cpp

Cache Prefetch Prediction Pruning

CPPP <Xt>

Prevents cache prefetch prediction past this instruction.

Details

Prevents cache prefetch prediction from reordering beyond this instruction, allowing precise control over cache prefetch behavior. This is an AArch64-only instruction requiring FEAT_CPP (Cache Prefetch Prediction). The source register Xt is ignored; the instruction acts as a prefetch prediction barrier. No condition flags are affected.

Pseudocode Operation

Cache_Prefetch_Prediction_Barrier()

Example

CPPP x3

Encoding

Binary Layout

1101010100

011

0111

0011

111

Format System

Opcode 0xD50B73E0

Extension FEAT_CPP

Operands

Xt
Reg

Reference (Arm A64 ISA)

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0xD50B73E0	CPP RCTX, <Xt>		A64		1101010100 \| 0 \| 01 \| 011 \| 0111 \| 0011 \| 111 \| Rt

Description

Cache Prefetch Prediction Restriction by Context prevents cache allocation predictions that predict execution addresses based on information gathered from earlier execution within a particular execution context. The actions of code in the target execution context or contexts appearing in program order before the instruction cannot exploitatively control cache prefetch predictions occurring after the instruction is complete and synchronized. For more information, see CPP RCTX, Cache Prefetch Prediction Restriction by Context.