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SWP, SWPA, SWPAL, SWPL

Swap word or doubleword in memory

This instruction atomically loads a 32-bit word or 64-bit doubleword from a memory location, and stores the value held in a register back to the same memory location. The value initially loaded from memory is returned in the destination register.

• If the destination register is not one of WZR or XZR, SWPA and SWPAL load from memory with acquire semantics.
• SWPL and SWPAL store to memory with release semantics.
• SWP has neither acquire nor release semantics.

For more information about memory ordering semantics, see Load-Acquire, Store-Release.

For information about addressing modes, see Load/Store addressing modes.

Integer
(FEAT_LSE)

Decode for all variants of this encoding

if !IsFeatureImplemented(FEAT_LSE) then EndOfDecode(Decode_UNDEF); end; let s : integer{} = UInt(Rs); let t : integer{} = UInt(Rt); let n : integer{} = UInt(Rn); let datasize : integer{} = 8 << UInt(size); let regsize : integer{} = if datasize == 64 then 64 else 32; let acquire : boolean = A == '1' && Rt != '11111'; let release : boolean = R == '1'; let tagchecked : boolean = n != 31;