feat(vm): [Phase 1 & 2] Dalvik VM interpreter — Interpreter Basic & Core Instruction Set Support

[haeter525]

Key Changes

Phase 1 - Interpreter Basic

Execution Engine

• engine.py: DalvikVM main loop with call-frame stack and invoke handling
• errors.py: DalvikVM runtime error types
• cmd_run.py: new dextrace run subcommand to run the Dalvik VM interpreter
• _io.py: shared DEX/APK loader; handles APK with missing classes.dex and malformed DEX input

Register File

• register_file.py: Dalvik register file (v0–v15) with bounds checking
• int_ops.py: integer arithmetic with overflow semantics

Call Stack & Frame

• call_frame.py: per-call register snapshot/restore for callee isolation
• state.py: VMState dataclass with pending_result lifecycle for invoke/move-result

Phase 2 - Core Instruction Set Support

• handlers/: arithmetic, array, branch, compare, field, move, type_conv opcode handlers

How to use

Installation

git clone -b android_emulator_enhance https://github.com/haeter525/DexTrace.git
cd DexTrace
pip install -e .

Phase 1 — execute const/16 v0, #42 → return-void

$ dextrace run tests/fixtures/samples/p1_const_return.dex --entry 'Lp1;->main()V' --dump-regs
return: void
registers: v0=42

• the register value v0 should be 42
• the return value should be void

Phase 2 — execute recursive Fibonacci

$ dextrace run tests/fixtures/samples/p2_fib_recursive.dex --entry 'Lp2/Fib;->fib(I)I' --arg 10
return: 55

• the return value should be 55

Tests

• All tests pass: pytest tests
• Phase 1 and Phase 2 commands above produce the expected output