private static boolean removePhiList(MethodNode mth, List<PhiInsn> insnToRemove) {
if (insnToRemove.isEmpty()) {
return false;
}
for (BlockNode block : mth.getBasicBlocks()) {
PhiListAttr phiList = block.get(AType.PHI_LIST);
if (phiList == null) {
continue;
}
List<PhiInsn> list = phiList.getList();
for (PhiInsn phiInsn : insnToRemove) {
if (list.remove(phiInsn)) {
for (InsnArg arg : phiInsn.getArguments()) {
SSAVar sVar = ((RegisterArg) arg).getSVar();
if (sVar != null) {
sVar.setUsedInPhi(null);
}
}
InstructionRemover.remove(mth, block, phiInsn);
}
}
if (list.isEmpty()) {
block.remove(AType.PHI_LIST);
}
}
insnToRemove.clear();
return true;
}
private static void renameVar(MethodNode mth, SSAVar[] vars, int[] vers, BlockNode block) {
SSAVar[] inputVars = Arrays.copyOf(vars, vars.length);
for (InsnNode insn : block.getInstructions()) {
if (insn.getType() != InsnType.PHI) {
for (InsnArg arg : insn.getArguments()) {
if (!arg.isRegister()) {
continue;
}
RegisterArg reg = (RegisterArg) arg;
int regNum = reg.getRegNum();
SSAVar var = vars[regNum];
if (var == null) {
throw new JadxRuntimeException(
"Not initialized variable reg: "
+ regNum
+ ", insn: "
+ insn
+ ", block:"
+ block
+ ", method: "
+ mth);
}
var.use(reg);
}
}
RegisterArg result = insn.getResult();
if (result != null) {
int regNum = result.getRegNum();
vars[regNum] = mth.makeNewSVar(regNum, vers, result);
}
}
for (BlockNode s : block.getSuccessors()) {
PhiListAttr phiList = s.get(AType.PHI_LIST);
if (phiList == null) {
continue;
}
int j = s.getPredecessors().indexOf(block);
if (j == -1) {
throw new JadxRuntimeException("Can't find predecessor for " + block + " " + s);
}
for (PhiInsn phiInsn : phiList.getList()) {
if (j >= phiInsn.getArgsCount()) {
continue;
}
int regNum = phiInsn.getResult().getRegNum();
SSAVar var = vars[regNum];
if (var == null) {
continue;
}
var.use(phiInsn.getArg(j));
var.setUsedInPhi(phiInsn);
}
}
for (BlockNode domOn : block.getDominatesOn()) {
renameVar(mth, vars, vers, domOn);
}
System.arraycopy(inputVars, 0, vars, 0, vars.length);
}
private static boolean removeUselessPhi(MethodNode mth) {
List<PhiInsn> insnToRemove = new ArrayList<PhiInsn>();
for (SSAVar var : mth.getSVars()) {
// phi result not used
if (var.getUseCount() == 0) {
InsnNode assignInsn = var.getAssign().getParentInsn();
if (assignInsn != null && assignInsn.getType() == InsnType.PHI) {
insnToRemove.add((PhiInsn) assignInsn);
}
}
}
for (BlockNode block : mth.getBasicBlocks()) {
PhiListAttr phiList = block.get(AType.PHI_LIST);
if (phiList == null) {
continue;
}
for (PhiInsn phi : phiList.getList()) {
removePhiWithSameArgs(phi, insnToRemove);
}
}
return removePhiList(mth, insnToRemove);
}
private static void removePhiWithSameArgs(PhiInsn phi, List<PhiInsn> insnToRemove) {
if (phi.getArgsCount() <= 1) {
insnToRemove.add(phi);
return;
}
boolean allSame = true;
SSAVar var = phi.getArg(0).getSVar();
for (int i = 1; i < phi.getArgsCount(); i++) {
if (var != phi.getArg(i).getSVar()) {
allSame = false;
break;
}
}
if (allSame) {
// replace
insnToRemove.add(phi);
SSAVar assign = phi.getResult().getSVar();
for (RegisterArg arg : new ArrayList<RegisterArg>(assign.getUseList())) {
assign.removeUse(arg);
var.use(arg);
}
}
}