1. 21 Dec, 2021 1 commit
    • Leszek Swirski's avatar
      [compiler] Share liveness across straight-line bytecode · 4465c321
      Leszek Swirski authored
      Straight-line bytecode with exactly one "next" bytecode (i.e. everything
      that can't affect control flow) will always have the same "out" liveness
      as the next bytecode's "in" liveness. For those cases, we can save a bit
      of time and memory by aliasing the pointers between the bytecode's out
      liveness and the next bytecode's in liveness, and skipping copying
      between them.
      
      This is done by specializing the current liveness update on whether this
      is the first pass (which will allocate and initialize the liveness
      bitvectors) or an update pass (which will revisit loops to collect
      liveness crossing over the back-edge, and propagate this liveness
      through the loop bodies). On the first pass, we can delay allocation of
      the out liveness until we know it needs to be union of multiple in
      livenesses, and on the update pass we can skip it if it is an alias.
      
      As a drive-by, tweak BitVector::CopyFrom to require copying from a
      vector with the same size (same as Union or Intersect), and move the
      only different sized vector use (in Resize) to be inline.
      
      Change-Id: Iad1b2e1b927a37ad925ef68e2a224152aaa2ba18
      Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3350452
      Auto-Submit: Leszek Swirski <leszeks@chromium.org>
      Reviewed-by: 's avatarMaya Lekova <mslekova@chromium.org>
      Commit-Queue: Maya Lekova <mslekova@chromium.org>
      Cr-Commit-Position: refs/heads/main@{#78425}
      4465c321
  2. 15 Jul, 2020 1 commit
  3. 10 Jul, 2020 1 commit
  4. 08 Dec, 2016 1 commit
  5. 29 Nov, 2016 3 commits