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.
Shu-Chun
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 <scw@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
smime.p7s