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Annotate some SmallVector methods as V8_PRESERVE_MOST

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SmallVectors are assumed to be small most of the time. Hence the {Grow}
method and others will most of the time not be called. So mark them
{V8_PRESERVE_MOST} to make caller code slimmer and faster.

R=dlehmann@chromium.org

Bug: v8:13565
Change-Id: Ia2bdcdff7e415b1d8a2717849c74604677a9dade
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4168413
Reviewed-by: Daniel Lehmann <dlehmann@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#85344}
This commit is contained in:
Clemens Backes 2023-01-16 17:36:09 +01:00 committed by V8 LUCI CQ
parent 79ed179625
commit d2119c0b68
1 changed files with 7 additions and 8 deletions
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15
src/base/small-vector.h
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@ -142,10 +142,10 @@ class SmallVector {
template <typename... Args>
void emplace_back(Args&&... args) {
T* end = end_;
if (V8_UNLIKELY(end == end_of_storage_)) end = Grow();
new (end) T(std::forward<Args>(args)...);
end_ = end + 1;
if (V8_UNLIKELY(end_ == end_of_storage_)) Grow();
void* storage = end_;
end_ += 1;
new (storage) T(std::forward<Args>(args)...);
}
void push_back(T x) { emplace_back(std::move(x)); }
@ -200,10 +200,10 @@ class SmallVector {
// Grows the backing store by a factor of two. Returns the new end of the used
// storage (this reduces binary size).
V8_NOINLINE T* Grow() { return Grow(0); }
V8_NOINLINE V8_PRESERVE_MOST void Grow() { Grow(0); }
// Grows the backing store by a factor of two, and at least to {min_capacity}.
V8_NOINLINE T* Grow(size_t min_capacity) {
V8_NOINLINE V8_PRESERVE_MOST void Grow(size_t min_capacity) {
size_t in_use = end_ - begin_;
size_t new_capacity =
base::bits::RoundUpToPowerOfTwo(std::max(min_capacity, 2 * capacity()));
@ -220,14 +220,13 @@ class SmallVector {
begin_ = new_storage;
end_ = new_storage + in_use;
end_of_storage_ = new_storage + new_capacity;
return end_;
}
T* AllocateDynamicStorage(size_t number_of_elements) {
return allocator_.allocate(number_of_elements);
}
void FreeDynamicStorage() {
V8_NOINLINE V8_PRESERVE_MOST void FreeDynamicStorage() {
DCHECK(is_big());
allocator_.deallocate(begin_, end_of_storage_ - begin_);
}