On 03/08/25 22:57 +0200, Luc Grosheintz wrote:
The combined effect of this sequence of change is:* a reduction in the number of template instantiations, by - avoiding needless dependency of IndexType, - special formulas for low-rank extents, - special formulas for (nearly) fully dynamic extents. * improved code quality, by - precomputing partial products of the static extents, - special cases for low-rank extents, - rewriting the condition E[i] == dynamic_extent in a more optimizer friendly manner. - effectively loop-unrolling extents::operator==. While simplistic micro-benchmarking shows the effectiveness of these changes, likely the stronger argument is presented in each commit: a) each change removes needless complexity, b) before/after examples of generated code show the effectiveness. Luc Grosheintz (8): libstdc++: Reduce template instantiations in <mdspan>. libstdc++: Precompute products of static extents. libstdc++: Improve low-rank layout_{left,right}::stride. libstdc++: Improve fully dynamic extents in mdspan. libstdc++: Improve nearly fully dynamic extents in mdspan. libstdc++: Reduce indirection in extents::extent. libstdc++: Improve extents::operator==. libstdc++: Replace numeric_limit with __int_traits in mdspan. libstdc++-v3/include/std/mdspan | 282 +++++++++++++----- .../mdspan/extents/class_mandates_neg.cc | 3 + 2 files changed, 208 insertions(+), 77 deletions(-)
I've now reviewed all the patches in this series, with all Tomasz's v3 patches making adjustments, and the whole series is OK for trunk. Some really nice codegen improvemens here, thanks!
