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Make qDetectCpuFeatures() return the CPU features it detected 

Micro (nano?) optimization.

Change-Id: Iba4b5c183776497d8ee1fffd1564aa53056f343d
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
bb10
Thiago Macieira 2018-11-06 14:44:05 -08:00
parent ffeefaac62
commit 121b0bfed5
2 changed files with 4 additions and 7 deletions
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3
src/corelib/tools/qsimd.cpp
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@ -529,7 +529,7 @@ Q_CORE_EXPORT QBasicAtomicInteger<quint64> qt_cpu_features[1] = { Q_BASIC_ATOMIC
Q_CORE_EXPORT QBasicAtomicInteger<unsigned> qt_cpu_features[2] = { Q_BASIC_ATOMIC_INITIALIZER(0), Q_BASIC_ATOMIC_INITIALIZER(0) };
#endif
void qDetectCpuFeatures()
quint64 qDetectCpuFeatures()
{
quint64 f = detectProcessorFeatures();
QByteArray disable = qgetenv("QT_NO_CPU_FEATURE");
@ -563,6 +563,7 @@ void qDetectCpuFeatures()
#ifndef Q_ATOMIC_INT64_IS_SUPPORTED
qt_cpu_features[1].store(f >> 32);
#endif
return f;
}
void qDumpCPUFeatures()

8
src/corelib/tools/qsimd_p.h
View File

@ -344,7 +344,7 @@ extern Q_CORE_EXPORT QBasicAtomicInteger<quint64> qt_cpu_features[1];
#else
extern Q_CORE_EXPORT QBasicAtomicInteger<unsigned> qt_cpu_features[2];
#endif
Q_CORE_EXPORT void qDetectCpuFeatures();
Q_CORE_EXPORT quint64 qDetectCpuFeatures();
static inline quint64 qCpuFeatures()
{
@ -353,11 +353,7 @@ static inline quint64 qCpuFeatures()
features |= quint64(qt_cpu_features[1].load()) << 32;
#endif
if (Q_UNLIKELY(features == 0)) {
qDetectCpuFeatures();
features = qt_cpu_features[0].load();
#ifndef Q_ATOMIC_INT64_IS_SUPPORTED
features |= quint64(qt_cpu_features[1].load()) << 32;
#endif
features = qDetectCpuFeatures();
Q_ASSUME(features != 0);
}
return features;