// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build ppc64 ppc64le

#include "go_asm.h"
#include "go_tls.h"
#include "funcdata.h"
#include "textflag.h"
#include "asm_ppc64x.h"

TEXT runtime·rt0_go(SB),NOSPLIT,$0
	// R1 = stack; R3 = argc; R4 = argv; R13 = C TLS base pointer

	// initialize essential registers
	BL	runtime·reginit(SB)

	SUB	$(FIXED_FRAME+16), R1
	MOVD	R2, 24(R1)		// stash the TOC pointer away again now we've created a new frame
	MOVW	R3, FIXED_FRAME+0(R1)	// argc
	MOVD	R4, FIXED_FRAME+8(R1)	// argv

	// create istack out of the given (operating system) stack.
	// _cgo_init may update stackguard.
	MOVD	$runtime·g0(SB), g
	MOVD	$(-64*1024), R31
	ADD	R31, R1, R3
	MOVD	R3, g_stackguard0(g)
	MOVD	R3, g_stackguard1(g)
	MOVD	R3, (g_stack+stack_lo)(g)
	MOVD	R1, (g_stack+stack_hi)(g)

	// if there is a _cgo_init, call it using the gcc ABI.
	MOVD	_cgo_init(SB), R12
	CMP	R0, R12
	BEQ	nocgo
	MOVD	R12, CTR		// r12 = "global function entry point"
	MOVD	R13, R5			// arg 2: TLS base pointer
	MOVD	$setg_gcc<>(SB), R4 	// arg 1: setg
	MOVD	g, R3			// arg 0: G
	// C functions expect 32 bytes of space on caller stack frame
	// and a 16-byte aligned R1
	MOVD	R1, R14			// save current stack
	SUB	$32, R1			// reserve 32 bytes
	RLDCR	$0, R1, $~15, R1	// 16-byte align
	BL	(CTR)			// may clobber R0, R3-R12
	MOVD	R14, R1			// restore stack
	MOVD	24(R1), R2
	XOR	R0, R0			// fix R0

nocgo:
	// update stackguard after _cgo_init
	MOVD	(g_stack+stack_lo)(g), R3
	ADD	$const__StackGuard, R3
	MOVD	R3, g_stackguard0(g)
	MOVD	R3, g_stackguard1(g)

	// set the per-goroutine and per-mach "registers"
	MOVD	$runtime·m0(SB), R3

	// save m->g0 = g0
	MOVD	g, m_g0(R3)
	// save m0 to g0->m
	MOVD	R3, g_m(g)

	BL	runtime·check(SB)

	// args are already prepared
	BL	runtime·args(SB)
	BL	runtime·osinit(SB)
	BL	runtime·schedinit(SB)

	// create a new goroutine to start program
	MOVD	$runtime·mainPC(SB), R3		// entry
	MOVDU	R3, -8(R1)
	MOVDU	R0, -8(R1)
	MOVDU	R0, -8(R1)
	MOVDU	R0, -8(R1)
	MOVDU	R0, -8(R1)
	MOVDU	R0, -8(R1)
	BL	runtime·newproc(SB)
	ADD	$(16+FIXED_FRAME), R1

	// start this M
	BL	runtime·mstart(SB)

	MOVD	R0, 0(R0)
	RET

DATA	runtime·mainPC+0(SB)/8,$runtime·main(SB)
GLOBL	runtime·mainPC(SB),RODATA,$8

TEXT runtime·breakpoint(SB),NOSPLIT|NOFRAME,$0-0
	MOVD	R0, 0(R0) // TODO: TD
	RET

TEXT runtime·asminit(SB),NOSPLIT|NOFRAME,$0-0
	RET

TEXT _cgo_reginit(SB),NOSPLIT|NOFRAME,$0-0
	// crosscall_ppc64 and crosscall2 need to reginit, but can't
	// get at the 'runtime.reginit' symbol.
	BR	runtime·reginit(SB)

TEXT runtime·reginit(SB),NOSPLIT|NOFRAME,$0-0
	// set R0 to zero, it's expected by the toolchain
	XOR R0, R0
	RET

/*
 *  go-routine
 */

// void gosave(Gobuf*)
// save state in Gobuf; setjmp
TEXT runtime·gosave(SB), NOSPLIT|NOFRAME, $0-8
	MOVD	buf+0(FP), R3
	MOVD	R1, gobuf_sp(R3)
	MOVD	LR, R31
	MOVD	R31, gobuf_pc(R3)
	MOVD	g, gobuf_g(R3)
	MOVD	R0, gobuf_lr(R3)
	MOVD	R0, gobuf_ret(R3)
	// Assert ctxt is zero. See func save.
	MOVD	gobuf_ctxt(R3), R3
	CMP	R0, R3
	BEQ	2(PC)
	BL	runtime·badctxt(SB)
	RET

// void gogo(Gobuf*)
// restore state from Gobuf; longjmp
TEXT runtime·gogo(SB), NOSPLIT, $16-8
	MOVD	buf+0(FP), R5

	// If ctxt is not nil, invoke deletion barrier before overwriting.
	MOVD	gobuf_ctxt(R5), R3
	CMP	R0, R3
	BEQ	nilctxt
	MOVD	$gobuf_ctxt(R5), R3
	MOVD	R3, FIXED_FRAME+0(R1)
	MOVD	R0, FIXED_FRAME+8(R1)
	BL	runtime·writebarrierptr_prewrite(SB)
	MOVD	buf+0(FP), R5

nilctxt:
	MOVD	gobuf_g(R5), g	// make sure g is not nil
	BL	runtime·save_g(SB)

	MOVD	0(g), R4
	MOVD	gobuf_sp(R5), R1
	MOVD	gobuf_lr(R5), R31
	MOVD	R31, LR
	MOVD	gobuf_ret(R5), R3
	MOVD	gobuf_ctxt(R5), R11
	MOVD	R0, gobuf_sp(R5)
	MOVD	R0, gobuf_ret(R5)
	MOVD	R0, gobuf_lr(R5)
	MOVD	R0, gobuf_ctxt(R5)
	CMP	R0, R0 // set condition codes for == test, needed by stack split
	MOVD	gobuf_pc(R5), R12
	MOVD	R12, CTR
	BR	(CTR)

// void mcall(fn func(*g))
// Switch to m->g0's stack, call fn(g).
// Fn must never return. It should gogo(&g->sched)
// to keep running g.
TEXT runtime·mcall(SB), NOSPLIT|NOFRAME, $0-8
	// Save caller state in g->sched
	MOVD	R1, (g_sched+gobuf_sp)(g)
	MOVD	LR, R31
	MOVD	R31, (g_sched+gobuf_pc)(g)
	MOVD	R0, (g_sched+gobuf_lr)(g)
	MOVD	g, (g_sched+gobuf_g)(g)

	// Switch to m->g0 & its stack, call fn.
	MOVD	g, R3
	MOVD	g_m(g), R8
	MOVD	m_g0(R8), g
	BL	runtime·save_g(SB)
	CMP	g, R3
	BNE	2(PC)
	BR	runtime·badmcall(SB)
	MOVD	fn+0(FP), R11			// context
	MOVD	0(R11), R12			// code pointer
	MOVD	R12, CTR
	MOVD	(g_sched+gobuf_sp)(g), R1	// sp = m->g0->sched.sp
	MOVDU	R3, -8(R1)
	MOVDU	R0, -8(R1)
	MOVDU	R0, -8(R1)
	MOVDU	R0, -8(R1)
	MOVDU	R0, -8(R1)
	BL	(CTR)
	MOVD	24(R1), R2
	BR	runtime·badmcall2(SB)

// systemstack_switch is a dummy routine that systemstack leaves at the bottom
// of the G stack. We need to distinguish the routine that
// lives at the bottom of the G stack from the one that lives
// at the top of the system stack because the one at the top of
// the system stack terminates the stack walk (see topofstack()).
TEXT runtime·systemstack_switch(SB), NOSPLIT, $0-0
	// We have several undefs here so that 16 bytes past
	// $runtime·systemstack_switch lies within them whether or not the
        // instructions that derive r2 from r12 are there.
	UNDEF
	UNDEF
	UNDEF
	BL	(LR)	// make sure this function is not leaf
	RET

// func systemstack(fn func())
TEXT runtime·systemstack(SB), NOSPLIT, $0-8
	MOVD	fn+0(FP), R3	// R3 = fn
	MOVD	R3, R11		// context
	MOVD	g_m(g), R4	// R4 = m

	MOVD	m_gsignal(R4), R5	// R5 = gsignal
	CMP	g, R5
	BEQ	noswitch

	MOVD	m_g0(R4), R5	// R5 = g0
	CMP	g, R5
	BEQ	noswitch

	MOVD	m_curg(R4), R6
	CMP	g, R6
	BEQ	switch

	// Bad: g is not gsignal, not g0, not curg. What is it?
	// Hide call from linker nosplit analysis.
	MOVD	$runtime·badsystemstack(SB), R12
	MOVD	R12, CTR
	BL	(CTR)

switch:
	// save our state in g->sched. Pretend to
	// be systemstack_switch if the G stack is scanned.
	MOVD	$runtime·systemstack_switch(SB), R6
	ADD     $16, R6 // get past prologue (including r2-setting instructions when they're there)
	MOVD	R6, (g_sched+gobuf_pc)(g)
	MOVD	R1, (g_sched+gobuf_sp)(g)
	MOVD	R0, (g_sched+gobuf_lr)(g)
	MOVD	g, (g_sched+gobuf_g)(g)

	// switch to g0
	MOVD	R5, g
	BL	runtime·save_g(SB)
	MOVD	(g_sched+gobuf_sp)(g), R3
	// make it look like mstart called systemstack on g0, to stop traceback
	SUB	$FIXED_FRAME, R3
	MOVD	$runtime·mstart(SB), R4
	MOVD	R4, 0(R3)
	MOVD	R3, R1

	// call target function
	MOVD	0(R11), R12	// code pointer
	MOVD	R12, CTR
	BL	(CTR)

	// restore TOC pointer. It seems unlikely that we will use systemstack
	// to call a function defined in another module, but the results of
	// doing so would be so confusing that it's worth doing this.
	MOVD	g_m(g), R3
	MOVD	m_curg(R3), g
	MOVD	(g_sched+gobuf_sp)(g), R3
	MOVD	24(R3), R2
	// switch back to g
	MOVD	g_m(g), R3
	MOVD	m_curg(R3), g
	BL	runtime·save_g(SB)
	MOVD	(g_sched+gobuf_sp)(g), R1
	MOVD	R0, (g_sched+gobuf_sp)(g)
	RET

noswitch:
	// already on m stack, just call directly
	MOVD	0(R11), R12	// code pointer
	MOVD	R12, CTR
	BL	(CTR)
	MOVD	24(R1), R2
	RET

/*
 * support for morestack
 */

// Called during function prolog when more stack is needed.
// Caller has already loaded:
// R3: framesize, R4: argsize, R5: LR
//
// The traceback routines see morestack on a g0 as being
// the top of a stack (for example, morestack calling newstack
// calling the scheduler calling newm calling gc), so we must
// record an argument size. For that purpose, it has no arguments.
TEXT runtime·morestack(SB),NOSPLIT|NOFRAME,$0-0
	// Cannot grow scheduler stack (m->g0).
	MOVD	g_m(g), R7
	MOVD	m_g0(R7), R8
	CMP	g, R8
	BNE	3(PC)
	BL	runtime·badmorestackg0(SB)
	BL	runtime·abort(SB)

	// Cannot grow signal stack (m->gsignal).
	MOVD	m_gsignal(R7), R8
	CMP	g, R8
	BNE	3(PC)
	BL	runtime·badmorestackgsignal(SB)
	BL	runtime·abort(SB)

	// Called from f.
	// Set g->sched to context in f.
	MOVD	R1, (g_sched+gobuf_sp)(g)
	MOVD	LR, R8
	MOVD	R8, (g_sched+gobuf_pc)(g)
	MOVD	R5, (g_sched+gobuf_lr)(g)
	// newstack will fill gobuf.ctxt.

	// Called from f.
	// Set m->morebuf to f's caller.
	MOVD	R5, (m_morebuf+gobuf_pc)(R7)	// f's caller's PC
	MOVD	R1, (m_morebuf+gobuf_sp)(R7)	// f's caller's SP
	MOVD	g, (m_morebuf+gobuf_g)(R7)

	// Call newstack on m->g0's stack.
	MOVD	m_g0(R7), g
	BL	runtime·save_g(SB)
	MOVD	(g_sched+gobuf_sp)(g), R1
	MOVDU   R0, -(FIXED_FRAME+8)(R1)	// create a call frame on g0
	MOVD	R11, FIXED_FRAME+0(R1)	// ctxt argument
	BL	runtime·newstack(SB)

	// Not reached, but make sure the return PC from the call to newstack
	// is still in this function, and not the beginning of the next.
	UNDEF

TEXT runtime·morestack_noctxt(SB),NOSPLIT|NOFRAME,$0-0
	MOVD	R0, R11
	BR	runtime·morestack(SB)

// reflectcall: call a function with the given argument list
// func call(argtype *_type, f *FuncVal, arg *byte, argsize, retoffset uint32).
// we don't have variable-sized frames, so we use a small number
// of constant-sized-frame functions to encode a few bits of size in the pc.
// Caution: ugly multiline assembly macros in your future!

#define DISPATCH(NAME,MAXSIZE)		\
	MOVD	$MAXSIZE, R31;		\
	CMP	R3, R31;		\
	BGT	4(PC);			\
	MOVD	$NAME(SB), R12;		\
	MOVD	R12, CTR;		\
	BR	(CTR)
// Note: can't just "BR NAME(SB)" - bad inlining results.

TEXT reflect·call(SB), NOSPLIT, $0-0
	BR	·reflectcall(SB)

TEXT ·reflectcall(SB), NOSPLIT|NOFRAME, $0-32
	MOVWZ argsize+24(FP), R3
	DISPATCH(runtime·call32, 32)
	DISPATCH(runtime·call64, 64)
	DISPATCH(runtime·call128, 128)
	DISPATCH(runtime·call256, 256)
	DISPATCH(runtime·call512, 512)
	DISPATCH(runtime·call1024, 1024)
	DISPATCH(runtime·call2048, 2048)
	DISPATCH(runtime·call4096, 4096)
	DISPATCH(runtime·call8192, 8192)
	DISPATCH(runtime·call16384, 16384)
	DISPATCH(runtime·call32768, 32768)
	DISPATCH(runtime·call65536, 65536)
	DISPATCH(runtime·call131072, 131072)
	DISPATCH(runtime·call262144, 262144)
	DISPATCH(runtime·call524288, 524288)
	DISPATCH(runtime·call1048576, 1048576)
	DISPATCH(runtime·call2097152, 2097152)
	DISPATCH(runtime·call4194304, 4194304)
	DISPATCH(runtime·call8388608, 8388608)
	DISPATCH(runtime·call16777216, 16777216)
	DISPATCH(runtime·call33554432, 33554432)
	DISPATCH(runtime·call67108864, 67108864)
	DISPATCH(runtime·call134217728, 134217728)
	DISPATCH(runtime·call268435456, 268435456)
	DISPATCH(runtime·call536870912, 536870912)
	DISPATCH(runtime·call1073741824, 1073741824)
	MOVD	$runtime·badreflectcall(SB), R12
	MOVD	R12, CTR
	BR	(CTR)

#define CALLFN(NAME,MAXSIZE)			\
TEXT NAME(SB), WRAPPER, $MAXSIZE-24;		\
	NO_LOCAL_POINTERS;			\
	/* copy arguments to stack */		\
	MOVD	arg+16(FP), R3;			\
	MOVWZ	argsize+24(FP), R4;			\
	MOVD	R1, R5;				\
	ADD	$(FIXED_FRAME-1), R5;			\
	SUB	$1, R3;				\
	ADD	R5, R4;				\
	CMP	R5, R4;				\
	BEQ	4(PC);				\
	MOVBZU	1(R3), R6;			\
	MOVBZU	R6, 1(R5);			\
	BR	-4(PC);				\
	/* call function */			\
	MOVD	f+8(FP), R11;			\
	MOVD	(R11), R12;			\
	MOVD	R12, CTR;			\
	PCDATA  $PCDATA_StackMapIndex, $0;	\
	BL	(CTR);				\
	MOVD	24(R1), R2;			\
	/* copy return values back */		\
	MOVD	argtype+0(FP), R7;		\
	MOVD	arg+16(FP), R3;			\
	MOVWZ	n+24(FP), R4;			\
	MOVWZ	retoffset+28(FP), R6;		\
	ADD	$FIXED_FRAME, R1, R5;		\
	ADD	R6, R5; 			\
	ADD	R6, R3;				\
	SUB	R6, R4;				\
	BL	callRet<>(SB);			\
	RET

// callRet copies return values back at the end of call*. This is a
// separate function so it can allocate stack space for the arguments
// to reflectcallmove. It does not follow the Go ABI; it expects its
// arguments in registers.
TEXT callRet<>(SB), NOSPLIT, $32-0
	MOVD	R7, FIXED_FRAME+0(R1)
	MOVD	R3, FIXED_FRAME+8(R1)
	MOVD	R5, FIXED_FRAME+16(R1)
	MOVD	R4, FIXED_FRAME+24(R1)
	BL	runtime·reflectcallmove(SB)
	RET

CALLFN(·call32, 32)
CALLFN(·call64, 64)
CALLFN(·call128, 128)
CALLFN(·call256, 256)
CALLFN(·call512, 512)
CALLFN(·call1024, 1024)
CALLFN(·call2048, 2048)
CALLFN(·call4096, 4096)
CALLFN(·call8192, 8192)
CALLFN(·call16384, 16384)
CALLFN(·call32768, 32768)
CALLFN(·call65536, 65536)
CALLFN(·call131072, 131072)
CALLFN(·call262144, 262144)
CALLFN(·call524288, 524288)
CALLFN(·call1048576, 1048576)
CALLFN(·call2097152, 2097152)
CALLFN(·call4194304, 4194304)
CALLFN(·call8388608, 8388608)
CALLFN(·call16777216, 16777216)
CALLFN(·call33554432, 33554432)
CALLFN(·call67108864, 67108864)
CALLFN(·call134217728, 134217728)
CALLFN(·call268435456, 268435456)
CALLFN(·call536870912, 536870912)
CALLFN(·call1073741824, 1073741824)

TEXT runtime·procyield(SB),NOSPLIT,$0-0
	RET

// void jmpdefer(fv, sp);
// called from deferreturn.
// 1. grab stored LR for caller
// 2. sub 8 bytes to get back to either nop or toc reload before deferreturn
// 3. BR to fn
// When dynamically linking Go, it is not sufficient to rewind to the BL
// deferreturn -- we might be jumping between modules and so we need to reset
// the TOC pointer in r2. To do this, codegen inserts MOVD 24(R1), R2 *before*
// the BL deferreturn and jmpdefer rewinds to that.
TEXT runtime·jmpdefer(SB), NOSPLIT|NOFRAME, $0-16
	MOVD	0(R1), R31
	SUB     $8, R31
	MOVD	R31, LR

	MOVD	fv+0(FP), R11
	MOVD	argp+8(FP), R1
	SUB	$FIXED_FRAME, R1
	MOVD	0(R11), R12
	MOVD	R12, CTR
	BR	(CTR)

// Save state of caller into g->sched. Smashes R31.
TEXT gosave<>(SB),NOSPLIT|NOFRAME,$0
	MOVD	LR, R31
	MOVD	R31, (g_sched+gobuf_pc)(g)
	MOVD	R1, (g_sched+gobuf_sp)(g)
	MOVD	R0, (g_sched+gobuf_lr)(g)
	MOVD	R0, (g_sched+gobuf_ret)(g)
	// Assert ctxt is zero. See func save.
	MOVD	(g_sched+gobuf_ctxt)(g), R31
	CMP	R0, R31
	BEQ	2(PC)
	BL	runtime·badctxt(SB)
	RET

// func asmcgocall(fn, arg unsafe.Pointer) int32
// Call fn(arg) on the scheduler stack,
// aligned appropriately for the gcc ABI.
// See cgocall.go for more details.
TEXT ·asmcgocall(SB),NOSPLIT,$0-20
	MOVD	fn+0(FP), R3
	MOVD	arg+8(FP), R4

	MOVD	R1, R7		// save original stack pointer
	MOVD	g, R5

	// Figure out if we need to switch to m->g0 stack.
	// We get called to create new OS threads too, and those
	// come in on the m->g0 stack already.
	MOVD	g_m(g), R6
	MOVD	m_g0(R6), R6
	CMP	R6, g
	BEQ	g0
	BL	gosave<>(SB)
	MOVD	R6, g
	BL	runtime·save_g(SB)
	MOVD	(g_sched+gobuf_sp)(g), R1

	// Now on a scheduling stack (a pthread-created stack).
g0:
	// Save room for two of our pointers, plus 32 bytes of callee
	// save area that lives on the caller stack.
	SUB	$48, R1
	RLDCR	$0, R1, $~15, R1	// 16-byte alignment for gcc ABI
	MOVD	R5, 40(R1)	// save old g on stack
	MOVD	(g_stack+stack_hi)(R5), R5
	SUB	R7, R5
	MOVD	R5, 32(R1)	// save depth in old g stack (can't just save SP, as stack might be copied during a callback)
	MOVD	R0, 0(R1)	// clear back chain pointer (TODO can we give it real back trace information?)
	// This is a "global call", so put the global entry point in r12
	MOVD	R3, R12
	MOVD	R12, CTR
	MOVD	R4, R3		// arg in r3
	BL	(CTR)

	// C code can clobber R0, so set it back to 0.  F27-F31 are
	// callee save, so we don't need to recover those.
	XOR	R0, R0
	// Restore g, stack pointer, toc pointer.
	// R3 is errno, so don't touch it
	MOVD	40(R1), g
	MOVD    (g_stack+stack_hi)(g), R5
	MOVD    32(R1), R6
	SUB     R6, R5
	MOVD    24(R5), R2
	BL	runtime·save_g(SB)
	MOVD	(g_stack+stack_hi)(g), R5
	MOVD	32(R1), R6
	SUB	R6, R5
	MOVD	R5, R1

	MOVW	R3, ret+16(FP)
	RET

// cgocallback(void (*fn)(void*), void *frame, uintptr framesize, uintptr ctxt)
// Turn the fn into a Go func (by taking its address) and call
// cgocallback_gofunc.
TEXT runtime·cgocallback(SB),NOSPLIT,$32-32
	MOVD	$fn+0(FP), R3
	MOVD	R3, FIXED_FRAME+0(R1)
	MOVD	frame+8(FP), R3
	MOVD	R3, FIXED_FRAME+8(R1)
	MOVD	framesize+16(FP), R3
	MOVD	R3, FIXED_FRAME+16(R1)
	MOVD	ctxt+24(FP), R3
	MOVD	R3, FIXED_FRAME+24(R1)
	MOVD	$runtime·cgocallback_gofunc(SB), R12
	MOVD	R12, CTR
	BL	(CTR)
	RET

// cgocallback_gofunc(FuncVal*, void *frame, uintptr framesize, uintptr ctxt)
// See cgocall.go for more details.
TEXT ·cgocallback_gofunc(SB),NOSPLIT,$16-32
	NO_LOCAL_POINTERS

	// Load m and g from thread-local storage.
	MOVB	runtime·iscgo(SB), R3
	CMP	R3, $0
	BEQ	nocgo
	BL	runtime·load_g(SB)
nocgo:

	// If g is nil, Go did not create the current thread.
	// Call needm to obtain one for temporary use.
	// In this case, we're running on the thread stack, so there's
	// lots of space, but the linker doesn't know. Hide the call from
	// the linker analysis by using an indirect call.
	CMP	g, $0
	BEQ	needm

	MOVD	g_m(g), R8
	MOVD	R8, savedm-8(SP)
	BR	havem

needm:
	MOVD	g, savedm-8(SP) // g is zero, so is m.
	MOVD	$runtime·needm(SB), R12
	MOVD	R12, CTR
	BL	(CTR)

	// Set m->sched.sp = SP, so that if a panic happens
	// during the function we are about to execute, it will
	// have a valid SP to run on the g0 stack.
	// The next few lines (after the havem label)
	// will save this SP onto the stack and then write
	// the same SP back to m->sched.sp. That seems redundant,
	// but if an unrecovered panic happens, unwindm will
	// restore the g->sched.sp from the stack location
	// and then systemstack will try to use it. If we don't set it here,
	// that restored SP will be uninitialized (typically 0) and
	// will not be usable.
	MOVD	g_m(g), R8
	MOVD	m_g0(R8), R3
	MOVD	R1, (g_sched+gobuf_sp)(R3)

havem:
	// Now there's a valid m, and we're running on its m->g0.
	// Save current m->g0->sched.sp on stack and then set it to SP.
	// Save current sp in m->g0->sched.sp in preparation for
	// switch back to m->curg stack.
	// NOTE: unwindm knows that the saved g->sched.sp is at 8(R1) aka savedsp-16(SP).
	MOVD	m_g0(R8), R3
	MOVD	(g_sched+gobuf_sp)(R3), R4
	MOVD	R4, savedsp-16(SP)
	MOVD	R1, (g_sched+gobuf_sp)(R3)

	// Switch to m->curg stack and call runtime.cgocallbackg.
	// Because we are taking over the execution of m->curg
	// but *not* resuming what had been running, we need to
	// save that information (m->curg->sched) so we can restore it.
	// We can restore m->curg->sched.sp easily, because calling
	// runtime.cgocallbackg leaves SP unchanged upon return.
	// To save m->curg->sched.pc, we push it onto the stack.
	// This has the added benefit that it looks to the traceback
	// routine like cgocallbackg is going to return to that
	// PC (because the frame we allocate below has the same
	// size as cgocallback_gofunc's frame declared above)
	// so that the traceback will seamlessly trace back into
	// the earlier calls.
	//
	// In the new goroutine, -8(SP) is unused (where SP refers to
	// m->curg's SP while we're setting it up, before we've adjusted it).
	MOVD	m_curg(R8), g
	BL	runtime·save_g(SB)
	MOVD	(g_sched+gobuf_sp)(g), R4 // prepare stack as R4
	MOVD	(g_sched+gobuf_pc)(g), R5
	MOVD	R5, -(FIXED_FRAME+16)(R4)
	MOVD	ctxt+24(FP), R3
	MOVD	R3, -16(R4)
	MOVD	$-(FIXED_FRAME+16)(R4), R1
	BL	runtime·cgocallbackg(SB)

	// Restore g->sched (== m->curg->sched) from saved values.
	MOVD	0(R1), R5
	MOVD	R5, (g_sched+gobuf_pc)(g)
	MOVD	$(FIXED_FRAME+16)(R1), R4
	MOVD	R4, (g_sched+gobuf_sp)(g)

	// Switch back to m->g0's stack and restore m->g0->sched.sp.
	// (Unlike m->curg, the g0 goroutine never uses sched.pc,
	// so we do not have to restore it.)
	MOVD	g_m(g), R8
	MOVD	m_g0(R8), g
	BL	runtime·save_g(SB)
	MOVD	(g_sched+gobuf_sp)(g), R1
	MOVD	savedsp-16(SP), R4
	MOVD	R4, (g_sched+gobuf_sp)(g)

	// If the m on entry was nil, we called needm above to borrow an m
	// for the duration of the call. Since the call is over, return it with dropm.
	MOVD	savedm-8(SP), R6
	CMP	R6, $0
	BNE	droppedm
	MOVD	$runtime·dropm(SB), R12
	MOVD	R12, CTR
	BL	(CTR)
droppedm:

	// Done!
	RET

// void setg(G*); set g. for use by needm.
TEXT runtime·setg(SB), NOSPLIT, $0-8
	MOVD	gg+0(FP), g
	// This only happens if iscgo, so jump straight to save_g
	BL	runtime·save_g(SB)
	RET

// void setg_gcc(G*); set g in C TLS.
// Must obey the gcc calling convention.
TEXT setg_gcc<>(SB),NOSPLIT|NOFRAME,$0-0
	// The standard prologue clobbers R31, which is callee-save in
	// the C ABI, so we have to use $-8-0 and save LR ourselves.
	MOVD	LR, R4
	// Also save g and R31, since they're callee-save in C ABI
	MOVD	R31, R5
	MOVD	g, R6

	MOVD	R3, g
	BL	runtime·save_g(SB)

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

TEXT runtime·getcallerpc(SB),NOSPLIT,$8-16
	MOVD	FIXED_FRAME+8(R1), R3		// LR saved by caller
	MOVD	R3, ret+8(FP)
	RET

TEXT runtime·abort(SB),NOSPLIT|NOFRAME,$0-0
	MOVW	(R0), R0
	UNDEF

#define	TBRL	268
#define	TBRU	269		/* Time base Upper/Lower */

// int64 runtime·cputicks(void)
TEXT runtime·cputicks(SB),NOSPLIT,$0-8
	MOVW	SPR(TBRU), R4
	MOVW	SPR(TBRL), R3
	MOVW	SPR(TBRU), R5
	CMPW	R4, R5
	BNE	-4(PC)
	SLD	$32, R5
	OR	R5, R3
	MOVD	R3, ret+0(FP)
	RET

// AES hashing not implemented for ppc64
TEXT runtime·aeshash(SB),NOSPLIT|NOFRAME,$0-0
	MOVW	(R0), R1
TEXT runtime·aeshash32(SB),NOSPLIT|NOFRAME,$0-0
	MOVW	(R0), R1
TEXT runtime·aeshash64(SB),NOSPLIT|NOFRAME,$0-0
	MOVW	(R0), R1
TEXT runtime·aeshashstr(SB),NOSPLIT|NOFRAME,$0-0
	MOVW	(R0), R1

TEXT runtime·memequal(SB),NOSPLIT,$0-25
	MOVD    a+0(FP), R3
	MOVD    b+8(FP), R4
	MOVD    size+16(FP), R5

	BL	runtime·memeqbody(SB)
	MOVB    R9, ret+24(FP)
	RET

// memequal_varlen(a, b unsafe.Pointer) bool
TEXT runtime·memequal_varlen(SB),NOSPLIT,$40-17
	MOVD	a+0(FP), R3
	MOVD	b+8(FP), R4
	CMP	R3, R4
	BEQ	eq
	MOVD	8(R11), R5    // compiler stores size at offset 8 in the closure
	BL	runtime·memeqbody(SB)
	MOVB	R9, ret+16(FP)
	RET
eq:
	MOVD	$1, R3
	MOVB	R3, ret+16(FP)
	RET

// Do an efficient memcmp for ppc64le
// R3 = s1 len
// R4 = s2 len
// R5 = s1 addr
// R6 = s2 addr
// R7 = addr of return value
TEXT cmpbodyLE<>(SB),NOSPLIT|NOFRAME,$0-0
	MOVD	R3,R8		// set up length
	CMP	R3,R4,CR2	// unequal?
	BC	12,8,setuplen	// BLT CR2
	MOVD	R4,R8		// use R4 for comparison len
setuplen:
	MOVD	R8,CTR		// set up loop counter
	CMP	R8,$8		// only optimize >=8
	BLT	simplecheck
	DCBT	(R5)		// cache hint
	DCBT	(R6)
	CMP	R8,$32		// optimize >= 32
	MOVD	R8,R9
	BLT	setup8a		// 8 byte moves only
setup32a:
	SRADCC	$5,R8,R9	// number of 32 byte chunks
	MOVD	R9,CTR

        // Special processing for 32 bytes or longer.
        // Loading this way is faster and correct as long as the
	// doublewords being compared are equal. Once they
	// are found unequal, reload them in proper byte order
	// to determine greater or less than.
loop32a:
	MOVD	0(R5),R9	// doublewords to compare
	MOVD	0(R6),R10	// get 4 doublewords
	MOVD	8(R5),R14
	MOVD	8(R6),R15
	CMPU	R9,R10		// bytes equal?
	MOVD	$0,R16		// set up for cmpne
	BNE	cmpne		// further compare for LT or GT
	MOVD	16(R5),R9	// get next pair of doublewords
	MOVD	16(R6),R10
	CMPU	R14,R15		// bytes match?
	MOVD	$8,R16		// set up for cmpne
	BNE	cmpne		// further compare for LT or GT
	MOVD	24(R5),R14	// get next pair of doublewords
	MOVD    24(R6),R15
	CMPU	R9,R10		// bytes match?
	MOVD	$16,R16		// set up for cmpne
	BNE	cmpne		// further compare for LT or GT
	MOVD	$-8,R16		// for cmpne, R5,R6 already inc by 32
	ADD	$32,R5		// bump up to next 32
	ADD	$32,R6
	CMPU    R14,R15		// bytes match?
	BC	8,2,loop32a	// br ctr and cr
	BNE	cmpne
	ANDCC	$24,R8,R9	// Any 8 byte chunks?
	BEQ	leftover	// and result is 0
setup8a:
	SRADCC	$3,R9,R9	// get the 8 byte count
	BEQ	leftover	// shifted value is 0
	MOVD	R9,CTR		// loop count for doublewords
loop8:
	MOVDBR	(R5+R0),R9	// doublewords to compare
	MOVDBR	(R6+R0),R10	// LE compare order
	ADD	$8,R5
	ADD	$8,R6
	CMPU	R9,R10		// match?
	BC	8,2,loop8	// bt ctr <> 0 && cr
	BGT	greater
	BLT	less
leftover:
	ANDCC	$7,R8,R9	// check for leftover bytes
	MOVD	R9,CTR		// save the ctr
	BNE	simple		// leftover bytes
	BC	12,10,equal	// test CR2 for length comparison
	BC	12,8,less
	BR	greater
simplecheck:
	CMP	R8,$0		// remaining compare length 0
	BNE	simple		// do simple compare
	BC	12,10,equal	// test CR2 for length comparison
	BC	12,8,less	// 1st len < 2nd len, result less
	BR	greater		// 1st len > 2nd len must be greater
simple:
	MOVBZ	0(R5), R9	// get byte from 1st operand
	ADD	$1,R5
	MOVBZ	0(R6), R10	// get byte from 2nd operand
	ADD	$1,R6
	CMPU	R9, R10
	BC	8,2,simple	// bc ctr <> 0 && cr
	BGT	greater		// 1st > 2nd
	BLT	less		// 1st < 2nd
	BC	12,10,equal	// test CR2 for length comparison
	BC	12,9,greater	// 2nd len > 1st len
	BR	less		// must be less
cmpne:				// only here is not equal
	MOVDBR	(R5+R16),R8	// reload in reverse order
	MOVDBR	(R6+R16),R9
	CMPU	R8,R9		// compare correct endianness
	BGT	greater		// here only if NE
less:
	MOVD	$-1,R3
	MOVD	R3,(R7)		// return value if A < B
	RET
equal:
	MOVD	$0,(R7)		// return value if A == B
	RET
greater:
	MOVD	$1,R3
	MOVD	R3,(R7)		// return value if A > B
	RET

// Do an efficient memcmp for ppc64 (BE)
// R3 = s1 len
// R4 = s2 len
// R5 = s1 addr
// R6 = s2 addr
// R7 = addr of return value
TEXT cmpbodyBE<>(SB),NOSPLIT|NOFRAME,$0-0
	MOVD	R3,R8		// set up length
	CMP	R3,R4,CR2	// unequal?
	BC	12,8,setuplen	// BLT CR2
	MOVD	R4,R8		// use R4 for comparison len
setuplen:
	MOVD	R8,CTR		// set up loop counter
	CMP	R8,$8		// only optimize >=8
	BLT	simplecheck
	DCBT	(R5)		// cache hint
	DCBT	(R6)
	CMP	R8,$32		// optimize >= 32
	MOVD	R8,R9
	BLT	setup8a		// 8 byte moves only

setup32a:
	SRADCC	$5,R8,R9	// number of 32 byte chunks
	MOVD	R9,CTR
loop32a:
	MOVD	0(R5),R9	// doublewords to compare
	MOVD	0(R6),R10	// get 4 doublewords
	MOVD	8(R5),R14
	MOVD	8(R6),R15
	CMPU	R9,R10		// bytes equal?
	BLT	less		// found to be less
	BGT	greater		// found to be greater
	MOVD	16(R5),R9	// get next pair of doublewords
	MOVD	16(R6),R10
	CMPU	R14,R15		// bytes match?
	BLT	less		// found less
	BGT	greater		// found greater
	MOVD	24(R5),R14	// get next pair of doublewords
	MOVD	24(R6),R15
	CMPU	R9,R10		// bytes match?
	BLT	less		// found to be less
	BGT	greater		// found to be greater
	ADD	$32,R5		// bump up to next 32
	ADD	$32,R6
	CMPU	R14,R15		// bytes match?
	BC	8,2,loop32a	// br ctr and cr
	BLT	less		// with BE, byte ordering is
	BGT	greater		// good for compare
	ANDCC	$24,R8,R9	// Any 8 byte chunks?
	BEQ	leftover	// and result is 0
setup8a:
	SRADCC	$3,R9,R9	// get the 8 byte count
	BEQ	leftover	// shifted value is 0
	MOVD	R9,CTR		// loop count for doublewords
loop8:
	MOVD	(R5),R9
	MOVD	(R6),R10
	ADD	$8,R5
	ADD	$8,R6
	CMPU	R9,R10		// match?
	BC	8,2,loop8	// bt ctr <> 0 && cr
	BGT	greater
	BLT	less
leftover:
	ANDCC	$7,R8,R9	// check for leftover bytes
	MOVD	R9,CTR		// save the ctr
	BNE	simple		// leftover bytes
	BC	12,10,equal	// test CR2 for length comparison
	BC	12,8,less
	BR	greater
simplecheck:
	CMP	R8,$0		// remaining compare length 0
	BNE	simple		// do simple compare
	BC	12,10,equal	// test CR2 for length comparison
	BC 	12,8,less	// 1st len < 2nd len, result less
	BR	greater		// same len, must be equal
simple:
	MOVBZ	0(R5),R9	// get byte from 1st operand
	ADD	$1,R5
	MOVBZ	0(R6),R10	// get byte from 2nd operand
	ADD	$1,R6
	CMPU	R9,R10
	BC	8,2,simple	// bc ctr <> 0 && cr
	BGT	greater		// 1st > 2nd
	BLT	less		// 1st < 2nd
	BC	12,10,equal	// test CR2 for length comparison
	BC	12,9,greater	// 2nd len > 1st len
less:
	MOVD	$-1,R3
	MOVD    R3,(R7)		// return value if A < B
	RET
equal:
	MOVD    $0,(R7)		// return value if A == B
	RET
greater:
	MOVD	$1,R3
	MOVD	R3,(R7)		// return value if A > B
	RET

// Do an efficient memequal for ppc64
// R3 = s1
// R4 = s2
// R5 = len
// R9 = return value
TEXT runtime·memeqbody(SB),NOSPLIT|NOFRAME,$0-0
	MOVD    R5,CTR
	CMP     R5,$8		// only optimize >=8
	BLT     simplecheck
	DCBT	(R3)		// cache hint
	DCBT	(R4)
	CMP	R5,$32		// optimize >= 32
	MOVD	R5,R6		// needed if setup8a branch
	BLT	setup8a		// 8 byte moves only
setup32a:                       // 8 byte aligned, >= 32 bytes
	SRADCC  $5,R5,R6        // number of 32 byte chunks to compare
	MOVD	R6,CTR
loop32a:
	MOVD    0(R3),R6        // doublewords to compare
	MOVD    0(R4),R7
	MOVD	8(R3),R8	//
	MOVD	8(R4),R9
	CMP     R6,R7           // bytes batch?
	BNE     noteq
	MOVD	16(R3),R6
	MOVD	16(R4),R7
	CMP     R8,R9		// bytes match?
	MOVD	24(R3),R8
	MOVD	24(R4),R9
	BNE     noteq
	CMP     R6,R7           // bytes match?
	BNE	noteq
	ADD     $32,R3		// bump up to next 32
	ADD     $32,R4
	CMP     R8,R9           // bytes match?
	BC      8,2,loop32a	// br ctr and cr
	BNE	noteq
	ANDCC	$24,R5,R6       // Any 8 byte chunks?
	BEQ	leftover	// and result is 0
setup8a:
	SRADCC  $3,R6,R6        // get the 8 byte count
	BEQ	leftover	// shifted value is 0
	MOVD    R6,CTR
loop8:
	MOVD    0(R3),R6        // doublewords to compare
	ADD	$8,R3
	MOVD    0(R4),R7
	ADD     $8,R4
	CMP     R6,R7           // match?
	BC	8,2,loop8	// bt ctr <> 0 && cr
	BNE     noteq
leftover:
	ANDCC   $7,R5,R6        // check for leftover bytes
	BEQ     equal
	MOVD    R6,CTR
	BR	simple
simplecheck:
	CMP	R5,$0
	BEQ	equal
simple:
	MOVBZ   0(R3), R6
	ADD	$1,R3
	MOVBZ   0(R4), R7
	ADD     $1,R4
	CMP     R6, R7
	BNE     noteq
	BC      8,2,simple
	BNE	noteq
	BR	equal
noteq:
	MOVD    $0, R9
	RET
equal:
	MOVD    $1, R9
	RET

TEXT bytes·Equal(SB),NOSPLIT,$0-49
	MOVD	a_len+8(FP), R4
	MOVD	b_len+32(FP), R5
	CMP	R5, R4		// unequal lengths are not equal
	BNE	noteq
	MOVD	a+0(FP), R3
	MOVD	b+24(FP), R4
	BL	runtime·memeqbody(SB)

	MOVBZ	R9,ret+48(FP)
	RET

noteq:
	MOVBZ	$0,ret+48(FP)
	RET

equal:
	MOVD	$1,R3
	MOVBZ	R3,ret+48(FP)
	RET

TEXT bytes·IndexByte(SB),NOSPLIT|NOFRAME,$0-40
	MOVD	s+0(FP), R3		// R3 = byte array pointer
	MOVD	s_len+8(FP), R4		// R4 = length
	MOVBZ	c+24(FP), R5		// R5 = byte
	MOVD	$ret+32(FP), R14	// R14 = &ret
	BR	runtime·indexbytebody<>(SB)

TEXT strings·IndexByte(SB),NOSPLIT|NOFRAME,$0-32
	MOVD	s+0(FP), R3	  // R3 = string
	MOVD	s_len+8(FP), R4	  // R4 = length
	MOVBZ	c+16(FP), R5	  // R5 = byte
	MOVD	$ret+24(FP), R14  // R14 = &ret
	BR	runtime·indexbytebody<>(SB)

TEXT runtime·indexbytebody<>(SB),NOSPLIT|NOFRAME,$0-0
	DCBT	(R3)		// Prepare cache line.
	MOVD	R3,R10		// Save base address for calculating the index later.
	RLDICR	$0,R3,$60,R8	// Align address to doubleword boundary in R8.
	RLDIMI	$8,R5,$48,R5	// Replicating the byte across the register.

	// Calculate last acceptable address and check for possible overflow
	// using a saturated add.
	// Overflows set last acceptable address to 0xffffffffffffffff.
	ADD	R4,R3,R7
	SUBC	R3,R7,R6
	SUBE	R0,R0,R9
	MOVW	R9,R6
	OR	R6,R7,R7

	RLDIMI	$16,R5,$32,R5
	CMPU	R4,$32		// Check if it's a small string (<32 bytes). Those will be processed differently.
	MOVD	$-1,R9
	WORD $0x54661EB8	// Calculate padding in R6 (rlwinm r6,r3,3,26,28).
	RLDIMI	$32,R5,$0,R5
	ADD	$-1,R7,R7
#ifdef GOARCH_ppc64le
	SLD	R6,R9,R9	// Prepare mask for Little Endian
#else
	SRD	R6,R9,R9	// Same for Big Endian
#endif
	BLE	small_string	// Jump to the small string case if it's <32 bytes.

	// Case for length >32 bytes
	MOVD	0(R8),R12	// Load one doubleword from the aligned address in R8.
	CMPB	R12,R5,R3	// Check for a match.
	AND	R9,R3,R3	// Mask bytes below s_base
	RLDICL	$0,R7,$61,R4	// length-1
	RLDICR	$0,R7,$60,R7	// Last doubleword in R7
	CMPU	R3,$0,CR7	// If we have a match, jump to the final computation
	BNE	CR7,done

	// Check for doubleword alignment and jump to the loop setup if aligned.
	MOVFL	R8,CR7
	BC	12,28,loop_setup

	// Not aligned, so handle the second doubleword
	MOVDU	8(R8),R12
	CMPB	R12,R5,R3
	CMPU	R3,$0,CR7
	BNE	CR7,done

loop_setup:
	// We are now aligned to a 16-byte boundary. We will load two doublewords
	// per loop iteration. The last doubleword is in R7, so our loop counter
	// starts at (R7-R8)/16.
	SUB	R8,R7,R6
	SRD	$4,R6,R6
	MOVD	R6,CTR

	// Note: when we have an align directive, align this loop to 32 bytes so
	// it fits in a single icache sector.
loop:
	// Load two doublewords, then compare and merge in a single register. We
	// will check two doublewords per iteration, then find out which of them
	// contains the byte later. This speeds up the search.
	MOVD	8(R8),R12
	MOVDU	16(R8),R11
	CMPB	R12,R5,R3
	CMPB	R11,R5,R9
	OR	R3,R9,R6
	CMPU	R6,$0,CR7
	BNE	CR7,found
	BC	16,0,loop

	// Counter zeroed, but we may have another doubleword to read
	CMPU	R8,R7
	BEQ	notfound

	MOVDU	8(R8),R12
	CMPB	R12,R5,R3
	CMPU	R3,$0,CR6
	BNE	CR6,done

notfound:
	MOVD	$-1,R3
	MOVD	R3,(R14)
	RET

found:
	// One of the doublewords from the loop contains the byte we are looking
	// for. Check the first doubleword and adjust the address if found.
	CMPU	R3,$0,CR6
	ADD	$-8,R8,R8
	BNE	CR6,done

	// Not found, so it must be in the second doubleword of the merged pair.
	MOVD	R9,R3
	ADD	$8,R8,R8

done:
	// At this point, R3 has 0xFF in the same position as the byte we are
	// looking for in the doubleword. Use that to calculate the exact index
	// of the byte.
#ifdef GOARCH_ppc64le
	ADD	$-1,R3,R11
	ANDN	R3,R11,R11
	POPCNTD	R11,R11		// Count trailing zeros (Little Endian).
#else
	CNTLZD	R3,R11		// Count leading zeros (Big Endian).
#endif
	CMPU	R8,R7		// Check if we are at the last doubleword.
	SRD	$3,R11		// Convert trailing zeros to bytes.
	ADD	R11,R8,R3
	CMPU	R11,R4,CR7	// If at the last doubleword, check the byte offset.
	BNE	return
	BLE	CR7,return
	MOVD	$-1,R3
	MOVD	R3,(R14)
	RET

return:
	SUB	R10,R3		// Calculate index.
	MOVD	R3,(R14)
	RET

small_string:
	// We unroll this loop for better performance.
	CMPU	R4,$0		// Check for length=0
	BEQ	notfound

	MOVD	0(R8),R12	// Load one doubleword from the aligned address in R8.
	CMPB	R12,R5,R3	// Check for a match.
	AND	R9,R3,R3	// Mask bytes below s_base.
	CMPU	R3,$0,CR7	// If we have a match, jump to the final computation.
	RLDICL	$0,R7,$61,R4	// length-1
	RLDICR	$0,R7,$60,R7	// Last doubleword in R7.
        CMPU	R8,R7
	BNE	CR7,done
	BEQ	notfound	// Hit length.

	MOVDU	8(R8),R12
	CMPB	R12,R5,R3
	CMPU	R3,$0,CR6
	CMPU	R8,R7
	BNE	CR6,done
	BEQ	notfound

	MOVDU	8(R8),R12
	CMPB	R12,R5,R3
	CMPU	R3,$0,CR6
	CMPU	R8,R7
	BNE	CR6,done
	BEQ	notfound

	MOVDU	8(R8),R12
	CMPB	R12,R5,R3
	CMPU	R3,$0,CR6
	CMPU	R8,R7
	BNE	CR6,done
	BEQ	notfound

	MOVDU	8(R8),R12
	CMPB	R12,R5,R3
	CMPU	R3,$0,CR6
	CMPU	R8,R7
	BNE	CR6,done
	BR	notfound

TEXT runtime·cmpstring(SB),NOSPLIT|NOFRAME,$0-40
	MOVD	s1_base+0(FP), R5
	MOVD	s1_len+8(FP), R3
	MOVD	s2_base+16(FP), R6
	MOVD	s2_len+24(FP), R4
	MOVD	$ret+32(FP), R7
#ifdef	GOARCH_ppc64le
	BR	cmpbodyLE<>(SB)
#else
	BR      cmpbodyBE<>(SB)
#endif

TEXT bytes·Compare(SB),NOSPLIT|NOFRAME,$0-56
	MOVD	s1+0(FP), R5
	MOVD	s1+8(FP), R3
	MOVD	s2+24(FP), R6
	MOVD	s2+32(FP), R4
	MOVD	$ret+48(FP), R7
#ifdef	GOARCH_ppc64le
	BR	cmpbodyLE<>(SB)
#else
	BR      cmpbodyBE<>(SB)
#endif

TEXT runtime·return0(SB), NOSPLIT, $0
	MOVW	$0, R3
	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) 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
	RET

// The top-most function running on a goroutine
// returns to goexit+PCQuantum.
//
// When dynamically linking Go, it can be returned to from a function
// implemented in a different module and so needs to reload the TOC pointer
// from the stack (although this function declares that it does not set up x-a
// frame, newproc1 does in fact allocate one for goexit and saves the TOC
// pointer in the correct place).
// goexit+_PCQuantum is halfway through the usual global entry point prologue
// that derives r2 from r12 which is a bit silly, but not harmful.
TEXT runtime·goexit(SB),NOSPLIT|NOFRAME,$0-0
	MOVD	24(R1), R2
	BL	runtime·goexit1(SB)	// does not return
	// traceback from goexit1 must hit code range of goexit
	MOVD	R0, R0	// NOP

TEXT runtime·sigreturn(SB),NOSPLIT,$0-0
	RET

// prepGoExitFrame saves the current TOC pointer (i.e. the TOC pointer for the
// module containing runtime) to the frame that goexit will execute in when
// the goroutine exits. It's implemented in assembly mainly because that's the
// easiest way to get access to R2.
TEXT runtime·prepGoExitFrame(SB),NOSPLIT,$0-8
      MOVD    sp+0(FP), R3
      MOVD    R2, 24(R3)
      RET

TEXT runtime·addmoduledata(SB),NOSPLIT|NOFRAME,$0-0
	ADD	$-8, R1
	MOVD	R31, 0(R1)
	MOVD	runtime·lastmoduledatap(SB), R4
	MOVD	R3, moduledata_next(R4)
	MOVD	R3, runtime·lastmoduledatap(SB)
	MOVD	0(R1), R31
	ADD	$8, R1
	RET

TEXT ·checkASM(SB),NOSPLIT,$0-1
	MOVW	$1, R3
	MOVB	R3, ret+0(FP)
	RET