dgh

Data Gathering Hint

DGH

Hints that multiple memory accesses should be merged.

Details

Data Gathering Hint is a system hint instruction that suggests to the processor that multiple small memory accesses should be merged or optimized. It provides a hint to the memory system and does not cause side effects visible to software. This is an AArch64-only instruction; it is NOP-like and has no effect on condition flags or general registers.

Pseudocode Operation

// Hints that multiple memory accesses should be merged

Example

DGH

Encoding

Binary Layout

11010101000000110010

0000

110

11111

Format System Hint

Opcode 0xD50320DF

Extension Base

Operands

Reference (Arm A64 ISA)

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0xD50320DF	DGH		A64		11010101000000110010 \| 0000 \| 110 \| 11111

Description

Data Gathering Hint is a hint instruction that indicates that it is not expected to be performance optimal to merge memory accesses with Normal Non-cacheable or Device-GRE attributes appearing in program order before the hint instruction with any memory accesses appearing after the hint instruction into a single memory transaction on an interconnect.

Operation

Hint_DGH();