One previous commit optimized fully dynamic extents; and another
refactored __size such that __fwd_prod is valid for __r = 0, ..., rank
(exclusive).
Therefore, by noticing that __rev_prod (and __fwd_prod) never accesses
the first (or last) extent, one can avoid pre-computing partial products
of static extents in those cases, if all other extents are dynamic.
We check that the size of the reference object file decreases further
and the .rodata sections for
__fwd_prod<dyn, ..., dyn, 11>
__rev_prod<3, dyn, ..., dyn>
are absent.
libstdc++-v3/ChangeLog:
* include/std/mdspan (__all_dynamic): Add arguments __begin
and __end.
(__fwd_prods): Relax condition for fully-dynamic extents to
cover (dyn, ..., dyn, X).
(__rev_partial_prods): Analogous for (X, dyn, ..., dyn).
Signed-off-by: Luc Grosheintz <luc.groshei...@gmail.com>
---
libstdc++-v3/include/std/mdspan | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/libstdc++-v3/include/std/mdspan b/libstdc++-v3/include/std/mdspan
index 49e3969134b..ccf1028466f 100644
--- a/libstdc++-v3/include/std/mdspan
+++ b/libstdc++-v3/include/std/mdspan
@@ -49,12 +49,13 @@ namespace std _GLIBCXX_VISIBILITY(default)
_GLIBCXX_BEGIN_NAMESPACE_VERSION
namespace __mdspan
{
+
template<array _Extents>
consteval bool
- __all_dynamic()
+ __all_dynamic(size_t __begin = 0, size_t __end = _Extents.size())
{
- for(auto __ext : _Extents)
- if (__ext != dynamic_extent)
+ for(size_t __i = __begin; __i < __end; ++__i)
+ if (_Extents[__i] != dynamic_extent)
return false;
return true;
}
@@ -469,7 +470,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return 1;
else if constexpr (__rank == 2)
return __r == 0 ? 1 : __exts.extent(0);
- else if constexpr (__all_dynamic<__sta_exts>())
+ else if constexpr (__all_dynamic<__sta_exts>(0, __rank-1))
return __extents_prod(__exts, 1, 0, __r);
else
{
@@ -488,7 +489,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return 1;
else if constexpr (__rank == 2)
return __r == 0 ? __exts.extent(1) : 1;
- else if constexpr (__all_dynamic<__sta_exts>())
+ else if constexpr (__all_dynamic<__sta_exts>(1, __rank))
return __extents_prod(__exts, 1, __r + 1, __rank);
else
{
--
2.50.0
