On Friday 24 July 2015 14:23:08 René J. V. Bertin wrote: > René J. V. Bertin wrote: > >> That shouldn't happen. QT_COMPILER_SUPPORTS_SSE4_2 should not be defined, > >> so this wouldn't evaluate to true: > >> > >> #if QT_COMPILER_SUPPORTS_HERE(SSE4_2) > > > > That's what I figured and that's why I tried the options. I'll see if I > > can > > reproduce the issue and report back. > > Sadly, I can. I cannot find any definition of QT_COMPILER_SUPPORTS_SSE4_2 > (is it maybe generated dynamically?!).
It should be in qconfig.h. > I checked, it's not auto-vectorised > code by the compiler that uses SSE4, but indeed that block of code in > qhash.cpp that shouldn't be included with -mno-sse4.2 . I'm a bit at a loss > re: how to debug this. I'm guessing that you'd have noticed if clang didn't > handle macros like QT_COMPILER_SUPPORTS(x) -> (QT_COMPILER_SUPPORTS_ ## x - > 0) correctly! The first thing to check is whether those macros did expand as expected. Check the preprocessed source of qhash.cpp (with the exact same compiler flags, only replacing -c with -E). Are the _mm_crc32_xxx calls there? For Clang, QT_COMPILER_SUPPORTS_HERE(x) expands to a check defined(__x__) [in this case, if __SSE4_2__ is defined]. Ah, that is actually the issue. You're on OS X. All 64-bit Mac hardware supports SSE 4.2, so that feature is always enabled when compiling 64-bit code. The -no-sse4.2 option has no effect on 64-bit, the same way that the -no-ssse3 option has no effect in 32-bit code. -- Thiago Macieira - thiago.macieira (AT) intel.com Software Architect - Intel Open Source Technology Center _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
