Load-Acquire RCpc Register Byte derives an address from a base register value, loads a byte from the derived address in memory, zero-extends it and writes it to a register.
The instruction has memory ordering semantics as described in Load-Acquire, Load-AcquirePC, and Store-Release, except that:
- There is no ordering requirement, separate from the requirements of a Load-AcquirePC or a Store-Release, created by having a Store-Release followed by a Load-AcquirePC instruction.
- The reading of a value written by a Store-Release by a Load-AcquirePC instruction by the same observer does not make the write of the Store-Release globally observed.
This difference in memory ordering is not described in the pseudocode.
For information about memory accesses, see Load/Store addressing modes.
Is the 32-bit name of the general-purpose register to be loaded, encoded in the "Rt" field.
Is the 64-bit name of the general-purpose base register or stack pointer, encoded in the "Rn" field.
bits(64) address; bits(8) data; if HaveMTEExt() then SetNotTagCheckedInstruction(!tag_checked); if n == 31 then CheckSPAlignment(); address = SP; else address = X[n]; data = Mem[address, 1, AccType_ORDERED]; X[t] = ZeroExtend(data, 32);
If PSTATE.DIT is 1, the timing of this instruction is insensitive to the value of the data being loaded or stored.