1. 05 May, 2022 1 commit
    • Caitlin Potter's avatar
      [js-perf-test] add microbenchmarks for (Object|Reflect).getOwnPropertyDescriptor · 190128ce
      Caitlin Potter authored
      Based on the robust test suite for checking property "has/in" queries, with the intention
      of measuring the performance of accessing getOwnPropertyDescriptor.
      
      Background: getOwnPropertyDescriptor and defineProperty were identified as hot code taking up
      a significant chunk of startup time in a customer application. This benchmark aims to measure
      the difference made by a modifying Object.getOwnPropertyDescriptor.
      
      By current measurements, the geometric mean time of the new version is typically 1/6 that of
      the current upstream implementation, using this test specifically (however, only on arm64 /
      Apple M1... On Linux/x64, the results look more reasonable at a roughly 5-12% improvement in
      score).
      
      In its current form, this benchmark does very little to attempt to verify the results of the
      object, which may result in branches being discarded in Turbofan (but given the enormous
      difference between x64 and arm64, I'm not positive this is what is happening, and have not yet
      verified this).
      
      BUG=
      
      Change-Id: I0f10735315313ed97efd00fcccaedc1272d4d314
      Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3624979
      Commit-Queue: Caitlin Potter <caitp@igalia.com>
      Reviewed-by: 's avatarToon Verwaest <verwaest@chromium.org>
      Cr-Commit-Position: refs/heads/main@{#80373}
      190128ce