// gcWriteBarrier does NOT follow the Go ABI. It accepts the
// number of bytes of buffer needed in DI, and returns a pointer
// to the buffer space in DI.
// It clobbers FLAGS. It does not clobber any general-purpose registers,
// but may clobber others (e.g., SSE registers).
// Typical use would be, when doing *(CX+88) = AX
//     CMPL    $0, runtime.writeBarrier(SB)
//     JEQ     dowrite

	BL	racecall<>(SB)
	MOVD	R15, R8	// restore the original function
	MOVD	R17, R6 // restore arg list addr
	// Call the atomic function.
	// racecall will call LLVM race code which might clobber r30 (g)
	MOVD	runtime·tls_g(SB), R10
	MOVD	0(R10), g

	MOVD	g_racectx(g), R3
	MOVD	R8, R4		// pc being called same TODO as above
	MOVD	(R1), R5	// caller pc from latest LR
	BL	racecall<>(SB)

	// Please refer to https://golang.org/issue/31827 .
	SAVE_R19_TO_R28(8*4)
	SAVE_F8_TO_F15(8*14)

	// If called from an external code context, g will not be set.
	// Save R0, since runtime·load_g will clobber it.
	MOVW	R0, 8(RSP)		// signum
	BL	runtime·load_g(SB)

	// Restore signum to R0.
	MOVW	8(RSP), R0
	// R1 and R2 already contain info and ctx, respectively.
	BL	runtime·sigtrampgo<ABIInternal>(SB)

	// cond: x.Uses == 1 && clobber(x)
	// result: @x.Block (MOVBUload <t> [off] {sym} ptr mem)
	for {
		t := v.Type
		x := v_0
		if x.Op != OpMIPSMOVBload {
			break
		}
		off := auxIntToInt32(x.AuxInt)
		sym := auxToSym(x.Aux)
		mem := x.Args[1]
		ptr := x.Args[0]
		if !(x.Uses == 1 && clobber(x)) {
			break
		}
		b = x.Block

// getclosureptr can only be used in an assignment statement
// at the entry of a function. Moreover, go:nosplit directive
// must be specified at the declaration of caller function,
// so that the function prolog does not clobber the closure register.
// for example:
//
//	//go:nosplit
//	func f(arg1, arg2, arg3 int) {
//		dx := getclosureptr()
//	}
//
// The compiler rewrites calls to this function into instructions that fetch the

time.

The GODEBUG variable controls debugging variables within the runtime.
It is a comma-separated list of name=val pairs setting these named variables:

	clobberfree: setting clobberfree=1 causes the garbage collector to
	clobber the memory content of an object with bad content when it frees
	the object.

	cpu.*: cpu.all=off disables the use of all optional instruction set extensions.

	// Reserve space for callee-save registers and arguments.
	MOVM.DB.W [R4-R11], (R13)
	SUB	$16, R13

	// If called from an external code context, g will not be set.
	// Save R0, since runtime·load_g will clobber it.
	MOVW	R0, 4(R13)		// signum
	BL	runtime·load_g(SB)

	MOVW	R1, 8(R13)
	MOVW	R2, 12(R13)
	BL	runtime·sigtrampgo(SB)

	// Restore callee-save registers.
	ADD	$16, R13
	MOVM.IA.W (R13), [R4-R11]

		// find the memory before the WB stores
		mem := stores[0].MemoryArg()
		pos := stores[0].Pos

		// If the source of a MoveWB is volatile (will be clobbered by a
		// function call), we need to copy it to a temporary location, as
		// marshaling the args of wbMove might clobber the value we're
		// trying to move.
		// Look for volatile source, copy it to temporary before we check
		// the write barrier flag.

	f43([]*int{&p, &r, &q})
	f43([]*int{&q, &p, &r})
}

//go:noescape
func f43(a []*int)

// Assigning to a sub-element that makes up an entire local variable
// should clobber that variable.
func f44(f func() [2]*int) interface{} { // ERROR "live at entry to f44: f"
	type T struct {
		s [1][2]*int
	}
	ret := T{} // ERROR "stack object ret T"
	ret.s[0] = f()
	return ret
}

	// result: (MSUBW a x y)
	for {
		a := v_0
		l := v_1
		if l.Op != OpARM64MULW {
			break
		}
		y := l.Args[1]
		x := l.Args[0]
		if !(v.Type.Size() <= 4 && l.Uses == 1 && clobber(l)) {
			break
		}
		v.reset(OpARM64MSUBW)
		v.AddArg3(a, x, y)
		return true
	}
	// match: (SUB a l:(MNEGW x y))
	// cond: v.Type.Size() <= 4 && l.Uses==1 && clobber(l)