libstdc++: Optimize std::for_each for segmented iterators
Optimizes `std::for_each` to handle segmented iterators more efficiently, reducing overhead.
The standard C++ library’s std::for_each algorithm has been optimized to better handle segmented iterators. This change splits the naive for-loop implementation from the more specialized logic for segmented iterators, improving performance by reducing unnecessary overhead when dealing with such iterator types.
In Details
This patch optimizes std::for_each within libstdc++'s <algorithm> header to specifically cater to segmented iterators. It refactors the implementation to separate the generic loop from the specialized path for segmented iterators, similar to a previous optimization. This avoids the overhead associated with the generic loop when a more direct segmented iterator approach is applicable, likely improving performance for certain data structures.
- std::for_each
- A standard C++ algorithm that applies a given function to each element in a range defined by two iterators. It is part of the
<algorithm>header. - segmented iterator
- An iterator that does not necessarily iterate over contiguous memory. It might refer to elements spread across different memory segments or managed in a non-linear fashion, common in certain specialized data structures or memory management schemes.
- STL
- The Standard Template Library, a collection of C++ generic classes and functions providing common data structures and algorithms, such as vectors, lists, maps, and sorting routines.