pli

Preload Instruction

PLI [<Rn>, #<imm>]

Hints memory system to bring instructions into cache.

Pseudocode Operation

address ← Rn + imm12
// Preload hint for instruction cache sent to memory system; no registers modified

Example

PLI [r1, #16]

Encoding

Binary Layout

1111010

31:25

0

24

U

23

1

22

01

21:20

Rn

19:16

1

15

1

14

1

13

1

12

imm12

11:0

 

Format Load/Store

Opcode 0xF450F000

Extension A32 (System)

Operands

• Rn
  First source / base general-purpose register
• imm
  Signed immediate value

Related

More in A32 (System)

Reference

View in Arm A64 ISA Reference ↗ Arm AArch32 ISA

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0xF450F000	PLI{<c>}{<q>} [<Rn> {, #{+/-}<imm>}]		A32		1111010 | 0 | U | 1 | 01 | Rn | 1 | 1 | 1 | 1 | imm12
0xF990F000	PLI{<c>}{<q>} [<Rn> {, #{+}<imm>}]		T32		111110011 | 00 | 1 | Rn | 1111 | imm12
0xF910FC00	PLI{<c>}{<q>} [<Rn> {, #-<imm>}]		T32		111110010 | 00 | 1 | Rn | 1111 | 1100 | imm8
0xF91FF000	PLI{<c>}{<q>} <label>		T32		11111001 | U | 00 | 11111 | 1111 | imm12
0xF650F060	PLI{<c>}{<q>} [<Rn>, {+/-}<Rm> , RRX]		A32		1111011 | 0 | U | 1 | 01 | Rn | 1 | 1 | 1 | 1 | 00000 | 11 | 0 | Rm
0xF650F000	PLI{<c>}{<q>} [<Rn>, {+/-}<Rm> {, <shift> #<amount>}]		A32		1111011 | 0 | U | 1 | 01 | Rn | 1 | 1 | 1 | 1 | imm5 | stype | 0 | Rm
0xF910F000	PLI{<c>}{<q>} [<Rn>, {+}<Rm> {, LSL #<amount>}]		T32		111110010 | 00 | 1 | Rn | 1111 | 000000 | imm2 | Rm

Description

Preload Instruction signals the memory system that instruction memory accesses from a specified address are likely in the near future. The memory system can respond by taking actions that are expected to speed up the memory accesses when they do occur, such as pre-loading the cache line containing the specified address into the instruction cache. The effect of a PLI instruction is implementation defined. For more information, see Preloading caches.

Operation

if ConditionPassed() then
    EncodingSpecificOperations();
    base = if n == 15 then Align(PC,4) else R[n];
    address = if add then (base + imm32) else (base - imm32);
    Hint_PreloadInstr(address);