core: remove redundant parenthesis for arithmetic operations

jadx-core/src/main/java/jadx/core/codegen/InsnGen.java

@@ -720,22 +720,19 @@ public class InsnGen {
 	}
 
 	private void makeArith(ArithNode insn, CodeWriter code, EnumSet<Flags> state) throws CodegenException {
-		ArithOp op = insn.getOp();
-		if (state.contains(Flags.BODY_ONLY)) {
-			// wrap insn in brackets for save correct operation order
+		// wrap insn in brackets for save correct operation order
+		boolean wrap = state.contains(Flags.BODY_ONLY)
+				&& !insn.getAttributes().contains(AttributeFlag.DONT_WRAP);
+		if (wrap) {
 			code.add('(');
-			addArg(code, insn.getArg(0));
-			code.add(' ');
-			code.add(op.getSymbol());
-			code.add(' ');
-			addArg(code, insn.getArg(1));
+		}
+		addArg(code, insn.getArg(0));
+		code.add(' ');
+		code.add(insn.getOp().getSymbol());
+		code.add(' ');
+		addArg(code, insn.getArg(1));
+		if (wrap) {
 			code.add(')');
-		} else {
-			addArg(code, insn.getArg(0));
-			code.add(' ');
-			code.add(op.getSymbol());
-			code.add(' ');
-			addArg(code, insn.getArg(1));
 		}
 	}
 

jadx-core/src/main/java/jadx/core/dex/attributes/AttributeFlag.java

@@ -13,6 +13,7 @@ public enum AttributeFlag {
 	RETURN, // block contains only return instruction
 
 	DECLARE_VAR,
+	DONT_WRAP,
 
 	DONT_SHRINK,
 	DONT_GENERATE,

jadx-core/src/main/java/jadx/core/dex/visitors/PrepareForCodeGen.java

 package jadx.core.dex.visitors;
 
+import jadx.core.dex.attributes.AttributeFlag;
 import jadx.core.dex.instructions.ArithNode;
+import jadx.core.dex.instructions.ArithOp;
 import jadx.core.dex.instructions.InsnType;
 import jadx.core.dex.instructions.args.InsnArg;
+import jadx.core.dex.instructions.args.InsnWrapArg;
 import jadx.core.dex.instructions.args.RegisterArg;
 import jadx.core.dex.instructions.mods.ConstructorInsn;
 import jadx.core.dex.nodes.BlockNode;
@@ -23,6 +26,7 @@ public class PrepareForCodeGen extends AbstractVisitor {
 		}
 		for (BlockNode block : blocks) {
 			removeInstructions(block);
+			removeBrackets(block);
 			modifyArith(block);
 		}
 	}
@@ -48,6 +52,36 @@ public class PrepareForCodeGen extends AbstractVisitor {
 		}
 	}
 
+	private static void removeBrackets(BlockNode block) {
+		for (InsnNode insn : block.getInstructions()) {
+			checkInsn(insn);
+		}
+	}
+
+	private static void checkInsn(InsnNode insn) {
+		if (insn.getType() == InsnType.ARITH) {
+			ArithNode arith = (ArithNode) insn;
+			ArithOp op = arith.getOp();
+			if (op == ArithOp.ADD || op == ArithOp.SUB) {
+				for (int i = 0; i < 2; i++) {
+					InsnArg arg = arith.getArg(i);
+					if (arg.isInsnWrap()) {
+						InsnNode wrapInsn = ((InsnWrapArg) arg).getWrapInsn();
+						wrapInsn.getAttributes().add(AttributeFlag.DONT_WRAP);
+						checkInsn(wrapInsn);
+					}
+				}
+			}
+		} else {
+			for (InsnArg arg : insn.getArguments()) {
+				if (arg.isInsnWrap()) {
+					InsnNode wrapInsn = ((InsnWrapArg) arg).getWrapInsn();
+					checkInsn(wrapInsn);
+				}
+			}
+		}
+	}
+
 	private static void modifyArith(BlockNode block) {
 		List<InsnNode> list = block.getInstructions();
 		for (int i = 0; i < list.size(); i++) {

jadx-core/src/test/java/jadx/tests/internal/arith/TestArith2.java

@@ -16,6 +16,10 @@ public class TestArith2 extends InternalJadxTest {
 		public int test1(int a) {
 			return (a + 2) * 3;
 		}
+
+		public int test2(int a, int b, int c) {
+			return a + b + c;
+		}
 	}
 
 	@Test
@@ -26,5 +30,8 @@ public class TestArith2 extends InternalJadxTest {
 
 		assertThat(code, containsString("return (a + 2) * 3;"));
 		assertThat(code, not(containsString("a + 2 * 3")));
+
+		assertThat(code, containsString("return a + b + c;"));
+		assertThat(code, not(containsString("return (a + b) + c;")));
 	}
 }