[cpp-threads] Brief tentative example x86 Implementation for C/C++ Memory Model

[Alexander Terekhov]

(cmpxchg aside for a moment)

Load Relaxed:  MOV (from memory)
Load Consume:  MOV (from memory)
Load Acquire:  MOV (from memory)
Load Seq_Cst:  LOCK XADD(0) // alternative: MFENCE,MOV (from memory)
Store Relaxed: MOV (into memory)
Store Release: MOV (into memory)
Store Seq Cst: LOCK XCHG    // alternative: MOV (into memory),MFENCE
Consume Fence: <ignore>
Acquire Fence: <ignore>
Release Fence: <ignore>
Acq_Rel Fence: <ignore>
Seq_Cst Fence: MFENCE

Any objections and/or questions?

TIA.

regards,
alexander.