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x86: Disable AVX support on 64-bit MinGW

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GCC for 64-bit Windows has a bug that it fails to properly re-align the
stack pointer for use with 256-bit memory addresses (AVX). Therefore,
there's about a 50/50 chance that any function using AVX will have an
improperly-aligned stack. In release mode, stack accesses should be
rare, but in debug mode they happen frequently. Either way, this is a
ticking time bomb, so we disable.

Clang is not affected.
32-bit MinGW is not affected.
64-bit in other OSes with GCC are not affected.

Fixes: QTBUG-73539
Change-Id: Id061f35c088044b69a15fffd1580967808f31671
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
This commit is contained in:
Thiago Macieira 2019-02-05 13:55:14 -08:00
parent b319d14110
commit 37352b23a9
1 changed files with 3 additions and 0 deletions
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3
config.tests/x86_simd/main.cpp
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@ -144,6 +144,9 @@ attribute_target("sha") void test_shani()
#endif #endif
#if T(AVX) #if T(AVX)
# if defined(__WIN64__) && defined(__GNUC__) && !defined(__clang__)
# error "AVX support is broken in 64-bit MinGW - https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49001"
# endif
attribute_target("avx") void test_avx() attribute_target("avx") void test_avx()
{ {
__m256d a = _mm256_setzero_pd(); __m256d a = _mm256_setzero_pd();