zlib-ng / zlib-ng / 27973531303 / 4

93%

develop: 93%

push

github

Use vaddvq_u32 for adler32 NEON horizontal reduction

Replace interleaved pairwise reduction with vaddvq_u32 to break the
dependency chain between s1 and s2 modulo computations. The original
code merged both accumulators through a shared addp, serializing the
subsequent umull/lsr/msub chains. Independent reductions allow them
to execute in parallel.

On AArch64 this maps to the ADDV instruction. A compatibility shim
in neon_intrins.h emulates this on 32-bit ARM using vadd and vpadd.

2136 of 2242 branches covered (95.27%)

Branch coverage included in aggregate %.

8640 of 9312 relevant lines covered (92.78%)

503322.21 hits per line