commit d3f74c985350ae7820f9c5293235a0eeae2a8424
author Benedikt Meurer <bmeurer@chromium.org> Mon Oct 29 19:34:46 2018
committer Commit Bot <commit-bot@chromium.org> Tue Oct 30 09:11:57 2018
tree 83316cac6a8813490086f55ed801fe46477ba0fa
parent 738c2a9fc65efbec42e16274ea92a6291acf0994

[turbofan] Enable loop peeling for various higher-order Array builtins.

This adds appropriate LoopExit nodes for the JSCallReducer lowerings of
the following higher order Array builtins:

  - Array.prototype.every()
  - Array.prototype.find()
  - Array.prototype.findIndex()
  - Array.prototype.some()

Loop peeling allows TurboFan to make loop invariant operations in the
callback passed to the higher order builtin fully redundant, and thus
completely eliminate the loop invariant code from the subsequent loop
iterations. This can have a huge performance impact, depending on what
kind of code runs inside of the callback. For example, on the micro-
benchmarks outlined in http://crbug.com/v8/8273 we go from

  forLoop: 364 ms.
  every: 443 ms.
  some: 432 ms.
  find: 522 ms.
  findIndex: 437 ms.

to

  forLoop: 369 ms.
  every: 354 ms.
  some: 348 ms.
  find: 419 ms.
  findIndex: 360 ms.

which is 20% improvement, and essentially brings the Array builtins (the
appropriate ones Array#some() and Array#every() in this case) on par
with the hand-written `for`-loop.

Bug: v8:1956, v8:8273
Change-Id: I9d32736e5402807b4ac79cd5ad15ceacd1945681
Reviewed-on: https://chromium-review.googlesource.com/c/1305935
Reviewed-by: Daniel Clifford <danno@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57110}