1973117 - Use packed elements check for StoreDenseElement

Status: ASSIGNED

(Core :: JavaScript Engine: JIT, task, P2)

Description

[Iain Ireland [:iain]]

In bug 1971446, we remove some hole checks from dense element access by instead checking the packed elements flag, which can be hoisted out of a loop. Jan pointed out that making a similar change to MStoreElement might help us common up even more checks.

Comment 1

[Iain Ireland [:iain]]

My quick prototype indicates that this is about a 20% improvement on a microbenchmark like this:

function foo(arr) {
  for (var i = 0; i < arr.length; i++) {
    arr[i] += 1;
  }
}

Comment 2

[Iain Ireland [:iain]]

Attachment: Bug 1973117: Support packed elements check for StoreDenseElement r=jandem