Richard Henderson <richard.hender...@linaro.org> writes:
> The first patch has been seen before. > > https://patchwork.ozlabs.org/patch/1115039/ > > It had a bug and I didn't fix it right away and then forgot. > Fixed now; I had mixed up the operand ordering for aarch32. > > The next 3 are something that I noticed while doing other stuff. > > In particular, pmull is used heavily during https transfers. > While cloning a repository, the old code peaks at 27% of the > total runtime, as measured by perf top. The new code does > not quite reach 3% repeating the same clone. > > In addition, the new helper functions are in the form that > will be required for the implementation of SVE2. > > The comment in patch 2 about ARMv8.4-DIT is perhaps a stretch, > but re-reading the pmull instruction description in the current > ARM ARM brought it to mind. > > Since TCG is officially not in the security domain, it's > probably not a bug to just claim to support DIT without > actually doing anything to ensure the algorithms used are in > fact timing independent of the data. > > On the other hand, I expect the bit distribution of stuff > going through these sort of hashing algorithms to approach > 50% 1's and 0's, so I also don't think we gain anything on > average to terminate the loop early. > > Thoughts on DIT specifically? It would be an interesting academic exercise to see if someone could exploit the JIT from the guest but as you say not a security domain so.... > > > r~ > > > Richard Henderson (4): > target/arm: Vectorize USHL and SSHL > target/arm: Convert PMUL.8 to gvec > target/arm: Convert PMULL.64 to gvec > target/arm: Convert PMULL.8 to gvec > > target/arm/helper-sve.h | 2 + > target/arm/helper.h | 21 ++- > target/arm/translate.h | 6 + > target/arm/neon_helper.c | 117 ------------- > target/arm/translate-a64.c | 83 ++++----- > target/arm/translate.c | 350 ++++++++++++++++++++++++++++++++----- > target/arm/vec_helper.c | 211 ++++++++++++++++++++++ > 7 files changed, 562 insertions(+), 228 deletions(-) -- Alex Bennée
