Bit functions: refactoring, extension, and optimisation

.github/workflows/ci-cell.yml

@@ -606,4 +606,6 @@ jobs:
           if [ "${{ inputs.c-compiler }}" = "mingw" ]; then
             export PATH="/mingw64/bin:$PATH"
           fi
+          # Gaps between pattern groups in the bit-functions harness.
+          export SIS_PERFTESTS_GROUPGAPS=1
           SIS_CMAKE_BUILD_DIR="${{ github.workspace }}/build" ./execute_performance_tests.sh -M

CHANGES.md

@@ -1,6 +1,17 @@
 # STLSoft - CHANGES <!-- omit in toc -->
 
 
+## 1.11.1-rc7 - 25th September 2026
+
+* Added `count_bits_by_intrinsic()` and `find_highest_bit_by_intrinsic()` (unselected by default; `count_bits()` keeps the 8-bit table; `find_highest_bit()` keeps the scan);
+* Added **stlsoft/api/external/bitfns.h** and **stlsoft/api/internal/bitfns.h** — detection and adaptations for `popcount` / `clz` / `_BitScanReverse` intrinsics (GCC/Clang builtins preferred over MSVC when both are visible);
+* Clang cccap — `STLSOFT_CLANG_VER`; documented shared `STLSOFT_GCC_VER` (also noted in GCC cccap);
+* Fixed `count_bits()` overloads when `STLSOFT_BIT_COUNT_BY_Kernighan` is defined;
+* Unit tests for intrinsic popcount / highest-bit helpers; broader width coverage for bit-function overloads;
+* Performance suite **test/performance/stlsoft/bit_functions** (density patterns, intrinsic rows, median / ns-per-call reporting);
+* Strategy note **strategy/BIT_FUNCTIONS.md** — measurements and default choice (table for `count_bits()`; keep intrinsics unselected pending cross-toolchain evidence);
+
+
 ## 1.11.1-rc6 - 21st September 2026
 
 * CMake/CI — optional **ACE** discovery (**cmake/FindACE.cmake**, **NO_ACE** / **prepare_cmake.sh --no-ace**); dedicated **cell-ace** job (**with-ace**);

NEWS.md

@@ -3,6 +3,7 @@
 
 | Date                | News Item                           | Details |
 | ------------------- | ----------------------------------- | ------- |
+| 25th September 2026 | Release of [STLSoft 1.11.1-rc7](https://github.com/synesissoftware/STLSoft/releases/tag/1.11.1-rc7) | bit-function intrinsics; table default for `count_bits()` |
 | 21st September 2026 | Release of [STLSoft 1.11.1-rc6](https://github.com/synesissoftware/STLSoft/releases/tag/1.11.1-rc6) | ACE/ATL/MFC CI; Clang/macOS `stricmp` aliases |
 | 4th August 2026     | Release of [STLSoft 1.11.1-rc5](https://github.com/synesissoftware/STLSoft/releases/tag/1.11.1-rc5) | `basic_simple_string<>#resize()`; **CHANGES.md**; docs |
 | 29th July 2026      | Release of [STLSoft 1.11.1-rc4](https://github.com/synesissoftware/STLSoft/releases/tag/1.11.1-rc4) | GitHub Actions CI; VC++ 18.x; MinGW |