ISB -- AArch32

This is a collection of Intel®’ IA32® Software Developer's Manuals (URL of the day) and AMD' AMD64 Architecture Programmer's Manual together with the related specifications, application notes, white papers, and change logs. The collection aims to keep all available revisions. It was originally created by Michal Necasek, see OS/2 Museum.

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ISB

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

It has encodings from the following instruction sets: A32 ( A1 ) and T32 ( T1 ) .

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
1	1	1	1	0	1	0	1	0	1	1	1	(1)	(1)	(1)	(1)	(1)	(1)	(1)	(1)	(0)	(0)	(0)	(0)	0	1	1	0	option
																								opcode

Decode for this encoding

15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
1	1	1	1	0	0	1	1	1	0	1	1	(1)	(1)	(1)	(1)	1	0	(0)	0	(1)	(1)	(1)	(1)	0	1	1	0	option
																								opc

Decode for this encoding

For more information about the CONSTRAINED UNPREDICTABLE behavior, see Architectural Constraints on UNPREDICTABLE behaviors.

Assembler Symbols

<c>	For the "A1" variant: see Standard assembler syntax fields. Must be AL or omitted.
	For the "T1" variant: see Standard assembler syntax fields.

<q>	See Standard assembler syntax fields.

Specifies an optional limitation on the barrier operation. Values are:

SY: Full system barrier operation, encoded as option = 0b1111. Can be omitted.

All other encodings of option are reserved. The corresponding instructions execute as full system barrier operations, but must not be relied upon by software.

ISB

A1

Encoding

Decode for this encoding

T1

Encoding

Decode for this encoding

Assembler Symbols

Operation