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How to add new instruction with dexlib2?


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I try to add new instruction,

// old

const/v4 v?, 0x0

// new

const/v4 v?, 0x0
const-string v?, "Hello" // new instruction

can someone help me, adding instruction without duplicate register number?

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I try with this code:

private static MethodImplementation addNewInstructions(@Nonnull MethodImplementation implementation) {

		MutableMethodImplementation mutableImplementation = new MutableMethodImplementation(implementation);

		List<BuilderInstruction> instructions = mutableImplementation.getInstructions();
		for (int i = 0; i < instructions.size(); i++) {
			Instruction instruction = instructions.get(i);
			if (instruction instanceof ReferenceInstruction) {

				if (((ReferenceInstruction) instruction).getReferenceType() == ReferenceType.METHOD) {

					Opcode opcode = instruction.getOpcode();

					if (!opcode.name.endsWith("range")) {
						mutableImplementation.addInstruction(i++, new BuilderInstruction21c(Opcode.CONST_STRING,
								0, new ImmutableStringReference("Hello World"))); // look

		return mutableImplementation;

after :

// before

.line 54
iget-object v0, p0, Lapp/test/MainActivity;->ed:Landroid/widget/TextView;

// after

.line 54
iget-object v0, p0, Lapp/test/MainActivity;->ed:Landroid/widget/TextView; // v0 already register

const-string v0, "Hello World" // v0 duplicate register

If i storing a new value in it, I'll be clobbering any value that was already there, and later code that expects the previous value will likely fail.

Edited by Modify
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