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  1. 23 Jul, 2019 1 commit
  3. 22 Jul, 2019 1 commit
    • Ben L. Titzer's avatar
      Reland "Reland "[arraybuffer] Rearchitect backing store ownership"" · 306cf403
      Ben L. Titzer authored 
      This is a reland of bc33f5ae

Original change's description:
> Reland "[arraybuffer] Rearchitect backing store ownership"
> 
> This is a reland of 31cd5d83
> 
> Original change's description:
> > [arraybuffer] Rearchitect backing store ownership
> > 
> > This CL completely rearchitects the ownership of array buffer backing stores,
> > consolidating ownership into a {BackingStore} C++ object that is tracked
> > throughout V8 using unique_ptr and shared_ptr where appropriate.
> > 
> > Overall, lifetime management is simpler and more explicit. The numerous
> > ways that array buffers were initialized have been streamlined to one
> > Attach() method on JSArrayBuffer. The array buffer tracker in the
> > GC implementation now manages std::shared_ptr<BackingStore> pointers,
> > and the construction and destruction of the BackingStore object itself
> > handles the underlying page or embedder-allocated memory.
> > 
> > The embedder API remains unchanged for now. We use the
> > v8::ArrayBuffer::Contents struct to hide an additional shared_ptr to
> > keep the backing store alive properly, even in the case of aliases
> > from live heap objects. Thus the embedder has a lower chance of making
> > a mistake. Long-term, we should move the embedder to a model where they
> > manage backing stores using shared_ptr to an opaque backing store object.
> > 
> > R=mlippautz@chromium.org
> > BUG=v8:9380,v8:9221
> > 
> > Change-Id: I48fae5ac85dcf6172a83f252439e77e7c1a16ccd
> > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1584323
> > Commit-Queue: Ben Titzer <titzer@chromium.org>
> > Reviewed-by: Ben Titzer <titzer@chromium.org>
> > Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> > Reviewed-by: Yang Guo <yangguo@chromium.org>
> > Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
> > Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> > Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#62572}
> 
> Bug: v8:9380, v8:9221
> Change-Id: If3f72967a8ebeb067c0edcfc16ed631e36829dbc
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1691906
> Commit-Queue: Ben Titzer <titzer@chromium.org>
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#62809}

Bug: v8:9380, v8:9221
Change-Id: I9a2525753ae2424108d074fa81df5f25d945c824
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1709409
Commit-Queue: Ben Titzer <titzer@chromium.org>
Reviewed-by: 's avatarYang Guo <yangguo@chromium.org>
Reviewed-by: 's avatarMichael Lippautz <mlippautz@chromium.org>
Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Reviewed-by: 's avatarMichael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62847}
      306cf403
  5. 18 Jul, 2019 2 commits
    • Clemens Hammacher's avatar
      Revert "Reland "[arraybuffer] Rearchitect backing store ownership"" · 6e0473f3
      Clemens Hammacher authored 
      This reverts commit bc33f5ae.

Reason for revert: Still failing (OOM on win32): https://ci.chromium.org/p/v8/builders/ci/V8%20Win32/22210

Original change's description:
> Reland "[arraybuffer] Rearchitect backing store ownership"
> 
> This is a reland of 31cd5d83
> 
> Original change's description:
> > [arraybuffer] Rearchitect backing store ownership
> > 
> > This CL completely rearchitects the ownership of array buffer backing stores,
> > consolidating ownership into a {BackingStore} C++ object that is tracked
> > throughout V8 using unique_ptr and shared_ptr where appropriate.
> > 
> > Overall, lifetime management is simpler and more explicit. The numerous
> > ways that array buffers were initialized have been streamlined to one
> > Attach() method on JSArrayBuffer. The array buffer tracker in the
> > GC implementation now manages std::shared_ptr<BackingStore> pointers,
> > and the construction and destruction of the BackingStore object itself
> > handles the underlying page or embedder-allocated memory.
> > 
> > The embedder API remains unchanged for now. We use the
> > v8::ArrayBuffer::Contents struct to hide an additional shared_ptr to
> > keep the backing store alive properly, even in the case of aliases
> > from live heap objects. Thus the embedder has a lower chance of making
> > a mistake. Long-term, we should move the embedder to a model where they
> > manage backing stores using shared_ptr to an opaque backing store object.
> > 
> > R=mlippautz@chromium.org
> > BUG=v8:9380,v8:9221
> > 
> > Change-Id: I48fae5ac85dcf6172a83f252439e77e7c1a16ccd
> > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1584323
> > Commit-Queue: Ben Titzer <titzer@chromium.org>
> > Reviewed-by: Ben Titzer <titzer@chromium.org>
> > Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> > Reviewed-by: Yang Guo <yangguo@chromium.org>
> > Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
> > Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> > Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#62572}
> 
> Bug: v8:9380, v8:9221
> Change-Id: If3f72967a8ebeb067c0edcfc16ed631e36829dbc
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1691906
> Commit-Queue: Ben Titzer <titzer@chromium.org>
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#62809}

TBR=ulan@chromium.org,yangguo@chromium.org,mstarzinger@chromium.org,titzer@chromium.org,gdeepti@chromium.org,mlippautz@chromium.org

Change-Id: Iea755df9aaa1e95d284135bd0a6681b1340b6832
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:9380, v8:9221
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1708487Reviewed-by: 's avatarClemens Hammacher <clemensh@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62811}
      6e0473f3
    • Ben L. Titzer's avatar
      Reland "[arraybuffer] Rearchitect backing store ownership" · bc33f5ae
      Ben L. Titzer authored 
      This is a reland of 31cd5d83

Original change's description:
> [arraybuffer] Rearchitect backing store ownership
> 
> This CL completely rearchitects the ownership of array buffer backing stores,
> consolidating ownership into a {BackingStore} C++ object that is tracked
> throughout V8 using unique_ptr and shared_ptr where appropriate.
> 
> Overall, lifetime management is simpler and more explicit. The numerous
> ways that array buffers were initialized have been streamlined to one
> Attach() method on JSArrayBuffer. The array buffer tracker in the
> GC implementation now manages std::shared_ptr<BackingStore> pointers,
> and the construction and destruction of the BackingStore object itself
> handles the underlying page or embedder-allocated memory.
> 
> The embedder API remains unchanged for now. We use the
> v8::ArrayBuffer::Contents struct to hide an additional shared_ptr to
> keep the backing store alive properly, even in the case of aliases
> from live heap objects. Thus the embedder has a lower chance of making
> a mistake. Long-term, we should move the embedder to a model where they
> manage backing stores using shared_ptr to an opaque backing store object.
> 
> R=mlippautz@chromium.org
> BUG=v8:9380,v8:9221
> 
> Change-Id: I48fae5ac85dcf6172a83f252439e77e7c1a16ccd
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1584323
> Commit-Queue: Ben Titzer <titzer@chromium.org>
> Reviewed-by: Ben Titzer <titzer@chromium.org>
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#62572}

Bug: v8:9380, v8:9221
Change-Id: If3f72967a8ebeb067c0edcfc16ed631e36829dbc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1691906
Commit-Queue: Ben Titzer <titzer@chromium.org>
Reviewed-by: 's avatarMichael Starzinger <mstarzinger@chromium.org>
Reviewed-by: 's avatarMichael Lippautz <mlippautz@chromium.org>
Reviewed-by: 's avatarDeepti Gandluri <gdeepti@chromium.org>
Reviewed-by: 's avatarYang Guo <yangguo@chromium.org>
Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62809}
      bc33f5ae
  7. 11 Jul, 2019 1 commit
  9. 27 Jun, 2019 1 commit
  11. 19 Jun, 2019 1 commit
  13. 27 May, 2019 3 commits
    • Benedikt Meurer's avatar
      Reland "[typedarray] Move external/data pointer to JSTypedArray." · 70bd7cf0
      Benedikt Meurer authored 
      This is a reland of 4b86fea5 with
copy&paste typo in CodeStubAssembler::AllocateByteArray() fixed
(bug led to holes in new space, which was crashing reproducibly
on the ia32 bot).

Original change's description:
> [typedarray] Move external/data pointer to JSTypedArray.
>
> As the next step in supporting huge typed arrays in V8, this moves the
> external/data pointer from the FixedTypedArrayBase backing store to the
> JSTypedArray instance itself, and replaces the special backing stores
> with a plain ByteArray (removing all the code for the FixedTypedArrayBase
> class hierarchy). By doing so, we can drastically simplify the system
> around typed arrays.
>
> Note: Several places in the code base used to check the instance type
> of the elements backing store of a JSTypedArray instead of checking the
> elements kind on the JSTypedArray map directly. Those had to be fixed,
> since the backing store is now always a ByteArray.
>
> Drive-by-fix: Move all the typed elements access related code into the
> elements.cc file to properly encapsulate the accesses.
>
> Doc: http://doc/1Z-wM2qwvAuxH46e9ivtkYvKzzwYZg8ymm0x0wJaomow
> Bug: chromium:951196, chromium:965583, v8:4153, v8:7881, v8:9183
> Change-Id: I8cc06b190c53e34155000b4560f5f3ef40621646
> Cq-Include-Trybots: luci.chromium.try:linux-rel,win7-rel
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1627535
> Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
> Reviewed-by: Peter Marshall <petermarshall@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Simon Zünd <szuend@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#61855}

Tbr: petermarshall@chromium.org
Bug: chromium:951196, chromium:965583, v8:4153, v8:7881, v8:9183
Change-Id: I87fcdb28532c5f08cc227332a4d59546cb423810
Cq-Include-Trybots: luci.chromium.try:linux-rel, win7-rel
Cq-Include-Trybots: luci.v8.try:v8_linux_shared_compile_rel
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1631592Reviewed-by: 's avatarBenedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61864}
      70bd7cf0
    • Clemens Hammacher's avatar
      Revert "[typedarray] Move external/data pointer to JSTypedArray." · e4db146a
      Clemens Hammacher authored 
      This reverts commit 4b86fea5.

Reason for revert: Fails on linux shared: https://ci.chromium.org/p/v8/builders/ci/V8%20Linux%20-%20shared/31045

Original change's description:
> [typedarray] Move external/data pointer to JSTypedArray.
> 
> As the next step in supporting huge typed arrays in V8, this moves the
> external/data pointer from the FixedTypedArrayBase backing store to the
> JSTypedArray instance itself, and replaces the special backing stores
> with a plain ByteArray (removing all the code for the FixedTypedArrayBase
> class hierarchy). By doing so, we can drastically simplify the system
> around typed arrays.
> 
> Note: Several places in the code base used to check the instance type
> of the elements backing store of a JSTypedArray instead of checking the
> elements kind on the JSTypedArray map directly. Those had to be fixed,
> since the backing store is now always a ByteArray.
> 
> Drive-by-fix: Move all the typed elements access related code into the
> elements.cc file to properly encapsulate the accesses.
> 
> Doc: http://doc/1Z-wM2qwvAuxH46e9ivtkYvKzzwYZg8ymm0x0wJaomow
> Bug: chromium:951196, chromium:965583, v8:4153, v8:7881, v8:9183
> Change-Id: I8cc06b190c53e34155000b4560f5f3ef40621646
> Cq-Include-Trybots: luci.chromium.try:linux-rel,win7-rel
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1627535
> Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
> Reviewed-by: Peter Marshall <petermarshall@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Simon Zünd <szuend@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#61855}

TBR=ulan@chromium.org,yangguo@chromium.org,titzer@chromium.org,sigurds@chromium.org,petermarshall@chromium.org,bmeurer@chromium.org,szuend@chromium.org

Change-Id: I0bc1f935de6063acf75a0f4bb8c0ba67428603fd
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:951196, chromium:965583, v8:4153, v8:7881, v8:9183
Cq-Include-Trybots: luci.chromium.try:linux-rel, win7-rel
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1631427Reviewed-by: 's avatarClemens Hammacher <clemensh@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61856}
      e4db146a
    • Benedikt Meurer's avatar
      [typedarray] Move external/data pointer to JSTypedArray. · 4b86fea5
      Benedikt Meurer authored 
      As the next step in supporting huge typed arrays in V8, this moves the
external/data pointer from the FixedTypedArrayBase backing store to the
JSTypedArray instance itself, and replaces the special backing stores
with a plain ByteArray (removing all the code for the FixedTypedArrayBase
class hierarchy). By doing so, we can drastically simplify the system
around typed arrays.

Note: Several places in the code base used to check the instance type
of the elements backing store of a JSTypedArray instead of checking the
elements kind on the JSTypedArray map directly. Those had to be fixed,
since the backing store is now always a ByteArray.

Drive-by-fix: Move all the typed elements access related code into the
elements.cc file to properly encapsulate the accesses.

Doc: http://doc/1Z-wM2qwvAuxH46e9ivtkYvKzzwYZg8ymm0x0wJaomow
Bug: chromium:951196, chromium:965583, v8:4153, v8:7881, v8:9183
Change-Id: I8cc06b190c53e34155000b4560f5f3ef40621646
Cq-Include-Trybots: luci.chromium.try:linux-rel,win7-rel
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1627535
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: 's avatarPeter Marshall <petermarshall@chromium.org>
Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Reviewed-by: 's avatarSimon Zünd <szuend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61855}
      4b86fea5
  15. 24 May, 2019 1 commit
  17. 23 May, 2019 1 commit
  19. 22 May, 2019 1 commit
  21. 13 May, 2019 1 commit
  23. 09 May, 2019 2 commits
  25. 08 May, 2019 1 commit
    • Maciej Goszczycki's avatar
      Reland "[heap] Set read-only space's and its pages' heap_ to null." · b672d089
      Maciej Goszczycki authored 
      Seems like the CodeBuilder CL actually caused this.

This is a reland of 964edc25

Original change's description:
> [heap] Set read-only space's and its pages' heap_ to null.
>
> Various small changes are required to enable this.
>
> HeapObject::GetReadOnlyRoots no longer uses the Space's heap when
> possible (see comment in ReadOnlyHeap::GetReadOnlyRoots definition).
> This requires that ReadOnlyRoots be construct-able using a raw pointer
> to the read-only space's roots array.
>
> Global read-only heap state is now cleared by tests where appropriate
> and extra DCHECKs in ReadOnlyHeap::SetUp should make catching future
> issues easier.
>
> String padding is now always cleared just before read-only space is
> sealed when not deserializing.
>
> Change-Id: I7d1db1c11567be5df06ff7066f3a699125f8b372
> Bug: v8:7464
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1535830
> Commit-Queue: Maciej Goszczycki <goszczycki@google.com>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Dan Elphick <delphick@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#61188}

Bug: v8:7464
Change-Id: If75bbd16c2e2af5b80cd60811dfd7866f8be8309
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1599186
Commit-Queue: Maciej Goszczycki <goszczycki@google.com>
Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Reviewed-by: 's avatarDan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61323}
      b672d089
  27. 03 May, 2019 1 commit
    • Maciej Goszczycki's avatar
      Revert "[heap] Set read-only space's and its pages' heap_ to null." · fa4b433f
      Maciej Goszczycki authored 
      This reverts commit 964edc25.

Reason for revert: chromium:959190

Original change's description:
> [heap] Set read-only space's and its pages' heap_ to null.
>
> Various small changes are required to enable this.
>
> HeapObject::GetReadOnlyRoots no longer uses the Space's heap when
> possible (see comment in ReadOnlyHeap::GetReadOnlyRoots definition).
> This requires that ReadOnlyRoots be construct-able using a raw pointer
> to the read-only space's roots array.
>
> Global read-only heap state is now cleared by tests where appropriate
> and extra DCHECKs in ReadOnlyHeap::SetUp should make catching future
> issues easier.
>
> String padding is now always cleared just before read-only space is
> sealed when not deserializing.
>
> Change-Id: I7d1db1c11567be5df06ff7066f3a699125f8b372
> Bug: v8:7464
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1535830
> Commit-Queue: Maciej Goszczycki <goszczycki@google.com>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Dan Elphick <delphick@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#61188}

TBR=ulan@chromium.org,hpayer@chromium.org,delphick@chromium.org,goszczycki@google.com

Change-Id: I53cecf3976dfeabae309040313351385f651f010
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7464, chromium:959190
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1591608Reviewed-by: 's avatarAdam Klein <adamk@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61217}
      fa4b433f
  29. 02 May, 2019 1 commit
    • Maciej Goszczycki's avatar
      [heap] Set read-only space's and its pages' heap_ to null. · 964edc25
      Maciej Goszczycki authored 
      Various small changes are required to enable this.

HeapObject::GetReadOnlyRoots no longer uses the Space's heap when
possible (see comment in ReadOnlyHeap::GetReadOnlyRoots definition).
This requires that ReadOnlyRoots be construct-able using a raw pointer
to the read-only space's roots array.

Global read-only heap state is now cleared by tests where appropriate
and extra DCHECKs in ReadOnlyHeap::SetUp should make catching future
issues easier.

String padding is now always cleared just before read-only space is
sealed when not deserializing.

Change-Id: I7d1db1c11567be5df06ff7066f3a699125f8b372
Bug: v8:7464
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1535830
Commit-Queue: Maciej Goszczycki <goszczycki@google.com>
Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Reviewed-by: 's avatarDan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61188}
      964edc25
  31. 18 Apr, 2019 1 commit
  33. 10 Apr, 2019 3 commits
  35. 25 Mar, 2019 1 commit
    • Mythri's avatar
      [lite] Allocate feedback vectors lazily · 7629afdb
      Mythri authored 
      Allocate feedback vectors lazily when the function's interrupt budget has
reached a specified threshold. This cl introduces a new field in the
ClosureFeedbackCellArray to track the interrupt budget for allocating
feedback vectors. Using the interrupt budget on the bytecode array could
cause problems when there are closures across native contexts and we may
delay allocating feedback vectors in one of them causing unexpected
performance cliffs. In the long term we may want to remove interrupt budget
from bytecode array and use context specific budget for tiering up decisions
as well.

Bug: v8:8394
Change-Id: Ia8fbb71f5e8543a92f14c44aa762973da82d445c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1520719
Commit-Queue: Mythri Alle <mythria@chromium.org>
Reviewed-by: 's avatarJaroslav Sevcik <jarin@chromium.org>
Reviewed-by: 's avatarMichael Lippautz <mlippautz@chromium.org>
Reviewed-by: 's avatarRoss McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60450}
      7629afdb
  37. 19 Mar, 2019 1 commit
    • Benedikt Meurer's avatar
      [turbofan] Significantly improve ConsString creation performance. · d6a60a0e
      Benedikt Meurer authored 
      This change significantly improves the performance of string
concatenation in optimized code for the case where the resulting string
is represented as a ConsString. On the relevant test cases we go from

  serializeNaive: 10762 ms.
  serializeClever: 7813 ms.
  serializeConcat: 10271 ms.

to

  serializeNaive: 10278 ms.
  serializeClever: 5533 ms.
  serializeConcat: 10310 ms.

which represents a 30% improvement on the "clever" benchmark, which
tests specifically the ConsString creation performance.

This was accomplished via a couple of different steps, which are briefly
outlined here:

  1. The empty_string gets its own map, so that we can easily recognize
     and handle it appropriately in the TurboFan type system. This
     allows us to express (and assert) that the inputs to NewConsString
     are non-empty strings, making sure that TurboFan no longer creates
     "crippled ConsStrings" with empty left or right hand sides.
  2. Further split the existing String types in TurboFan to be able to
     distinguish between OneByte and TwoByte strings on the type system
     level. This allows us to avoid having to dynamically lookup the
     resulting ConsString map in case of ConsString creation (i.e. when
     we know that both input strings are OneByte strings or at least
     one of the input strings is TwoByte).
  3. We also introduced more finegrained feedback for the Add bytecode
     in the interpreter, having it collect feedback about ConsStrings,
     specifically ConsOneByteString and ConsTwoByteString. This feedback
     can be used by TurboFan to only inline the relevant code for what
     was seen so far. This allows us to remove the Octane/Splay specific
     magic in JSTypedLowering to detect ConsString creation, and instead
     purely rely on the feedback of what was seen so far (also making it
     possible to change the semantics of NewConsString to be a low-level
     operator, which is only introduced in SimplifiedLowering by looking
     at the input types of StringConcat).
  4. On top of the before mentioned type and interpreter changes we added
     new operators CheckNonEmptyString, CheckNonEmptyOneByteString, and
     CheckNonEmptyTwoByteString, which perform the appropriate (dynamic)
     checks.

There are several more improvements that are possible based on this, but
since the change was already quite big, we decided not to put everything
into the first change, but do some follow up tweaks to the type system,
and builtin optimizations later.

Tbr: mstarzinger@chromium.org
Bug: v8:8834, v8:8931, v8:8939, v8:8951
Change-Id: Ia24e17c6048bf2b04df966d3cd441f0edda05c93
Cq-Include-Trybots: luci.chromium.try:linux-blink-rel
Doc: https://bit.ly/fast-string-concatenation-in-javascript
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1499497
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: 's avatarYang Guo <yangguo@chromium.org>
Reviewed-by: 's avatarJaroslav Sevcik <jarin@chromium.org>
Reviewed-by: 's avatarMythri Alle <mythria@chromium.org>
Reviewed-by: 's avatarBenedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60318}
      d6a60a0e
  39. 14 Mar, 2019 1 commit
  41. 12 Mar, 2019 1 commit
  43. 04 Mar, 2019 1 commit
    • Benedikt Meurer's avatar
      [cleanup] Remove obsolete "one byte data hint" for strings. · 683cf6f4
      Benedikt Meurer authored 
      In the early days of Chrome when we used WebKit there was no support for
ASCII strings on the C++ side, so we put a hint onto these two-byte
strings that said "string only contains one byte data", such that
internally in V8 when these were involved in string operations, we could
instead create the *cheaper* one byte strings.

Nowadays Blink properly supports one-byte string representations and
this additional hint only comes with overhead, since we check it in
quite a few places (i.e. on the hot path for string concatenation), plus
we end up consuming more memory due to the additional string maps.
Removing the hint also frees one bit in the InstanceType zoo for
strings.

This alone improves performance on the `bench-dom-serialize.js` test case
by around **3%**.

Tbr: mstarzinger@chromium.org
Bug: v8:6622, v8:8834, v8:8939
Cq-Include-Trybots: luci.chromium.try:linux-blink-rel
Change-Id: I0753f2859cee7b5a37b6f0da64d8ec39fcb044ff
Doc: https://bit.ly/fast-string-concatenation-in-javascript
Reviewed-on: https://chromium-review.googlesource.com/c/1498478
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: 's avatarYang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60006}
      683cf6f4
  45. 27 Feb, 2019 1 commit
  47. 15 Feb, 2019 1 commit
  49. 30 Jan, 2019 1 commit
  51. 18 Jan, 2019 1 commit
  53. 08 Jan, 2019 2 commits
  55. 07 Jan, 2019 1 commit
  57. 26 Dec, 2018 1 commit
  59. 20 Dec, 2018 1 commit
  61. 18 Dec, 2018 3 commits