• Benedikt Meurer's avatar
    [builtins] Optimize PromiseResolveThenableJob for the common case. · 1f8dcc5d
    Benedikt Meurer authored
    The idea here is that in case the `thenable` is a JSPromise and `then`
    is the initial `Promise.prototype.then` method, and the @@species lookup
    chain is intact, we can skip creating the temporary promise and the
    closures (with the shared context), and instead directly call into our
    PerformPromiseThen. This is sound since - given above mentioned
    conditions - our short-cut
    
      PerformPromiseThen(thenable, undefined, undefined, promise_to_resolve)
    
    is not observably different from the actual
    
      resolve, reject = CreateResolvingFunctions(promise_to_resolve)
      result_capability = NewPromiseCapability(%Promise%)
      PerformPromiseThen(thenable, resolve, reject, result_capability)
    
    except through PromiseHooks (and potentially via the async stack
    traces). So we disable the fast-path if either promise hooks are enabled
    or the debugger is active for now.
    
    This improves the performance on the wikipedia benchmark by 20-25% and
    the bluebird-doxbee benchmark by around 20%.
    
    Bug: v8:7253
    Change-Id: I23c92ad365c2b71d65057573f2d8febe2afe00b0
    Reviewed-on: https://chromium-review.googlesource.com/911800
    Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
    Reviewed-by: 's avatarSathya Gunasekaran <gsathya@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#51261}
    1f8dcc5d
builtins-internal-gen.cc 38.8 KB