1. 26 Oct, 2018 1 commit
    • Peter Marshall's avatar
      [typedarray] Use fast path for Float32Array.from(float_64_array) and similar · c7c0e110
      Peter Marshall authored
      Currently, because the source float_64_array has an iterator, it hits
      the code in the "check_iterator" section of TypedArrayFrom which calls
      IterableToList. This builds a temporary PACKED_ELEMENTS array (and boxes
      all of the numeric values as HeapNumbers), then uses this as the source
      array.
      
      This patch checks if the source array is a TypedArray, and if the iterator
      is the built-in one (where we know the iterator's behaviour). If both are
      true then it bypasses the creation of this temporary array and uses the
      original TypedArray as the source.
      
      This allows it to take advantage of the existing fast code for copying one
      typed array to another.
      
      R=hablich@chromium.org, petermarshall@chromium.org
      
      Bug: chromium:884671
      Change-Id: I19a944c9d6d5d07699c7dc3ad7196fc871200b62
      Reviewed-on: https://chromium-review.googlesource.com/c/1297312Reviewed-by: 's avatarPeter Marshall <petermarshall@chromium.org>
      Reviewed-by: 's avatarBenedikt Meurer <bmeurer@chromium.org>
      Commit-Queue: Peter Marshall <petermarshall@chromium.org>
      Cr-Commit-Position: refs/heads/master@{#57022}
      c7c0e110