• Dan Elphick's avatar
    [heap] Make ReadOnlySpace use bump pointer allocation · 81c34968
    Dan Elphick authored
    This changes ReadOnlySpace to no longer be a PagedSpace but instead it
    is now a BaseSpace. BasicSpace is a new base class that Space inherits
    from and which has no allocation methods and does not dictate how the
    pages should be held.
    
    ReadOnlySpace unlike Space holds its pages as a
    std::vector<ReadOnlyPage>, where ReadOnlyPage directly subclasses
    BasicMemoryChunk, meaning they do not have prev_ and next_ pointers and
    cannot be held in a heap::List. This is desirable since with pointer
    compression we would like to remap these pages to different memory
    addresses which would be impossible with a heap::List.
    
    Since ReadOnlySpace no longer uses most of the code from the other
    Spaces it makes sense to simplify its memory allocation to use a simple
    bump pointer and always allocate a new page whenever an allocation
    exceeds the remaining space on the final page.
    
    Change-Id: Iee6d9f96cfb174b4026ee671ee4f897909b38418
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2209060
    Commit-Queue: Dan Elphick <delphick@chromium.org>
    Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#68137}
    81c34968
read-only-heap.h 4.78 KB