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  1. 31 Aug, 2020 9 commits
    • Alex Kodat's avatar
      [cpu-profiler] Ensure sampled thread has Isolate lock under Windows · dfb3f7da
      Alex Kodat authored 
      While the sampler checked if the sampled thread had the Isolate locked
(if locks are being used) under Linux, the check was not done under
Windows (or Fuchsia) which meant that in a multi-threading application
under Windows, thread locking was not checked making it prone to seg
faults and the like as the profiler would be extracting info from a
heap in motion. The fix was to move the lock check into CpuSampler
and Ticker (--prof) so all OSes would do the correct check.

The basic concept is that on all operating systems a CpuProfiler, and
so its corresponding CpuCampler, the profiler is tied to a thread.
This is not based on first principles or anything, it's simply the
way it works in V8, though it is a useful conceit as it makes
visualization and interpretation of profile data much easier.

To collect a sample on a thread associated with a profiler the thread
must be stopped for obvious reasons -- walking the stack of a running
thread is a formula for disaster. The mechanism for stopping a thread
is OS-specific and is done in sample.cc. There are currently three
basic approaches, one for Linux/Unix variants, one for Windows and one
for Fuchsia. The approaches vary as to which thread actually collects
the sample -- under Linux the sample is actually collected on the
(interrupted) sampled thread whereas under Fuchsia/Windows it's on
a separate thread.

However, in a multi-threaded environment (where Locker is used), it's
not sufficient for the sampled thread to be stopped. Because the stack
walk involves looking in the Isolate heap, no other thread can be
messing with the heap while the sample is collected. The only ways to
ensure this would be to either stop all threads whenever collecting a
sample, or to ensure that the thread being sampled holds the Isolate
lock so prevents other threads from messing with the heap. While there
might be something to be said for the "stop all threads" approach, the
current approach in V8 is to only stop the sampled thread so, if in a
multi-threaded environment, the profiler must check if the thread being
sampled holds the Isolate lock.

Since this check must be done, independent of which thread the sample
is being collected on (since it varies from OS to OS), the approach is
to save the thread id of the thread to be profiled/sampled when the
CpuSampler is instantiated (on all OSes it is instantiated on the
sampled thread) and then check that thread id against the Isolate lock
holder thread id before collecting a sample. If it matches, we know
sample.cc has stop the sampled thread, one way or another, and we know
that no other thread can mess with the heap (since the stopped thread
holds the Isolate lock) so it's safe to walk the stack and collect data
from the heap so the sample can be taken. It it doesn't match, we can't
safely collect the sample so we don't.

Bug: v8:10850
Change-Id: Iab2493130b9328430d7e5f5d3cf90ad6d10b1892
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2377108Reviewed-by: 's avatarPeter Marshall <petermarshall@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69623}
      dfb3f7da
    • Gus Caplan's avatar
      fix PerformCastCheck on v8::Data · 61216077
      Gus Caplan authored 
      PerformCheckCast<Data>() itself should not invoke Data::Cast(), since
there is no such method and every publicly available value can be
casted to it anyway. This is an issue in e.g.
GetDataFromSnapshotOnce<Data>().

Change-Id: I5d9ee89657c31bc0ca1fb16e704df58911c85f6c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2383030
Commit-Queue: Gus Caplan <snek@chromium.org>
Reviewed-by: 's avatarJakob Gruber <jgruber@chromium.org>
Reviewed-by: 's avatarUlan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69622}
      61216077
    • Martin Bidlingmaier's avatar
      [regexp] Support some non-trivial EXPERIMENTAL patterns · 13667065
      Martin Bidlingmaier authored 
      This CL adds support for disjunctions and some quantification in
EXPERIMENTAL regexp patterns. It is implemented using a new bytecode
format and an NFA-based breadth-first interpreter.

R=jgruber@chromium.org

Bug: v8:10765
Change-Id: Idd49a3bbc9a9fcc2be80d822c9d84a638e53e777
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2370634
Commit-Queue: Martin Bidlingmaier <mbid@google.com>
Reviewed-by: 's avatarDominik Inführ <dinfuehr@chromium.org>
Reviewed-by: 's avatarJakob Gruber <jgruber@chromium.org>
Reviewed-by: 's avatarClemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69621}
      13667065
    • Nico Hartmann's avatar
      [turbofan] Fix incorrect typing of constant with reverse stack · 97e79b25
      Nico Hartmann authored 
      Bug: chromium:1120729
Change-Id: I27533a2426a63ec6b67d34d94f3cae554fc95d91
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2379852
Auto-Submit: Nico Hartmann <nicohartmann@chromium.org>
Reviewed-by: 's avatarJakob Gruber <jgruber@chromium.org>
Reviewed-by: 's avatarVictor Gomes <victorgomes@chromium.org>
Commit-Queue: Nico Hartmann <nicohartmann@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69620}
      97e79b25
    • Jakob Gruber's avatar
      [compiler] Revisit graph end after a gasm reduction in call reducer · f8061c6c
      Jakob Gruber authored 
      The graph assembler calls MergeControlToEnd as part of Unreachable
node creation; this causes issues when used inside the GraphReducer
framework, since the reducer is not notified by gasm that the end node
should be revisited.

The (hacky) fix in this CL is to always mark the end node for
revisitation after a gasm reduction has taken place.

Bug: v8:8888,chromium:1123379
Change-Id: I350bb7144add04a0c3fd7f3d88c07fcfe1cd42e3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2384772
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: 's avatarTobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69619}
      f8061c6c
    • Marja Hölttä's avatar
      [super property speed] Invert benchmark graphs · 925effd0
      Marja Hölttä authored 
      The goal is to have one graph per test case, and inside the graph,
4 different lines:
- baseline
- baseline noopt
- super-ic
- super-ic noopt

Bug: v8:9237
Change-Id: I511b5555487a3d96698a3fb648abf76a13f76858
No-Try: True
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2384770Reviewed-by: 's avatarPeter Marshall <petermarshall@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69618}
      925effd0
    • Jakob Kummerow's avatar
      [test] Make a few tests robust to GC stress · b5a33eba
      Jakob Kummerow authored 
      A recent unrelated change caused these tests to get unlucky in
GC stress mode. Their "assertOptimized" expectations rely on
certain type feedback data not getting flushed at the wrong time.

Bug: v8:10846
Change-Id: I86d0b0c049539e4a69aa764cc6ec92465ca12beb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2381458Reviewed-by: 's avatarMaya Lekova <mslekova@chromium.org>
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Auto-Submit: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69617}
      b5a33eba
    • v8-ci-autoroll-builder's avatar
      Update V8 DEPS. · 9d6c42ce
      v8-ci-autoroll-builder authored 
      Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/0efd610..2dbf41f

Rolling v8/third_party/depot_tools: https://chromium.googlesource.com/chromium/tools/depot_tools/+log/6c48487..c73782c

TBR=machenbach@chromium.org,tmrts@chromium.org,v8-waterfall-sheriff@grotations.appspotmail.com

Change-Id: I6ca1f3428fd4c73446ecc2927a5493b42c39a73d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2384549Reviewed-by: 's avatarv8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Commit-Queue: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#69616}
      9d6c42ce
    • 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
  3. 29 Aug, 2020 1 commit
  5. 28 Aug, 2020 18 commits
  7. 27 Aug, 2020 12 commits