• Dan Elphick's avatar
    Reland "[heap] Make ReadOnlySpace use bump pointer allocation" · 32b911f9
    Dan Elphick authored
    This reverts commit f78d69fa.
    
    With https://chromium-review.googlesource.com/c/v8/v8/+/2243216,
    incorrect MemoryChunk::FromHeapObject uses are now fixed.
    
    Original change's description:
    > Revert "[heap] Make ReadOnlySpace use bump pointer allocation"
    > 
    > This reverts commit 81c34968 and also
    > 490f3580 which depends on the former.
    > 
    > Reason for revert: Break CFI tests in chromium https://ci.chromium.org/p/chromium/builders/ci/Linux%20CFI/17438
    > Original change's description:
    > > [heap] Make ReadOnlySpace use bump pointer allocation
    > >
    > > 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: Ulan Degenbaev <ulan@chromium.org>
    > > Cr-Commit-Position: refs/heads/master@{#68137}
    > 
    > TBR=ulan@chromium.org,delphick@chromium.org
    > 
    > # Not skipping CQ checks because original CL landed > 1 day ago.
    > 
    > Change-Id: I68c9834872e55eb833be081f8ff99b786bfa9894
    > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2232552
    > Commit-Queue: Dan Elphick <delphick@chromium.org>
    > Reviewed-by: Dan Elphick <delphick@chromium.org>
    > Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
    > Cr-Commit-Position: refs/heads/master@{#68211}
    
    TBR=ulan@chromium.org,delphick@chromium.org
    
    # Not skipping CQ checks because original CL landed > 1 day ago.
    
    Change-Id: Id5b3cce41b5dec1dca816c05848d183790b1cc05
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2250254Reviewed-by: 's avatarDan Elphick <delphick@chromium.org>
    Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
    Commit-Queue: Dan Elphick <delphick@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#68407}
    32b911f9
paged-spaces.cc 36.8 KB