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qsimd.cpp: Remove workaround for GCC 4.2

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That's long fallen out of support in Qt.

Change-Id: I938b024e38bf4aac9154fffd14f7a603baa24e04
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
This commit is contained in:
Thiago Macieira 2017-11-16 10:58:54 -08:00
parent a4113d0c64
commit 8e387e7fa7
1 changed files with 0 additions and 26 deletions
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26
src/corelib/tools/qsimd.cpp
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@ -652,32 +652,6 @@ Q_CORE_EXPORT QBasicAtomicInteger<unsigned> qt_cpu_features[2] = { Q_BASIC_ATOMI
void qDetectCpuFeatures()
{
#if defined(Q_CC_GNU) && !defined(Q_CC_CLANG) && !defined(Q_CC_INTEL)
# if Q_CC_GNU < 403
// GCC 4.2 (at least the one that comes with Apple's XCode, on Mac) is
// known to be broken beyond repair in dealing with the inline assembly
// above. It will generate bad code that could corrupt important registers
// like the PIC register. The behaviour of code after this function would
// be totally unpredictable.
//
// For that reason, simply forego the CPUID check at all and return the set
// of features that we found at compile time, through the #defines from the
// compiler. This should at least allow code to execute, even if none of
// the specialized code found in Qt GUI and elsewhere will ever be enabled
// (it's the user's fault for using a broken compiler).
//
// This also disables the runtime checking that the processor actually
// contains all the features that the code required. Qt 4 ran for years
// like that, so it shouldn't be a problem.
qt_cpu_features[0].store(minFeature | quint32(QSimdInitialized));
#ifndef Q_ATOMIC_INT64_IS_SUPPORTED
qt_cpu_features[1].store(minFeature >> 32);
#endif
return;
# endif
#endif
quint64 f = detectProcessorFeatures();
QByteArray disable = qgetenv("QT_NO_CPU_FEATURE");
if (!disable.isEmpty()) {