8",
+        )
+
+        test_file = (tmp_path / "CalculatorTest.java").resolve()
+        test_source = (
+            "import org.junit.jupiter.api.Test;\n"
+            "\n"
+            "public class CalculatorTest {\n"
+            "    @Test\n"
+            "    public void testAdd() {\n"
+            "        Calculator calc = new Calculator();\n"
+            "        assertEquals(4, calc.add(2, 2));\n"
+            "    }\n"
+            "}\n"
+        )
+        test_file.write_text(test_source, encoding="utf-8")
+
+        func = FunctionToOptimize(
+            function_name="add",
+            file_path=source_file,
+            starting_line=2,
+            ending_line=4,
+            parents=[],
+            is_method=True,
+            language="java",
+        )
+
+        success, result = instrument_existing_test(
+            test_string=test_source, function_to_optimize=func, mode="behavior", test_path=test_file
+        )
+
+        assert success is True
+        assert result == (
+            "import org.junit.jupiter.api.Test;\n"
+            "import java.sql.Connection;\n"
+            "import java.sql.DriverManager;\n"
+            "import java.sql.PreparedStatement;\n"
+            "\n"
+            '@SuppressWarnings("CheckReturnValue")\n'
+            "public class CalculatorTest__perfinstrumented {\n"
+            "    @Test\n"
+            "    public void testAdd() {\n"
+            "        // Codeflash behavior instrumentation\n"
+            '        int _cf_loop1 = Integer.parseInt(System.getenv("CODEFLASH_LOOP_INDEX"));\n'
+            "        int _cf_iter1 = 1;\n"
+            '        String _cf_mod1 = "CalculatorTest__perfinstrumented";\n'
+            '        String _cf_cls1 = "CalculatorTest__perfinstrumented";\n'
+            '        String _cf_fn1 = "add";\n'
+            '        String _cf_outputFile1 = System.getenv("CODEFLASH_OUTPUT_FILE");\n'
+            '        String _cf_testIteration1 = System.getenv("CODEFLASH_TEST_ITERATION");\n'
+            '        if (_cf_testIteration1 == null) _cf_testIteration1 = "0";\n'
+            '        String _cf_test1 = "testAdd";\n'
+            "        Calculator calc = new Calculator();\n"
+            "        Object _cf_result1_1 = null;\n"
+            "        long _cf_end1_1 = -1;\n"
+            "        long _cf_start1_1 = 0;\n"
+            "        byte[] _cf_serializedResult1_1 = null;\n"
+            '        System.out.println("!$######" + _cf_mod1 + ":" + _cf_cls1 + "." + _cf_test1 + ":" + _cf_fn1 + ":" + _cf_loop1 + ":L11_1" + "######$!");\n'
+            "        try {\n"
+            "            _cf_start1_1 = System.nanoTime();\n"
+            "            _cf_result1_1 = calc.add(2, 2);\n"
+            "            _cf_end1_1 = System.nanoTime();\n"
+            "            _cf_serializedResult1_1 = com.codeflash.Serializer.serialize((Object) _cf_result1_1);\n"
+            "        } finally {\n"
+            "            long _cf_end1_1_finally = System.nanoTime();\n"
+            "            long _cf_dur1_1 = (_cf_end1_1 != -1 ? _cf_end1_1 : _cf_end1_1_finally) - _cf_start1_1;\n"
+            '            System.out.println("!######" + _cf_mod1 + ":" + _cf_cls1 + "." + _cf_test1 + ":" + _cf_fn1 + ":" + _cf_loop1 + ":" + "L11_1" + "######!");\n'
+            "            // Write to SQLite if output file is set\n"
+            "            if (_cf_outputFile1 != null && !_cf_outputFile1.isEmpty()) {\n"
+            "                try {\n"
+            '                    Class.forName("org.sqlite.JDBC");\n'
+            '                    try (Connection _cf_conn1_1 = DriverManager.getConnection("jdbc:sqlite:" + _cf_outputFile1)) {\n'
+            "                        try (java.sql.Statement _cf_stmt1_1 = _cf_conn1_1.createStatement()) {\n"
+            '                            _cf_stmt1_1.execute("CREATE TABLE IF NOT EXISTS test_results (" +\n'
+            '                                "test_module_path TEXT, test_class_name TEXT, test_function_name TEXT, " +\n'
+            '                                "function_getting_tested TEXT, loop_index INTEGER, iteration_id TEXT, " +\n'
+            '                                "runtime INTEGER, return_value BLOB, verification_type TEXT)");\n'
+            "                        }\n"
+            '                        String _cf_sql1_1 = "INSERT INTO test_results VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)";\n'
+            "                        try (PreparedStatement _cf_pstmt1_1 = _cf_conn1_1.prepareStatement(_cf_sql1_1)) {\n"
+            "                            _cf_pstmt1_1.setString(1, _cf_mod1);\n"
+            "                            _cf_pstmt1_1.setString(2, _cf_cls1);\n"
+            "                            _cf_pstmt1_1.setString(3, _cf_test1);\n"
+            "                            _cf_pstmt1_1.setString(4, _cf_fn1);\n"
+            "                            _cf_pstmt1_1.setInt(5, _cf_loop1);\n"
+            '                            _cf_pstmt1_1.setString(6, "L11_1");\n'
+            "                            _cf_pstmt1_1.setLong(7, _cf_dur1_1);\n"
+            "                            _cf_pstmt1_1.setBytes(8, _cf_serializedResult1_1);\n"
+            '                            _cf_pstmt1_1.setString(9, "function_call");\n'
+            "                            _cf_pstmt1_1.executeUpdate();\n"
+            "                        }\n"
+            "                    }\n"
+            "                } catch (Exception _cf_e1_1) {\n"
+            '                    System.err.println("CodeflashHelper: SQLite error: " + _cf_e1_1.getMessage());\n'
+            "                }\n"
+            "            }\n"
+            "        }\n"
+            "        assertEquals(4, (int)_cf_result1_1);\n"
+            "    }\n"
+            "}\n"
+        )
+
+    def test_void_discovery_with_require_return_false(self):
+        """Void methods should be discovered when require_return=False."""
+        from codeflash.languages.base import FunctionFilterCriteria
+        from codeflash.languages.java.discovery import discover_functions_from_source
+
+        source = (
+            "public class Example {\n"
+            "    public void doSomething() {\n"
+            '        System.out.println("hello");\n'
+            "    }\n"
+            "\n"
+            "    public int getValue() {\n"
+            "        return 42;\n"
+            "    }\n"
+            "}\n"
+        )
+
+        criteria_no_return = FunctionFilterCriteria(require_return=False)
+        functions = discover_functions_from_source(source, filter_criteria=criteria_no_return)
+        method_names = {f.function_name for f in functions}
+        assert "doSomething" in method_names
+        assert "getValue" in method_names
+
+        criteria_require_return = FunctionFilterCriteria(require_return=True)
+        functions = discover_functions_from_source(source, filter_criteria=criteria_require_return)
+        method_names = {f.function_name for f in functions}
+        assert "doSomething" not in method_names
+        assert "getValue" in method_names
+
+    def test_performance_mode_void_method_generates_valid_code(self, tmp_path: Path):
+        """Void methods in performance mode should generate valid timing code."""
+        source_file = (tmp_path / "Sorter.java").resolve()
+        source_file.write_text(
+            "public class Sorter {\n"
+            "    public void sort(int[] data) {\n"
+            "        java.util.Arrays.sort(data);\n"
+            "    }\n"
+            "}\n",
+            encoding="utf-8",
+        )
+
+        test_file = (tmp_path / "SorterTest.java").resolve()
+        test_source = (
+            "import org.junit.jupiter.api.Test;\n"
+            "\n"
+            "public class SorterTest {\n"
+            "    @Test\n"
+            "    public void testSort() {\n"
+            "        Sorter sorter = new Sorter();\n"
+            "        int[] data = {3, 1, 2};\n"
+            "        sorter.sort(data);\n"
+            "    }\n"
+            "}\n"
+        )
+        test_file.write_text(test_source, encoding="utf-8")
+
+        func = FunctionToOptimize(
+            function_name="sort",
+            file_path=source_file,
+            starting_line=2,
+            ending_line=4,
+            parents=[],
+            is_method=True,
+            language="java",
+        )
+
+        success, result = instrument_existing_test(
+            test_string=test_source, function_to_optimize=func, mode="performance", test_path=test_file
+        )
+
+        assert success is True
+        assert result == (
+            "import org.junit.jupiter.api.Test;\n"
+            "\n"
+            '@SuppressWarnings("CheckReturnValue")\n'
+            "public class SorterTest__perfonlyinstrumented {\n"
+            "    @Test\n"
+            "    public void testSort() {\n"
+            "        // Codeflash timing instrumentation with inner loop for JIT warmup\n"
+            '        int _cf_outerLoop1 = Integer.parseInt(System.getenv("CODEFLASH_LOOP_INDEX"));\n'
+            '        int _cf_maxInnerIterations1 = Integer.parseInt(System.getenv().getOrDefault("CODEFLASH_INNER_ITERATIONS", "10"));\n'
+            '        int _cf_innerIterations1 = Integer.parseInt(System.getenv().getOrDefault("CODEFLASH_INNER_ITERATIONS", "10"));\n'
+            '        String _cf_mod1 = "SorterTest__perfonlyinstrumented";\n'
+            '        String _cf_cls1 = "SorterTest__perfonlyinstrumented";\n'
+            '        String _cf_test1 = "testSort";\n'
+            '        String _cf_fn1 = "sort";\n'
+            "        \n"
+            "        Sorter sorter = new Sorter();\n"
+            "        int[] data = {3, 1, 2};\n"
+            "        for (int _cf_i1 = 0; _cf_i1 < _cf_innerIterations1; _cf_i1++) {\n"
+            "            int _cf_loopId1 = _cf_outerLoop1 * _cf_maxInnerIterations1 + _cf_i1;\n"
+            '            System.out.println("!$######" + _cf_mod1 + ":" + _cf_cls1 + "." + _cf_test1 + ":" + _cf_fn1 + ":" + _cf_loopId1 + ":" + "L9_1" + "######$!");\n'
+            "            long _cf_end1 = -1;\n"
+            "            long _cf_start1 = 0;\n"
+            "            try {\n"
+            "                _cf_start1 = System.nanoTime();\n"
+            "                sorter.sort(data);\n"
+            "                _cf_end1 = System.nanoTime();\n"
+            "            } finally {\n"
+            "                long _cf_end1_finally = System.nanoTime();\n"
+            "                long _cf_dur1 = (_cf_end1 != -1 ? _cf_end1 : _cf_end1_finally) - _cf_start1;\n"
+            '                System.out.println("!######" + _cf_mod1 + ":" + _cf_cls1 + "." + _cf_test1 + ":" + _cf_fn1 + ":" + _cf_loopId1 + ":" + "L9_1" + ":" + _cf_dur1 + "######!");\n'
+            "            }\n"
+            "        }\n"
+            "    }\n"
+            "}\n"
+        )