Skip to content

V
V8
Switch branch/tag
  1. 28 Apr, 2021 1 commit
  3. 16 Mar, 2021 1 commit
  5. 12 Mar, 2021 1 commit
  7. 11 Mar, 2021 1 commit
  9. 17 Nov, 2020 1 commit
  11. 31 Aug, 2020 1 commit
    • Jake Hughes's avatar
      [heap] Add object start bitmap for conservative stack scanning · 5f6aa2e5
      Jake Hughes authored 
      With conservative stack scanning enabled, a snapshot of the call stack
upon entry to GC will be used to determine part of the root-set. When
the collector walks the stack, it looks at each value and determines
whether it could be a potential on-heap object pointer. However, unlike
with Handles, these on-stack pointers aren't guaranteed to point to the
start of the object: the compiler may decide hide these pointers, and
create interior pointers in C++ frames which the GC doesn't know about.

The solution to this is to include an object start bitmap in the header
of each page. Each bit in the bitmap represents a word in the page
payload which is set when an object is allocated. This means that when
the collector finds an arbitrary potential pointer into the page, it can
walk backwards through the bitmap until it finds the relevant object's
base pointer. To prevent the bitmap becoming stale after compaction, it
is rebuilt during object sweeping.

This is experimental, and currently only works with inline allocation
disabled, and single generational collection.

Bug: v8:10614
Change-Id: I28ebd9562f58f335f8b3c2d1189cdf39feaa1f52
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2375195
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Reviewed-by: 's avatarMichael Achenbach <machenbach@chromium.org>
Reviewed-by: 's avatarDominik Inführ <dinfuehr@chromium.org>
Reviewed-by: 's avatarAnton Bikineev <bikineev@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69615}
      5f6aa2e5
  13. 12 Aug, 2020 1 commit
  15. 10 Jul, 2020 1 commit
  17. 18 Jun, 2020 1 commit
    • 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
  19. 17 Jun, 2020 1 commit
    • Dan Elphick's avatar
      [heap] Use BasicMemoryChunk::FromHeapObject more · 6f267e8a
      Dan Elphick authored 
      Since ReadOnlySpace pages will soon not be MemoryChunks, change most
uses of MemoryChunk::FromHeapObject and FromAddress to use the
BasicMemoryChunk variants and which use the new MemoryChunk::cast
function that takes a BasicMemoryChunk and DCHECKs !InReadOnlySpace().

To enable this, it also moves into BasicMemoryChunk several MemoryChunk
functions that just require a BasicMemoryChunk.

Bug: v8:10454
Change-Id: I80875b2c2446937ac2c2bc9287d36e71cc050c38
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2243216
Commit-Queue: Dan Elphick <delphick@chromium.org>
Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68390}
      6f267e8a
  21. 05 Jun, 2020 1 commit
    • Dan Elphick's avatar
      Revert "[heap] Make ReadOnlySpace use bump pointer allocation" · f78d69fa
      Dan Elphick authored 
      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: 's avatarDan Elphick <delphick@chromium.org>
Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68211}
      f78d69fa
  23. 03 Jun, 2020 2 commits
    • 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
    • Dan Elphick's avatar
      [heap] Move MemoryChunk fields to BasicMemoryChunk · ae489dec
      Dan Elphick authored 
      This moves several fields that will be needed by ReadOnlySpace pages
when it stops using MemoryChunk into BasicMemoryChunk.

Additionally AllocationStats is moved from spaces.h into
allocation-stats.h.

Bug: v8:10473, v8:10454
Change-Id: I76a66565a260126e629bd7588a5418267dfa8423
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2228722Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68134}
      ae489dec
  25. 18 May, 2020 1 commit
  27. 14 May, 2020 2 commits
  29. 05 May, 2020 1 commit