[PATCH v3 0/2] riscv: lib: add optimized memcmp() and extend KUnit tests

[Milan Tripkovic]

This v3 series introduces an optimized RISC-V memcmp() implementation and
extends the KUnit string tests to cover functional correctness and
benchmarking of memcmp().

The memcmp() implementation incorporates review feedback from earlier
versions, improving alignment handling, loop structure, Zbb usage, and
overall correctness.

The KUnit updates add comprehensive memcmp() test coverage and a benchmark
mode, with v3 addressing structural cleanups and style issues raised during
review.

Signed-off-by: Milan Tripkovic <Milan.Tripkovic at rt-rk.com>

---
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/20260514121359.931999-1-milant2002@gmail.com/
		
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/20260512141007.1193033-1-milant2002@gmail.com/
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         | 125 ++++++++++++++++++++++++++++++++
 arch/riscv/purgatory/Makefile   |   5 +-
 lib/tests/string_kunit.c        | 116 +++++++++++++++++++++++++++++
 5 files changed, 248 insertions(+), 1 deletion(-)
 create mode 100644 arch/riscv/lib/memcmp.S

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2.43.0