On Tue, 18 Jun 2024 at 07:22, Matthias Kretz <m.kr...@gsi.de> wrote: > > Tested on x86_64-linux-gnu (also -m32 and -mx32), aarch64-linux-gnu, and arm- > linux-gnueabi(hf). > > OK for trunk and backports? OK, to go for GCC 11.5 as early as possible?
OK for all branches, thanks. > > ----------------------- 8< ----------------------- > > With the change to the AVX512 find_last_set implementation, the change > to AVX512 operator!= is unnecessary. However, the latter was not > producing optimal code and unnecessarily set the padding bits. In > theory, the compiler could determine that with the new != > implementation, the bit operation for clearing the padding bits is a > no-op and can be elided. > > Signed-off-by: Matthias Kretz <m.kr...@gsi.de> > > libstdc++-v3/ChangeLog: > > PR libstdc++/115454 > * include/experimental/bits/simd_x86.h (_S_not_equal_to): Use > neq comparison instead of bitwise negation after eq. > (_S_find_last_set): Clear unused high bits before computing > bit_width. > * testsuite/experimental/simd/pr115454_find_last_set.cc: New > test. > --- > .../include/experimental/bits/simd_x86.h | 26 +++++----- > .../simd/pr115454_find_last_set.cc | 49 +++++++++++++++++++ > 2 files changed, 62 insertions(+), 13 deletions(-) > create mode 100644 libstdc++-v3/testsuite/experimental/simd/ > pr115454_find_last_set.cc > > > -- > ────────────────────────────────────────────────────────────────────────── > Dr. Matthias Kretz https://mattkretz.github.io > GSI Helmholtz Centre for Heavy Ion Research https://gsi.de > stdₓ::simd > ──────────────────────────────────────────────────────────────────────────
