q1.As = ASUB
				q1.From.Type = obj.TYPE_CONST
				q1.From.Offset = int64(c.autosize)
				q1.Reg = REGSP
				q1.To.Type = obj.TYPE_REG
				q1.To.Reg = REG_R20

				prologueEnd = q1

				// STP (R29, R30), -8(R20)
				q1 = obj.Appendp(q1, c.newprog)
				q1.Pos = p.Pos
				q1.As = ASTP
				q1.From.Type = obj.TYPE_REGREG
				q1.From.Reg = REGFP
				q1.From.Offset = REGLINK
				q1.To.Type = obj.TYPE_MEM

	MOVW	$0, R1
	RET

// Called from cgo wrappers, this function returns g->m->curg.stack.hi.
// Must obey the gcc calling convention.
TEXT _cgo_topofstack(SB),NOSPLIT|NOFRAME,$0
	// g (R30), R3 and REGTMP (R23) might be clobbered by load_g. R30 and R23
	// are callee-save in the gcc calling convention, so save them.
	MOVW	R23, R8
	MOVW	g, R9
	MOVW	R31, R10 // this call frame does not save LR

	JAL	runtime·load_g(SB)

				// if(g->panic != nil && g->panic->argp == FP) g->panic->argp = bottom-of-frame
				//
				//	MOV	g_panic(g), R20
				//	BEQ	R20, end
				//	MOV	panic_argp(R20), R24
				//	ADD	$(autosize+FIXED_FRAME), R3, R30
				//	BNE	R24, R30, end
				//	ADD	$FIXED_FRAME, R3, R24
				//	MOV	R24, panic_argp(R20)
				// end:
				//	NOP
				//
				// The NOP is needed to give the jumps somewhere to land.

TEXT runtime·return0(SB), NOSPLIT, $0
	MOVW	$0, R1
	RET

// Called from cgo wrappers, this function returns g->m->curg.stack.hi.
// Must obey the gcc calling convention.
TEXT _cgo_topofstack(SB),NOSPLIT,$16
	// g (R30) and REGTMP (R23)  might be clobbered by load_g. They
	// are callee-save in the gcc calling convention, so save them.
	MOVV	R23, savedR23-16(SP)
	MOVV	g, savedG-8(SP)

	JAL	runtime·load_g(SB)
	MOVV	g_m(g), R1

	PPC64DWARFRegisters[REG_XER] = 76
}

/*
 * GENERAL:
 *
 * compiler allocates R3 up as temps
 * compiler allocates register variables R7-R27
 * compiler allocates external registers R30 down
 *
 * compiler allocates register variables F17-F26
 * compiler allocates external registers F26 down
 */
const (
	BIG = 32768 - 8
)

const (
	/* mark flags */
	LABEL    = 1 << 0

// Clobbers R19, R20.
TEXT	racecall<>(SB), NOSPLIT|NOFRAME, $0-0
	MOVD	g_m(g), R10
	// Switch to g0 stack.
	MOVD	RSP, R19	// callee-saved, preserved across the CALL
	MOVD	R30, R20	// callee-saved, preserved across the CALL
	MOVD	m_g0(R10), R11
	CMP	R11, g
	BEQ	call	// already on g0
	MOVD	(g_sched+gobuf_sp)(R11), R12
	MOVD	R12, RSP
call:

To prevent accidental misuse, the register is named <code>R18_PLATFORM</code>.
<code>R27</code> and <code>R28</code> are reserved by the compiler and linker.
<code>R29</code> is the frame pointer.
<code>R30</code> is the link register.
</p>

<p>
Instruction modifiers are appended to the instruction following a period.
The only modifiers are <code>P</code> (postincrement) and <code>W</code>
(preincrement):

TEXT __cgo_topofstack(SB),NOSPLIT|NOFRAME,$0
#else
TEXT _cgo_topofstack(SB),NOSPLIT|NOFRAME,$0
#endif
	// g (R30) and R31 are callee-save in the C ABI, so save them
	MOVD	g, R4
	MOVD	R31, R5
	MOVD	LR, R6

	BL	runtime·load_g(SB)	// clobbers g (R30), R31
	MOVD	g_m(g), R3
	MOVD	m_curg(R3), R3
	MOVD	(g_stack+stack_hi)(R3), R3

	MOVD	R4, g
	MOVD	R5, R31
	MOVD	R6, LR