Add an optimized strnlen() implementation for RISC-V. This version
includes a generic optimization and a Zbb-powered optimization using
the 'orc.b' instruction, derived from the strlen() implementation.
Benchmark results (QEMU TCG, rv64):
Length | Original (MB/s) | Optimized (MB/s) | Improvement
-------|-----------------|------------------|------------
16 B | 179 | 309 | +72.6%
512 B | 347 | 1562 | +350.1%
4096 B | 356 | 1878 | +427.5%
Suggested-by: Qingfang Deng <dqfext@gmail.com>
Signed-off-by: Feng Jiang <jiangfeng@kylinos.cn>
Link: https://patch.msgid.link/20260130025018.172925-7-jiangfeng@kylinos.cn
Signed-off-by: Paul Walmsley <pjw@kernel.org>
