941760 - Handle conditional initialization in definite properties analysis

Status: RESOLVED INCOMPLETE

(Core :: JavaScript Engine: JIT, defect, P3)

Description

[Brian Hackett [Laid off!]]

When analyzing new properties in functions like the following:

function Foo(x) {
  if (x)
    this.f = 0;
  else
    this.f = 1;
}
new Foo(...);

The resulting type won't have any definite properties since Foo's new property isn't added in code that is definitely executed.  |f| will, however, definitely be added taking both branches of the |if| into account.  It would be nice to handle this case; it both seems realistic to encounter and happens in the octane richards benchmark.  Tweaking that benchmark so that the property becomes definite increases our score by 1000 points (23k -> 24k) so this seems like an easy win.

Comment 1

[André Bargull [:anba]]

Definite properties analysis has been removed.