RCWSET, RCWSETA, RCWSETAL, RCWSETL

Read check write atomic bit set on doubleword in memory

This instruction atomically loads a 64-bit doubleword from memory, performs a bitwise OR with the value held in a register on it, and conditionally stores the result back to memory. Storing of the result 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, RCWSETA and RCWSETAL load from memory with acquire semantics.
• RCWSETL and RCWSETAL store to memory with release semantics.
• RCWSET 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;