Col-E/SimAnalyzer

Instruction tracking does not include void calls on objects

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#3 opened on Jul 30, 2020

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Description

Given the following example:

NEW Type
DUP
INVOKESPECIAL Type.<init>()V
INVOKEVOID Type.enableThing()V
ASTORE t
ALOAD t
ARETURN

The tracked instructions will not include the constructor or void call.

  • Type.<init>()V
  • Type.enableThing()V

This is not a clear edge-case fix since ASM tosses values of invoke calls that return void. This is done in Frame#executeInvokeInsn(...)

  private void executeInvokeInsn(AbstractInsnNode insn, final String desc, final Interpreter<V> interpreter) {
// ... snip
    if (Type.getReturnType(methodDescriptor) == Type.VOID_TYPE) {
      interpreter.naryOperation(insn, valueList);
    } else {
      push(interpreter.naryOperation(insn, valueList));
    }
  }

There is a test case that asserts the current behavior: TestInstructionTracking

Contributor guide

Research direction
Examine the Frame#executeInvokeInsn method in ASM's analysis package to understand how void return types are handled. Then modify the instruction tracking logic to include void method calls and constructor invocations. Update the test case in TestInstructionTracking to verify the new behavior.
Tech stack
java
Domain
tooling
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
JavaASM
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70