yield

Yield (Thumb)

YIELD

Yield hint (Thumb).

Details

Yield is a hint instruction that suggests the processor may improve performance by yielding to other threads or tasks. It does not perform any operation if the yield hint is not implemented. No registers, memory, or condition flags are modified. YIELD is available in all privilege levels and is used for spinlock and busy-wait optimization.

Pseudocode Operation

HintYield()

Example

YIELD

Encoding

Binary Layout
10111111
0001
0000
 
Format Thumb System
Opcode 0xBF10
Extension T32 (Base)

Operands

Reference (Arm AArch32 ISA)

Instruction Forms

Encoding Instruction ISA Bit pattern
0x0320F001 YIELD{<c>}{<q>} A32 cond | 00110 | 0 | 10 | 00 | 00 | 1 | 1 | 1 | 1 | 000000000001
0xBF10 YIELD{<c>}{<q>} T32 10111111 | 0001 | 0000
0xF3AF8001 YIELD{<c>}.W T32 111100111010 | 1 | 1 | 1 | 1 | 10 | 0 | 0 | 0 | 000 | 0000 | 0001

Description

YIELD is a hint instruction. Software with a multithreading capability can use a YIELD instruction to indicate to the PE that it is performing a task, for example a spin-lock, that could be swapped out to improve overall system performance. The PE can use this hint to suspend and resume multiple software threads if it supports the capability. For more information about the recommended use of this instruction see The Yield instruction.

Operation

if ConditionPassed() then
    EncodingSpecificOperations();
    Hint_Yield();