Prefetch Memory (immediate) signals the memory system that data memory accesses from a specified address are likely to occur in the near future. The memory system can respond by taking actions that are expected to speed up the memory accesses when they do occur, such as preloading the cache line containing the specified address into one or more caches.
The effect of a PRFM instruction is IMPLEMENTATION DEFINED. For more information, see Prefetch memory.
For information about memory accesses, see Load/Store addressing modes.
31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 0 | imm12 | Rn | Rt | |||||||||||||||||||
size | VR | opc |
bits(64) offset = LSL(ZeroExtend(imm12, 64), 3);
<prfop> |
Is the prefetch operation, defined as <type><target><policy>. <type> is one of:
<target> is one of:
<policy> is one of:
For more information on these prefetch operations, see Prefetch memory. For other encodings of the "Rt" field, use <imm5>.
|
<imm5> |
Is the prefetch operation encoding as an immediate, in the range 0 to 31, encoded in the "Rt" field. This syntax is only for encodings that are not accessible using <prfop>. |
<Xn|SP> |
Is the 64-bit name of the general-purpose base register or stack pointer, encoded in the "Rn" field. |
<pimm> |
Is the optional positive immediate byte offset, a multiple of 8 in the range 0 to 32760, defaulting to 0 and encoded in the "imm12" field as <pimm>/8. |
bits(64) address; boolean privileged = PSTATE.EL != EL0; AccessDescriptor accdesc = CreateAccDescGPR(MemOp_PREFETCH, FALSE, privileged, FALSE); if n == 31 then address = SP[]; else address = X[n, 64]; address = GenerateAddress(address, offset, accdesc); Prefetch(address, t<4:0>);
Internal version only: aarchmrs v2023-12_rel, pseudocode v2023-12_rel, sve v2023-12_rel ; Build timestamp: 2023-12-15T16:46
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