[GROOVY-11309] Optimise bytecode for empty list expressions

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 2.5.23, 3.0.20, 4.0.18, 5.0.0-alpha-5
• Component/s: class generator, Compiler, performance

Language

groovy

• Assignee: Unassigned
• Reporter: Oscar N
• Created: 07/Feb/24 21:17
• Updated: 20/Feb/24 04:00

Description

I have the following code:

class Book {
    String title
    String blurb = ''
    List<String> authors = []
}

When checking the compiled output, the creation of the empty list goes through ScriptBytecodeAdapter:

@Generated
public Book() {
    String var1 = "";
    this.blurb = var1;
    List var2 = ScriptBytecodeAdapter.createList(new Object[0]);
    this.authors = var2;
    MetaClass var3 = this.$getStaticMetaClass();
    this.metaClass = var3;
}

This case can be simplified to "List var2 = new ArrayList()", which would avoid some overhead and slightly improve @POJO support.

Issue Links

• links to: GitHub Pull Request #2054