[GROOVY-11288] Unnecessary bytecode generated after variable assignment

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 2.5.23, 3.0.20, 5.0.0-alpha-4, 4.0.17
• Component/s: bytecode, Compiler

Language

groovy

• Assignee: Unassigned
• Reporter: Oscar N
• Created: 18/Jan/24 15:08
• Updated: 18/Jan/24 20:22

Description

I have the following code:

package org.example

import groovy.transform.CompileStatic

@CompileStatic
final class Main {
    static void main(String[] args) {
        int three = 3
        String str = 'foo'
    }
}

When looking at the compiled output, the variable is loaded and immediately popped after storing:

// access flags 0x89
public static varargs main([Ljava/lang/String;)V
 L0
  LINENUMBER 8 L0
  ICONST_3
  ISTORE 1
 L1
  ILOAD 1
  POP
 L2
  LINENUMBER 9 L2
  LDC "foo"
  ASTORE 2
 L3
  ALOAD 2
  POP
 L4
  LINENUMBER 10 L4
  RETURN
  LOCALVARIABLE args [Ljava/lang/String; L0 L4 0
  LOCALVARIABLE three I L1 L4 1
  LOCALVARIABLE str Ljava/lang/String; L3 L4 2
  MAXSTACK = 1
  MAXLOCALS = 3

This issue also occurs in dynamic compilation mode.