Hi Tomasz,
I've finished submdspan for the padded layouts. Essentially,
it can reuse everything that's already here. There's a few
small changes.
Do you want to first review v1; or should a immediately
replace it with v2?
Thank you,
Luc
On 11/14/25 15:09, Luc Grosheintz wrote:
This sequence of 6 patches implements submdspan for layout_left,
layout_right and layout_stride.
The first commit is preparatory (move code, generalize code
and fix some formatting issues). Then, each commit implements:
- submdspan_canonicalize_slices,
- submdspan_extents (with review comments on previous patch),
- submdspan_mapping: layout_left, layout_right, layout_stride.
There's one deviation related to checking:
0 <= slice_begin[k] <= slice_end[k] <= exts.extent(k)
explained in detail in the corresponding commit message.
The check that if slice_begin[k] == exts.extent(k) when computing the
offset, adds a "chunk of code" that's not needed and blocks certain
optimizations. The corresponding commit message has more details.
Luc Grosheintz (6):
libstdc++: Prepare mdspan-related code for submdspan.
libstdc++: Implement submdspan_canonicalize_slices. [PR110352]
libstdc++: Implement submdspan_extents. [PR110352]
libstdc++: Implement submdspan and submdspan_mapping for layout_left.
[PR110352]
libstdc++: Implement submdspan_mapping for layout_right. [PR110352]
libstdc++: Implement submdspan_mapping for layout_stride. [PR110352]
libstdc++-v3/include/std/mdspan | 841 +++++++++++++++++-
libstdc++-v3/src/c++23/std.cc.in | 6 +-
.../testsuite/23_containers/mdspan/int_like.h | 34 +-
.../padded_traits.h => layout_traits.h} | 65 +-
.../23_containers/mdspan/layouts/ctors.cc | 2 +-
.../23_containers/mdspan/layouts/mapping.cc | 2 +-
.../23_containers/mdspan/layouts/padded.cc | 2 +-
.../mdspan/layouts/padded_neg.cc | 2 +-
.../mdspan/submdspan/submdspan.cc | 371 ++++++++
.../submdspan_canonicalize_slices.cc | 212 +++++
.../submdspan_canonicalize_slices_neg.cc | 208 +++++
.../mdspan/submdspan/submdspan_extents.cc | 169 ++++
.../mdspan/submdspan/submdspan_extents_neg.cc | 48 +
.../mdspan/submdspan/submdspan_mapping.cc | 160 ++++
.../mdspan/submdspan/submdspan_neg.cc | 120 +++
15 files changed, 2194 insertions(+), 48 deletions(-)
rename libstdc++-v3/testsuite/23_containers/mdspan/{layouts/padded_traits.h
=> layout_traits.h} (70%)
create mode 100644
libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan.cc
create mode 100644
libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_canonicalize_slices.cc
create mode 100644
libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_canonicalize_slices_neg.cc
create mode 100644
libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_extents.cc
create mode 100644
libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_extents_neg.cc
create mode 100644
libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_mapping.cc
create mode 100644
libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_neg.cc
