• Mythri A's avatar
    [turboprop] Record handle to map in dynamic map checks operator · adfdccc0
    Mythri A authored
    Monomorphic loads are quite common and it is important to keep these
    load accesses fast. Dynamic map checks increases the overhead for these
    monomorphic accesses by having to actually verify the IC state and check
    against a map from the feedback vector This was causing a significant
    (~2-3%) regression in JavaScript duration. To keep the common case of
    monomorphic checks fast, we now want to add a check against expected
    map (which passes in most cases) and move the rest of the checks to a
    builtin. i.e. we want dynamic map checks (when generating the code for
    loads in monomorphic state) to look like:
    
    if (incoming_map != HeapConstant(expected_map))
      call_builtin;
    
    This helps us to keep the most common case fast and still gets the
    benefits of dynamic map checks.
    
    This cl is the first in the series of cls that will add this
    functionality. This cl makes the expected_map available for dynamic map
    checks operator. In follow up cls, we will add a builtin and update
    the code to use the builtin.
    
    
    Bug: v8:10582
    Change-Id: I10992c6ba1fb005592de962310c208cff6829119
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2397894Reviewed-by: 's avatarGeorg Neis <neis@chromium.org>
    Reviewed-by: 's avatarSathya Gunasekaran  <gsathya@chromium.org>
    Reviewed-by: 's avatarJakob Gruber <jgruber@chromium.org>
    Commit-Queue: Mythri Alle <mythria@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#69798}
    adfdccc0
js-native-context-specialization.cc 144 KB