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| author | Lars Knoll <lars.knoll@qt.io> | 2020-02-09 15:51:03 +0100 |
|---|---|---|
| committer | Lars Knoll <lars.knoll@qt.io> | 2020-04-09 20:04:00 +0200 |
| commit | 73ddfa25b41ddf475b70b7089e3b4d2402494f01 (patch) | |
| tree | 59f3399c54f19b2e772640e126e55620774c6399 /src/corelib/tools/qhashfunctions.h | |
| parent | 09bdf907cfc41fc20c809c26a5c79cf3b4bf3b14 (diff) | |
Optimize hashing of floating point numbers
Change-Id: Id5e091b135c006b10987f229f45319228edb8675
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Diffstat (limited to 'src/corelib/tools/qhashfunctions.h')
| -rw-r--r-- | src/corelib/tools/qhashfunctions.h | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/src/corelib/tools/qhashfunctions.h b/src/corelib/tools/qhashfunctions.h index f519925798..ef83682433 100644 --- a/src/corelib/tools/qhashfunctions.h +++ b/src/corelib/tools/qhashfunctions.h @@ -120,7 +120,14 @@ Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline size_t qHash(quint64 key, size_t s return QHashPrivate::hash(size_t(key), seed); } Q_DECL_CONST_FUNCTION constexpr inline size_t qHash(qint64 key, size_t seed = 0) noexcept { return qHash(quint64(key), seed); } -Q_CORE_EXPORT Q_DECL_CONST_FUNCTION size_t qHash(float key, size_t seed = 0) noexcept; +Q_DECL_CONST_FUNCTION inline size_t qHash(float key, size_t seed = 0) noexcept +{ + // ensure -0 gets mapped to 0 + key += 0.0f; + uint k; + memcpy(&k, &key, sizeof(float)); + return QHashPrivate::hash(k, seed); +} Q_CORE_EXPORT Q_DECL_CONST_FUNCTION size_t qHash(double key, size_t seed = 0) noexcept; #if !defined(Q_OS_DARWIN) || defined(Q_CLANG_QDOC) Q_CORE_EXPORT Q_DECL_CONST_FUNCTION size_t qHash(long double key, size_t seed = 0) noexcept; |