Add AddSubTransformer

deob-ast/src/main/java/dev/openrs2/deob/ast/AstDeobfuscator.java

@@ -12,6 +12,7 @@ import com.github.javaparser.symbolsolver.resolution.typesolvers.JavaParserTypeS
 import com.github.javaparser.symbolsolver.resolution.typesolvers.ReflectionTypeSolver;
 import com.github.javaparser.utils.SourceRoot;
 import com.google.common.collect.ImmutableList;
+import dev.openrs2.deob.ast.transform.AddSubTransformer;
 import dev.openrs2.deob.ast.transform.BinaryExprOrderTransformer;
 import dev.openrs2.deob.ast.transform.ComplementTransformer;
 import dev.openrs2.deob.ast.transform.IfElseTransformer;
@@ -23,7 +24,8 @@ public final class AstDeobfuscator {
 		new NegativeLiteralTransformer(),
 		new ComplementTransformer(),
 		new IfElseTransformer(),
-		new BinaryExprOrderTransformer()
+		new BinaryExprOrderTransformer(),
+		new AddSubTransformer()
 	);
 
 	public static void main(String[] args) {

deob-ast/src/main/java/dev/openrs2/deob/ast/transform/AddSubTransformer.java

@@ -0,0 +1,51 @@
+package dev.openrs2.deob.ast.transform;
+
+import com.github.javaparser.ast.CompilationUnit;
+import com.github.javaparser.ast.Node;
+import com.github.javaparser.ast.expr.BinaryExpr;
+import com.github.javaparser.ast.expr.Expression;
+import com.github.javaparser.ast.expr.UnaryExpr;
+import dev.openrs2.deob.ast.util.ExprUtils;
+import dev.openrs2.deob.ast.util.NodeUtils;
+import dev.openrs2.deob.ast.util.TypeUtils;
+
+public final class AddSubTransformer extends Transformer {
+	private static boolean isNegative(Expression expr) {
+		if (expr.isUnaryExpr()) {
+			return expr.asUnaryExpr().getOperator() == UnaryExpr.Operator.MINUS;
+		} else if (expr.isIntegerLiteralExpr()) {
+			return expr.asIntegerLiteralExpr().asInt() < 0;
+		} else if (expr.isLongLiteralExpr()) {
+			return expr.asLongLiteralExpr().asLong() < 0;
+		} else {
+			return false;
+		}
+	}
+
+	@Override
+	public void transform(CompilationUnit unit) {
+		NodeUtils.walk(unit, Node.TreeTraversal.POSTORDER, BinaryExpr.class, expr -> {
+			var op = expr.getOperator();
+			var left = expr.getLeft();
+			var right = expr.getRight();
+
+			var type = expr.calculateResolvedType();
+			if (op == BinaryExpr.Operator.PLUS && TypeUtils.isString(type)) {
+				return;
+			}
+
+			if (op == BinaryExpr.Operator.PLUS && isNegative(right)) {
+				/* x + -y => x - y */
+				expr.setOperator(BinaryExpr.Operator.MINUS);
+				expr.setRight(ExprUtils.negate(right));
+			} else if (op == BinaryExpr.Operator.PLUS && isNegative(left)) {
+				/* -x + y => y - x */
+				// TODO(gpe): check for side effects before applying this transform
+			} else if (op == BinaryExpr.Operator.MINUS && isNegative(right)) {
+				/* x - -y => x + y */
+				expr.setOperator(BinaryExpr.Operator.PLUS);
+				expr.setRight(ExprUtils.negate(right));
+			}
+		});
+	}
+}

deob-ast/src/main/java/dev/openrs2/deob/ast/transform/BinaryExprOrderTransformer.java

@@ -5,8 +5,8 @@ import java.util.Optional;
 import com.github.javaparser.ast.CompilationUnit;
 import com.github.javaparser.ast.Node;
 import com.github.javaparser.ast.expr.BinaryExpr;
-import com.github.javaparser.resolution.types.ResolvedType;
 import dev.openrs2.deob.ast.util.NodeUtils;
+import dev.openrs2.deob.ast.util.TypeUtils;
 
 public final class BinaryExprOrderTransformer extends Transformer {
 	private static Optional<BinaryExpr.Operator> flip(BinaryExpr.Operator op) {
@@ -34,16 +34,12 @@ public final class BinaryExprOrderTransformer extends Transformer {
 		}
 	}
 
-	private static boolean isString(ResolvedType type) {
-		return type.isReferenceType() && type.asReferenceType().getQualifiedName().equals("java.lang.String");
-	}
-
 	@Override
 	public void transform(CompilationUnit unit) {
 		NodeUtils.walk(unit, Node.TreeTraversal.POSTORDER, BinaryExpr.class, expr -> {
 			flip(expr.getOperator()).ifPresent(op -> {
 				var type = expr.calculateResolvedType();
-				if (op == BinaryExpr.Operator.PLUS && isString(type)) {
+				if (op == BinaryExpr.Operator.PLUS && TypeUtils.isString(type)) {
 					return;
 				}
 

deob-ast/src/main/java/dev/openrs2/deob/ast/transform/NegativeLiteralTransformer.java

@@ -1,22 +1,10 @@
 package dev.openrs2.deob.ast.transform;
 
 import com.github.javaparser.ast.CompilationUnit;
-import com.github.javaparser.ast.expr.Expression;
-import com.github.javaparser.ast.expr.IntegerLiteralExpr;
 import com.github.javaparser.ast.expr.UnaryExpr;
 import dev.openrs2.deob.ast.util.ExprUtils;
 
 public final class NegativeLiteralTransformer extends Transformer {
-	private static Expression negate(Expression expr) {
-		if (expr.isIntegerLiteralExpr()) {
-			return new IntegerLiteralExpr(-expr.asIntegerLiteralExpr().asInt());
-		} else if (expr.isLongLiteralExpr()) {
-			return ExprUtils.createLong(-expr.asLongLiteralExpr().asLong());
-		} else {
-			throw new IllegalArgumentException();
-		}
-	}
-
 	@Override
 	public void transform(CompilationUnit unit) {
 		unit.findAll(UnaryExpr.class).forEach(expr -> {
@@ -29,7 +17,7 @@ public final class NegativeLiteralTransformer extends Transformer {
 			if (op == UnaryExpr.Operator.PLUS) {
 				expr.replace(operand);
 			} else if (op == UnaryExpr.Operator.MINUS) {
-				expr.replace(negate(operand));
+				expr.replace(ExprUtils.negate(operand));
 			}
 		});
 	}

deob-ast/src/main/java/dev/openrs2/deob/ast/util/ExprUtils.java

@@ -1,7 +1,9 @@
 package dev.openrs2.deob.ast.util;
 
 import com.github.javaparser.ast.expr.Expression;
+import com.github.javaparser.ast.expr.IntegerLiteralExpr;
 import com.github.javaparser.ast.expr.LongLiteralExpr;
+import com.github.javaparser.ast.expr.UnaryExpr;
 
 public final class ExprUtils {
 	public static boolean isIntegerOrLongLiteral(Expression expr) {
@@ -12,6 +14,18 @@ public final class ExprUtils {
 		return new LongLiteralExpr(Long.toString(value).concat("L"));
 	}
 
+	public static Expression negate(Expression expr) {
+		if (expr.isUnaryExpr() && expr.asUnaryExpr().getOperator() == UnaryExpr.Operator.MINUS) {
+			return expr.asUnaryExpr().getExpression().clone();
+		} else if (expr.isIntegerLiteralExpr()) {
+			return new IntegerLiteralExpr(-expr.asIntegerLiteralExpr().asInt());
+		} else if (expr.isLongLiteralExpr()) {
+			return createLong(-expr.asLongLiteralExpr().asLong());
+		} else {
+			throw new IllegalArgumentException();
+		}
+	}
+
 	private ExprUtils() {
 		/* empty */
 	}

deob-ast/src/main/java/dev/openrs2/deob/ast/util/TypeUtils.java

@@ -0,0 +1,13 @@
+package dev.openrs2.deob.ast.util;
+
+import com.github.javaparser.resolution.types.ResolvedType;
+
+public final class TypeUtils {
+	public static boolean isString(ResolvedType type) {
+		return type.isReferenceType() && type.asReferenceType().getQualifiedName().equals("java.lang.String");
+	}
+
+	private TypeUtils() {
+		/* empty */
+	}
+}