On 23/07/2020 08.04, Shu-Chun Weng wrote: > Do we have the flexibility to do that for util/bufferiszero.c as well? > Otherwise, we are using different mechanisms to detect (compile test.c > with -mavx2) and actually use (GCC pragma & __attribute__((target(*))))) > the feature in production.
That's true ... so it's likely better to keep the pragmas in the configure script, indeed! Thanks, Thomas > Shu-Chun > > On Wed, Jul 22, 2020 at 9:55 PM Thomas Huth <th...@redhat.com > <mailto:th...@redhat.com>> wrote: > > On 23/07/2020 02.27, Shu-Chun Weng wrote: > > Since clang does not support "#pragma GCC", the instruction sets are > > always disabled. In this change, we > > > > 1. wrap "#pragma GCC" inside "#ifndef __clang__", > > 2. only retain them around "#include <{e,i,s}mmintrin.h>" to work > > around gcc bug, > > 3. and annotate each function with `__attribute__((target(*)))` which > > is recognized by both gcc and clang. > > > > Signed-off-by: Shu-Chun Weng <s...@google.com <mailto:s...@google.com>> > > --- > > configure | 16 ++++++++++++++-- > > util/bufferiszero.c | 33 +++++++++++++++++++++++---------- > > 2 files changed, 37 insertions(+), 12 deletions(-) > > > > diff --git a/configure b/configure > > index 4bd80ed507..d9ce3aa5db 100755 > > --- a/configure > > +++ b/configure > > @@ -5808,10 +5808,16 @@ fi > > > > if test "$cpuid_h" = "yes" && test "$avx2_opt" != "no"; then > > cat > $TMPC << EOF > > +#include <cpuid.h> > > +#ifndef __clang__ > > #pragma GCC push_options > > #pragma GCC target("avx2") > > -#include <cpuid.h> > > +#endif > > #include <immintrin.h> > > +#ifndef __clang__ > > +#pragma GCC pop_options > > +#endif > > +__attribute__((target("avx2"))) > > static int bar(void *a) { > > __m256i x = *(__m256i *)a; > > return _mm256_testz_si256(x, x); > > I wonder whether it would make more sense to pass "-mavx2" to the > compile_object call afterwards and simply remove the #pragmas here? > Did you try that already? > > Thomas >