Instructions behind strlen

strlen

Versions

• x86: sse2 - sse4.2 (avx?)
• x86: avx2
• x86: avx-512 (*)
• arm: v7
• arm: v8
• emulation

headers

• immintrin.h
• arm_neon.h

load(aligned_s)

• x86
• arm

what is avx-512 for us?

set 0

• _mm*_setzero_si*
• vdupq_n_u8

logicals

cur == zero

• _mm*_cmpeq_epi8
• vceqq_u8
• 0x80 blog with avx512f

first_true = any + real_first_true

VC find

real first true

• get bits
• std::countr_zero

top_bits

movemask

top_bits arm-v8

any

• top_bits
• v8: vmaxvq_u32
• v7: any - v7

Missed

• power pc
• webassembly
• arm: helium
• arm: sve/sve2