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Vector: Use memmove() for moving trivial types around more

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This can definitely be improved with better trivial type detection and
by using the TypedTransfer template in more places.

It's a bit annoying that we can't get <type_traits> in Vector.h since
it's included in the toolchain compilation before we have libstdc++.
This commit is contained in:
Andreas Kling 2019-08-07 11:53:21 +02:00
parent bebe7c4cff
commit b48b6c0caa
Notes: sideshowbarker 2024-07-19 12:50:46 +09:00 
Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/b48b6c0caaf
2 changed files with 38 additions and 5 deletions
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12
AK/Traits.h
View file

@ -12,32 +12,44 @@ struct GenericTraits {
template<typename T>
struct Traits : public GenericTraits<T> {
static constexpr bool is_trivial() { return false; }
};
template<>
struct Traits<int> : public GenericTraits<int> {
static constexpr bool is_trivial() { return true; }
static unsigned hash(int i) { return int_hash(i); }
static void dump(int i) { kprintf("%d", i); }
};
template<>
struct Traits<unsigned> : public GenericTraits<unsigned> {
static constexpr bool is_trivial() { return true; }
static unsigned hash(unsigned u) { return int_hash(u); }
static void dump(unsigned u) { kprintf("%u", u); }
};
template<>
struct Traits<u16> : public GenericTraits<u16> {
static constexpr bool is_trivial() { return true; }
static unsigned hash(u16 u) { return int_hash(u); }
static void dump(u16 u) { kprintf("%u", u); }
};
template<>
struct Traits<char> : public GenericTraits<char> {
static constexpr bool is_trivial() { return true; }
static unsigned hash(char c) { return int_hash(c); }
static void dump(char c) { kprintf("%c", c); }
};
template<typename T>
struct Traits<T*> {
static unsigned hash(const T* p)
{
return int_hash((unsigned)(__PTRDIFF_TYPE__)p);
}
static constexpr bool is_trivial() { return true; }
static void dump(const T* p) { kprintf("%p", p); }
static bool equals(const T* a, const T* b) { return a == b; }
};

31
AK/Vector.h
View file

@ -63,6 +63,30 @@ private:
int m_index { 0 };
};
template<typename T>
class TypedTransfer {
public:
static void move(T* destination, T* source, size_t count)
{
if constexpr (Traits<T>::is_trivial()) {
memmove(destination, source, count * sizeof(T));
return;
}
for (size_t i = 0; i < count; ++i)
new (&destination[i]) T(AK::move(source[i]));
}
static void copy(T* destination, const T* source, size_t count)
{
if constexpr (Traits<T>::is_trivial()) {
memmove(destination, source, count * sizeof(T));
return;
}
for (size_t i = 0; i < count; ++i)
new (&destination[i]) T(source[i]);
}
};
template<typename T, int inline_capacity = 0>
class Vector {
public:
@ -379,9 +403,7 @@ public:
}
Vector tmp = move(other);
for (int i = 0; i < tmp.size(); ++i)
new (slot(i)) T(move(tmp.at(i)));
TypedTransfer<T>::move(slot(0), tmp.data(), tmp.size());
m_size += other_size;
}
@ -390,8 +412,7 @@ public:
if (!count)
return;
grow_capacity(size() + count);
for (int i = 0; i < count; ++i)
new (slot(m_size + i)) T(values[i]);
TypedTransfer<T>::copy(slot(m_size), values, count);
m_size += count;
}