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Details

Type: Bug
Resolution: Done
Priority: P5: Not important
Fix Version/s: 5.11.1
Affects Version/s: 5.9, 5.10, 5.11
Component/s: Core: Other
Labels:
None

Commits:
de40f24706d0f3c4cc13900380aacc90d6879356

Description

Commit [0] contains comment in src/corelib/tools/qsimd_p.h:

// All processors that support AVX support AES, PCLMULQDQ

It's not true for AES. For example all mobile Sandybridge Core i3 support AVX but don't support AES accordingly to [1]. See [2] for example.

So this code will be wrong for those cores:

#  if defined(__AVX__) && defined(QT_COMPILER_SUPPORTS_SIMD_ALWAYS)
// AES, PCLMULQDQ instructions:
// All processors that support AVX support AES, PCLMULQDQ
// (but neither MSVC nor the Intel compiler define these macros)
#    define __AES__                         1
#    define __PCLMUL__                      1
#  endif

This affects all releases starting from 5.9.0.

[0] https://code.qt.io/cgit/qt/qtbase.git/commit/?id=418184c2a0ad97cce12717a43f84fa6f12ece189
[1] https://ark.intel.com/
[2] https://ark.intel.com/products/53438