SVE Instruction List by Dougall Johnson
CLASTB (scalar): Conditionally extract last element to general-purpose register
CLASTB Xdn, Pg, Xdn, Zm.D (SVE (SME
float64_t svclastb[_n_f64](svbool_t pg, float64_t fallback, svfloat64_t data)
int64_t svclastb[_n_s64](svbool_t pg, int64_t fallback, svint64_t data)
uint64_t svclastb[_n_u64](svbool_t pg, uint64_t fallback, svuint64_t data)
128-bit SVE

Set (4) to the last (leftmost) 64-bit element from (2) where the corresponding predicate bit in (1) is non-zero. If there are no such elements, preserve the value from (3).
256-bit SVE

Set (4) to the last (leftmost) 64-bit element from (2) where the corresponding predicate bit in (1) is non-zero. If there are no such elements, preserve the value from (3).
512-bit SVE

Set (4) to the last (leftmost) 64-bit element from (2) where the corresponding predicate bit in (1) is non-zero. If there are no such elements, preserve the value from (3).
Larger sizes
1024-bit SVE

Set (4) to the last (leftmost) 64-bit element from (2) where the corresponding predicate bit in (1) is non-zero. If there are no such elements, preserve the value from (3).
2048-bit SVE

Set (4) to the last (leftmost) 64-bit element from (2) where the corresponding predicate bit in (1) is non-zero. If there are no such elements, preserve the value from (3).
Report mistakes or give feedback
Inspired by and based on the x86/x64 SIMD Instruction List by Daytime.