LDADD, LDADDA, LDADDAL, LDADDL

Atomic add on word or doubleword in memory atomically loads a 32-bit word or 64-bit doubleword from memory, adds the value held in a register to it, and stores the result back to memory. The value initially loaded from memory is returned in the destination register.

• If the destination register is not one of WZR or XZR, LDADDA and LDADDAL load from memory with acquire semantics.
• LDADDL and LDADDAL store to memory with release semantics.
• LDADD has neither acquire nor release semantics.

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

For information about memory accesses see Load/Store addressing modes.

This instruction is used by the alias STADD, STADDL.

Integer
(FEAT_LSE)

if !HaveAtomicExt() then UNDEFINED; integer t = UInt(Rt); integer n = UInt(Rn); integer s = UInt(Rs); integer datasize = 8 << UInt(size); integer regsize = if datasize == 64 then 64 else 32; AccType ldacctype = if A == '1' && Rt != '11111' then AccType_ORDEREDATOMICRW else AccType_ATOMICRW; AccType stacctype = if R == '1' then AccType_ORDEREDATOMICRW else AccType_ATOMICRW; MemAtomicOp op; case opc of when '000' op = MemAtomicOp_ADD; when '001' op = MemAtomicOp_BIC; when '010' op = MemAtomicOp_EOR; when '011' op = MemAtomicOp_ORR; when '100' op = MemAtomicOp_SMAX; when '101' op = MemAtomicOp_SMIN; when '110' op = MemAtomicOp_UMAX; when '111' op = MemAtomicOp_UMIN; boolean tag_checked = n != 31;