test: Adds a test for HexStr that checks all 256 bytes
This makes sure the whole HexStr mapping table is checked.
bench: Adds a benchmark for HexStr
Benchmarks conversion of a full binary block into hex, like it is done in rest.cpp.
util: optimizes HexStr
In my benchmark, this rewrite improves runtime 27% (g++) to 46% (clang++) for the benchmark HexStrBench:
Note that the idea for this change comes from denis2342 in PR 23364. This is a rewrite so no unaligned accesses occur.
Also, the lookup table is now calculated at compile time, which hopefully makes the code a bit easier to review.
Before
| ns/byte | byte/s | err% | total | benchmark |--------------------:|--------------------:|--------:|----------:|:---------- | 0.52 | 1,924,791,810.24 | 0.2% | 0.01 | `HexStrBench` (clang) | 0.65 | 1,547,633,014.74 | 0.3% | 0.01 | `HexStrBench` (gcc)
After
| ns/byte | byte/s | err% | total | benchmark |--------------------:|--------------------:|--------:|----------:|:---------- | 0.35 | 2,827,553,475.08 | 0.5% | 0.01 | `HexStrBench` (clang) | 0.36 | 2,761,315,307.88 | 0.4% | 0.01 | `HexStrBench (gcc)`
This is a backport of core#24852
Depends on D17138