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Vector: Use memcpy to implement remove() for trivial types

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This is a lot faster than the generic code path.
Also added some unit testing for this.
This commit is contained in:
Andreas Kling 2019-08-12 10:35:05 +02:00
parent 6228e18a09
commit 2c7b0b8893
Notes: sideshowbarker 2024-07-19 12:43:38 +09:00 
Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/2c7b0b88935
2 changed files with 54 additions and 4 deletions
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45
AK/Tests/TestVector.cpp
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@ -207,4 +207,49 @@ BENCHMARK_CASE(vector_append_trivial)
}
}
BENCHMARK_CASE(vector_remove_trivial)
{
// This should be super fast thanks to Vector using memmove.
Vector<int> ints;
for (int i = 0; i < 10000; ++i) {
ints.append(i);
}
while (!ints.is_empty()) {
ints.remove(0);
}
EXPECT_EQ(ints.size(), 0);
}
TEST_CASE(vector_remove)
{
Vector<int> ints;
ints.append(1);
ints.append(2);
ints.append(3);
ints.append(4);
ints.append(5);
ints.remove(1);
EXPECT_EQ(ints.size(), 4);
EXPECT_EQ(ints[0], 1);
EXPECT_EQ(ints[1], 3);
EXPECT_EQ(ints[2], 4);
EXPECT_EQ(ints[3], 5);
ints.remove(0);
EXPECT_EQ(ints.size(), 3);
EXPECT_EQ(ints[0], 3);
EXPECT_EQ(ints[1], 4);
EXPECT_EQ(ints[2], 5);
ints.take_last();
EXPECT_EQ(ints.size(), 2);
EXPECT_EQ(ints[0], 3);
EXPECT_EQ(ints[1], 4);
ints.take_first();
EXPECT_EQ(ints.size(), 1);
EXPECT_EQ(ints[0], 4);
}
TEST_MAIN(Vector)

13
AK/Vector.h
View File

@ -266,10 +266,15 @@ public:
void remove(int index)
{
ASSERT(index < m_size);
at(index).~T();
for (int i = index + 1; i < m_size; ++i) {
new (slot(i - 1)) T(move(at(i)));
at(i).~T();
if constexpr (Traits<T>::is_trivial()) {
TypedTransfer<T>::copy(slot(index), slot(index + 1), m_size - index - 1);
} else {
at(index).~T();
for (int i = index + 1; i < m_size; ++i) {
new (slot(i - 1)) T(move(at(i)));
at(i).~T();
}
}
--m_size;