N, _ := NewModulusFromBig(n)
	A := NewNat().setBig(a).ExpandFor(N)
	B := NewNat().setBig(b).ExpandFor(N)

	if A.Mul(B, N).IsZero() != 1 {
		t.Error("a * b mod (a * b) != 0")
	}

	i := new(big.Int).ModInverse(a, b)
	N, _ = NewModulusFromBig(b)
	A = NewNat().setBig(a).ExpandFor(N)
	I := NewNat().setBig(i).ExpandFor(N)
	one := NewNat().setBig(big.NewInt(1)).ExpandFor(N)

	if A.Mul(I, N).Equal(one) != 1 {

		}

		// Move all the stores to the root.
		for i := int64(0); i < n; i++ {
			v := a[i].store
			if v == root {
				v.Aux = cv.Type // widen store type
				v.Pos = pos
				v.SetArg(0, ptr)
				v.SetArg(1, cv)
				v.SetArg(2, mem)
			} else {
				clobber(v)
				v.Type = types.Types[types.TBOOL] // erase memory type
			}
		}
		return true
	}

			if fwdSig[i] != _SIG_DFL && fwdSig[i] != _SIG_IGN {
				setsigstack(i)
			} else if fwdSig[i] == _SIG_IGN {
				sigInitIgnored(i)
			}
			continue
		}

		handlingSig[i] = 1
		setsig(i, abi.FuncPCABIInternal(sighandler))
	}
}

//go:nosplit
//go:nowritebarrierrec
func sigInstallGoHandler(sig uint32) bool {
	// For some signals, we respect an inherited SIG_IGN handler

		for b, r := range newmemphis {
			fmt.Printf("after b=%s, rewrite=%s\n", b, r.String())
		}
	}

	// Apply collected rewrites.
	for _, r := range newmemphis {
		for _, rw := range r.rewrites {
			rw.v.SetArg(rw.i, r.after)
		}
	}

	// Rewrite backedges to include reschedule checks.
	for _, emc := range tofixBackedges {
		e := emc.e
		headerMemPhi := emc.m
		h := e.b
		i := e.i
		p := h.Preds[i]

func (x *Nat) set(y *Nat) *Nat {
	x.reset(len(y.limbs))
	copy(x.limbs, y.limbs)
	return x
}

// setBig assigns x = n, optionally resizing n to the appropriate size.
//
// The announced length of x is set based on the actual bit size of the input,
// ignoring leading zeroes.
func (x *Nat) setBig(n *big.Int) *Nat {
	limbs := n.Bits()
	x.reset(len(limbs))
	for i := range limbs {
		x.limbs[i] = uint(limbs[i])

func mdestroy(mp *m) {
}

func sigtramp()

type sigactiont struct {
	sa_sigaction uintptr
	sa_mask      sigset
	sa_flags     int32
}

//go:nosplit
//go:nowritebarrierrec
func setsig(i uint32, fn uintptr) {
	var sa sigactiont
	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
	sa.sa_mask = sigset_all

	_SIG_SETMASK = 3
	_SS_DISABLE  = 4
)

//extern SigTabTT runtime·sigtab[];

type sigset uint32

var sigset_all = ^sigset(0)

//go:nosplit
//go:nowritebarrierrec
func setsig(i uint32, fn uintptr) {
	var sa usigactiont
	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
	sa.sa_mask = ^uint32(0)

func mdestroy(mp *m) {
}

func sigtramp()

type sigactiont struct {
	sa_handler uintptr
	sa_flags   int32
	sa_mask    sigset
}

// See os_freebsd2.go, os_freebsd_amd64.go for setsig function

//go:nosplit
//go:nowritebarrierrec
func setsigstack(i uint32) {
	var sa sigactiont
	sigaction(i, nil, &sa)
	if sa.sa_flags&_SA_ONSTACK != 0 {
		return
	}
	sa.sa_flags |= _SA_ONSTACK

// resources in minit, semacreate, or elsewhere. Do not take locks after calling this.
func mdestroy(mp *m) {
}

func sigtramp()

//go:nosplit
//go:nowritebarrierrec
func setsig(i uint32, fn uintptr) {
	var sa sigactiont

	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
	sa.sa_mask = sigset_all

	for _, b := range f.Blocks {
		for _, v := range b.Values {
			for i, a := range v.Args {
				if a.Op == OpSPanchored || opcodeTable[a.Op].nilCheck {
					v.SetArg(i, a.Args[0])
				}
			}
		}
		for i, c := range b.ControlValues() {
			if c.Op == OpSPanchored || opcodeTable[c.Op].nilCheck {
				b.ReplaceControl(i, c.Args[0])
			}
		}
	}