dcba

Data Cache Block Allocate

dcba RA, RB

Allocates a cache block without loading from memory (optimization for overwrite).

Encoding

Binary Layout

31

0:5

/

6:10

RA

11:15

RB

16:20

758

21:30

/

31

 

Format X-form

Opcode 0x7C0005EC

Extension Base

Operands

• RA
  Base
• RB
  Index

Example

dcba r4, r5

Related

More in Base

Reference

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

Description

Allocates a cache block at the effective address (RA + RB) into the data cache without loading data from memory. This instruction is used as an optimization hint when the application will overwrite the entire cache block, avoiding unnecessary memory traffic. No condition registers or status fields are modified.

Operation

EA ← (RA) + (RB)
Allocate cache block at EA without loading from memory