isb

Instruction Synchronization Barrier (A32)

ISB <option>

Flushes the pipeline.

Details

Instruction Synchronization Barrier: flushes the instruction pipeline and refetches following instructions, ensuring all previous instructions have completed. No flags are affected. Restricted to A32 instruction set.

Pseudocode Operation

if ConditionPassed() then
  InstructionSynchronizationBarrier(option)

Example

ISB option

Encoding

Binary Layout
111101010111
1
1
1
1
1
1
1
1
0
0
0
0
0110
option
 
Format System
Opcode 0xF57FF060
Extension A32 (Base)

Operands

  • option
    SY

Reference (Arm AArch32 ISA)

Instruction Forms

Encoding Instruction ISA Bit pattern
0xF57FF060 ISB{<c>}{<q>} {<option>} A32 111101010111 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0110 | option
0xF3BF8F60 ISB{<c>}{<q>} {<option>} T32 111100111011 | 1 | 1 | 1 | 1 | 10 | 0 | 0 | 1 | 1 | 1 | 1 | 0110 | option

Description

Instruction Synchronization Barrier flushes the pipeline in the PE and is a context synchronization event. For more information, see Instruction Synchronization Barrier (ISB).

Operation

if ConditionPassed() then
    EncodingSpecificOperations();
    InstructionSynchronizationBarrier();