1. 23 Jun, 2021 1 commit
    • Mihir Shah's avatar
      A jump-table implementation for constant case switch statements · 9711289d
      Mihir Shah authored
      The change is made since for switch statements with lots of cases,
      where each case is a constant integer, the emitted bytecode is still
      a series of jumps, when we can instead use a jump table.
      
      If there are 6 or more cases (similar to GCC) of Smi literals, and
      if the max Smi case minus the min Smi case is not more than 3 times
      the number of cases, we use a jump table up front to handle Smi's,
      and then use traditional if-else logic for the rest of the cases.
      
      We then use the jump table in interpreter/bytecode-jump-table to
      do the optimization.
      
      This tries to go off issue 9738 in v8's issue tracker. It is not
      exactly the same, since that recommends doing the work at JIT-time,
      but has similar ideas. It also partially goes off issue 10764.
      
      Bug: v8:9738
      Change-Id: Ic805682ee3abf9ce464bb733b427fa0c83a6e10c
      Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2904926Reviewed-by: 's avatarLeszek Swirski <leszeks@chromium.org>
      Commit-Queue: Leszek Swirski <leszeks@chromium.org>
      Cr-Commit-Position: refs/heads/master@{#75323}
      9711289d