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[heap] Use MemCopy in CopyElements

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This CL uses MemCopy in CopyElements, because we think that the input
FixedArrays can never overlap. This CL also adds a DCHECK to ensure
this. If our assumption is wrong, it will be interesting to learn why.

Change-Id: Ib8258b934f43b82b1281481c592762e43b35938f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1549154
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60589}
This commit is contained in:
Sigurd Schneider 2019-04-03 11:31:11 +02:00 committed by Commit Bot
parent 433de3ffad
commit 6116c6b2a8
1 changed files with 3 additions and 2 deletions
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5
src/heap/heap.cc
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@ -1535,6 +1535,8 @@ void Heap::CopyElements(FixedArray dst_array, FixedArray src_array,
DCHECK_NE(dst_array->map(), ReadOnlyRoots(this).fixed_cow_array_map());
ObjectSlot dst = dst_array->RawFieldOfElementAt(dst_index);
ObjectSlot src = src_array->RawFieldOfElementAt(src_index);
// Ensure ranges do not overlap.
DCHECK(dst + len <= src || src + len <= dst);
if (FLAG_concurrent_marking && incremental_marking()->IsMarking()) {
if (dst < src) {
for (int i = 0; i < len; i++) {
@ -1553,8 +1555,7 @@ void Heap::CopyElements(FixedArray dst_array, FixedArray src_array,
}
}
} else {
// TODO(sigurds): Figure out whether we can use MemCopy here.
MemMove(dst.ToVoidPtr(), src.ToVoidPtr(), len * kTaggedSize);
MemCopy(dst.ToVoidPtr(), src.ToVoidPtr(), len * kTaggedSize);
}
if (mode == SKIP_WRITE_BARRIER) return;
FIXED_ARRAY_ELEMENTS_WRITE_BARRIER(this, dst_array, dst_index, len);