use byte matcher to find Config annotation descriptor instead of ClassNode

danyadev · danyadev · commit 17619eedcc48 · 2026-05-20T07:39:42.000+03:00
diff --git a/src/main/java/com/falsepattern/lib/internal/asm/transformers/ConfigOrderTransformer.java b/src/main/java/com/falsepattern/lib/internal/asm/transformers/ConfigOrderTransformer.java
@@ -25,6 +25,8 @@
 import com.falsepattern.lib.config.Config;
 import com.falsepattern.lib.internal.Tags;
 import com.falsepattern.lib.internal.impl.config.DeclOrderInternal;
+import com.falsepattern.lib.turboasm.BytePatternMatcher;
+import com.falsepattern.lib.turboasm.ClassHeaderMetadata;
 import com.falsepattern.lib.turboasm.ClassNodeHandle;
 import com.falsepattern.lib.turboasm.TurboClassTransformer;
 import lombok.val;
@@ -37,6 +39,8 @@ public class ConfigOrderTransformer implements TurboClassTransformer {
     private static final String DESC_CONFIG_IGNORE = Type.getDescriptor(Config.Ignore.class);
     private static final String DESC_ORDER = Type.getDescriptor(DeclOrderInternal.class);
 
+    final BytePatternMatcher configAnnotationMatcher = new BytePatternMatcher(DESC_CONFIG, BytePatternMatcher.Mode.Equals);
+
     @Override
     public String name() {
         return "ConfigOrderTransformer";
@@ -49,17 +53,12 @@ public String owner() {
 
     @Override
     public boolean shouldTransformClass(@NotNull String className, @NotNull ClassNodeHandle classNode) {
-        val cn = classNode.getNode();
-        if (cn == null)
+        final ClassHeaderMetadata metadata = classNode.getOriginalMetadata();
+        if (metadata == null) {
             return false;
-        if (cn.visibleAnnotations != null) {
-            for (val ann : cn.visibleAnnotations) {
-                if (DESC_CONFIG.equals(ann.desc)) {
-                    return true;
-                }
-            }
         }
-        return false;
+
+        return metadata.matchesBytes(configAnnotationMatcher);
     }
 
     @Override
@@ -75,7 +74,9 @@ public boolean transformClass(@NotNull String className, @NotNull ClassNodeHandl
                 || (field.access & Opcodes.ACC_STATIC) == 0
                 || (field.access & Opcodes.ACC_FINAL) != 0) {
                 continue;
-            } else if (field.visibleAnnotations != null) {
+            }
+
+            if (field.visibleAnnotations != null) {
                 for (val ann : field.visibleAnnotations) {
                     if (DESC_CONFIG_IGNORE.equals(ann.desc)) {
                         continue outer;
diff --git a/src/main/java/com/falsepattern/lib/turboasm/BytePatternMatcher.java b/src/main/java/com/falsepattern/lib/turboasm/BytePatternMatcher.java
@@ -0,0 +1,137 @@
+package com.falsepattern.lib.turboasm;
+
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
+
+public class BytePatternMatcher {
+    final Mode mode;
+    // first byte -> matched patterns
+    final byte[][][] byFirst = new byte[256][][];
+    int minPatternLen = Integer.MAX_VALUE;
+
+    public enum Mode {
+        /** Checks if the constant pool entry contains a pattern */
+        Contains,
+        /** Checks if the whole constant pool entry equals a pattern */
+        Equals,
+        /** Checks if the constant pool entry starts with a pattern */
+        StartsWith
+    }
+
+    public BytePatternMatcher(String strPattern, Mode mode) {
+        this(new String[] {strPattern}, mode);
+    }
+
+    public BytePatternMatcher(String[] strPatterns, Mode mode) {
+        this.mode = mode;
+
+        final byte[][] patterns = new byte[strPatterns.length][];
+        final int[] bucketSizes = new int[256];
+        final int[] bucketIndices = new int[Math.min(strPatterns.length, 256)];
+        int bucketsCount = 0;
+
+        for (int i = 0; i < strPatterns.length; i++) {
+            final byte[] pattern = strPatterns[i].getBytes(StandardCharsets.UTF_8);
+            patterns[i] = pattern;
+
+            if (pattern.length < minPatternLen) {
+                minPatternLen = pattern.length;
+            }
+
+            final int bucketIndex = pattern[0] & 0xFF;
+            if (bucketSizes[bucketIndex]++ == 0) {
+                bucketIndices[bucketsCount++] = bucketIndex;
+            }
+        }
+
+        // Ascending sorting by length
+        Arrays.sort(patterns, (a, b) -> Integer.compare(a.length, b.length));
+
+        for (int i = 0; i < bucketsCount; i++) {
+            final int bucketIndex = bucketIndices[i];
+            byFirst[bucketIndex] = new byte[bucketSizes[bucketIndex]][];
+            bucketSizes[bucketIndex] = 0; // reuse as write index
+        }
+
+        for (final byte[] pattern : patterns) {
+            final int bucketIndex = pattern[0] & 0xFF;
+            byFirst[bucketIndex][bucketSizes[bucketIndex]++] = pattern;
+        }
+    }
+
+    public boolean matches(byte[] bytes, int start, int len) {
+        if (len < minPatternLen) {
+            return false;
+        }
+
+        return switch (mode) {
+            case Contains -> contains(bytes, start, len);
+            case Equals -> equals(bytes, start, len);
+            case StartsWith -> startsWith(bytes, start, len);
+        };
+    }
+
+    private boolean contains(byte[] bytes, int start, int len) {
+        final int end = start + len;
+
+        for (int pos = start; pos <= end - minPatternLen; pos++) {
+            final byte[][] patterns = byFirst[bytes[pos] & 0xFF];
+            if (patterns == null) {
+                continue;
+            }
+
+            for (final byte[] pattern : patterns) {
+                if (pattern.length > end - pos) {
+                    break;
+                }
+
+                int k = pattern.length - 1;
+                while (k > 0 && bytes[pos + k] == pattern[k]) k--;
+                if (k == 0) return true;
+            }
+        }
+
+        return false;
+    }
+
+    private boolean equals(byte[] bytes, int start, int len) {
+        final byte[][] patterns = byFirst[bytes[start] & 0xFF];
+        if (patterns == null) {
+            return false;
+        }
+
+        for (final byte[] pattern : patterns) {
+            if (pattern.length < len) {
+                continue;
+            }
+            if (pattern.length > len) {
+                break;
+            }
+
+            int k = pattern.length - 1;
+            while (k > 0 && bytes[start + k] == pattern[k]) k--;
+            if (k == 0) return true;
+        }
+
+        return false;
+    }
+
+    private boolean startsWith(byte[] bytes, int start, int len) {
+        final byte[][] patterns = byFirst[bytes[start] & 0xFF];
+        if (patterns == null) {
+            return false;
+        }
+
+        for (final byte[] pattern : patterns) {
+            if (pattern.length > len) {
+                break;
+            }
+
+            int k = pattern.length - 1;
+            while (k > 0 && bytes[start + k] == pattern[k]) k--;
+            if (k == 0) return true;
+        }
+
+        return false;
+    }
+}
diff --git a/src/main/java/com/falsepattern/lib/turboasm/ClassHeaderMetadata.java b/src/main/java/com/falsepattern/lib/turboasm/ClassHeaderMetadata.java
@@ -31,6 +31,7 @@
 import java.io.DataInputStream;
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 
@@ -39,6 +40,7 @@
  */
 public final class ClassHeaderMetadata implements FastClassAccessor {
 
+    public final byte[] classBytes;
     public final int minorVersion;
     public final int majorVersion;
     public final int constantPoolEntryCount;
@@ -47,6 +49,9 @@ public final class ClassHeaderMetadata implements FastClassAccessor {
     /** Type of each parsed constant pool entry, zero-indexed! */
     public final ConstantPoolEntryTypes @NotNull [] constantPoolEntryTypes;
 
+    /** Approximately only half of the entries are utf-8, so this array can be used to iterate over them more quickly */
+    public final int @NotNull [] constantPoolUtf8EntryOffsets;
+
     public final int constantPoolEndOffset;
     public final int accessFlags;
     public final int thisClassIndex;
@@ -66,15 +71,17 @@ public ClassHeaderMetadata(byte @NotNull [] bytes) {
         if (!isValidClass(bytes)) {
             throw new IllegalArgumentException("Invalid class detected");
         }
+        this.classBytes = bytes;
         this.minorVersion = u16(bytes, Offsets.minorVersionU16);
         this.majorVersion = u16(bytes, Offsets.majorVersionU16);
         this.constantPoolEntryCount = u16(bytes, Offsets.constantPoolCountU16);
         this.constantPoolEntryOffsets = new int[constantPoolEntryCount];
         this.constantPoolEntryTypes = new ConstantPoolEntryTypes[constantPoolEntryCount];
         // scan through CP entries
-        final int cpOff;
         {
             int off = Offsets.constantPoolStart;
+            final int[] utf8EntryOffsets = new int[constantPoolEntryCount];
+            int utf8Entries = 0;
             for (int entry = 0; entry < constantPoolEntryCount - 1; entry++) {
                 constantPoolEntryOffsets[entry] = off;
                 ConstantPoolEntryTypes type = ConstantPoolEntryTypes.parse(bytes, off);
@@ -84,18 +91,18 @@ public ClassHeaderMetadata(byte @NotNull [] bytes) {
                     entry++;
                     constantPoolEntryOffsets[entry] = off;
                     constantPoolEntryTypes[entry] = type;
+                } else if (type == ConstantPoolEntryTypes.Utf8) {
+                    utf8EntryOffsets[utf8Entries++] = off;
                 }
                 off += type.byteLength(bytes, off);
             }
-            cpOff = off;
-            this.constantPoolEndOffset = cpOff;
+            this.constantPoolEndOffset = off;
+            this.constantPoolUtf8EntryOffsets = Arrays.copyOf(utf8EntryOffsets, utf8Entries);
         }
-        this.accessFlags = u16(bytes, cpOff + Offsets.pastCpAccessFlagsU16);
-        this.thisClassIndex = u16(bytes, cpOff + Offsets.pastCpThisClassU16);
-        this.superClassIndex = u16(bytes, cpOff + Offsets.pastCpSuperClassU16);
-        this.interfacesCount = u16(bytes, cpOff + Offsets.pastCpInterfacesCountU16);
-        this.interfaceIndices = new int[this.interfacesCount];
-        List<String> interfaceNames = new ArrayList<>(this.interfacesCount);
+        this.accessFlags = u16(bytes, this.constantPoolEndOffset + Offsets.pastCpAccessFlagsU16);
+        this.thisClassIndex = u16(bytes, this.constantPoolEndOffset + Offsets.pastCpThisClassU16);
+        this.superClassIndex = u16(bytes, this.constantPoolEndOffset + Offsets.pastCpSuperClassU16);
+        this.interfacesCount = u16(bytes, this.constantPoolEndOffset + Offsets.pastCpInterfacesCountU16);
 
         // Parse this&super names
         if (constantPoolEntryTypes[thisClassIndex - 1] != ConstantPoolEntryTypes.Class) {
@@ -121,8 +128,10 @@ public ClassHeaderMetadata(byte @NotNull [] bytes) {
         }
 
         // Parse interface names
+        List<String> interfaceNames = new ArrayList<>(this.interfacesCount);
+        this.interfaceIndices = new int[this.interfacesCount];
         for (int i = 0; i < this.interfacesCount; i++) {
-            final int interfaceOffset = cpOff + Offsets.pastCpInterfacesList + i * 2;
+            final int interfaceOffset = this.constantPoolEndOffset + Offsets.pastCpInterfacesList + i * 2;
             final int interfaceIndex = u16(bytes, interfaceOffset);
             if (constantPoolEntryTypes[interfaceIndex - 1] != ConstantPoolEntryTypes.Class) {
                 throw new IllegalArgumentException("Interface " + i + " index is not a class ref");
@@ -314,11 +323,26 @@ public static int majorVersion(byte @NotNull [] classBytes) {
     }
 
     /**
-     * Searches for a sub"string" (byte array) in a longer byte array. Not efficient for long search strings.
-     * @param classBytes The long byte string to search in.
-     * @param substring The short substring to search for.
-     * @return If the substring was found somewhere in the long string.
+     * Searches for byte patterns in the constant pool.
+     * @param matcher A configured byte matcher with patterns to search for.
+     * @return {@code true} if there is a match for at least one constant pool entry.
      */
+    public boolean matchesBytes(final BytePatternMatcher matcher) {
+        for (final int offset : constantPoolUtf8EntryOffsets) {
+            // first byte is entry type, second and third bytes are length
+            final int length = u16(classBytes, offset + 1);
+            final int start = offset + 3;
+
+            if (matcher.matches(classBytes, start, length)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    /** @deprecated This method is very slow, use {@link #matchesBytes} instead */
+    @Deprecated
     public static boolean hasSubstring(final byte @Nullable [] classBytes, final byte @NotNull [] substring) {
         if (classBytes == null) {
             return false;
