dstt

Data Stream Touch Transient

dstt RA, RB, STRM

Initiates a transient (non-temporal) data stream prefetch.

Encoding

Binary Layout

31

0:5

STRM

6:10

RA

11:15

RB

16:20

342

21:30

/

31

 

Format X-form

Opcode 0x7C0002AC

Extension Base

Operands

• RA
  Base
• RB
  Index
• STRM
  Stream ID

Example

dstt 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 loaded in the near future and not reused. The instruction computes an effective address from RA and RB and hints to the memory subsystem to begin streaming data with transient semantics specified by STRM. This is an advisory instruction that may reduce cache pollution for one-time accesses.

Operation

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