package jadx.core.dex.visitors.regions;
import jadx.core.dex.attributes.AFlag;
import jadx.core.dex.instructions.args.ArgType;
import jadx.core.dex.nodes.IBlock;
import jadx.core.dex.nodes.IContainer;
import jadx.core.dex.nodes.IRegion;
import jadx.core.dex.nodes.MethodNode;
import jadx.core.dex.regions.Region;
import jadx.core.dex.regions.conditions.IfCondition;
import jadx.core.dex.regions.conditions.IfCondition.Mode;
import jadx.core.dex.regions.conditions.IfRegion;
import jadx.core.dex.visitors.AbstractVisitor;
import jadx.core.utils.RegionUtils;
import java.util.List;
import static jadx.core.utils.RegionUtils.insnsCount;
public class IfRegionVisitor extends AbstractVisitor implements IRegionVisitor, IRegionIterativeVisitor {
@Override
public void visit(MethodNode mth) {
// collapse ternary operators
DepthRegionTraversal.traverseAllIterative(mth, new IRegionIterativeVisitor() {
@Override
public boolean visitRegion(MethodNode mth, IRegion region) {
if (region instanceof IfRegion) {
return TernaryMod.makeTernaryInsn(mth, (IfRegion) region);
}
return false;
}
});
DepthRegionTraversal.traverseAll(mth, this);
DepthRegionTraversal.traverseAllIterative(mth, this);
}
@Override
public void enterRegion(MethodNode mth, IRegion region) {
if (region instanceof IfRegion) {
processIfRegion(mth, (IfRegion) region);
}
}
@Override
public boolean visitRegion(MethodNode mth, IRegion region) {
if (region instanceof IfRegion) {
return removeRedundantElseBlock(mth, (IfRegion) region);
}
return false;
}
@Override
public void processBlock(MethodNode mth, IBlock container) {
}
@Override
public void leaveRegion(MethodNode mth, IRegion region) {
}
private static void processIfRegion(MethodNode mth, IfRegion ifRegion) {
simplifyIfCondition(ifRegion);
moveReturnToThenBlock(mth, ifRegion);
moveBreakToThenBlock(ifRegion);
markElseIfChains(ifRegion);
}
private static void simplifyIfCondition(IfRegion ifRegion) {
if (ifRegion.simplifyCondition()) {
IfCondition condition = ifRegion.getCondition();
if (condition.getMode() == Mode.NOT) {
invertIfRegion(ifRegion);
}
}
IContainer elseRegion = ifRegion.getElseRegion();
if (elseRegion == null || RegionUtils.isEmpty(elseRegion)) {
return;
}
boolean thenIsEmpty = RegionUtils.isEmpty(ifRegion.getThenRegion());
if (thenIsEmpty || hasSimpleReturnBlock(ifRegion.getThenRegion())) {
invertIfRegion(ifRegion);
}
if (!thenIsEmpty) {
// move 'if' from then to make 'else if' chain
if (isIfRegion(ifRegion.getThenRegion())
&& !isIfRegion(elseRegion)) {
invertIfRegion(ifRegion);
}
}
}
private static boolean isIfRegion(IContainer container) {
if (container instanceof IfRegion) {
return true;
}
if (container instanceof IRegion) {
List<IContainer> subBlocks = ((IRegion) container).getSubBlocks();
if (subBlocks.size() == 1 && subBlocks.get(0) instanceof IfRegion) {
return true;
}
}
return false;
}
private static void moveReturnToThenBlock(MethodNode mth, IfRegion ifRegion) {
if (!mth.getReturnType().equals(ArgType.VOID)
&& hasSimpleReturnBlock(ifRegion.getElseRegion())
/*&& insnsCount(ifRegion.getThenRegion()) < 2*/) {
invertIfRegion(ifRegion);
}
}
private static void moveBreakToThenBlock(IfRegion ifRegion) {
if (ifRegion.getElseRegion() != null
&& RegionUtils.hasBreakInsn(ifRegion.getElseRegion())) {
invertIfRegion(ifRegion);
}
}
/**
* Mark if-else-if chains
*/
private static void markElseIfChains(IfRegion ifRegion) {
if (hasSimpleReturnBlock(ifRegion.getThenRegion())) {
return;
}
IContainer elsRegion = ifRegion.getElseRegion();
if (elsRegion instanceof Region) {
List<IContainer> subBlocks = ((Region) elsRegion).getSubBlocks();
if (subBlocks.size() == 1 && subBlocks.get(0) instanceof IfRegion) {
subBlocks.get(0).add(AFlag.ELSE_IF_CHAIN);
elsRegion.add(AFlag.ELSE_IF_CHAIN);
}
}
}
private static boolean removeRedundantElseBlock(MethodNode mth, IfRegion ifRegion) {
if (ifRegion.getElseRegion() == null
|| ifRegion.contains(AFlag.ELSE_IF_CHAIN)
|| ifRegion.getElseRegion().contains(AFlag.ELSE_IF_CHAIN)) {
return false;
}
if (!hasBranchTerminator(ifRegion.getThenRegion())) {
return false;
}
// code style check:
// will remove 'return;' from 'then' and 'else' with one instruction
// see #jadx.tests.integration.conditions.TestConditions9
if (mth.getReturnType() == ArgType.VOID
&& insnsCount(ifRegion.getThenRegion()) == 2
&& insnsCount(ifRegion.getElseRegion()) == 2) {
return false;
}
IRegion parent = ifRegion.getParent();
Region newRegion = new Region(parent);
if (parent.replaceSubBlock(ifRegion, newRegion)) {
newRegion.add(ifRegion);
newRegion.add(ifRegion.getElseRegion());
ifRegion.setElseRegion(null);
return true;
}
return false;
}
private static boolean hasBranchTerminator(IContainer region) {
// TODO: check for exception throw
return RegionUtils.hasExitBlock(region)
|| RegionUtils.hasBreakInsn(region);
}
private static void invertIfRegion(IfRegion ifRegion) {
IContainer elseRegion = ifRegion.getElseRegion();
if (elseRegion != null) {
ifRegion.invert();
}
}
private static boolean hasSimpleReturnBlock(IContainer region) {
if (region == null) {
return false;
}
if (region.contains(AFlag.RETURN)) {
return true;
}
if (region instanceof IRegion) {
List<IContainer> subBlocks = ((IRegion) region).getSubBlocks();
return subBlocks.size() == 1 && subBlocks.get(0).contains(AFlag.RETURN);
}
return false;
}
}