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LibWeb: Avoid sorting InvalidationSet hashes

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Keep the cached equality precheck, but compute the set hash with
order-independent aggregate values instead of materializing and sorting
the per-property hashes.

This avoids allocation and sorting in a hot equality path while leaving
correctness to the existing full property comparison after hash matches.
This commit is contained in:
Andreas Kling 2026-06-13 21:49:29 +02:00 committed by Andreas Kling
parent 7426185b9d
commit f52852cd83
1 changed files with 11 additions and 12 deletions
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23
Libraries/LibWeb/CSS/InvalidationSet.cpp
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@ -4,7 +4,6 @@
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/QuickSort.h>
#include <LibWeb/CSS/InvalidationSet.h>
namespace Web::CSS {
@ -62,18 +61,18 @@ u32 InvalidationSet::hash() const
if (m_hash.has_value())
return *m_hash;
u32 hash = 0;
hash = pair_int_hash(hash, m_needs_invalidate_self);
hash = pair_int_hash(hash, m_needs_invalidate_whole_subtree);
u32 property_hash_sum = 0;
u32 property_hash_xor = 0;
for (auto const& property : m_properties) {
auto property_hash = AK::Traits<Property>::hash(property);
property_hash_sum += property_hash;
property_hash_xor ^= pair_int_hash(property_hash, 0x9e3779b9);
}
Vector<u32> property_hashes;
property_hashes.ensure_capacity(m_properties.size());
for (auto const& property : m_properties)
property_hashes.unchecked_append(AK::Traits<Property>::hash(property));
quick_sort(property_hashes);
for (auto property_hash : property_hashes)
hash = pair_int_hash(hash, property_hash);
auto hash = pair_int_hash(m_needs_invalidate_self, m_needs_invalidate_whole_subtree);
hash = pair_int_hash(hash, m_properties.size());
hash = pair_int_hash(hash, property_hash_sum);
hash = pair_int_hash(hash, property_hash_xor);
m_hash = hash;
return hash;