PRFB (scalar plus vector)

Gather prefetch bytes (scalar plus vector)

Gather prefetch of bytes from the active memory addresses generated by a 64-bit scalar base plus vector index. The index values are optionally sign or zero-extended from 32 to 64 bits. Inactive addresses are not prefetched from memory.

The <prfop> symbol specifies the prefetch hint as a combination of three options: access type PLD for load or PST for store; target cache level L1, L2 or L3; temporality (KEEP for temporal or STRM for non-temporal).

This instruction is illegal when executed in Streaming SVE mode, unless FEAT_SME_FA64 is implemented and enabled.

It has encodings from 3 classes: 32-bit scaled offset , 32-bit unpacked scaled offset and 64-bit scaled offset

32-bit scaled offset

if !HaveSVE() then UNDEFINED; constant integer esize = 32; integer g = UInt(Pg); integer n = UInt(Rn); integer m = UInt(Zm); integer level = UInt(prfop<2:1>); boolean stream = (prfop<0> == '1'); pref_hint = if prfop<3> == '0' then Prefetch_READ else Prefetch_WRITE; constant integer offs_size = 32; boolean offs_unsigned = (xs == '0'); integer scale = 0;

32-bit unpacked scaled offset

if !HaveSVE() then UNDEFINED; constant integer esize = 64; integer g = UInt(Pg); integer n = UInt(Rn); integer m = UInt(Zm); integer level = UInt(prfop<2:1>); boolean stream = (prfop<0> == '1'); pref_hint = if prfop<3> == '0' then Prefetch_READ else Prefetch_WRITE; constant integer offs_size = 32; boolean offs_unsigned = (xs == '0'); integer scale = 0;

64-bit scaled offset

if !HaveSVE() then UNDEFINED; constant integer esize = 64; integer g = UInt(Pg); integer n = UInt(Rn); integer m = UInt(Zm); integer level = UInt(prfop<2:1>); boolean stream = (prfop<0> == '1'); pref_hint = if prfop<3> == '0' then Prefetch_READ else Prefetch_WRITE; constant integer offs_size = 64; boolean offs_unsigned = TRUE; integer scale = 0;