This v5 series provides an optimized RISC-V memcmp() implementation along with extended KUnit tests for functional verification and benchmarking
The memcmp() implementation now uses word-aligned loads for the generic path and leverages Zbb for fast sign resolution on supported hardware. A robust fallback to byte-by-byte comparison is implemented for non-Zbb systems to ensure correctness and stability across different toolchains and hardware revisions. Signed-off-by: Milan Tripkovic <[email protected]> --- v5 changes: - Removed redundant warm-up from test case - Optimized generic memcmp path with word-aligned loads. - Implemented non-ZBB fallback to byte comparison per review. - Link to v4: https://lore.kernel.org/all/[email protected]/ v4 changes: - Fixed build error: call to undeclared function 'STRING_BENCH' - Link to v3: https://lore.kernel.org/all/[email protected]/ v3 changes: - Split memcmp benchmark into wrapper (string_bench_memcmp) and worker function (do_string_bench_memcmp). - Removed all C99 mixed declarations; moved all variable declarations to the top of each function. - Converted len, iterations and loop counters in the benchmark to u64 to avoid implicit casts. - Cleaned up spacing, indentation and minor style issues. - Added #if defined(CONFIG_RISCV_ISA_ZBB)... in memcmp.S - Link to v2: https://lore.kernel.org/all/[email protected]/ v2 changes: - Added alignment checks for buffers to avoid expensive misaligned loads. - Optimized the loop using end-pointers to reduce per-iteration overhead. - Implemented word-aligned tail handling using ZBB shifts. - Removed redundant pointer equality (a0 == a1) check. - Retained BE support via #ifndef; ZBB rev8 is used for the LE fast-path. - Fixed KUnit build failures for Clang and non-benchmark configs. - Link to v1: https://lore.kernel.org/all/[email protected]/ Milan Tripkovic (2): riscv: lib: add memcmp() implementation lib/string_kunit: extend benchmarks and unit test to memcmp() arch/riscv/include/asm/string.h | 2 + arch/riscv/lib/Makefile | 1 + arch/riscv/lib/memcmp.S | 106 ++++++++++++++++++++++++++++++ arch/riscv/purgatory/Makefile | 5 +- lib/tests/string_kunit.c | 110 ++++++++++++++++++++++++++++++++ 5 files changed, 223 insertions(+), 1 deletion(-) create mode 100644 arch/riscv/lib/memcmp.S -- 2.43.0
