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deps: V8: cherry-pick d3a1a5b6c491

Original commit message:

    [objects] Fix memory leak in PrototypeUsers::Add

    PrototypeUsers::Add now iterates the WeakArrayList to find empty slots
    before growing the array. Not reusing empty slots caused a memory leak.

    It might also be desirable to shrink the WeakArrayList in the future.
    Right now it is only compacted when invoking CreateBlob.

    Also removed unused PrototypeUsers::IsEmptySlot declaration.

    Bug: v8:10031
    Change-Id: I570ec78fca37e8f0c794f1f40846a4daab47c225
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1967317
    Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
    Reviewed-by: Igor Sheludko <ishell@chromium.org>
    Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#65456}

Refs: v8/v8@d3a1a5b
Fixes: #30753

PR-URL: #31005
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Rich Trott <rtrott@gmail.com>
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targos authored and BridgeAR committed Dec 17, 2019
1 parent afecc97 commit 7e13ae77570bc4f73725dfc88c5c43ac20d97820
Showing with 18 additions and 2 deletions.
  1. +1 −1 common.gypi
  2. +16 −0 deps/v8/src/objects/objects.cc
  3. +1 −1 deps/v8/src/objects/prototype-info.h
@@ -39,7 +39,7 @@

# Reset this number to 0 on major V8 upgrades.
# Increment by one for each non-official patch applied to deps/v8.
'v8_embedder_string': '-node.23',
'v8_embedder_string': '-node.24',

##### V8 defaults for Node.js #####

@@ -4038,6 +4038,13 @@ Handle<WeakArrayList> PrototypeUsers::Add(Isolate* isolate,

// If there are empty slots, use one of them.
int empty_slot = Smi::ToInt(empty_slot_index(*array));

if (empty_slot == kNoEmptySlotsMarker) {
// GCs might have cleared some references, rescan the array for empty slots.
PrototypeUsers::ScanForEmptySlots(*array);
empty_slot = Smi::ToInt(empty_slot_index(*array));
}

if (empty_slot != kNoEmptySlotsMarker) {
DCHECK_GE(empty_slot, kFirstIndex);
CHECK_LT(empty_slot, array->length());
@@ -4060,6 +4067,15 @@ Handle<WeakArrayList> PrototypeUsers::Add(Isolate* isolate,
return array;
}

// static
void PrototypeUsers::ScanForEmptySlots(WeakArrayList array) {
for (int i = kFirstIndex; i < array.length(); i++) {
if (array.Get(i)->IsCleared()) {
PrototypeUsers::MarkSlotEmpty(array, i);
}
}
}

WeakArrayList PrototypeUsers::Compact(Handle<WeakArrayList> array, Heap* heap,
CompactionCallback callback,
AllocationType allocation) {
@@ -99,7 +99,7 @@ class V8_EXPORT_PRIVATE PrototypeUsers : public WeakArrayList {
static inline Smi empty_slot_index(WeakArrayList array);
static inline void set_empty_slot_index(WeakArrayList array, int index);

static void IsSlotEmpty(WeakArrayList array, int index);
static void ScanForEmptySlots(WeakArrayList array);

DISALLOW_IMPLICIT_CONSTRUCTORS(PrototypeUsers);
};

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