RCWSWP, RCWSWPA, RCWSWPAL, RCWSWPL

Read check write swap doubleword in memory

This instruction atomically loads a 64-bit doubleword from a memory location, and conditionally stores the value held in a register back to the same memory location. Storing back to memory is conditional on RCW Checks. The value initially loaded from memory is returned in the destination register. If the RCW Checks fail, the architecture permits writing the value read from the location to memory. If the write is performed, the read and the write occur atomically such that no other modification of the memory location can take place between the read and the write. This instruction updates the condition flags based on the result of the RCW Checks.

• If the destination register is not XZR, RCWSWPA and RCWSWPAL load from memory with acquire semantics.
• RCWSWPL and RCWSWPAL store to memory with release semantics.
• RCWSWP has neither acquire nor release semantics.

Integer
(FEAT_THE)

Decode for all variants of this encoding

if !IsFeatureImplemented(FEAT_THE) then EndOfDecode(Decode_UNDEF); end; let s : integer{} = UInt(Rs); let t : integer{} = UInt(Rt); let n : integer{} = UInt(Rn); let soft : boolean = FALSE; let acquire : boolean = A == '1' && t != 31; let release : boolean = R == '1'; let tagchecked : boolean = n != 31;