cosp

Call Out Speculation

COSP <Xt>

Prevents speculation from determining that the instruction is executed.

Pseudocode Operation

if FEAT_CSV3 == '0' then
  UNDEFINED
else
  CommitSpeculation(X[t])

Example

COSP x3

Encoding

Binary Layout

1101010100

31:22

0

21

01

20:19

011

18:16

0111

15:12

0011

11:8

110

7:5

Rt

4:0

 

Format System

Opcode 0xD50B73C0

Extension FEAT_CSV3 (Speculation)

Operands

• Xt
  Reg

Related

More in FEAT_CSV3 (Speculation)

Reference

View in Arm A64 ISA Reference ↗ Arm A64 ISA

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0xD50B73C0	COSP RCTX, <Xt>		A64		1101010100 | 0 | 01 | 011 | 0111 | 0011 | 110 | Rt

Description

Clear Other Speculative Prediction Restriction by Context prevents predictions, other than Cache prefetch, Control flow, and Data Value predictions, that predict execution addresses based on information gathered from earlier execution within a particular execution context. Predictions, other than Cache prefetch, Control flow, and Data Value predictions, determined by the actions of code in the target execution context or contexts appearing in program order before the instruction cannot exploitatively control any speculative access occurring after the instruction is complete and synchronized.