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Precise sweeping makes zapping of garbage memory when trimming arrays obsolete

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BUG=
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/439863006

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22867 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
hpayer@chromium.org 2014-08-05 12:09:23 +00:00
parent 947899e1e1
commit c76318bc30
1 changed files with 0 additions and 27 deletions
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27
src/heap/heap.cc
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@ -3260,15 +3260,6 @@ void Heap::AdjustLiveBytes(Address address, int by, InvocationMode mode) {
}
static void ZapFixedArrayForTrimming(Address address, int elements_to_trim) {
Object** zap = reinterpret_cast<Object**>(address);
zap++; // Header of filler must be at least one word so skip that.
for (int i = 1; i < elements_to_trim; i++) {
*zap++ = Smi::FromInt(0);
}
}
FixedArrayBase* Heap::LeftTrimFixedArray(FixedArrayBase* object,
int elements_to_trim) {
const int element_size = object->IsFixedArray() ? kPointerSize : kDoubleSize;
@ -3291,15 +3282,6 @@ FixedArrayBase* Heap::LeftTrimFixedArray(FixedArrayBase* object,
// Calculate location of new array start.
Address new_start = object->address() + bytes_to_trim;
if (bytes_to_trim > FreeSpace::kHeaderSize &&
object->IsFixedArray() &&
!new_space()->Contains(object)) {
// If we are doing a big trim in old space then we zap the space that was
// formerly part of the array so that the GC (aided by the card-based
// remembered set) won't find pointers to new-space there.
ZapFixedArrayForTrimming(object->address(), elements_to_trim);
}
// Technically in new space this write might be omitted (except for
// debug mode which iterates through the heap), but to play safer
// we still do it.
@ -3348,15 +3330,6 @@ void Heap::RightTrimFixedArray(FixedArrayBase* object, int elements_to_trim) {
// Calculate location of new array end.
Address new_end = object->address() + object->Size() - bytes_to_trim;
if (bytes_to_trim > FreeSpace::kHeaderSize &&
object->IsFixedArray() &&
(mode != Heap::FROM_GC || Heap::ShouldZapGarbage())) {
// If we are doing a big trim in old space then we zap the space that was
// formerly part of the array so that the GC (aided by the card-based
// remembered set) won't find pointers to new-space there.
ZapFixedArrayForTrimming(new_end, elements_to_trim);
}
// Technically in new space this write might be omitted (except for
// debug mode which iterates through the heap), but to play safer
// we still do it.