//arg0=ptr,arg1=mem, returns void.  Faults if ptr is nil.
		{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpsp}}, clobberFlags: true, nilCheck: true, faultOnNilArg0: true},
		// LoweredWB invokes runtime.gcWriteBarrier{auxint}. arg0=mem, auxint=# of buffer entries needed.
		// It saves all GP registers if necessary, but may clobber others.
		// Returns a pointer to a write barrier buffer in R11.