prof.stack[1] = abi.FuncPCABIInternal(_LostContendedRuntimeLock) + sys.PCQuantum
		prof.stack[2] = 0
		return
	}

	var nstk int
	gp := getg()
	sp := getcallersp()
	pc := getcallerpc()
	systemstack(func() {
		var u unwinder
		u.initAt(pc, sp, 0, gp, unwindSilentErrors|unwindJumpStack)
		nstk = 1 + tracebackPCs(&u, skip, prof.stack[1:])
	})
	if nstk < len(prof.stack) {

	traceback1(pc, sp, lr, gp, 0)
}

// tracebacktrap is like traceback but expects that the PC and SP were obtained
// from a trap, not from gp->sched or gp->syscallpc/gp->syscallsp or getcallerpc/getcallersp.
// Because they are from a trap instead of from a saved pair,
// the initial PC must not be rewound to the previous instruction.
// (All the saved pairs record a PC that is a return address, so we

(ClosureCall ...) => (CALLclosure ...)
(InterCall ...) => (CALLinter ...)
(TailCall ...) => (CALLtail ...)

// Miscellaneous
(GetClosurePtr ...) => (LoweredGetClosurePtr ...)
(GetCallerSP ...) => (LoweredGetCallerSP ...)
(GetCallerPC ...) => (LoweredGetCallerPC ...)
(IsNonNil ptr) => (NotEqual (CMPconst [0] ptr))
(IsInBounds idx len) => (LessThan (CMPU idx len))
(IsSliceInBounds idx len) => (LessEqual (CMPU idx len))

(NilCheck ...) => (LoweredNilCheck ...)
(GetG ...) => (LoweredGetG ...)
(GetClosurePtr ...) => (LoweredGetClosurePtr ...)
(GetCallerSP ...) => (LoweredGetCallerSP ...)
(GetCallerPC ...) => (LoweredGetCallerPC ...)
(Addr {sym} base) => (MOVDaddr {sym} base)
(LocalAddr <t> {sym} base mem) && t.Elem().HasPointers() => (MOVDaddr {sym} (SPanchored base mem))

(IsInBounds idx len) => (LessThanU (CMP idx len))
(IsSliceInBounds idx len) => (LessEqualU (CMP idx len))

// pseudo-ops
(GetClosurePtr ...) => (LoweredGetClosurePtr ...)
(GetCallerSP ...) => (LoweredGetCallerSP ...)
(GetCallerPC ...) => (LoweredGetCallerPC ...)

// Absorb pseudo-ops into blocks.
(If (Equal cc) yes no) => (EQ cc yes no)
(If (NotEqual cc) yes no) => (NE cc yes no)

(GetG mem) && v.Block.Func.OwnAux.Fn.ABI() != obj.ABIInternal => (LoweredGetG mem) // only lower in old ABI. in new ABI we have a G register.
(GetClosurePtr ...) => (LoweredGetClosurePtr ...)
(GetCallerPC ...) => (LoweredGetCallerPC ...)
(GetCallerSP ...) => (LoweredGetCallerSP ...)

(HasCPUFeature {s}) => (SETNE (CMPLconst [0] (LoweredHasCPUFeature {s})))
(Addr {sym} base) => (LEAQ {sym} base)

// NOTE: The returned pointer may keep the whole map live, so don't
// hold onto it for very long.
func mapaccess1(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
	if raceenabled && h != nil {
		callerpc := getcallerpc()
		pc := abi.FuncPCABIInternal(mapaccess1)
		racereadpc(unsafe.Pointer(h), callerpc, pc)
		raceReadObjectPC(t.Key, key, callerpc, pc)
	}
	if msanenabled && h != nil {
		msanread(key, t.Key.Size_)
	}

		{name: "LoweredGetCallerSP", argLength: 1, reg: gp01, rematerializeable: true},
		// LoweredGetCallerPC evaluates to the PC to which its "caller" will return.
		// I.e., if f calls g "calls" getcallerpc,
		// the result should be the PC within f that g will return to.
		// See runtime/stubs.go for a more detailed discussion.
		{name: "LoweredGetCallerPC", reg: gp01, rematerializeable: true},

		{name: "LoweredGetCallerSP", argLength: 1, reg: gp01, rematerializeable: true},

		// LoweredGetCallerPC evaluates to the PC to which its "caller" will return.
		// I.e., if f calls g "calls" getcallerpc,
		// the result should be the PC within f that g will return to.
		// See runtime/stubs.go for a more detailed discussion.
		{name: "LoweredGetCallerPC", reg: gp01, rematerializeable: true},

		// Constant flag value.