Ejemplo n.º 1
0
Archivo: main.go Proyecto: rsc/tmp
func readprog(b *bufio.Reader, p *liblink.Prog) {
	if !undef[p] {
		panic("double-def")
	}
	delete(undef, p)
	p.Pc = rdint(b)
	p.Lineno = int32(rdint(b))
	p.Link = rdprog(b)
	p.As = int16(rdint(b))
	p.Reg = uint8(rdint(b))
	p.Scond = uint8(rdint(b))
	p.Width = int8(rdint(b))
	readaddr(b, &p.From)
	readaddr(b, &p.To)
}
Ejemplo n.º 2
0
Archivo: obj5.go Proyecto: rsc/tmp
func stacksplit(ctxt *liblink.Link, p *liblink.Prog, framesize int32, noctxt int) *liblink.Prog {
	// MOVW			g_stackguard(g), R1
	p = liblink.Appendp(ctxt, p)

	p.As = AMOVW
	p.From.Type_ = D_OREG
	p.From.Reg = REGG
	p.From.Offset = 2 * int64(ctxt.Arch.Ptrsize) // G.stackguard0
	if ctxt.Cursym.Cfunc != 0 {
		p.From.Offset = 3 * int64(ctxt.Arch.Ptrsize) // G.stackguard1
	}
	p.To.Type_ = D_REG
	p.To.Reg = 1

	if framesize <= liblink.StackSmall {
		// small stack: SP < stackguard
		//	CMP	stackguard, SP
		p = liblink.Appendp(ctxt, p)

		p.As = ACMP
		p.From.Type_ = D_REG
		p.From.Reg = 1
		p.Reg = REGSP
	} else if framesize <= liblink.StackBig {
		// large stack: SP-framesize < stackguard-StackSmall
		//	MOVW $-framesize(SP), R2
		//	CMP stackguard, R2
		p = liblink.Appendp(ctxt, p)

		p.As = AMOVW
		p.From.Type_ = D_CONST
		p.From.Reg = REGSP
		p.From.Offset = int64(-framesize)
		p.To.Type_ = D_REG
		p.To.Reg = 2

		p = liblink.Appendp(ctxt, p)
		p.As = ACMP
		p.From.Type_ = D_REG
		p.From.Reg = 1
		p.Reg = 2
	} else {

		// Such a large stack we need to protect against wraparound
		// if SP is close to zero.
		//	SP-stackguard+StackGuard < framesize + (StackGuard-StackSmall)
		// The +StackGuard on both sides is required to keep the left side positive:
		// SP is allowed to be slightly below stackguard. See stack.h.
		//	CMP $StackPreempt, R1
		//	MOVW.NE $StackGuard(SP), R2
		//	SUB.NE R1, R2
		//	MOVW.NE $(framesize+(StackGuard-StackSmall)), R3
		//	CMP.NE R3, R2
		p = liblink.Appendp(ctxt, p)

		p.As = ACMP
		p.From.Type_ = D_CONST
		p.From.Offset = int64(uint32(liblink.StackPreempt & (1<<32 - 1)))
		p.Reg = 1

		p = liblink.Appendp(ctxt, p)
		p.As = AMOVW
		p.From.Type_ = D_CONST
		p.From.Reg = REGSP
		p.From.Offset = liblink.StackGuard
		p.To.Type_ = D_REG
		p.To.Reg = 2
		p.Scond = C_SCOND_NE

		p = liblink.Appendp(ctxt, p)
		p.As = ASUB
		p.From.Type_ = D_REG
		p.From.Reg = 1
		p.To.Type_ = D_REG
		p.To.Reg = 2
		p.Scond = C_SCOND_NE

		p = liblink.Appendp(ctxt, p)
		p.As = AMOVW
		p.From.Type_ = D_CONST
		p.From.Offset = int64(framesize) + (liblink.StackGuard - liblink.StackSmall)
		p.To.Type_ = D_REG
		p.To.Reg = 3
		p.Scond = C_SCOND_NE

		p = liblink.Appendp(ctxt, p)
		p.As = ACMP
		p.From.Type_ = D_REG
		p.From.Reg = 3
		p.Reg = 2
		p.Scond = C_SCOND_NE
	}

	// MOVW.LS	R14, R3
	p = liblink.Appendp(ctxt, p)

	p.As = AMOVW
	p.Scond = C_SCOND_LS
	p.From.Type_ = D_REG
	p.From.Reg = REGLINK
	p.To.Type_ = D_REG
	p.To.Reg = 3

	// BL.LS		runtime.morestack(SB) // modifies LR, returns with LO still asserted
	p = liblink.Appendp(ctxt, p)

	p.As = ABL
	p.Scond = C_SCOND_LS
	p.To.Type_ = D_BRANCH
	if ctxt.Cursym.Cfunc != 0 {
		p.To.Sym = liblink.Linklookup(ctxt, "runtime.morestackc", 0)
	} else {

		p.To.Sym = ctxt.Symmorestack[noctxt]
	}

	// BLS	start
	p = liblink.Appendp(ctxt, p)

	p.As = ABLS
	p.To.Type_ = D_BRANCH
	p.Pcond = ctxt.Cursym.Text.Link

	return p
}
Ejemplo n.º 3
0
Archivo: obj5.go Proyecto: rsc/tmp
func settextflag(p *liblink.Prog, f int) {
	p.Reg = uint8(f)
}
Ejemplo n.º 4
0
Archivo: obj5.go Proyecto: rsc/tmp
func addstacksplit(ctxt *liblink.Link, cursym *liblink.LSym) {
	var p *liblink.Prog
	var pl *liblink.Prog
	var p1 *liblink.Prog
	var p2 *liblink.Prog
	var q *liblink.Prog
	var q1 *liblink.Prog
	var q2 *liblink.Prog
	var o int
	var autosize int32
	var autoffset int32

	autosize = 0

	if ctxt.Symmorestack[0] == nil {
		ctxt.Symmorestack[0] = liblink.Linklookup(ctxt, "runtime.morestack", 0)
		ctxt.Symmorestack[1] = liblink.Linklookup(ctxt, "runtime.morestack_noctxt", 0)
	}

	q = nil

	ctxt.Cursym = cursym

	if cursym.Text == nil || cursym.Text.Link == nil {
		return
	}

	softfloat(ctxt, cursym)

	p = cursym.Text
	autoffset = int32(p.To.Offset)
	if autoffset < 0 {
		autoffset = 0
	}
	cursym.Locals = autoffset
	cursym.Args = p.To.Offset2

	if ctxt.Debugzerostack != 0 {
		if autoffset != 0 && !(p.Reg&liblink.NOSPLIT != 0) {
			// MOVW $4(R13), R1
			p = liblink.Appendp(ctxt, p)

			p.As = AMOVW
			p.From.Type_ = D_CONST
			p.From.Reg = 13
			p.From.Offset = 4
			p.To.Type_ = D_REG
			p.To.Reg = 1

			// MOVW $n(R13), R2
			p = liblink.Appendp(ctxt, p)

			p.As = AMOVW
			p.From.Type_ = D_CONST
			p.From.Reg = 13
			p.From.Offset = 4 + int64(autoffset)
			p.To.Type_ = D_REG
			p.To.Reg = 2

			// MOVW $0, R3
			p = liblink.Appendp(ctxt, p)

			p.As = AMOVW
			p.From.Type_ = D_CONST
			p.From.Offset = 0
			p.To.Type_ = D_REG
			p.To.Reg = 3

			// L:
			//	MOVW.nil R3, 0(R1) +4
			//	CMP R1, R2
			//	BNE L
			pl = liblink.Appendp(ctxt, p)
			p = pl

			p.As = AMOVW
			p.From.Type_ = D_REG
			p.From.Reg = 3
			p.To.Type_ = D_OREG
			p.To.Reg = 1
			p.To.Offset = 4
			p.Scond |= C_PBIT

			p = liblink.Appendp(ctxt, p)
			p.As = ACMP
			p.From.Type_ = D_REG
			p.From.Reg = 1
			p.Reg = 2

			p = liblink.Appendp(ctxt, p)
			p.As = ABNE
			p.To.Type_ = D_BRANCH
			p.Pcond = pl
		}
	}

	/*
	 * find leaf subroutines
	 * strip NOPs
	 * expand RET
	 * expand BECOME pseudo
	 */
	for p = cursym.Text; p != nil; p = p.Link {

		switch p.As {
		case ACASE:
			if ctxt.Flag_shared != 0 {
				linkcase(p)
			}

		case ATEXT:
			p.Mark |= LEAF

		case ARET:
			break

		case ADIV,
			ADIVU,
			AMOD,
			AMODU:
			q = p
			if ctxt.Sym_div == nil {
				initdiv(ctxt)
			}
			cursym.Text.Mark &^= LEAF
			continue

		case ANOP:
			q1 = p.Link
			q.Link = q1 /* q is non-nop */
			if q1 != nil {
				q1.Mark |= p.Mark
			}
			continue

		case ABL,
			ABX,
			ADUFFZERO,
			ADUFFCOPY:
			cursym.Text.Mark &^= LEAF
			fallthrough

		case ABCASE,
			AB,
			ABEQ,
			ABNE,
			ABCS,
			ABHS,
			ABCC,
			ABLO,
			ABMI,
			ABPL,
			ABVS,
			ABVC,
			ABHI,
			ABLS,
			ABGE,
			ABLT,
			ABGT,
			ABLE:
			q1 = p.Pcond
			if q1 != nil {
				for q1.As == ANOP {
					q1 = q1.Link
					p.Pcond = q1
				}
			}

			break
		}

		q = p
	}

	for p = cursym.Text; p != nil; p = p.Link {
		o = int(p.As)
		switch o {
		case ATEXT:
			autosize = int32(p.To.Offset + 4)
			if autosize <= 4 {
				if cursym.Text.Mark&LEAF != 0 {
					p.To.Offset = -4
					autosize = 0
				}
			}

			if !(autosize != 0) && !(cursym.Text.Mark&LEAF != 0) {
				if ctxt.Debugvlog != 0 {
					fmt.Fprintf(ctxt.Bso, "save suppressed in: %s\n", cursym.Name)
					liblink.Bflush(ctxt.Bso)
				}

				cursym.Text.Mark |= LEAF
			}

			if cursym.Text.Mark&LEAF != 0 {
				cursym.Leaf = 1
				if !(autosize != 0) {
					break
				}
			}

			if !(p.Reg&liblink.NOSPLIT != 0) {
				p = stacksplit(ctxt, p, autosize, bool2int(!(cursym.Text.Reg&liblink.NEEDCTXT != 0))) // emit split check
			}

			// MOVW.W		R14,$-autosize(SP)
			p = liblink.Appendp(ctxt, p)

			p.As = AMOVW
			p.Scond |= C_WBIT
			p.From.Type_ = D_REG
			p.From.Reg = REGLINK
			p.To.Type_ = D_OREG
			p.To.Offset = int64(-autosize)
			p.To.Reg = REGSP
			p.Spadj = autosize

			if cursym.Text.Reg&liblink.WRAPPER != 0 {
				// if(g->panic != nil && g->panic->argp == FP) g->panic->argp = bottom-of-frame
				//
				//	MOVW g_panic(g), R1
				//	CMP $0, R1
				//	B.EQ end
				//	MOVW panic_argp(R1), R2
				//	ADD $(autosize+4), R13, R3
				//	CMP R2, R3
				//	B.NE end
				//	ADD $4, R13, R4
				//	MOVW R4, panic_argp(R1)
				// end:
				//	NOP
				//
				// The NOP is needed to give the jumps somewhere to land.
				// It is a liblink NOP, not an ARM NOP: it encodes to 0 instruction bytes.

				p = liblink.Appendp(ctxt, p)

				p.As = AMOVW
				p.From.Type_ = D_OREG
				p.From.Reg = REGG
				p.From.Offset = 4 * int64(ctxt.Arch.Ptrsize) // G.panic
				p.To.Type_ = D_REG
				p.To.Reg = 1

				p = liblink.Appendp(ctxt, p)
				p.As = ACMP
				p.From.Type_ = D_CONST
				p.From.Offset = 0
				p.Reg = 1

				p = liblink.Appendp(ctxt, p)
				p.As = ABEQ
				p.To.Type_ = D_BRANCH
				p1 = p

				p = liblink.Appendp(ctxt, p)
				p.As = AMOVW
				p.From.Type_ = D_OREG
				p.From.Reg = 1
				p.From.Offset = 0 // Panic.argp
				p.To.Type_ = D_REG
				p.To.Reg = 2

				p = liblink.Appendp(ctxt, p)
				p.As = AADD
				p.From.Type_ = D_CONST
				p.From.Offset = int64(autosize) + 4
				p.Reg = 13
				p.To.Type_ = D_REG
				p.To.Reg = 3

				p = liblink.Appendp(ctxt, p)
				p.As = ACMP
				p.From.Type_ = D_REG
				p.From.Reg = 2
				p.Reg = 3

				p = liblink.Appendp(ctxt, p)
				p.As = ABNE
				p.To.Type_ = D_BRANCH
				p2 = p

				p = liblink.Appendp(ctxt, p)
				p.As = AADD
				p.From.Type_ = D_CONST
				p.From.Offset = 4
				p.Reg = 13
				p.To.Type_ = D_REG
				p.To.Reg = 4

				p = liblink.Appendp(ctxt, p)
				p.As = AMOVW
				p.From.Type_ = D_REG
				p.From.Reg = 4
				p.To.Type_ = D_OREG
				p.To.Reg = 1
				p.To.Offset = 0 // Panic.argp

				p = liblink.Appendp(ctxt, p)

				p.As = ANOP
				p1.Pcond = p
				p2.Pcond = p
			}

		case ARET:
			nocache5(p)
			if cursym.Text.Mark&LEAF != 0 {
				if !(autosize != 0) {
					p.As = AB
					p.From = zprg5.From
					if p.To.Sym != nil { // retjmp
						p.To.Type_ = D_BRANCH
					} else {

						p.To.Type_ = D_OREG
						p.To.Offset = 0
						p.To.Reg = REGLINK
					}

					break
				}
			}

			p.As = AMOVW
			p.Scond |= C_PBIT
			p.From.Type_ = D_OREG
			p.From.Offset = int64(autosize)
			p.From.Reg = REGSP
			p.To.Type_ = D_REG
			p.To.Reg = REGPC

			// If there are instructions following
			// this ARET, they come from a branch
			// with the same stackframe, so no spadj.
			if p.To.Sym != nil { // retjmp
				p.To.Reg = REGLINK
				q2 = liblink.Appendp(ctxt, p)
				q2.As = AB
				q2.To.Type_ = D_BRANCH
				q2.To.Sym = p.To.Sym
				p.To.Sym = nil
				p = q2
			}

		case AADD:
			if p.From.Type_ == D_CONST && p.From.Reg == NREG && p.To.Type_ == D_REG && p.To.Reg == REGSP {
				p.Spadj = int32(-p.From.Offset)
			}

		case ASUB:
			if p.From.Type_ == D_CONST && p.From.Reg == NREG && p.To.Type_ == D_REG && p.To.Reg == REGSP {
				p.Spadj = int32(p.From.Offset)
			}

		case ADIV,
			ADIVU,
			AMOD,
			AMODU:
			if ctxt.Debugdivmod != 0 {
				break
			}
			if p.From.Type_ != D_REG {
				break
			}
			if p.To.Type_ != D_REG {
				break
			}
			q1 = p

			/* MOV a,4(SP) */
			p = liblink.Appendp(ctxt, p)

			p.As = AMOVW
			p.Lineno = q1.Lineno
			p.From.Type_ = D_REG
			p.From.Reg = q1.From.Reg
			p.To.Type_ = D_OREG
			p.To.Reg = REGSP
			p.To.Offset = 4

			/* MOV b,REGTMP */
			p = liblink.Appendp(ctxt, p)

			p.As = AMOVW
			p.Lineno = q1.Lineno
			p.From.Type_ = D_REG
			p.From.Reg = int8(q1.Reg)
			if q1.Reg == NREG {
				p.From.Reg = q1.To.Reg
			}
			p.To.Type_ = D_REG
			p.To.Reg = REGTMP
			p.To.Offset = 0

			/* CALL appropriate */
			p = liblink.Appendp(ctxt, p)

			p.As = ABL
			p.Lineno = q1.Lineno
			p.To.Type_ = D_BRANCH
			switch o {
			case ADIV:
				p.To.Sym = ctxt.Sym_div

			case ADIVU:
				p.To.Sym = ctxt.Sym_divu

			case AMOD:
				p.To.Sym = ctxt.Sym_mod

			case AMODU:
				p.To.Sym = ctxt.Sym_modu
				break
			}

			/* MOV REGTMP, b */
			p = liblink.Appendp(ctxt, p)

			p.As = AMOVW
			p.Lineno = q1.Lineno
			p.From.Type_ = D_REG
			p.From.Reg = REGTMP
			p.From.Offset = 0
			p.To.Type_ = D_REG
			p.To.Reg = q1.To.Reg

			/* ADD $8,SP */
			p = liblink.Appendp(ctxt, p)

			p.As = AADD
			p.Lineno = q1.Lineno
			p.From.Type_ = D_CONST
			p.From.Reg = NREG
			p.From.Offset = 8
			p.Reg = NREG
			p.To.Type_ = D_REG
			p.To.Reg = REGSP
			p.Spadj = -8

			/* Keep saved LR at 0(SP) after SP change. */
			/* MOVW 0(SP), REGTMP; MOVW REGTMP, -8!(SP) */
			/* TODO: Remove SP adjustments; see issue 6699. */
			q1.As = AMOVW

			q1.From.Type_ = D_OREG
			q1.From.Reg = REGSP
			q1.From.Offset = 0
			q1.Reg = NREG
			q1.To.Type_ = D_REG
			q1.To.Reg = REGTMP

			/* SUB $8,SP */
			q1 = liblink.Appendp(ctxt, q1)

			q1.As = AMOVW
			q1.From.Type_ = D_REG
			q1.From.Reg = REGTMP
			q1.Reg = NREG
			q1.To.Type_ = D_OREG
			q1.To.Reg = REGSP
			q1.To.Offset = -8
			q1.Scond |= C_WBIT
			q1.Spadj = 8

		case AMOVW:
			if (p.Scond&C_WBIT != 0) && p.To.Type_ == D_OREG && p.To.Reg == REGSP {
				p.Spadj = int32(-p.To.Offset)
			}
			if (p.Scond&C_PBIT != 0) && p.From.Type_ == D_OREG && p.From.Reg == REGSP && p.To.Reg != REGPC {
				p.Spadj = int32(-p.From.Offset)
			}
			if p.From.Type_ == D_CONST && p.From.Reg == REGSP && p.To.Type_ == D_REG && p.To.Reg == REGSP {
				p.Spadj = int32(-p.From.Offset)
			}
			break
		}
	}
}
Ejemplo n.º 5
0
Archivo: obj9.go Proyecto: rsc/tmp
/*
// instruction scheduling
	if(debug['Q'] == 0)
		return;

	curtext = nil;
	q = nil;	// p - 1
	q1 = firstp;	// top of block
	o = 0;		// count of instructions
	for(p = firstp; p != nil; p = p1) {
		p1 = p->link;
		o++;
		if(p->mark & NOSCHED){
			if(q1 != p){
				sched(q1, q);
			}
			for(; p != nil; p = p->link){
				if(!(p->mark & NOSCHED))
					break;
				q = p;
			}
			p1 = p;
			q1 = p;
			o = 0;
			continue;
		}
		if(p->mark & (LABEL|SYNC)) {
			if(q1 != p)
				sched(q1, q);
			q1 = p;
			o = 1;
		}
		if(p->mark & (BRANCH|SYNC)) {
			sched(q1, p);
			q1 = p1;
			o = 0;
		}
		if(o >= NSCHED) {
			sched(q1, p);
			q1 = p1;
			o = 0;
		}
		q = p;
	}
*/
func stacksplit(ctxt *liblink.Link, p *liblink.Prog, framesize int32, noctxt int) *liblink.Prog {

	var q *liblink.Prog
	var q1 *liblink.Prog

	// MOVD	g_stackguard(g), R3
	p = liblink.Appendp(ctxt, p)

	p.As = AMOVD
	p.From.Type_ = D_OREG
	p.From.Reg = REGG
	p.From.Offset = 2 * int64(ctxt.Arch.Ptrsize) // G.stackguard0
	if ctxt.Cursym.Cfunc != 0 {
		p.From.Offset = 3 * int64(ctxt.Arch.Ptrsize) // G.stackguard1
	}
	p.To.Type_ = D_REG
	p.To.Reg = 3

	q = nil
	if framesize <= liblink.StackSmall {
		// small stack: SP < stackguard
		//	CMP	stackguard, SP
		p = liblink.Appendp(ctxt, p)

		p.As = ACMPU
		p.From.Type_ = D_REG
		p.From.Reg = 3
		p.To.Type_ = D_REG
		p.To.Reg = REGSP
	} else if framesize <= liblink.StackBig {
		// large stack: SP-framesize < stackguard-StackSmall
		//	ADD $-framesize, SP, R4
		//	CMP stackguard, R4
		p = liblink.Appendp(ctxt, p)

		p.As = AADD
		p.From.Type_ = D_CONST
		p.From.Offset = int64(-framesize)
		p.Reg = REGSP
		p.To.Type_ = D_REG
		p.To.Reg = 4

		p = liblink.Appendp(ctxt, p)
		p.As = ACMPU
		p.From.Type_ = D_REG
		p.From.Reg = 3
		p.To.Type_ = D_REG
		p.To.Reg = 4
	} else {

		// Such a large stack we need to protect against wraparound.
		// If SP is close to zero:
		//	SP-stackguard+StackGuard <= framesize + (StackGuard-StackSmall)
		// The +StackGuard on both sides is required to keep the left side positive:
		// SP is allowed to be slightly below stackguard. See stack.h.
		//
		// Preemption sets stackguard to StackPreempt, a very large value.
		// That breaks the math above, so we have to check for that explicitly.
		//	// stackguard is R3
		//	CMP	R3, $StackPreempt
		//	BEQ	label-of-call-to-morestack
		//	ADD	$StackGuard, SP, R4
		//	SUB	R3, R4
		//	MOVD	$(framesize+(StackGuard-StackSmall)), R31
		//	CMPU	R31, R4
		p = liblink.Appendp(ctxt, p)

		p.As = ACMP
		p.From.Type_ = D_REG
		p.From.Reg = 3
		p.To.Type_ = D_CONST
		p.To.Offset = liblink.StackPreempt

		p = liblink.Appendp(ctxt, p)
		q = p
		p.As = ABEQ
		p.To.Type_ = D_BRANCH

		p = liblink.Appendp(ctxt, p)
		p.As = AADD
		p.From.Type_ = D_CONST
		p.From.Offset = liblink.StackGuard
		p.Reg = REGSP
		p.To.Type_ = D_REG
		p.To.Reg = 4

		p = liblink.Appendp(ctxt, p)
		p.As = ASUB
		p.From.Type_ = D_REG
		p.From.Reg = 3
		p.To.Type_ = D_REG
		p.To.Reg = 4

		p = liblink.Appendp(ctxt, p)
		p.As = AMOVD
		p.From.Type_ = D_CONST
		p.From.Offset = int64(framesize) + liblink.StackGuard - liblink.StackSmall
		p.To.Type_ = D_REG
		p.To.Reg = REGTMP

		p = liblink.Appendp(ctxt, p)
		p.As = ACMPU
		p.From.Type_ = D_REG
		p.From.Reg = REGTMP
		p.To.Type_ = D_REG
		p.To.Reg = 4
	}

	// q1: BLT	done
	p = liblink.Appendp(ctxt, p)
	q1 = p

	p.As = ABLT
	p.To.Type_ = D_BRANCH

	// MOVD	LR, R5
	p = liblink.Appendp(ctxt, p)

	p.As = AMOVD
	p.From.Type_ = D_SPR
	p.From.Offset = D_LR
	p.To.Type_ = D_REG
	p.To.Reg = 5
	if q != nil {
		q.Pcond = p
	}

	// BL	runtime.morestack(SB)
	p = liblink.Appendp(ctxt, p)

	p.As = ABL
	p.To.Type_ = D_BRANCH
	if ctxt.Cursym.Cfunc != 0 {
		p.To.Sym = liblink.Linklookup(ctxt, "runtime.morestackc", 0)
	} else {

		p.To.Sym = ctxt.Symmorestack[noctxt]
	}

	// BR	start
	p = liblink.Appendp(ctxt, p)

	p.As = ABR
	p.To.Type_ = D_BRANCH
	p.Pcond = ctxt.Cursym.Text.Link

	// placeholder for q1's jump target
	p = liblink.Appendp(ctxt, p)

	p.As = ANOP // zero-width place holder
	q1.Pcond = p

	return p
}
Ejemplo n.º 6
0
Archivo: obj9.go Proyecto: rsc/tmp
func addstacksplit(ctxt *liblink.Link, cursym *liblink.LSym) {
	var p *liblink.Prog
	var q *liblink.Prog
	var p1 *liblink.Prog
	var p2 *liblink.Prog
	var q1 *liblink.Prog
	var o int
	var mov int
	var aoffset int
	var textstksiz int64
	var textarg int64
	var autosize int32

	if ctxt.Symmorestack[0] == nil {
		ctxt.Symmorestack[0] = liblink.Linklookup(ctxt, "runtime.morestack", 0)
		ctxt.Symmorestack[1] = liblink.Linklookup(ctxt, "runtime.morestack_noctxt", 0)
	}

	// TODO(minux): add morestack short-cuts with small fixed frame-size.
	ctxt.Cursym = cursym

	if cursym.Text == nil || cursym.Text.Link == nil {
		return
	}

	p = cursym.Text
	parsetextconst(p.To.Offset, &textstksiz, &textarg)

	cursym.Args = int32(p.To.Offset >> 32)
	cursym.Locals = int32(textstksiz)

	/*
	 * find leaf subroutines
	 * strip NOPs
	 * expand RET
	 * expand BECOME pseudo
	 */
	if ctxt.Debugvlog != 0 {

		fmt.Fprintf(ctxt.Bso, "%5.2f noops\n", liblink.Cputime())
	}
	liblink.Bflush(ctxt.Bso)

	q = nil
	for p = cursym.Text; p != nil; p = p.Link {
		switch p.As {
		/* too hard, just leave alone */
		case ATEXT:
			q = p

			p.Mark |= LABEL | LEAF | SYNC
			if p.Link != nil {
				p.Link.Mark |= LABEL
			}

		case ANOR:
			q = p
			if p.To.Type_ == D_REG {
				if p.To.Reg == REGZERO {
					p.Mark |= LABEL | SYNC
				}
			}

		case ALWAR,
			ASTWCCC,
			AECIWX,
			AECOWX,
			AEIEIO,
			AICBI,
			AISYNC,
			ATLBIE,
			ATLBIEL,
			ASLBIA,
			ASLBIE,
			ASLBMFEE,
			ASLBMFEV,
			ASLBMTE,
			ADCBF,
			ADCBI,
			ADCBST,
			ADCBT,
			ADCBTST,
			ADCBZ,
			ASYNC,
			ATLBSYNC,
			APTESYNC,
			ATW,
			AWORD,
			ARFI,
			ARFCI,
			ARFID,
			AHRFID:
			q = p
			p.Mark |= LABEL | SYNC
			continue

		case AMOVW,
			AMOVWZ,
			AMOVD:
			q = p
			switch p.From.Type_ {
			case D_MSR,
				D_SPR,
				D_FPSCR,
				D_CREG,
				D_DCR:
				p.Mark |= LABEL | SYNC
			}

			switch p.To.Type_ {
			case D_MSR,
				D_SPR,
				D_FPSCR,
				D_CREG,
				D_DCR:
				p.Mark |= LABEL | SYNC
			}

			continue

		case AFABS,
			AFABSCC,
			AFADD,
			AFADDCC,
			AFCTIW,
			AFCTIWCC,
			AFCTIWZ,
			AFCTIWZCC,
			AFDIV,
			AFDIVCC,
			AFMADD,
			AFMADDCC,
			AFMOVD,
			AFMOVDU,
			/* case AFMOVDS: */
			AFMOVS,
			AFMOVSU,

			/* case AFMOVSD: */
			AFMSUB,
			AFMSUBCC,
			AFMUL,
			AFMULCC,
			AFNABS,
			AFNABSCC,
			AFNEG,
			AFNEGCC,
			AFNMADD,
			AFNMADDCC,
			AFNMSUB,
			AFNMSUBCC,
			AFRSP,
			AFRSPCC,
			AFSUB,
			AFSUBCC:
			q = p

			p.Mark |= FLOAT
			continue

		case ABL,
			ABCL,
			ADUFFZERO,
			ADUFFCOPY:
			cursym.Text.Mark &^= LEAF
			fallthrough

		case ABC,
			ABEQ,
			ABGE,
			ABGT,
			ABLE,
			ABLT,
			ABNE,
			ABR,
			ABVC,
			ABVS:
			p.Mark |= BRANCH
			q = p
			q1 = p.Pcond
			if q1 != nil {
				for q1.As == ANOP {
					q1 = q1.Link
					p.Pcond = q1
				}

				if !(q1.Mark&LEAF != 0) {
					q1.Mark |= LABEL
				}
			} else {

				p.Mark |= LABEL
			}
			q1 = p.Link
			if q1 != nil {
				q1.Mark |= LABEL
			}
			continue

		case AFCMPO,
			AFCMPU:
			q = p
			p.Mark |= FCMP | FLOAT
			continue

		case ARETURN:
			q = p
			if p.Link != nil {
				p.Link.Mark |= LABEL
			}
			continue

		case ANOP:
			q1 = p.Link
			q.Link = q1 /* q is non-nop */
			q1.Mark |= p.Mark
			continue

		default:
			q = p
			continue
		}
	}

	autosize = 0
	for p = cursym.Text; p != nil; p = p.Link {
		o = int(p.As)
		switch o {
		case ATEXT:
			mov = AMOVD
			aoffset = 0
			autosize = int32(textstksiz + 8)
			if (p.Mark&LEAF != 0) && autosize <= 8 {
				autosize = 0
			} else if autosize&4 != 0 {
				autosize += 4
			}
			p.To.Offset = int64(uint64(p.To.Offset)&(0xffffffff<<32) | uint64(uint32(autosize-8)))

			if !(p.Reg&liblink.NOSPLIT != 0) {
				p = stacksplit(ctxt, p, autosize, bool2int(!(cursym.Text.Reg&liblink.NEEDCTXT != 0))) // emit split check
			}

			q = p

			if autosize != 0 {
				/* use MOVDU to adjust R1 when saving R31, if autosize is small */
				if !(cursym.Text.Mark&LEAF != 0) && autosize >= -BIG && autosize <= BIG {

					mov = AMOVDU
					aoffset = int(-autosize)
				} else {

					q = liblink.Appendp(ctxt, p)
					q.As = AADD
					q.Lineno = p.Lineno
					q.From.Type_ = D_CONST
					q.From.Offset = int64(-autosize)
					q.To.Type_ = D_REG
					q.To.Reg = REGSP
					q.Spadj = +autosize
				}
			} else if !(cursym.Text.Mark&LEAF != 0) {
				if ctxt.Debugvlog != 0 {
					fmt.Fprintf(ctxt.Bso, "save suppressed in: %s\n", cursym.Name)
					liblink.Bflush(ctxt.Bso)
				}

				cursym.Text.Mark |= LEAF
			}

			if cursym.Text.Mark&LEAF != 0 {
				cursym.Leaf = 1
				break
			}

			q = liblink.Appendp(ctxt, q)
			q.As = AMOVD
			q.Lineno = p.Lineno
			q.From.Type_ = D_SPR
			q.From.Offset = D_LR
			q.To.Type_ = D_REG
			q.To.Reg = REGTMP

			q = liblink.Appendp(ctxt, q)
			q.As = int16(mov)
			q.Lineno = p.Lineno
			q.From.Type_ = D_REG
			q.From.Reg = REGTMP
			q.To.Type_ = D_OREG
			q.To.Offset = int64(aoffset)
			q.To.Reg = REGSP
			if q.As == AMOVDU {
				q.Spadj = int32(-aoffset)
			}

			if cursym.Text.Reg&liblink.WRAPPER != 0 {
				// if(g->panic != nil && g->panic->argp == FP) g->panic->argp = bottom-of-frame
				//
				//	MOVD g_panic(g), R3
				//	CMP R0, R3
				//	BEQ end
				//	MOVD panic_argp(R3), R4
				//	ADD $(autosize+8), R1, R5
				//	CMP R4, R5
				//	BNE end
				//	ADD $8, R1, R6
				//	MOVD R6, panic_argp(R3)
				// end:
				//	NOP
				//
				// The NOP is needed to give the jumps somewhere to land.
				// It is a liblink NOP, not a ppc64 NOP: it encodes to 0 instruction bytes.

				q = liblink.Appendp(ctxt, q)

				q.As = AMOVD
				q.From.Type_ = D_OREG
				q.From.Reg = REGG
				q.From.Offset = 4 * int64(ctxt.Arch.Ptrsize) // G.panic
				q.To.Type_ = D_REG
				q.To.Reg = 3

				q = liblink.Appendp(ctxt, q)
				q.As = ACMP
				q.From.Type_ = D_REG
				q.From.Reg = 0
				q.To.Type_ = D_REG
				q.To.Reg = 3

				q = liblink.Appendp(ctxt, q)
				q.As = ABEQ
				q.To.Type_ = D_BRANCH
				p1 = q

				q = liblink.Appendp(ctxt, q)
				q.As = AMOVD
				q.From.Type_ = D_OREG
				q.From.Reg = 3
				q.From.Offset = 0 // Panic.argp
				q.To.Type_ = D_REG
				q.To.Reg = 4

				q = liblink.Appendp(ctxt, q)
				q.As = AADD
				q.From.Type_ = D_CONST
				q.From.Offset = int64(autosize) + 8
				q.Reg = REGSP
				q.To.Type_ = D_REG
				q.To.Reg = 5

				q = liblink.Appendp(ctxt, q)
				q.As = ACMP
				q.From.Type_ = D_REG
				q.From.Reg = 4
				q.To.Type_ = D_REG
				q.To.Reg = 5

				q = liblink.Appendp(ctxt, q)
				q.As = ABNE
				q.To.Type_ = D_BRANCH
				p2 = q

				q = liblink.Appendp(ctxt, q)
				q.As = AADD
				q.From.Type_ = D_CONST
				q.From.Offset = 8
				q.Reg = REGSP
				q.To.Type_ = D_REG
				q.To.Reg = 6

				q = liblink.Appendp(ctxt, q)
				q.As = AMOVD
				q.From.Type_ = D_REG
				q.From.Reg = 6
				q.To.Type_ = D_OREG
				q.To.Reg = 3
				q.To.Offset = 0 // Panic.argp

				q = liblink.Appendp(ctxt, q)

				q.As = ANOP
				p1.Pcond = q
				p2.Pcond = q
			}

		case ARETURN:
			if p.From.Type_ == D_CONST {
				ctxt.Diag("using BECOME (%P) is not supported!", p)
				break
			}

			if p.To.Sym != nil { // retjmp
				p.As = ABR
				p.To.Type_ = D_BRANCH
				break
			}

			if cursym.Text.Mark&LEAF != 0 {
				if !(autosize != 0) {
					p.As = ABR
					p.From = zprg.From
					p.To.Type_ = D_SPR
					p.To.Offset = D_LR
					p.Mark |= BRANCH
					break
				}

				p.As = AADD
				p.From.Type_ = D_CONST
				p.From.Offset = int64(autosize)
				p.To.Type_ = D_REG
				p.To.Reg = REGSP
				p.Spadj = -autosize

				q = ctxt.Arch.Prg()
				q.As = ABR
				q.Lineno = p.Lineno
				q.To.Type_ = D_SPR
				q.To.Offset = D_LR
				q.Mark |= BRANCH
				q.Spadj = +autosize

				q.Link = p.Link
				p.Link = q
				break
			}

			p.As = AMOVD
			p.From.Type_ = D_OREG
			p.From.Offset = 0
			p.From.Reg = REGSP
			p.To.Type_ = D_REG
			p.To.Reg = REGTMP

			q = ctxt.Arch.Prg()
			q.As = AMOVD
			q.Lineno = p.Lineno
			q.From.Type_ = D_REG
			q.From.Reg = REGTMP
			q.To.Type_ = D_SPR
			q.To.Offset = D_LR

			q.Link = p.Link
			p.Link = q
			p = q

			if false {
				// Debug bad returns
				q = ctxt.Arch.Prg()

				q.As = AMOVD
				q.Lineno = p.Lineno
				q.From.Type_ = D_OREG
				q.From.Offset = 0
				q.From.Reg = REGTMP
				q.To.Type_ = D_REG
				q.To.Reg = REGTMP

				q.Link = p.Link
				p.Link = q
				p = q
			}

			if autosize != 0 {
				q = ctxt.Arch.Prg()
				q.As = AADD
				q.Lineno = p.Lineno
				q.From.Type_ = D_CONST
				q.From.Offset = int64(autosize)
				q.To.Type_ = D_REG
				q.To.Reg = REGSP
				q.Spadj = -autosize

				q.Link = p.Link
				p.Link = q
			}

			q1 = ctxt.Arch.Prg()
			q1.As = ABR
			q1.Lineno = p.Lineno
			q1.To.Type_ = D_SPR
			q1.To.Offset = D_LR
			q1.Mark |= BRANCH
			q1.Spadj = +autosize

			q1.Link = q.Link
			q.Link = q1

		case AADD:
			if p.To.Type_ == D_REG && p.To.Reg == REGSP && p.From.Type_ == D_CONST {
				p.Spadj = int32(-p.From.Offset)
			}
			break
		}
	}
}