dststt

Data Stream Touch for Store Transient

dststt RA, RB, STRM

Initiates a transient prefetch for writing.

Encoding

Binary Layout

31

0:5

STRM

6:10

RA

11:15

RB

16:20

374

21:30

/

31

 

Format X-form

Opcode 0x7C0002EC

Extension Base

Operands

• RA
  Base
• RB
  Index
• STRM
  Stream ID

Example

dststt r4, r5, 0

Related

More in Base

Reference

View in PowerISA v3.1C Specification ↗ OPF Power ISA v3.1C

Description

Initiates a hardware prefetch stream for transient (non-temporal) data that is likely to be written in the near future and not reused. The instruction computes an effective address from RA and RB and hints to the memory subsystem to prepare the cache line for write operations with transient semantics. This advisory instruction supports transient store-stream prefetching to reduce cache pollution.

Operation

EA ← (RA | 0) + RB; InitiateDataStream(EA, STRM, isStore=1, isTransient=1)