com.googlecode.dex2jar.ir.ts.EndRemover Maven / Gradle / Ivy
package com.googlecode.dex2jar.ir.ts;
import com.googlecode.dex2jar.ir.IrMethod;
import com.googlecode.dex2jar.ir.LabelAndLocalMapper;
import com.googlecode.dex2jar.ir.Trap;
import com.googlecode.dex2jar.ir.expr.Local;
import com.googlecode.dex2jar.ir.stmt.*;
import com.googlecode.dex2jar.ir.stmt.Stmt.ST;
import java.util.ArrayList;
/**
* Try to clean following between a {@link Trap}
*
* - Move {@link Stmt}s outside a {@link Trap} if {@link Stmt}s are not throw
* - Remove {@link Trap} if all {@link Stmt}s are not throw
* - ...;GOTO L2; ... ; L2: ; return; => ...;return ; ... ; L2: ; return;
*
*
* @author bob
*
*/
public class EndRemover implements Transformer {
private static final LabelAndLocalMapper keepLocal = new LabelAndLocalMapper() {
@Override
public Local map(Local local) {
return local;
}
};
@Override
public void transform(IrMethod irMethod) {
for (Trap trap : new ArrayList(irMethod.traps)) {// copy the list and we can remove one from original list
LabelStmt start = null;
boolean removeTrap = true;
for (Stmt p = trap.start.getNext(); p != null && p != trap.end;) {
boolean notThrow = Cfg.notThrow(p);
if (!notThrow) {
start = null;
p = p.getNext();
removeTrap = false;
continue;
}
switch (p.st) {
case LABEL:
if (start != null) {
move4Label(irMethod.stmts, start, p.getPre(), (LabelStmt) p);
}
start = (LabelStmt) p;
p = p.getNext();
break;
case GOTO:
case RETURN:
case RETURN_VOID:
if (start != null) {
Stmt tmp = p.getNext();
move4End(irMethod.stmts, start, p);
start = null;
p = tmp;
} else {
p = p.getNext();
}
break;
default:
p = p.getNext();
}
}
if (removeTrap) {
irMethod.traps.remove(trap);
}
}
StmtList stmts = irMethod.stmts;
for (Stmt p = stmts.getFirst(); p != null; p = p.getNext()) {
if (p.st == ST.GOTO) {
LabelStmt target = ((GotoStmt) p).target;
Stmt next = target.getNext();
if (next != null && (next.st == ST.RETURN || next.st == ST.RETURN_VOID)) {
Stmt nnext = next.clone(keepLocal);
stmts.insertAfter(p, nnext);
stmts.remove(p);
p = nnext;
}
}
}
}
private void move4Label(StmtList stmts, LabelStmt start, Stmt end, LabelStmt label) {
move4End(stmts, start, end);
stmts.insertAfter(end, Stmts.nGoto(label));
}
private void move4End(StmtList stmts, LabelStmt start, Stmt end) {
Stmt g1 = Stmts.nGoto(start);
stmts.insertBefore(start, g1);
Stmt last = stmts.getLast();
while (last.st == ST.GOTO && ((GotoStmt) last).target == start) {
stmts.remove(last);
last = stmts.getLast();
}
stmts.move(start, end, last);
}
}