示例#1
0
文件: ggen.go 项目: glycerine/zygomys
// Called after regopt and peep have run.
// Expand CHECKNIL pseudo-op into actual nil pointer check.
func expandchecks(firstp *obj.Prog) {
	var p1 *obj.Prog
	var p2 *obj.Prog

	for p := firstp; p != nil; p = p.Link {
		if p.As != obj.ACHECKNIL {
			continue
		}
		if gc.Debug_checknil != 0 && p.Lineno > 1 { // p->lineno==1 in generated wrappers
			gc.Warnl(p.Lineno, "generated nil check")
		}

		// check is
		//	CMP arg, $0
		//	JNE 2(PC) (likely)
		//	MOV AX, 0
		p1 = gc.Ctxt.NewProg()

		p2 = gc.Ctxt.NewProg()
		gc.Clearp(p1)
		gc.Clearp(p2)
		p1.Link = p2
		p2.Link = p.Link
		p.Link = p1
		p1.Lineno = p.Lineno
		p2.Lineno = p.Lineno
		p1.Pc = 9999
		p2.Pc = 9999
		p.As = cmpptr
		p.To.Type = obj.TYPE_CONST
		p.To.Offset = 0
		p1.As = x86.AJNE
		p1.From.Type = obj.TYPE_CONST
		p1.From.Offset = 1 // likely
		p1.To.Type = obj.TYPE_BRANCH
		p1.To.Val = p2.Link

		// crash by write to memory address 0.
		// if possible, since we know arg is 0, use 0(arg),
		// which will be shorter to encode than plain 0.
		p2.As = x86.AMOVL

		p2.From.Type = obj.TYPE_REG
		p2.From.Reg = x86.REG_AX
		if regtyp(&p.From) {
			p2.To.Type = obj.TYPE_MEM
			p2.To.Reg = p.From.Reg
		} else {
			p2.To.Type = obj.TYPE_MEM
			p2.To.Reg = x86.REG_NONE
		}

		p2.To.Offset = 0
	}
}
示例#2
0
func Prog(as obj.As) *obj.Prog {
	var p *obj.Prog

	if as == obj.AGLOBL {
		if ddumped {
			Fatalf("already dumped data")
		}
		if dpc == nil {
			dpc = Ctxt.NewProg()
			dfirst = dpc
		}

		p = dpc
		dpc = Ctxt.NewProg()
		p.Link = dpc
	} else {
		p = Pc
		Pc = Ctxt.NewProg()
		Clearp(Pc)
		p.Link = Pc
	}

	if lineno == 0 && Debug['K'] != 0 {
		Warn("prog: line 0")
	}

	p.As = as
	p.Lineno = lineno
	return p
}
示例#3
0
文件: ggen.go 项目: glycerine/zygomys
// Called after regopt and peep have run.
// Expand CHECKNIL pseudo-op into actual nil pointer check.
func expandchecks(firstp *obj.Prog) {
	var p1 *obj.Prog

	for p := firstp; p != nil; p = p.Link {
		if gc.Debug_checknil != 0 && gc.Ctxt.Debugvlog != 0 {
			fmt.Printf("expandchecks: %v\n", p)
		}
		if p.As != obj.ACHECKNIL {
			continue
		}
		if gc.Debug_checknil != 0 && p.Lineno > 1 { // p->lineno==1 in generated wrappers
			gc.Warnl(p.Lineno, "generated nil check")
		}
		if p.From.Type != obj.TYPE_REG {
			gc.Fatalf("invalid nil check %v\n", p)
		}

		// check is
		//	CBNZ arg, 2(PC)
		//	MOVD ZR, 0(arg)
		p1 = gc.Ctxt.NewProg()
		gc.Clearp(p1)
		p1.Link = p.Link
		p.Link = p1
		p1.Lineno = p.Lineno
		p1.Pc = 9999

		p.As = arm64.ACBNZ
		p.To.Type = obj.TYPE_BRANCH
		p.To.Val = p1.Link

		// crash by write to memory address 0.
		p1.As = arm64.AMOVD
		p1.From.Type = obj.TYPE_REG
		p1.From.Reg = arm64.REGZERO
		p1.To.Type = obj.TYPE_MEM
		p1.To.Reg = p.From.Reg
		p1.To.Offset = 0
	}
}
示例#4
0
文件: ggen.go 项目: glycerine/zygomys
// Called after regopt and peep have run.
// Expand CHECKNIL pseudo-op into actual nil pointer check.
func expandchecks(firstp *obj.Prog) {
	var reg int
	var p1 *obj.Prog

	for p := firstp; p != nil; p = p.Link {
		if p.As != obj.ACHECKNIL {
			continue
		}
		if gc.Debug_checknil != 0 && p.Lineno > 1 { // p->lineno==1 in generated wrappers
			gc.Warnl(p.Lineno, "generated nil check")
		}
		if p.From.Type != obj.TYPE_REG {
			gc.Fatalf("invalid nil check %v", p)
		}
		reg = int(p.From.Reg)

		// check is
		//	CMP arg, $0
		//	MOV.EQ arg, 0(arg)
		p1 = gc.Ctxt.NewProg()

		gc.Clearp(p1)
		p1.Link = p.Link
		p.Link = p1
		p1.Lineno = p.Lineno
		p1.Pc = 9999
		p1.As = arm.AMOVW
		p1.From.Type = obj.TYPE_REG
		p1.From.Reg = int16(reg)
		p1.To.Type = obj.TYPE_MEM
		p1.To.Reg = int16(reg)
		p1.To.Offset = 0
		p1.Scond = arm.C_SCOND_EQ
		p.As = arm.ACMP
		p.From.Type = obj.TYPE_CONST
		p.From.Reg = 0
		p.From.Offset = 0
		p.Reg = int16(reg)
	}
}
示例#5
0
文件: obj5.go 项目: glycerine/zygomys
func xfol(ctxt *obj.Link, p *obj.Prog, last **obj.Prog) {
	var q *obj.Prog
	var r *obj.Prog
	var i int

loop:
	if p == nil {
		return
	}
	a := p.As
	if a == AB {
		q = p.Pcond
		if q != nil && q.As != obj.ATEXT {
			p.Mark |= FOLL
			p = q
			if p.Mark&FOLL == 0 {
				goto loop
			}
		}
	}

	if p.Mark&FOLL != 0 {
		i = 0
		q = p
		for ; i < 4; i, q = i+1, q.Link {
			if q == *last || q == nil {
				break
			}
			a = q.As
			if a == obj.ANOP {
				i--
				continue
			}

			if a == AB || (a == obj.ARET && q.Scond == C_SCOND_NONE) || a == ARFE || a == obj.AUNDEF {
				goto copy
			}
			if q.Pcond == nil || (q.Pcond.Mark&FOLL != 0) {
				continue
			}
			if a != ABEQ && a != ABNE {
				continue
			}

		copy:
			for {
				r = ctxt.NewProg()
				*r = *p
				if r.Mark&FOLL == 0 {
					fmt.Printf("can't happen 1\n")
				}
				r.Mark |= FOLL
				if p != q {
					p = p.Link
					(*last).Link = r
					*last = r
					continue
				}

				(*last).Link = r
				*last = r
				if a == AB || (a == obj.ARET && q.Scond == C_SCOND_NONE) || a == ARFE || a == obj.AUNDEF {
					return
				}
				r.As = ABNE
				if a == ABNE {
					r.As = ABEQ
				}
				r.Pcond = p.Link
				r.Link = p.Pcond
				if r.Link.Mark&FOLL == 0 {
					xfol(ctxt, r.Link, last)
				}
				if r.Pcond.Mark&FOLL == 0 {
					fmt.Printf("can't happen 2\n")
				}
				return
			}
		}

		a = AB
		q = ctxt.NewProg()
		q.As = a
		q.Lineno = p.Lineno
		q.To.Type = obj.TYPE_BRANCH
		q.To.Offset = p.Pc
		q.Pcond = p
		p = q
	}

	p.Mark |= FOLL
	(*last).Link = p
	*last = p
	if a == AB || (a == obj.ARET && p.Scond == C_SCOND_NONE) || a == ARFE || a == obj.AUNDEF {
		return
	}

	if p.Pcond != nil {
		if a != ABL && a != ABX && p.Link != nil {
			q = obj.Brchain(ctxt, p.Link)
			if a != obj.ATEXT {
				if q != nil && (q.Mark&FOLL != 0) {
					p.As = relinv(a)
					p.Link = p.Pcond
					p.Pcond = q
				}
			}

			xfol(ctxt, p.Link, last)
			q = obj.Brchain(ctxt, p.Pcond)
			if q == nil {
				q = p.Pcond
			}
			if q.Mark&FOLL != 0 {
				p.Pcond = q
				return
			}

			p = q
			goto loop
		}
	}

	p = p.Link
	goto loop
}
示例#6
0
文件: objz.go 项目: glycerine/zygomys
func xfol(ctxt *obj.Link, p *obj.Prog, last **obj.Prog) {
	var q *obj.Prog
	var r *obj.Prog
	var b obj.As

	for p != nil {
		a := p.As
		if a == ABR {
			q = p.Pcond
			if (p.Mark&NOSCHED != 0) || q != nil && (q.Mark&NOSCHED != 0) {
				p.Mark |= FOLL
				(*last).Link = p
				*last = p
				(*last).Pc = pc_cnt
				pc_cnt += 1
				p = p.Link
				xfol(ctxt, p, last)
				p = q
				if p != nil && p.Mark&FOLL == 0 {
					continue
				}
				return
			}

			if q != nil {
				p.Mark |= FOLL
				p = q
				if p.Mark&FOLL == 0 {
					continue
				}
			}
		}

		if p.Mark&FOLL != 0 {
			q = p
			for i := 0; i < 4; i, q = i+1, q.Link {
				if q == *last || (q.Mark&NOSCHED != 0) {
					break
				}
				b = 0 /* set */
				a = q.As
				if a == obj.ANOP {
					i--
					continue
				}
				if a != ABR && a != obj.ARET {
					if q.Pcond == nil || (q.Pcond.Mark&FOLL != 0) {
						continue
					}
					b = relinv(a)
					if b == 0 {
						continue
					}
				}

				for {
					r = ctxt.NewProg()
					*r = *p
					if r.Mark&FOLL == 0 {
						fmt.Printf("can't happen 1\n")
					}
					r.Mark |= FOLL
					if p != q {
						p = p.Link
						(*last).Link = r
						*last = r
						(*last).Pc = pc_cnt
						pc_cnt += 1
						continue
					}

					(*last).Link = r
					*last = r
					(*last).Pc = pc_cnt
					pc_cnt += 1
					if a == ABR || a == obj.ARET {
						return
					}
					r.As = b
					r.Pcond = p.Link
					r.Link = p.Pcond
					if r.Link.Mark&FOLL == 0 {
						xfol(ctxt, r.Link, last)
					}
					if r.Pcond.Mark&FOLL == 0 {
						fmt.Printf("can't happen 2\n")
					}
					return
				}
			}

			a = ABR
			q = ctxt.NewProg()
			q.As = a
			q.Lineno = p.Lineno
			q.To.Type = obj.TYPE_BRANCH
			q.To.Offset = p.Pc
			q.Pcond = p
			p = q
		}

		p.Mark |= FOLL
		(*last).Link = p
		*last = p
		(*last).Pc = pc_cnt
		pc_cnt += 1

		if a == ABR || a == obj.ARET {
			if p.Mark&NOSCHED != 0 {
				p = p.Link
				continue
			}

			return
		}

		if p.Pcond != nil {
			if a != ABL && p.Link != nil {
				xfol(ctxt, p.Link, last)
				p = p.Pcond
				if p == nil || (p.Mark&FOLL != 0) {
					return
				}
				continue
			}
		}

		p = p.Link
	}
}
示例#7
0
文件: obj7.go 项目: glycerine/zygomys
func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
	ctxt.Cursym = cursym

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

	p := cursym.Text
	textstksiz := p.To.Offset
	aoffset := int32(textstksiz)

	cursym.Args = p.To.Val.(int32)
	cursym.Locals = int32(textstksiz)

	/*
	 * find leaf subroutines
	 * strip NOPs
	 * expand RET
	 */
	ctxt.Bso.Flush()
	q := (*obj.Prog)(nil)
	var q1 *obj.Prog
	for p := cursym.Text; p != nil; p = p.Link {
		switch p.As {
		case obj.ATEXT:
			p.Mark |= LEAF

		case obj.ARET:
			break

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

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

		case ACBNZ,
			ACBZ,
			ACBNZW,
			ACBZW,
			ATBZ,
			ATBNZ,
			AB,
			ABEQ,
			ABNE,
			ABCS,
			ABHS,
			ABCC,
			ABLO,
			ABMI,
			ABPL,
			ABVS,
			ABVC,
			ABHI,
			ABLS,
			ABGE,
			ABLT,
			ABGT,
			ABLE,
			AADR, /* strange */
			AADRP:
			q1 = p.Pcond

			if q1 != nil {
				for q1.As == obj.ANOP {
					q1 = q1.Link
					p.Pcond = q1
				}
			}

			break
		}

		q = p
	}

	var q2 *obj.Prog
	var retjmp *obj.LSym
	for p := cursym.Text; p != nil; p = p.Link {
		o := p.As
		switch o {
		case obj.ATEXT:
			cursym.Text = p
			if textstksiz < 0 {
				ctxt.Autosize = 0
			} else {
				ctxt.Autosize = int32(textstksiz + 8)
			}
			if (cursym.Text.Mark&LEAF != 0) && ctxt.Autosize <= 8 {
				ctxt.Autosize = 0
			} else if ctxt.Autosize&(16-1) != 0 {
				// The frame includes an LR.
				// If the frame size is 8, it's only an LR,
				// so there's no potential for breaking references to
				// local variables by growing the frame size,
				// because there are no local variables.
				// But otherwise, if there is a non-empty locals section,
				// the author of the code is responsible for making sure
				// that the frame size is 8 mod 16.
				if ctxt.Autosize == 8 {
					ctxt.Autosize += 8
					cursym.Locals += 8
				} else {
					ctxt.Diag("%v: unaligned frame size %d - must be 8 mod 16 (or 0)", p, ctxt.Autosize-8)
				}
			}
			p.To.Offset = int64(ctxt.Autosize) - 8
			if ctxt.Autosize == 0 && !(cursym.Text.Mark&LEAF != 0) {
				if ctxt.Debugvlog != 0 {
					fmt.Fprintf(ctxt.Bso, "save suppressed in: %s\n", cursym.Text.From.Sym.Name)
				}
				ctxt.Bso.Flush()
				cursym.Text.Mark |= LEAF
			}

			if !(p.From3.Offset&obj.NOSPLIT != 0) {
				p = stacksplit(ctxt, p, ctxt.Autosize) // emit split check
			}

			aoffset = ctxt.Autosize
			if aoffset > 0xF0 {
				aoffset = 0xF0
			}
			if cursym.Text.Mark&LEAF != 0 {
				cursym.Leaf = true
				if ctxt.Autosize == 0 {
					break
				}
				aoffset = 0
			}

			q = p
			if ctxt.Autosize > aoffset {
				q = ctxt.NewProg()
				q.As = ASUB
				q.Lineno = p.Lineno
				q.From.Type = obj.TYPE_CONST
				q.From.Offset = int64(ctxt.Autosize) - int64(aoffset)
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REGSP
				q.Spadj = int32(q.From.Offset)
				q.Link = p.Link
				p.Link = q
				if cursym.Text.Mark&LEAF != 0 {
					break
				}
			}

			q1 = ctxt.NewProg()
			q1.As = AMOVD
			q1.Lineno = p.Lineno
			q1.From.Type = obj.TYPE_REG
			q1.From.Reg = REGLINK
			q1.To.Type = obj.TYPE_MEM
			q1.Scond = C_XPRE
			q1.To.Offset = int64(-aoffset)
			q1.To.Reg = REGSP
			q1.Link = q.Link
			q1.Spadj = aoffset
			q.Link = q1

			if cursym.Text.From3.Offset&obj.WRAPPER != 0 {
				// if(g->panic != nil && g->panic->argp == FP) g->panic->argp = bottom-of-frame
				//
				//	MOV g_panic(g), R1
				//	CMP ZR, R1
				//	BEQ end
				//	MOV panic_argp(R1), R2
				//	ADD $(autosize+8), RSP, R3
				//	CMP R2, R3
				//	BNE end
				//	ADD $8, RSP, R4
				//	MOVD R4, panic_argp(R1)
				// end:
				//	NOP
				//
				// The NOP is needed to give the jumps somewhere to land.
				// It is a liblink NOP, not a ARM64 NOP: it encodes to 0 instruction bytes.
				q = q1

				q = obj.Appendp(ctxt, q)
				q.As = AMOVD
				q.From.Type = obj.TYPE_MEM
				q.From.Reg = REGG
				q.From.Offset = 4 * int64(ctxt.Arch.PtrSize) // G.panic
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REG_R1

				q = obj.Appendp(ctxt, q)
				q.As = ACMP
				q.From.Type = obj.TYPE_REG
				q.From.Reg = REGZERO
				q.Reg = REG_R1

				q = obj.Appendp(ctxt, q)
				q.As = ABEQ
				q.To.Type = obj.TYPE_BRANCH
				q1 = q

				q = obj.Appendp(ctxt, q)
				q.As = AMOVD
				q.From.Type = obj.TYPE_MEM
				q.From.Reg = REG_R1
				q.From.Offset = 0 // Panic.argp
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REG_R2

				q = obj.Appendp(ctxt, q)
				q.As = AADD
				q.From.Type = obj.TYPE_CONST
				q.From.Offset = int64(ctxt.Autosize) + 8
				q.Reg = REGSP
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REG_R3

				q = obj.Appendp(ctxt, q)
				q.As = ACMP
				q.From.Type = obj.TYPE_REG
				q.From.Reg = REG_R2
				q.Reg = REG_R3

				q = obj.Appendp(ctxt, q)
				q.As = ABNE
				q.To.Type = obj.TYPE_BRANCH
				q2 = q

				q = obj.Appendp(ctxt, q)
				q.As = AADD
				q.From.Type = obj.TYPE_CONST
				q.From.Offset = 8
				q.Reg = REGSP
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REG_R4

				q = obj.Appendp(ctxt, q)
				q.As = AMOVD
				q.From.Type = obj.TYPE_REG
				q.From.Reg = REG_R4
				q.To.Type = obj.TYPE_MEM
				q.To.Reg = REG_R1
				q.To.Offset = 0 // Panic.argp

				q = obj.Appendp(ctxt, q)

				q.As = obj.ANOP
				q1.Pcond = q
				q2.Pcond = q
			}

		case obj.ARET:
			nocache(p)
			if p.From.Type == obj.TYPE_CONST {
				ctxt.Diag("using BECOME (%v) is not supported!", p)
				break
			}

			retjmp = p.To.Sym
			p.To = obj.Addr{}
			if cursym.Text.Mark&LEAF != 0 {
				if ctxt.Autosize != 0 {
					p.As = AADD
					p.From.Type = obj.TYPE_CONST
					p.From.Offset = int64(ctxt.Autosize)
					p.To.Type = obj.TYPE_REG
					p.To.Reg = REGSP
					p.Spadj = -ctxt.Autosize
				}
			} else {
				/* want write-back pre-indexed SP+autosize -> SP, loading REGLINK*/
				aoffset = ctxt.Autosize

				if aoffset > 0xF0 {
					aoffset = 0xF0
				}
				p.As = AMOVD
				p.From.Type = obj.TYPE_MEM
				p.Scond = C_XPOST
				p.From.Offset = int64(aoffset)
				p.From.Reg = REGSP
				p.To.Type = obj.TYPE_REG
				p.To.Reg = REGLINK
				p.Spadj = -aoffset
				if ctxt.Autosize > aoffset {
					q = ctxt.NewProg()
					q.As = AADD
					q.From.Type = obj.TYPE_CONST
					q.From.Offset = int64(ctxt.Autosize) - int64(aoffset)
					q.To.Type = obj.TYPE_REG
					q.To.Reg = REGSP
					q.Link = p.Link
					q.Spadj = int32(-q.From.Offset)
					q.Lineno = p.Lineno
					p.Link = q
					p = q
				}
			}

			if p.As != obj.ARET {
				q = ctxt.NewProg()
				q.Lineno = p.Lineno
				q.Link = p.Link
				p.Link = q
				p = q
			}

			if retjmp != nil { // retjmp
				p.As = AB
				p.To.Type = obj.TYPE_BRANCH
				p.To.Sym = retjmp
				p.Spadj = +ctxt.Autosize
				break
			}

			p.As = obj.ARET
			p.To.Type = obj.TYPE_MEM
			p.To.Offset = 0
			p.To.Reg = REGLINK
			p.Spadj = +ctxt.Autosize

		case AADD, ASUB:
			if p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP && p.From.Type == obj.TYPE_CONST {
				if p.As == AADD {
					p.Spadj = int32(-p.From.Offset)
				} else {
					p.Spadj = int32(+p.From.Offset)
				}
			}
			break
		}
	}
}
示例#8
0
文件: obj6.go 项目: glycerine/zygomys
func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
	if ctxt.Headtype == obj.Hplan9 && ctxt.Plan9privates == nil {
		ctxt.Plan9privates = obj.Linklookup(ctxt, "_privates", 0)
	}

	ctxt.Cursym = cursym

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

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

	var bpsize int
	if p.Mode == 64 && ctxt.Framepointer_enabled && autoffset > 0 && p.From3.Offset&obj.NOFRAME == 0 {
		// Make room for to save a base pointer. If autoffset == 0,
		// this might do something special like a tail jump to
		// another function, so in that case we omit this.
		bpsize = ctxt.Arch.PtrSize
		autoffset += int32(bpsize)
		p.To.Offset += int64(bpsize)
	} else {
		bpsize = 0
	}

	textarg := int64(p.To.Val.(int32))
	cursym.Args = int32(textarg)
	cursym.Locals = int32(p.To.Offset)

	// TODO(rsc): Remove.
	if p.Mode == 32 && cursym.Locals < 0 {
		cursym.Locals = 0
	}

	// TODO(rsc): Remove 'p.Mode == 64 &&'.
	if p.Mode == 64 && autoffset < obj.StackSmall && p.From3Offset()&obj.NOSPLIT == 0 {
		for q := p; q != nil; q = q.Link {
			if q.As == obj.ACALL {
				goto noleaf
			}
			if (q.As == obj.ADUFFCOPY || q.As == obj.ADUFFZERO) && autoffset >= obj.StackSmall-8 {
				goto noleaf
			}
		}

		p.From3.Offset |= obj.NOSPLIT
	noleaf:
	}

	if p.From3Offset()&obj.NOSPLIT == 0 || p.From3Offset()&obj.WRAPPER != 0 {
		p = obj.Appendp(ctxt, p)
		p = load_g_cx(ctxt, p) // load g into CX
	}

	if cursym.Text.From3Offset()&obj.NOSPLIT == 0 {
		p = stacksplit(ctxt, p, autoffset, int32(textarg)) // emit split check
	}

	if autoffset != 0 {
		if autoffset%int32(ctxt.Arch.RegSize) != 0 {
			ctxt.Diag("unaligned stack size %d", autoffset)
		}
		p = obj.Appendp(ctxt, p)
		p.As = AADJSP
		p.From.Type = obj.TYPE_CONST
		p.From.Offset = int64(autoffset)
		p.Spadj = autoffset
	} else {
		// zero-byte stack adjustment.
		// Insert a fake non-zero adjustment so that stkcheck can
		// recognize the end of the stack-splitting prolog.
		p = obj.Appendp(ctxt, p)

		p.As = obj.ANOP
		p.Spadj = int32(-ctxt.Arch.PtrSize)
		p = obj.Appendp(ctxt, p)
		p.As = obj.ANOP
		p.Spadj = int32(ctxt.Arch.PtrSize)
	}

	deltasp := autoffset

	if bpsize > 0 {
		// Save caller's BP
		p = obj.Appendp(ctxt, p)

		p.As = AMOVQ
		p.From.Type = obj.TYPE_REG
		p.From.Reg = REG_BP
		p.To.Type = obj.TYPE_MEM
		p.To.Reg = REG_SP
		p.To.Scale = 1
		p.To.Offset = int64(autoffset) - int64(bpsize)

		// Move current frame to BP
		p = obj.Appendp(ctxt, p)

		p.As = ALEAQ
		p.From.Type = obj.TYPE_MEM
		p.From.Reg = REG_SP
		p.From.Scale = 1
		p.From.Offset = int64(autoffset) - int64(bpsize)
		p.To.Type = obj.TYPE_REG
		p.To.Reg = REG_BP
	}

	if cursym.Text.From3Offset()&obj.WRAPPER != 0 {
		// if(g->panic != nil && g->panic->argp == FP) g->panic->argp = bottom-of-frame
		//
		//	MOVQ g_panic(CX), BX
		//	TESTQ BX, BX
		//	JEQ end
		//	LEAQ (autoffset+8)(SP), DI
		//	CMPQ panic_argp(BX), DI
		//	JNE end
		//	MOVQ SP, panic_argp(BX)
		// end:
		//	NOP
		//
		// The NOP is needed to give the jumps somewhere to land.
		// It is a liblink NOP, not an x86 NOP: it encodes to 0 instruction bytes.

		p = obj.Appendp(ctxt, p)

		p.As = AMOVQ
		p.From.Type = obj.TYPE_MEM
		p.From.Reg = REG_CX
		p.From.Offset = 4 * int64(ctxt.Arch.PtrSize) // G.panic
		p.To.Type = obj.TYPE_REG
		p.To.Reg = REG_BX
		if ctxt.Headtype == obj.Hnacl && p.Mode == 64 {
			p.As = AMOVL
			p.From.Type = obj.TYPE_MEM
			p.From.Reg = REG_R15
			p.From.Scale = 1
			p.From.Index = REG_CX
		}
		if p.Mode == 32 {
			p.As = AMOVL
		}

		p = obj.Appendp(ctxt, p)
		p.As = ATESTQ
		p.From.Type = obj.TYPE_REG
		p.From.Reg = REG_BX
		p.To.Type = obj.TYPE_REG
		p.To.Reg = REG_BX
		if ctxt.Headtype == obj.Hnacl || p.Mode == 32 {
			p.As = ATESTL
		}

		p = obj.Appendp(ctxt, p)
		p.As = AJEQ
		p.To.Type = obj.TYPE_BRANCH
		p1 := p

		p = obj.Appendp(ctxt, p)
		p.As = ALEAQ
		p.From.Type = obj.TYPE_MEM
		p.From.Reg = REG_SP
		p.From.Offset = int64(autoffset) + int64(ctxt.Arch.RegSize)
		p.To.Type = obj.TYPE_REG
		p.To.Reg = REG_DI
		if ctxt.Headtype == obj.Hnacl || p.Mode == 32 {
			p.As = ALEAL
		}

		p = obj.Appendp(ctxt, p)
		p.As = ACMPQ
		p.From.Type = obj.TYPE_MEM
		p.From.Reg = REG_BX
		p.From.Offset = 0 // Panic.argp
		p.To.Type = obj.TYPE_REG
		p.To.Reg = REG_DI
		if ctxt.Headtype == obj.Hnacl && p.Mode == 64 {
			p.As = ACMPL
			p.From.Type = obj.TYPE_MEM
			p.From.Reg = REG_R15
			p.From.Scale = 1
			p.From.Index = REG_BX
		}
		if p.Mode == 32 {
			p.As = ACMPL
		}

		p = obj.Appendp(ctxt, p)
		p.As = AJNE
		p.To.Type = obj.TYPE_BRANCH
		p2 := p

		p = obj.Appendp(ctxt, p)
		p.As = AMOVQ
		p.From.Type = obj.TYPE_REG
		p.From.Reg = REG_SP
		p.To.Type = obj.TYPE_MEM
		p.To.Reg = REG_BX
		p.To.Offset = 0 // Panic.argp
		if ctxt.Headtype == obj.Hnacl && p.Mode == 64 {
			p.As = AMOVL
			p.To.Type = obj.TYPE_MEM
			p.To.Reg = REG_R15
			p.To.Scale = 1
			p.To.Index = REG_BX
		}
		if p.Mode == 32 {
			p.As = AMOVL
		}

		p = obj.Appendp(ctxt, p)
		p.As = obj.ANOP
		p1.Pcond = p
		p2.Pcond = p
	}

	var a int
	var pcsize int
	for ; p != nil; p = p.Link {
		pcsize = int(p.Mode) / 8
		a = int(p.From.Name)
		if a == obj.NAME_AUTO {
			p.From.Offset += int64(deltasp) - int64(bpsize)
		}
		if a == obj.NAME_PARAM {
			p.From.Offset += int64(deltasp) + int64(pcsize)
		}
		if p.From3 != nil {
			a = int(p.From3.Name)
			if a == obj.NAME_AUTO {
				p.From3.Offset += int64(deltasp) - int64(bpsize)
			}
			if a == obj.NAME_PARAM {
				p.From3.Offset += int64(deltasp) + int64(pcsize)
			}
		}
		a = int(p.To.Name)
		if a == obj.NAME_AUTO {
			p.To.Offset += int64(deltasp) - int64(bpsize)
		}
		if a == obj.NAME_PARAM {
			p.To.Offset += int64(deltasp) + int64(pcsize)
		}

		switch p.As {
		default:
			continue

		case APUSHL, APUSHFL:
			deltasp += 4
			p.Spadj = 4
			continue

		case APUSHQ, APUSHFQ:
			deltasp += 8
			p.Spadj = 8
			continue

		case APUSHW, APUSHFW:
			deltasp += 2
			p.Spadj = 2
			continue

		case APOPL, APOPFL:
			deltasp -= 4
			p.Spadj = -4
			continue

		case APOPQ, APOPFQ:
			deltasp -= 8
			p.Spadj = -8
			continue

		case APOPW, APOPFW:
			deltasp -= 2
			p.Spadj = -2
			continue

		case obj.ARET:
			break
		}

		if autoffset != deltasp {
			ctxt.Diag("unbalanced PUSH/POP")
		}

		if autoffset != 0 {
			if bpsize > 0 {
				// Restore caller's BP
				p.As = AMOVQ

				p.From.Type = obj.TYPE_MEM
				p.From.Reg = REG_SP
				p.From.Scale = 1
				p.From.Offset = int64(autoffset) - int64(bpsize)
				p.To.Type = obj.TYPE_REG
				p.To.Reg = REG_BP
				p = obj.Appendp(ctxt, p)
			}

			p.As = AADJSP
			p.From.Type = obj.TYPE_CONST
			p.From.Offset = int64(-autoffset)
			p.Spadj = -autoffset
			p = obj.Appendp(ctxt, p)
			p.As = obj.ARET

			// If there are instructions following
			// this ARET, they come from a branch
			// with the same stackframe, so undo
			// the cleanup.
			p.Spadj = +autoffset
		}

		if p.To.Sym != nil { // retjmp
			p.As = obj.AJMP
		}
	}
}

func indir_cx(ctxt *obj.Link, p *obj.Prog, a *obj.Addr) {
	if ctxt.Headtype == obj.Hnacl && p.Mode == 64 {
		a.Type = obj.TYPE_MEM
		a.Reg = REG_R15
		a.Index = REG_CX
		a.Scale = 1
		return
	}

	a.Type = obj.TYPE_MEM
	a.Reg = REG_CX
}

// Append code to p to load g into cx.
// Overwrites p with the first instruction (no first appendp).
// Overwriting p is unusual but it lets use this in both the
// prologue (caller must call appendp first) and in the epilogue.
// Returns last new instruction.
func load_g_cx(ctxt *obj.Link, p *obj.Prog) *obj.Prog {
	p.As = AMOVQ
	if ctxt.Arch.PtrSize == 4 {
		p.As = AMOVL
	}
	p.From.Type = obj.TYPE_MEM
	p.From.Reg = REG_TLS
	p.From.Offset = 0
	p.To.Type = obj.TYPE_REG
	p.To.Reg = REG_CX

	next := p.Link
	progedit(ctxt, p)
	for p.Link != next {
		p = p.Link
	}

	if p.From.Index == REG_TLS {
		p.From.Scale = 2
	}

	return p
}

// Append code to p to check for stack split.
// Appends to (does not overwrite) p.
// Assumes g is in CX.
// Returns last new instruction.
func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32, textarg int32) *obj.Prog {
	cmp := ACMPQ
	lea := ALEAQ
	mov := AMOVQ
	sub := ASUBQ

	if ctxt.Headtype == obj.Hnacl || p.Mode == 32 {
		cmp = ACMPL
		lea = ALEAL
		mov = AMOVL
		sub = ASUBL
	}

	var q1 *obj.Prog
	if framesize <= obj.StackSmall {
		// small stack: SP <= stackguard
		//	CMPQ SP, stackguard
		p = obj.Appendp(ctxt, p)

		p.As = cmp
		p.From.Type = obj.TYPE_REG
		p.From.Reg = REG_SP
		indir_cx(ctxt, p, &p.To)
		p.To.Offset = 2 * int64(ctxt.Arch.PtrSize) // G.stackguard0
		if ctxt.Cursym.Cfunc {
			p.To.Offset = 3 * int64(ctxt.Arch.PtrSize) // G.stackguard1
		}
	} else if framesize <= obj.StackBig {
		// large stack: SP-framesize <= stackguard-StackSmall
		//	LEAQ -xxx(SP), AX
		//	CMPQ AX, stackguard
		p = obj.Appendp(ctxt, p)

		p.As = lea
		p.From.Type = obj.TYPE_MEM
		p.From.Reg = REG_SP
		p.From.Offset = -(int64(framesize) - obj.StackSmall)
		p.To.Type = obj.TYPE_REG
		p.To.Reg = REG_AX

		p = obj.Appendp(ctxt, p)
		p.As = cmp
		p.From.Type = obj.TYPE_REG
		p.From.Reg = REG_AX
		indir_cx(ctxt, p, &p.To)
		p.To.Offset = 2 * int64(ctxt.Arch.PtrSize) // G.stackguard0
		if ctxt.Cursym.Cfunc {
			p.To.Offset = 3 * int64(ctxt.Arch.PtrSize) // G.stackguard1
		}
	} 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.
		//	MOVQ	stackguard, CX
		//	CMPQ	CX, $StackPreempt
		//	JEQ	label-of-call-to-morestack
		//	LEAQ	StackGuard(SP), AX
		//	SUBQ	CX, AX
		//	CMPQ	AX, $(framesize+(StackGuard-StackSmall))

		p = obj.Appendp(ctxt, p)

		p.As = mov
		indir_cx(ctxt, p, &p.From)
		p.From.Offset = 2 * int64(ctxt.Arch.PtrSize) // G.stackguard0
		if ctxt.Cursym.Cfunc {
			p.From.Offset = 3 * int64(ctxt.Arch.PtrSize) // G.stackguard1
		}
		p.To.Type = obj.TYPE_REG
		p.To.Reg = REG_SI

		p = obj.Appendp(ctxt, p)
		p.As = cmp
		p.From.Type = obj.TYPE_REG
		p.From.Reg = REG_SI
		p.To.Type = obj.TYPE_CONST
		p.To.Offset = obj.StackPreempt
		if p.Mode == 32 {
			p.To.Offset = int64(uint32(obj.StackPreempt & (1<<32 - 1)))
		}

		p = obj.Appendp(ctxt, p)
		p.As = AJEQ
		p.To.Type = obj.TYPE_BRANCH
		q1 = p

		p = obj.Appendp(ctxt, p)
		p.As = lea
		p.From.Type = obj.TYPE_MEM
		p.From.Reg = REG_SP
		p.From.Offset = obj.StackGuard
		p.To.Type = obj.TYPE_REG
		p.To.Reg = REG_AX

		p = obj.Appendp(ctxt, p)
		p.As = sub
		p.From.Type = obj.TYPE_REG
		p.From.Reg = REG_SI
		p.To.Type = obj.TYPE_REG
		p.To.Reg = REG_AX

		p = obj.Appendp(ctxt, p)
		p.As = cmp
		p.From.Type = obj.TYPE_REG
		p.From.Reg = REG_AX
		p.To.Type = obj.TYPE_CONST
		p.To.Offset = int64(framesize) + (obj.StackGuard - obj.StackSmall)
	}

	// common
	jls := obj.Appendp(ctxt, p)
	jls.As = AJLS
	jls.To.Type = obj.TYPE_BRANCH

	var last *obj.Prog
	for last = ctxt.Cursym.Text; last.Link != nil; last = last.Link {
	}

	spfix := obj.Appendp(ctxt, last)
	spfix.As = obj.ANOP
	spfix.Spadj = -framesize

	call := obj.Appendp(ctxt, spfix)
	call.Lineno = ctxt.Cursym.Text.Lineno
	call.Mode = ctxt.Cursym.Text.Mode
	call.As = obj.ACALL
	call.To.Type = obj.TYPE_BRANCH
	call.To.Name = obj.NAME_EXTERN
	morestack := "runtime.morestack"
	switch {
	case ctxt.Cursym.Cfunc:
		morestack = "runtime.morestackc"
	case ctxt.Cursym.Text.From3Offset()&obj.NEEDCTXT == 0:
		morestack = "runtime.morestack_noctxt"
	}
	call.To.Sym = obj.Linklookup(ctxt, morestack, 0)
	// When compiling 386 code for dynamic linking, the call needs to be adjusted
	// to follow PIC rules. This in turn can insert more instructions, so we need
	// to keep track of the start of the call (where the jump will be to) and the
	// end (which following instructions are appended to).
	callend := call
	progedit(ctxt, callend)
	for ; callend.Link != nil; callend = callend.Link {
		progedit(ctxt, callend.Link)
	}

	jmp := obj.Appendp(ctxt, callend)
	jmp.As = obj.AJMP
	jmp.To.Type = obj.TYPE_BRANCH
	jmp.Pcond = ctxt.Cursym.Text.Link
	jmp.Spadj = +framesize

	jls.Pcond = call
	if q1 != nil {
		q1.Pcond = call
	}

	return jls
}

func follow(ctxt *obj.Link, s *obj.LSym) {
	ctxt.Cursym = s

	firstp := ctxt.NewProg()
	lastp := firstp
	xfol(ctxt, s.Text, &lastp)
	lastp.Link = nil
	s.Text = firstp.Link
}

func nofollow(a obj.As) bool {
	switch a {
	case obj.AJMP,
		obj.ARET,
		AIRETL,
		AIRETQ,
		AIRETW,
		ARETFL,
		ARETFQ,
		ARETFW,
		obj.AUNDEF:
		return true
	}

	return false
}

func pushpop(a obj.As) bool {
	switch a {
	case APUSHL,
		APUSHFL,
		APUSHQ,
		APUSHFQ,
		APUSHW,
		APUSHFW,
		APOPL,
		APOPFL,
		APOPQ,
		APOPFQ,
		APOPW,
		APOPFW:
		return true
	}

	return false
}

func relinv(a obj.As) obj.As {
	switch a {
	case AJEQ:
		return AJNE
	case AJNE:
		return AJEQ
	case AJLE:
		return AJGT
	case AJLS:
		return AJHI
	case AJLT:
		return AJGE
	case AJMI:
		return AJPL
	case AJGE:
		return AJLT
	case AJPL:
		return AJMI
	case AJGT:
		return AJLE
	case AJHI:
		return AJLS
	case AJCS:
		return AJCC
	case AJCC:
		return AJCS
	case AJPS:
		return AJPC
	case AJPC:
		return AJPS
	case AJOS:
		return AJOC
	case AJOC:
		return AJOS
	}

	log.Fatalf("unknown relation: %s", obj.Aconv(a))
	return 0
}

func xfol(ctxt *obj.Link, p *obj.Prog, last **obj.Prog) {
	var q *obj.Prog
	var i int
	var a obj.As

loop:
	if p == nil {
		return
	}
	if p.As == obj.AJMP {
		q = p.Pcond
		if q != nil && q.As != obj.ATEXT {
			/* mark instruction as done and continue layout at target of jump */
			p.Mark |= DONE

			p = q
			if p.Mark&DONE == 0 {
				goto loop
			}
		}
	}

	if p.Mark&DONE != 0 {
		/*
		 * p goes here, but already used it elsewhere.
		 * copy up to 4 instructions or else branch to other copy.
		 */
		i = 0
		q = p
		for ; i < 4; i, q = i+1, q.Link {
			if q == nil {
				break
			}
			if q == *last {
				break
			}
			a = q.As
			if a == obj.ANOP {
				i--
				continue
			}

			if nofollow(a) || pushpop(a) {
				break // NOTE(rsc): arm does goto copy
			}
			if q.Pcond == nil || q.Pcond.Mark&DONE != 0 {
				continue
			}
			if a == obj.ACALL || a == ALOOP {
				continue
			}
			for {
				if p.As == obj.ANOP {
					p = p.Link
					continue
				}

				q = obj.Copyp(ctxt, p)
				p = p.Link
				q.Mark |= DONE
				(*last).Link = q
				*last = q
				if q.As != a || q.Pcond == nil || q.Pcond.Mark&DONE != 0 {
					continue
				}

				q.As = relinv(q.As)
				p = q.Pcond
				q.Pcond = q.Link
				q.Link = p
				xfol(ctxt, q.Link, last)
				p = q.Link
				if p.Mark&DONE != 0 {
					return
				}
				goto loop
				/* */
			}
		}
		q = ctxt.NewProg()
		q.As = obj.AJMP
		q.Lineno = p.Lineno
		q.To.Type = obj.TYPE_BRANCH
		q.To.Offset = p.Pc
		q.Pcond = p
		p = q
	}

	/* emit p */
	p.Mark |= DONE

	(*last).Link = p
	*last = p
	a = p.As

	/* continue loop with what comes after p */
	if nofollow(a) {
		return
	}
	if p.Pcond != nil && a != obj.ACALL {
		/*
		 * some kind of conditional branch.
		 * recurse to follow one path.
		 * continue loop on the other.
		 */
		q = obj.Brchain(ctxt, p.Pcond)
		if q != nil {
			p.Pcond = q
		}
		q = obj.Brchain(ctxt, p.Link)
		if q != nil {
			p.Link = q
		}
		if p.From.Type == obj.TYPE_CONST {
			if p.From.Offset == 1 {
				/*
				 * expect conditional jump to be taken.
				 * rewrite so that's the fall-through case.
				 */
				p.As = relinv(a)

				q = p.Link
				p.Link = p.Pcond
				p.Pcond = q
			}
		} else {
			q = p.Link
			if q.Mark&DONE != 0 {
				if a != ALOOP {
					p.As = relinv(a)
					p.Link = p.Pcond
					p.Pcond = q
				}
			}
		}

		xfol(ctxt, p.Link, last)
		if p.Pcond.Mark&DONE != 0 {
			return
		}
		p = p.Pcond
		goto loop
	}

	p = p.Link
	goto loop
}

var unaryDst = map[obj.As]bool{
	ABSWAPL:    true,
	ABSWAPQ:    true,
	ACMPXCHG8B: true,
	ADECB:      true,
	ADECL:      true,
	ADECQ:      true,
	ADECW:      true,
	AINCB:      true,
	AINCL:      true,
	AINCQ:      true,
	AINCW:      true,
	ANEGB:      true,
	ANEGL:      true,
	ANEGQ:      true,
	ANEGW:      true,
	ANOTB:      true,
	ANOTL:      true,
	ANOTQ:      true,
	ANOTW:      true,
	APOPL:      true,
	APOPQ:      true,
	APOPW:      true,
	ASETCC:     true,
	ASETCS:     true,
	ASETEQ:     true,
	ASETGE:     true,
	ASETGT:     true,
	ASETHI:     true,
	ASETLE:     true,
	ASETLS:     true,
	ASETLT:     true,
	ASETMI:     true,
	ASETNE:     true,
	ASETOC:     true,
	ASETOS:     true,
	ASETPC:     true,
	ASETPL:     true,
	ASETPS:     true,
	AFFREE:     true,
	AFLDENV:    true,
	AFSAVE:     true,
	AFSTCW:     true,
	AFSTENV:    true,
	AFSTSW:     true,
	AFXSAVE:    true,
	AFXSAVE64:  true,
	ASTMXCSR:   true,
}

var Linkamd64 = obj.LinkArch{
	Arch:       sys.ArchAMD64,
	Preprocess: preprocess,
	Assemble:   span6,
	Follow:     follow,
	Progedit:   progedit,
	UnaryDst:   unaryDst,
}

var Linkamd64p32 = obj.LinkArch{
	Arch:       sys.ArchAMD64P32,
	Preprocess: preprocess,
	Assemble:   span6,
	Follow:     follow,
	Progedit:   progedit,
	UnaryDst:   unaryDst,
}

var Link386 = obj.LinkArch{
	Arch:       sys.Arch386,
	Preprocess: preprocess,
	Assemble:   span6,
	Follow:     follow,
	Progedit:   progedit,
	UnaryDst:   unaryDst,
}
示例#9
0
文件: ggen.go 项目: glycerine/zygomys
// Called after regopt and peep have run.
// Expand CHECKNIL pseudo-op into actual nil pointer check.
func expandchecks(firstp *obj.Prog) {
	var p1 *obj.Prog
	var p2 *obj.Prog

	for p := firstp; p != nil; p = p.Link {
		if gc.Debug_checknil != 0 && gc.Ctxt.Debugvlog != 0 {
			fmt.Printf("expandchecks: %v\n", p)
		}
		if p.As != obj.ACHECKNIL {
			continue
		}
		if gc.Debug_checknil != 0 && p.Lineno > 1 { // p->lineno==1 in generated wrappers
			gc.Warnl(p.Lineno, "generated nil check")
		}
		if p.From.Type != obj.TYPE_REG {
			gc.Fatalf("invalid nil check %v\n", p)
		}

		/*
			// check is
			//	TD $4, R0, arg (R0 is always zero)
			// eqv. to:
			// 	tdeq r0, arg
			// NOTE: this needs special runtime support to make SIGTRAP recoverable.
			reg = p->from.reg;
			p->as = ATD;
			p->from = p->to = p->from3 = zprog.from;
			p->from.type = TYPE_CONST;
			p->from.offset = 4;
			p->from.reg = 0;
			p->reg = REGZERO;
			p->to.type = TYPE_REG;
			p->to.reg = reg;
		*/
		// check is
		//	CMP arg, R0
		//	BNE 2(PC) [likely]
		//	MOVD R0, 0(R0)
		p1 = gc.Ctxt.NewProg()

		p2 = gc.Ctxt.NewProg()
		gc.Clearp(p1)
		gc.Clearp(p2)
		p1.Link = p2
		p2.Link = p.Link
		p.Link = p1
		p1.Lineno = p.Lineno
		p2.Lineno = p.Lineno
		p1.Pc = 9999
		p2.Pc = 9999
		p.As = ppc64.ACMP
		p.To.Type = obj.TYPE_REG
		p.To.Reg = ppc64.REGZERO
		p1.As = ppc64.ABNE

		//p1->from.type = TYPE_CONST;
		//p1->from.offset = 1; // likely
		p1.To.Type = obj.TYPE_BRANCH

		p1.To.Val = p2.Link

		// crash by write to memory address 0.
		p2.As = ppc64.AMOVD

		p2.From.Type = obj.TYPE_REG
		p2.From.Reg = ppc64.REGZERO
		p2.To.Type = obj.TYPE_MEM
		p2.To.Reg = ppc64.REGZERO
		p2.To.Offset = 0
	}
}
示例#10
0
文件: obj9.go 项目: glycerine/zygomys
func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
	// 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
	textstksiz := p.To.Offset
	if textstksiz == -8 {
		// Compatibility hack.
		p.From3.Offset |= obj.NOFRAME
		textstksiz = 0
	}
	if textstksiz%8 != 0 {
		ctxt.Diag("frame size %d not a multiple of 8", textstksiz)
	}
	if p.From3.Offset&obj.NOFRAME != 0 {
		if textstksiz != 0 {
			ctxt.Diag("NOFRAME functions must have a frame size of 0, not %d", textstksiz)
		}
	}

	cursym.Args = p.To.Val.(int32)
	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", obj.Cputime())
	}
	ctxt.Bso.Flush()

	var q *obj.Prog
	var q1 *obj.Prog
	for p := cursym.Text; p != nil; p = p.Link {
		switch p.As {
		/* too hard, just leave alone */
		case obj.ATEXT:
			q = p

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

		case ANOR:
			q = p
			if p.To.Type == obj.TYPE_REG {
				if p.To.Reg == REGZERO {
					p.Mark |= LABEL | SYNC
				}
			}

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

		case AMOVW, AMOVWZ, AMOVD:
			q = p
			if p.From.Reg >= REG_SPECIAL || p.To.Reg >= REG_SPECIAL {
				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,
			obj.ADUFFZERO,
			obj.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 == obj.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 obj.ARET:
			q = p
			if p.Link != nil {
				p.Link.Mark |= LABEL
			}
			continue

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

		default:
			q = p
			continue
		}
	}

	autosize := int32(0)
	var aoffset int
	var mov obj.As
	var p1 *obj.Prog
	var p2 *obj.Prog
	for p := cursym.Text; p != nil; p = p.Link {
		o := p.As
		switch o {
		case obj.ATEXT:
			mov = AMOVD
			aoffset = 0
			autosize = int32(textstksiz)

			if p.Mark&LEAF != 0 && autosize == 0 && p.From3.Offset&obj.NOFRAME == 0 {
				// A leaf function with no locals has no frame.
				p.From3.Offset |= obj.NOFRAME
			}

			if p.From3.Offset&obj.NOFRAME == 0 {
				// If there is a stack frame at all, it includes
				// space to save the LR.
				autosize += int32(ctxt.FixedFrameSize())
			}

			p.To.Offset = int64(autosize)

			q = p

			if ctxt.Flag_shared && cursym.Name != "runtime.duffzero" && cursym.Name != "runtime.duffcopy" && cursym.Name != "runtime.stackBarrier" {
				// When compiling Go into PIC, all functions must start
				// with instructions to load the TOC pointer into r2:
				//
				//	addis r2, r12, .TOC.-func@ha
				//	addi r2, r2, .TOC.-func@l+4
				//
				// We could probably skip this prologue in some situations
				// but it's a bit subtle. However, it is both safe and
				// necessary to leave the prologue off duffzero and
				// duffcopy as we rely on being able to jump to a specific
				// instruction offset for them, and stackBarrier is only
				// ever called from an overwritten LR-save slot on the
				// stack (when r12 will not be remotely the right thing)
				// but fortunately does not access global data.
				//
				// These are AWORDS because there is no (afaict) way to
				// generate the addis instruction except as part of the
				// load of a large constant, and in that case there is no
				// way to use r12 as the source.
				q = obj.Appendp(ctxt, q)
				q.As = AWORD
				q.Lineno = p.Lineno
				q.From.Type = obj.TYPE_CONST
				q.From.Offset = 0x3c4c0000
				q = obj.Appendp(ctxt, q)
				q.As = AWORD
				q.Lineno = p.Lineno
				q.From.Type = obj.TYPE_CONST
				q.From.Offset = 0x38420000
				rel := obj.Addrel(ctxt.Cursym)
				rel.Off = 0
				rel.Siz = 8
				rel.Sym = obj.Linklookup(ctxt, ".TOC.", 0)
				rel.Type = obj.R_ADDRPOWER_PCREL
			}

			if cursym.Text.From3.Offset&obj.NOSPLIT == 0 {
				q = stacksplit(ctxt, q, autosize) // emit split check
			}

			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 = obj.Appendp(ctxt, q)
					q.As = AADD
					q.Lineno = p.Lineno
					q.From.Type = obj.TYPE_CONST
					q.From.Offset = int64(-autosize)
					q.To.Type = obj.TYPE_REG
					q.To.Reg = REGSP
					q.Spadj = +autosize
				}
			} else if cursym.Text.Mark&LEAF == 0 {
				// A very few functions that do not return to their caller
				// (e.g. gogo) are not identified as leaves but still have
				// no frame.
				cursym.Text.Mark |= LEAF
			}

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

			q = obj.Appendp(ctxt, q)
			q.As = AMOVD
			q.Lineno = p.Lineno
			q.From.Type = obj.TYPE_REG
			q.From.Reg = REG_LR
			q.To.Type = obj.TYPE_REG
			q.To.Reg = REGTMP

			q = obj.Appendp(ctxt, q)
			q.As = mov
			q.Lineno = p.Lineno
			q.From.Type = obj.TYPE_REG
			q.From.Reg = REGTMP
			q.To.Type = obj.TYPE_MEM
			q.To.Offset = int64(aoffset)
			q.To.Reg = REGSP
			if q.As == AMOVDU {
				q.Spadj = int32(-aoffset)
			}

			if ctxt.Flag_shared {
				q = obj.Appendp(ctxt, q)
				q.As = AMOVD
				q.Lineno = p.Lineno
				q.From.Type = obj.TYPE_REG
				q.From.Reg = REG_R2
				q.To.Type = obj.TYPE_MEM
				q.To.Reg = REGSP
				q.To.Offset = 24
			}

			if cursym.Text.From3.Offset&obj.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 = obj.Appendp(ctxt, q)

				q.As = AMOVD
				q.From.Type = obj.TYPE_MEM
				q.From.Reg = REGG
				q.From.Offset = 4 * int64(ctxt.Arch.PtrSize) // G.panic
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REG_R3

				q = obj.Appendp(ctxt, q)
				q.As = ACMP
				q.From.Type = obj.TYPE_REG
				q.From.Reg = REG_R0
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REG_R3

				q = obj.Appendp(ctxt, q)
				q.As = ABEQ
				q.To.Type = obj.TYPE_BRANCH
				p1 = q

				q = obj.Appendp(ctxt, q)
				q.As = AMOVD
				q.From.Type = obj.TYPE_MEM
				q.From.Reg = REG_R3
				q.From.Offset = 0 // Panic.argp
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REG_R4

				q = obj.Appendp(ctxt, q)
				q.As = AADD
				q.From.Type = obj.TYPE_CONST
				q.From.Offset = int64(autosize) + ctxt.FixedFrameSize()
				q.Reg = REGSP
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REG_R5

				q = obj.Appendp(ctxt, q)
				q.As = ACMP
				q.From.Type = obj.TYPE_REG
				q.From.Reg = REG_R4
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REG_R5

				q = obj.Appendp(ctxt, q)
				q.As = ABNE
				q.To.Type = obj.TYPE_BRANCH
				p2 = q

				q = obj.Appendp(ctxt, q)
				q.As = AADD
				q.From.Type = obj.TYPE_CONST
				q.From.Offset = ctxt.FixedFrameSize()
				q.Reg = REGSP
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REG_R6

				q = obj.Appendp(ctxt, q)
				q.As = AMOVD
				q.From.Type = obj.TYPE_REG
				q.From.Reg = REG_R6
				q.To.Type = obj.TYPE_MEM
				q.To.Reg = REG_R3
				q.To.Offset = 0 // Panic.argp

				q = obj.Appendp(ctxt, q)

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

		case obj.ARET:
			if p.From.Type == obj.TYPE_CONST {
				ctxt.Diag("using BECOME (%v) is not supported!", p)
				break
			}

			retTarget := p.To.Sym

			if cursym.Text.Mark&LEAF != 0 {
				if autosize == 0 {
					p.As = ABR
					p.From = obj.Addr{}
					if retTarget == nil {
						p.To.Type = obj.TYPE_REG
						p.To.Reg = REG_LR
					} else {
						p.To.Type = obj.TYPE_BRANCH
						p.To.Sym = retTarget
					}
					p.Mark |= BRANCH
					break
				}

				p.As = AADD
				p.From.Type = obj.TYPE_CONST
				p.From.Offset = int64(autosize)
				p.To.Type = obj.TYPE_REG
				p.To.Reg = REGSP
				p.Spadj = -autosize

				q = ctxt.NewProg()
				q.As = ABR
				q.Lineno = p.Lineno
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REG_LR
				q.Mark |= BRANCH
				q.Spadj = +autosize

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

			p.As = AMOVD
			p.From.Type = obj.TYPE_MEM
			p.From.Offset = 0
			p.From.Reg = REGSP
			p.To.Type = obj.TYPE_REG
			p.To.Reg = REGTMP

			q = ctxt.NewProg()
			q.As = AMOVD
			q.Lineno = p.Lineno
			q.From.Type = obj.TYPE_REG
			q.From.Reg = REGTMP
			q.To.Type = obj.TYPE_REG
			q.To.Reg = REG_LR

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

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

				q.As = AMOVD
				q.Lineno = p.Lineno
				q.From.Type = obj.TYPE_MEM
				q.From.Offset = 0
				q.From.Reg = REGTMP
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REGTMP

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

			if autosize != 0 {
				q = ctxt.NewProg()
				q.As = AADD
				q.Lineno = p.Lineno
				q.From.Type = obj.TYPE_CONST
				q.From.Offset = int64(autosize)
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REGSP
				q.Spadj = -autosize

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

			q1 = ctxt.NewProg()
			q1.As = ABR
			q1.Lineno = p.Lineno
			if retTarget == nil {
				q1.To.Type = obj.TYPE_REG
				q1.To.Reg = REG_LR
			} else {
				q1.To.Type = obj.TYPE_BRANCH
				q1.To.Sym = retTarget
			}
			q1.Mark |= BRANCH
			q1.Spadj = +autosize

			q1.Link = q.Link
			q.Link = q1
		case AADD:
			if p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP && p.From.Type == obj.TYPE_CONST {
				p.Spadj = int32(-p.From.Offset)
			}
		}
	}
}
示例#11
0
文件: obj9.go 项目: glycerine/zygomys
func xfol(ctxt *obj.Link, p *obj.Prog, last **obj.Prog) {
	var q *obj.Prog
	var r *obj.Prog
	var b obj.As
	var i int

loop:
	if p == nil {
		return
	}
	a := p.As
	if a == ABR {
		q = p.Pcond
		if (p.Mark&NOSCHED != 0) || q != nil && (q.Mark&NOSCHED != 0) {
			p.Mark |= FOLL
			(*last).Link = p
			*last = p
			p = p.Link
			xfol(ctxt, p, last)
			p = q
			if p != nil && p.Mark&FOLL == 0 {
				goto loop
			}
			return
		}

		if q != nil {
			p.Mark |= FOLL
			p = q
			if p.Mark&FOLL == 0 {
				goto loop
			}
		}
	}

	if p.Mark&FOLL != 0 {
		i = 0
		q = p
		for ; i < 4; i, q = i+1, q.Link {
			if q == *last || (q.Mark&NOSCHED != 0) {
				break
			}
			b = 0 /* set */
			a = q.As
			if a == obj.ANOP {
				i--
				continue
			}

			if a == ABR || a == obj.ARET || a == ARFI || a == ARFCI || a == ARFID || a == AHRFID {
				goto copy
			}
			if q.Pcond == nil || (q.Pcond.Mark&FOLL != 0) {
				continue
			}
			b = relinv(a)
			if b == 0 {
				continue
			}

		copy:
			for {
				r = ctxt.NewProg()
				*r = *p
				if r.Mark&FOLL == 0 {
					fmt.Printf("can't happen 1\n")
				}
				r.Mark |= FOLL
				if p != q {
					p = p.Link
					(*last).Link = r
					*last = r
					continue
				}

				(*last).Link = r
				*last = r
				if a == ABR || a == obj.ARET || a == ARFI || a == ARFCI || a == ARFID || a == AHRFID {
					return
				}
				r.As = b
				r.Pcond = p.Link
				r.Link = p.Pcond
				if r.Link.Mark&FOLL == 0 {
					xfol(ctxt, r.Link, last)
				}
				if r.Pcond.Mark&FOLL == 0 {
					fmt.Printf("can't happen 2\n")
				}
				return
			}
		}

		a = ABR
		q = ctxt.NewProg()
		q.As = a
		q.Lineno = p.Lineno
		q.To.Type = obj.TYPE_BRANCH
		q.To.Offset = p.Pc
		q.Pcond = p
		p = q
	}

	p.Mark |= FOLL
	(*last).Link = p
	*last = p
	if a == ABR || a == obj.ARET || a == ARFI || a == ARFCI || a == ARFID || a == AHRFID {
		if p.Mark&NOSCHED != 0 {
			p = p.Link
			goto loop
		}

		return
	}

	if p.Pcond != nil {
		if a != ABL && p.Link != nil {
			xfol(ctxt, p.Link, last)
			p = p.Pcond
			if p == nil || (p.Mark&FOLL != 0) {
				return
			}
			goto loop
		}
	}

	p = p.Link
	goto loop
}
示例#12
0
文件: asm0.go 项目: glycerine/zygomys
func span0(ctxt *obj.Link, cursym *obj.LSym) {
	p := cursym.Text
	if p == nil || p.Link == nil { // handle external functions and ELF section symbols
		return
	}
	ctxt.Cursym = cursym
	ctxt.Autosize = int32(p.To.Offset + 8)

	if oprange[AOR&obj.AMask] == nil {
		buildop(ctxt)
	}

	c := int64(0)
	p.Pc = c

	var m int
	var o *Optab
	for p = p.Link; p != nil; p = p.Link {
		ctxt.Curp = p
		p.Pc = c
		o = oplook(ctxt, p)
		m = int(o.size)
		if m == 0 {
			if p.As != obj.ANOP && p.As != obj.AFUNCDATA && p.As != obj.APCDATA && p.As != obj.AUSEFIELD {
				ctxt.Diag("zero-width instruction\n%v", p)
			}
			continue
		}

		c += int64(m)
	}

	cursym.Size = c

	/*
	 * if any procedure is large enough to
	 * generate a large SBRA branch, then
	 * generate extra passes putting branches
	 * around jmps to fix. this is rare.
	 */
	bflag := 1

	var otxt int64
	var q *obj.Prog
	for bflag != 0 {
		if ctxt.Debugvlog != 0 {
			fmt.Fprintf(ctxt.Bso, "%5.2f span1\n", obj.Cputime())
		}
		bflag = 0
		c = 0
		for p = cursym.Text.Link; p != nil; p = p.Link {
			p.Pc = c
			o = oplook(ctxt, p)

			// very large conditional branches
			if o.type_ == 6 && p.Pcond != nil {
				otxt = p.Pcond.Pc - c
				if otxt < -(1<<17)+10 || otxt >= (1<<17)-10 {
					q = ctxt.NewProg()
					q.Link = p.Link
					p.Link = q
					q.As = AJMP
					q.Lineno = p.Lineno
					q.To.Type = obj.TYPE_BRANCH
					q.Pcond = p.Pcond
					p.Pcond = q
					q = ctxt.NewProg()
					q.Link = p.Link
					p.Link = q
					q.As = AJMP
					q.Lineno = p.Lineno
					q.To.Type = obj.TYPE_BRANCH
					q.Pcond = q.Link.Link

					addnop(ctxt, p.Link)
					addnop(ctxt, p)
					bflag = 1
				}
			}

			m = int(o.size)
			if m == 0 {
				if p.As != obj.ANOP && p.As != obj.AFUNCDATA && p.As != obj.APCDATA && p.As != obj.AUSEFIELD {
					ctxt.Diag("zero-width instruction\n%v", p)
				}
				continue
			}

			c += int64(m)
		}

		cursym.Size = c
	}

	c += -c & (FuncAlign - 1)
	cursym.Size = c

	/*
	 * lay out the code, emitting code and data relocations.
	 */

	cursym.Grow(cursym.Size)

	bp := cursym.P
	var i int32
	var out [4]uint32
	for p := cursym.Text.Link; p != nil; p = p.Link {
		ctxt.Pc = p.Pc
		ctxt.Curp = p
		o = oplook(ctxt, p)
		if int(o.size) > 4*len(out) {
			log.Fatalf("out array in span0 is too small, need at least %d for %v", o.size/4, p)
		}
		asmout(ctxt, p, o, out[:])
		for i = 0; i < int32(o.size/4); i++ {
			ctxt.Arch.ByteOrder.PutUint32(bp, out[i])
			bp = bp[4:]
		}
	}
}
示例#13
0
文件: obj0.go 项目: glycerine/zygomys
func sched(ctxt *obj.Link, p0, pe *obj.Prog) {
	var sch [NSCHED]Sch

	/*
	 * build side structure
	 */
	s := sch[:]
	for p := p0; ; p = p.Link {
		s[0].p = *p
		markregused(ctxt, &s[0])
		if p == pe {
			break
		}
		s = s[1:]
	}
	se := s

	for i := cap(sch) - cap(se); i >= 0; i-- {
		s = sch[i:]
		if s[0].p.Mark&DELAY == 0 {
			continue
		}
		if -cap(s) < -cap(se) {
			if !conflict(&s[0], &s[1]) {
				continue
			}
		}

		var t []Sch
		var j int
		for j = cap(sch) - cap(s) - 1; j >= 0; j-- {
			t = sch[j:]
			if t[0].comp {
				if s[0].p.Mark&BRANCH != 0 {
					goto no2
				}
			}
			if t[0].p.Mark&DELAY != 0 {
				if -cap(s) >= -cap(se) || conflict(&t[0], &s[1]) {
					goto no2
				}
			}
			for u := t[1:]; -cap(u) <= -cap(s); u = u[1:] {
				if depend(ctxt, &u[0], &t[0]) {
					goto no2
				}
			}
			goto out2
		no2:
		}

		if s[0].p.Mark&BRANCH != 0 {
			s[0].nop = 1
		}
		continue

	out2:
		// t[0] is the instruction being moved to fill the delay
		stmp := t[0]
		copy(t[:i-j], t[1:i-j+1])
		s[0] = stmp

		if t[i-j-1].p.Mark&BRANCH != 0 {
			// t[i-j] is being put into a branch delay slot
			// combine its Spadj with the branch instruction
			t[i-j-1].p.Spadj += t[i-j].p.Spadj
			t[i-j].p.Spadj = 0
		}

		i--
	}

	/*
	 * put it all back
	 */
	var p *obj.Prog
	var q *obj.Prog
	for s, p = sch[:], p0; -cap(s) <= -cap(se); s, p = s[1:], q {
		q = p.Link
		if q != s[0].p.Link {
			*p = s[0].p
			p.Link = q
		}
		for s[0].nop != 0 {
			s[0].nop--
			addnop(ctxt, p)
		}
	}
}

func markregused(ctxt *obj.Link, s *Sch) {
	p := &s.p
	s.comp = compound(ctxt, p)
	s.nop = 0
	if s.comp {
		s.set.ireg |= 1 << (REGTMP - REG_R0)
		s.used.ireg |= 1 << (REGTMP - REG_R0)
	}

	ar := 0  /* dest is really reference */
	ad := 0  /* source/dest is really address */
	ld := 0  /* opcode is load instruction */
	sz := 20 /* size of load/store for overlap computation */

	/*
	 * flags based on opcode
	 */
	switch p.As {
	case obj.ATEXT:
		ctxt.Autosize = int32(p.To.Offset + 8)
		ad = 1

	case AJAL:
		c := p.Reg
		if c == 0 {
			c = REGLINK
		}
		s.set.ireg |= 1 << uint(c-REG_R0)
		ar = 1
		ad = 1

	case ABGEZAL,
		ABLTZAL:
		s.set.ireg |= 1 << (REGLINK - REG_R0)
		fallthrough
	case ABEQ,
		ABGEZ,
		ABGTZ,
		ABLEZ,
		ABLTZ,
		ABNE:
		ar = 1
		ad = 1

	case ABFPT,
		ABFPF:
		ad = 1
		s.used.cc |= E_FCR

	case ACMPEQD,
		ACMPEQF,
		ACMPGED,
		ACMPGEF,
		ACMPGTD,
		ACMPGTF:
		ar = 1
		s.set.cc |= E_FCR
		p.Mark |= FCMP

	case AJMP:
		ar = 1
		ad = 1

	case AMOVB,
		AMOVBU:
		sz = 1
		ld = 1

	case AMOVH,
		AMOVHU:
		sz = 2
		ld = 1

	case AMOVF,
		AMOVW,
		AMOVWL,
		AMOVWR:
		sz = 4
		ld = 1

	case AMOVD,
		AMOVV,
		AMOVVL,
		AMOVVR:
		sz = 8
		ld = 1

	case ADIV,
		ADIVU,
		AMUL,
		AMULU,
		AREM,
		AREMU,
		ADIVV,
		ADIVVU,
		AMULV,
		AMULVU,
		AREMV,
		AREMVU:
		s.set.cc = E_HILO
		fallthrough
	case AADD,
		AADDU,
		AADDV,
		AADDVU,
		AAND,
		ANOR,
		AOR,
		ASGT,
		ASGTU,
		ASLL,
		ASRA,
		ASRL,
		ASLLV,
		ASRAV,
		ASRLV,
		ASUB,
		ASUBU,
		ASUBV,
		ASUBVU,
		AXOR,

		AADDD,
		AADDF,
		AADDW,
		ASUBD,
		ASUBF,
		ASUBW,
		AMULF,
		AMULD,
		AMULW,
		ADIVF,
		ADIVD,
		ADIVW:
		if p.Reg == 0 {
			if p.To.Type == obj.TYPE_REG {
				p.Reg = p.To.Reg
			}
			//if(p->reg == NREG)
			//	print("botch %P\n", p);
		}
	}

	/*
	 * flags based on 'to' field
	 */
	c := int(p.To.Class)
	if c == 0 {
		c = aclass(ctxt, &p.To) + 1
		p.To.Class = int8(c)
	}
	c--
	switch c {
	default:
		fmt.Printf("unknown class %d %v\n", c, p)

	case C_ZCON,
		C_SCON,
		C_ADD0CON,
		C_AND0CON,
		C_ADDCON,
		C_ANDCON,
		C_UCON,
		C_LCON,
		C_NONE,
		C_SBRA,
		C_LBRA,
		C_ADDR,
		C_TEXTSIZE:
		break

	case C_HI,
		C_LO:
		s.set.cc |= E_HILO

	case C_FCREG:
		s.set.cc |= E_FCR

	case C_MREG:
		s.set.cc |= E_MCR

	case C_ZOREG,
		C_SOREG,
		C_LOREG:
		c = int(p.To.Reg)
		s.used.ireg |= 1 << uint(c-REG_R0)
		if ad != 0 {
			break
		}
		s.size = uint8(sz)
		s.soffset = regoff(ctxt, &p.To)

		m := uint32(ANYMEM)
		if c == REGSB {
			m = E_MEMSB
		}
		if c == REGSP {
			m = E_MEMSP
		}

		if ar != 0 {
			s.used.cc |= m
		} else {
			s.set.cc |= m
		}

	case C_SACON,
		C_LACON:
		s.used.ireg |= 1 << (REGSP - REG_R0)

	case C_SECON,
		C_LECON:
		s.used.ireg |= 1 << (REGSB - REG_R0)

	case C_REG:
		if ar != 0 {
			s.used.ireg |= 1 << uint(p.To.Reg-REG_R0)
		} else {
			s.set.ireg |= 1 << uint(p.To.Reg-REG_R0)
		}

	case C_FREG:
		if ar != 0 {
			s.used.freg |= 1 << uint(p.To.Reg-REG_F0)
		} else {
			s.set.freg |= 1 << uint(p.To.Reg-REG_F0)
		}
		if ld != 0 && p.From.Type == obj.TYPE_REG {
			p.Mark |= LOAD
		}

	case C_SAUTO,
		C_LAUTO:
		s.used.ireg |= 1 << (REGSP - REG_R0)
		if ad != 0 {
			break
		}
		s.size = uint8(sz)
		s.soffset = regoff(ctxt, &p.To)

		if ar != 0 {
			s.used.cc |= E_MEMSP
		} else {
			s.set.cc |= E_MEMSP
		}

	case C_SEXT,
		C_LEXT:
		s.used.ireg |= 1 << (REGSB - REG_R0)
		if ad != 0 {
			break
		}
		s.size = uint8(sz)
		s.soffset = regoff(ctxt, &p.To)

		if ar != 0 {
			s.used.cc |= E_MEMSB
		} else {
			s.set.cc |= E_MEMSB
		}
	}

	/*
	 * flags based on 'from' field
	 */
	c = int(p.From.Class)
	if c == 0 {
		c = aclass(ctxt, &p.From) + 1
		p.From.Class = int8(c)
	}
	c--
	switch c {
	default:
		fmt.Printf("unknown class %d %v\n", c, p)

	case C_ZCON,
		C_SCON,
		C_ADD0CON,
		C_AND0CON,
		C_ADDCON,
		C_ANDCON,
		C_UCON,
		C_LCON,
		C_NONE,
		C_SBRA,
		C_LBRA,
		C_ADDR,
		C_TEXTSIZE:
		break

	case C_HI,
		C_LO:
		s.used.cc |= E_HILO

	case C_FCREG:
		s.used.cc |= E_FCR

	case C_MREG:
		s.used.cc |= E_MCR

	case C_ZOREG,
		C_SOREG,
		C_LOREG:
		c = int(p.From.Reg)
		s.used.ireg |= 1 << uint(c-REG_R0)
		if ld != 0 {
			p.Mark |= LOAD
		}
		s.size = uint8(sz)
		s.soffset = regoff(ctxt, &p.From)

		m := uint32(ANYMEM)
		if c == REGSB {
			m = E_MEMSB
		}
		if c == REGSP {
			m = E_MEMSP
		}

		s.used.cc |= m

	case C_SACON,
		C_LACON:
		c = int(p.From.Reg)
		if c == 0 {
			c = REGSP
		}
		s.used.ireg |= 1 << uint(c-REG_R0)

	case C_SECON,
		C_LECON:
		s.used.ireg |= 1 << (REGSB - REG_R0)

	case C_REG:
		s.used.ireg |= 1 << uint(p.From.Reg-REG_R0)

	case C_FREG:
		s.used.freg |= 1 << uint(p.From.Reg-REG_F0)
		if ld != 0 && p.To.Type == obj.TYPE_REG {
			p.Mark |= LOAD
		}

	case C_SAUTO,
		C_LAUTO:
		s.used.ireg |= 1 << (REGSP - REG_R0)
		if ld != 0 {
			p.Mark |= LOAD
		}
		if ad != 0 {
			break
		}
		s.size = uint8(sz)
		s.soffset = regoff(ctxt, &p.From)

		s.used.cc |= E_MEMSP

	case C_SEXT:
	case C_LEXT:
		s.used.ireg |= 1 << (REGSB - REG_R0)
		if ld != 0 {
			p.Mark |= LOAD
		}
		if ad != 0 {
			break
		}
		s.size = uint8(sz)
		s.soffset = regoff(ctxt, &p.From)

		s.used.cc |= E_MEMSB
	}

	c = int(p.Reg)
	if c != 0 {
		if REG_F0 <= c && c <= REG_F31 {
			s.used.freg |= 1 << uint(c-REG_F0)
		} else {
			s.used.ireg |= 1 << uint(c-REG_R0)
		}
	}
	s.set.ireg &^= (1 << (REGZERO - REG_R0)) /* R0 can't be set */
}

/*
 * test to see if two instructions can be
 * interchanged without changing semantics
 */
func depend(ctxt *obj.Link, sa, sb *Sch) bool {
	if sa.set.ireg&(sb.set.ireg|sb.used.ireg) != 0 {
		return true
	}
	if sb.set.ireg&sa.used.ireg != 0 {
		return true
	}

	if sa.set.freg&(sb.set.freg|sb.used.freg) != 0 {
		return true
	}
	if sb.set.freg&sa.used.freg != 0 {
		return true
	}

	/*
	 * special case.
	 * loads from same address cannot pass.
	 * this is for hardware fifo's and the like
	 */
	if sa.used.cc&sb.used.cc&E_MEM != 0 {
		if sa.p.Reg == sb.p.Reg {
			if regoff(ctxt, &sa.p.From) == regoff(ctxt, &sb.p.From) {
				return true
			}
		}
	}

	x := (sa.set.cc & (sb.set.cc | sb.used.cc)) | (sb.set.cc & sa.used.cc)
	if x != 0 {
		/*
		 * allow SB and SP to pass each other.
		 * allow SB to pass SB iff doffsets are ok
		 * anything else conflicts
		 */
		if x != E_MEMSP && x != E_MEMSB {
			return true
		}
		x = sa.set.cc | sb.set.cc | sa.used.cc | sb.used.cc
		if x&E_MEM != 0 {
			return true
		}
		if offoverlap(sa, sb) {
			return true
		}
	}

	return false
}

func offoverlap(sa, sb *Sch) bool {
	if sa.soffset < sb.soffset {
		if sa.soffset+int32(sa.size) > sb.soffset {
			return true
		}
		return false
	}
	if sb.soffset+int32(sb.size) > sa.soffset {
		return true
	}
	return false
}

/*
 * test 2 adjacent instructions
 * and find out if inserted instructions
 * are desired to prevent stalls.
 */
func conflict(sa, sb *Sch) bool {
	if sa.set.ireg&sb.used.ireg != 0 {
		return true
	}
	if sa.set.freg&sb.used.freg != 0 {
		return true
	}
	if sa.set.cc&sb.used.cc != 0 {
		return true
	}
	return false
}

func compound(ctxt *obj.Link, p *obj.Prog) bool {
	o := oplook(ctxt, p)
	if o.size != 4 {
		return true
	}
	if p.To.Type == obj.TYPE_REG && p.To.Reg == REGSB {
		return true
	}
	return false
}

func follow(ctxt *obj.Link, s *obj.LSym) {
	ctxt.Cursym = s

	firstp := ctxt.NewProg()
	lastp := firstp
	xfol(ctxt, s.Text, &lastp)
	lastp.Link = nil
	s.Text = firstp.Link
}

func xfol(ctxt *obj.Link, p *obj.Prog, last **obj.Prog) {
	var q *obj.Prog
	var r *obj.Prog
	var i int

loop:
	if p == nil {
		return
	}
	a := p.As
	if a == AJMP {
		q = p.Pcond
		if (p.Mark&NOSCHED != 0) || q != nil && (q.Mark&NOSCHED != 0) {
			p.Mark |= FOLL
			(*last).Link = p
			*last = p
			p = p.Link
			xfol(ctxt, p, last)
			p = q
			if p != nil && p.Mark&FOLL == 0 {
				goto loop
			}
			return
		}

		if q != nil {
			p.Mark |= FOLL
			p = q
			if p.Mark&FOLL == 0 {
				goto loop
			}
		}
	}

	if p.Mark&FOLL != 0 {
		i = 0
		q = p
		for ; i < 4; i, q = i+1, q.Link {
			if q == *last || (q.Mark&NOSCHED != 0) {
				break
			}
			a = q.As
			if a == obj.ANOP {
				i--
				continue
			}

			if a == AJMP || a == ARET || a == ARFE {
				goto copy
			}
			if q.Pcond == nil || (q.Pcond.Mark&FOLL != 0) {
				continue
			}
			if a != ABEQ && a != ABNE {
				continue
			}

		copy:
			for {
				r = ctxt.NewProg()
				*r = *p
				if r.Mark&FOLL == 0 {
					fmt.Printf("can't happen 1\n")
				}
				r.Mark |= FOLL
				if p != q {
					p = p.Link
					(*last).Link = r
					*last = r
					continue
				}

				(*last).Link = r
				*last = r
				if a == AJMP || a == ARET || a == ARFE {
					return
				}
				r.As = ABNE
				if a == ABNE {
					r.As = ABEQ
				}
				r.Pcond = p.Link
				r.Link = p.Pcond
				if r.Link.Mark&FOLL == 0 {
					xfol(ctxt, r.Link, last)
				}
				if r.Pcond.Mark&FOLL == 0 {
					fmt.Printf("can't happen 2\n")
				}
				return
			}
		}

		a = AJMP
		q = ctxt.NewProg()
		q.As = a
		q.Lineno = p.Lineno
		q.To.Type = obj.TYPE_BRANCH
		q.To.Offset = p.Pc
		q.Pcond = p
		p = q
	}

	p.Mark |= FOLL
	(*last).Link = p
	*last = p
	if a == AJMP || a == ARET || a == ARFE {
		if p.Mark&NOSCHED != 0 {
			p = p.Link
			goto loop
		}

		return
	}

	if p.Pcond != nil {
		if a != AJAL && p.Link != nil {
			xfol(ctxt, p.Link, last)
			p = p.Pcond
			if p == nil || (p.Mark&FOLL != 0) {
				return
			}
			goto loop
		}
	}

	p = p.Link
	goto loop
}

var Linkmips64 = obj.LinkArch{
	Arch:       sys.ArchMIPS64,
	Preprocess: preprocess,
	Assemble:   span0,
	Follow:     follow,
	Progedit:   progedit,
}

var Linkmips64le = obj.LinkArch{
	Arch:       sys.ArchMIPS64LE,
	Preprocess: preprocess,
	Assemble:   span0,
	Follow:     follow,
	Progedit:   progedit,
}
示例#14
0
文件: obj0.go 项目: glycerine/zygomys
func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
	// TODO(minux): add morestack short-cuts with small fixed frame-size.
	ctxt.Cursym = cursym

	// a switch for enabling/disabling instruction scheduling
	nosched := true

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

	p := cursym.Text
	textstksiz := p.To.Offset

	cursym.Args = p.To.Val.(int32)
	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", obj.Cputime())
	}
	ctxt.Bso.Flush()

	var q *obj.Prog
	var q1 *obj.Prog
	for p := cursym.Text; p != nil; p = p.Link {
		switch p.As {
		/* too hard, just leave alone */
		case obj.ATEXT:
			q = p

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

		/* too hard, just leave alone */
		case AMOVW,
			AMOVV:
			q = p
			if p.To.Type == obj.TYPE_REG && p.To.Reg >= REG_SPECIAL {
				p.Mark |= LABEL | SYNC
				break
			}
			if p.From.Type == obj.TYPE_REG && p.From.Reg >= REG_SPECIAL {
				p.Mark |= LABEL | SYNC
			}

		/* too hard, just leave alone */
		case ASYSCALL,
			AWORD,
			ATLBWR,
			ATLBWI,
			ATLBP,
			ATLBR:
			q = p
			p.Mark |= LABEL | SYNC

		case ANOR:
			q = p
			if p.To.Type == obj.TYPE_REG {
				if p.To.Reg == REGZERO {
					p.Mark |= LABEL | SYNC
				}
			}

		case ABGEZAL,
			ABLTZAL,
			AJAL,
			obj.ADUFFZERO,
			obj.ADUFFCOPY:
			cursym.Text.Mark &^= LEAF
			fallthrough

		case AJMP,
			ABEQ,
			ABGEZ,
			ABGTZ,
			ABLEZ,
			ABLTZ,
			ABNE,
			ABFPT, ABFPF:
			if p.As == ABFPT || p.As == ABFPF {
				// We don't treat ABFPT and ABFPF as branches here,
				// so that we will always fill nop (0x0) in their
				// delay slot during assembly.
				// This is to workaround a kernel FPU emulator bug
				// where it uses the user stack to simulate the
				// instruction in the delay slot if it's not 0x0,
				// and somehow that leads to SIGSEGV when the kernel
				// jump to the stack.
				p.Mark |= SYNC
			} else {
				p.Mark |= BRANCH
			}
			q = p
			q1 = p.Pcond
			if q1 != nil {
				for q1.As == obj.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 ARET:
			q = p
			if p.Link != nil {
				p.Link.Mark |= LABEL
			}
			continue

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

		default:
			q = p
			continue
		}
	}

	autosize := int32(0)
	var p1 *obj.Prog
	var p2 *obj.Prog
	for p := cursym.Text; p != nil; p = p.Link {
		o := p.As
		switch o {
		case obj.ATEXT:
			autosize = int32(textstksiz + 8)
			if (p.Mark&LEAF != 0) && autosize <= 8 {
				autosize = 0
			} else if autosize&4 != 0 {
				autosize += 4
			}
			p.To.Offset = int64(autosize) - 8

			if p.From3.Offset&obj.NOSPLIT == 0 {
				p = stacksplit(ctxt, p, autosize) // emit split check
			}

			q = p

			if autosize != 0 {
				q = obj.Appendp(ctxt, p)
				q.As = AADDV
				q.Lineno = p.Lineno
				q.From.Type = obj.TYPE_CONST
				q.From.Offset = int64(-autosize)
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REGSP
				q.Spadj = +autosize
			} else if cursym.Text.Mark&LEAF == 0 {
				if cursym.Text.From3.Offset&obj.NOSPLIT != 0 {
					if ctxt.Debugvlog != 0 {
						fmt.Fprintf(ctxt.Bso, "save suppressed in: %s\n", cursym.Name)
						ctxt.Bso.Flush()
					}

					cursym.Text.Mark |= LEAF
				}
			}

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

			q = obj.Appendp(ctxt, q)
			q.As = AMOVV
			q.Lineno = p.Lineno
			q.From.Type = obj.TYPE_REG
			q.From.Reg = REGLINK
			q.To.Type = obj.TYPE_MEM
			q.To.Offset = int64(0)
			q.To.Reg = REGSP

			if cursym.Text.From3.Offset&obj.WRAPPER != 0 {
				// if(g->panic != nil && g->panic->argp == FP) g->panic->argp = bottom-of-frame
				//
				//	MOVV	g_panic(g), R1
				//	BEQ		R1, end
				//	MOVV	panic_argp(R1), R2
				//	ADDV	$(autosize+8), R29, R3
				//	BNE		R2, R3, end
				//	ADDV	$8, R29, R2
				//	MOVV	R2, panic_argp(R1)
				// end:
				//	NOP
				//
				// The NOP is needed to give the jumps somewhere to land.
				// It is a liblink NOP, not an mips NOP: it encodes to 0 instruction bytes.

				q = obj.Appendp(ctxt, q)

				q.As = AMOVV
				q.From.Type = obj.TYPE_MEM
				q.From.Reg = REGG
				q.From.Offset = 4 * int64(ctxt.Arch.PtrSize) // G.panic
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REG_R1

				q = obj.Appendp(ctxt, q)
				q.As = ABEQ
				q.From.Type = obj.TYPE_REG
				q.From.Reg = REG_R1
				q.To.Type = obj.TYPE_BRANCH
				q.Mark |= BRANCH
				p1 = q

				q = obj.Appendp(ctxt, q)
				q.As = AMOVV
				q.From.Type = obj.TYPE_MEM
				q.From.Reg = REG_R1
				q.From.Offset = 0 // Panic.argp
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REG_R2

				q = obj.Appendp(ctxt, q)
				q.As = AADDV
				q.From.Type = obj.TYPE_CONST
				q.From.Offset = int64(autosize) + 8
				q.Reg = REGSP
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REG_R3

				q = obj.Appendp(ctxt, q)
				q.As = ABNE
				q.From.Type = obj.TYPE_REG
				q.From.Reg = REG_R2
				q.Reg = REG_R3
				q.To.Type = obj.TYPE_BRANCH
				q.Mark |= BRANCH
				p2 = q

				q = obj.Appendp(ctxt, q)
				q.As = AADDV
				q.From.Type = obj.TYPE_CONST
				q.From.Offset = 8
				q.Reg = REGSP
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REG_R2

				q = obj.Appendp(ctxt, q)
				q.As = AMOVV
				q.From.Type = obj.TYPE_REG
				q.From.Reg = REG_R2
				q.To.Type = obj.TYPE_MEM
				q.To.Reg = REG_R1
				q.To.Offset = 0 // Panic.argp

				q = obj.Appendp(ctxt, q)

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

		case ARET:
			if p.From.Type == obj.TYPE_CONST {
				ctxt.Diag("using BECOME (%v) is not supported!", p)
				break
			}

			if p.To.Sym != nil { // retjmp
				p.As = AJMP
				p.To.Type = obj.TYPE_BRANCH
				break
			}

			if cursym.Text.Mark&LEAF != 0 {
				if autosize == 0 {
					p.As = AJMP
					p.From = obj.Addr{}
					p.To.Type = obj.TYPE_MEM
					p.To.Offset = 0
					p.To.Reg = REGLINK
					p.Mark |= BRANCH
					break
				}

				p.As = AADDV
				p.From.Type = obj.TYPE_CONST
				p.From.Offset = int64(autosize)
				p.To.Type = obj.TYPE_REG
				p.To.Reg = REGSP
				p.Spadj = -autosize

				q = ctxt.NewProg()
				q.As = AJMP
				q.Lineno = p.Lineno
				q.To.Type = obj.TYPE_MEM
				q.To.Offset = 0
				q.To.Reg = REGLINK
				q.Mark |= BRANCH
				q.Spadj = +autosize

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

			p.As = AMOVV
			p.From.Type = obj.TYPE_MEM
			p.From.Offset = 0
			p.From.Reg = REGSP
			p.To.Type = obj.TYPE_REG
			p.To.Reg = REG_R4

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

				q.As = AMOVV
				q.Lineno = p.Lineno
				q.From.Type = obj.TYPE_MEM
				q.From.Offset = 0
				q.From.Reg = REG_R4
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REGTMP

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

			if autosize != 0 {
				q = ctxt.NewProg()
				q.As = AADDV
				q.Lineno = p.Lineno
				q.From.Type = obj.TYPE_CONST
				q.From.Offset = int64(autosize)
				q.To.Type = obj.TYPE_REG
				q.To.Reg = REGSP
				q.Spadj = -autosize

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

			q1 = ctxt.NewProg()
			q1.As = AJMP
			q1.Lineno = p.Lineno
			q1.To.Type = obj.TYPE_MEM
			q1.To.Offset = 0
			q1.To.Reg = REG_R4
			q1.Mark |= BRANCH
			q1.Spadj = +autosize

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

		case AADDV,
			AADDVU:
			if p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP && p.From.Type == obj.TYPE_CONST {
				p.Spadj = int32(-p.From.Offset)
			}
		}
	}

	if nosched {
		// if we don't do instruction scheduling, simply add
		// NOP after each branch instruction.
		for p = cursym.Text; p != nil; p = p.Link {
			if p.Mark&BRANCH != 0 {
				addnop(ctxt, p)
			}
		}
		return
	}

	// instruction scheduling
	q = nil          // p - 1
	q1 = cursym.Text // top of block
	o := 0           // count of instructions
	for p = cursym.Text; p != nil; p = p1 {
		p1 = p.Link
		o++
		if p.Mark&NOSCHED != 0 {
			if q1 != p {
				sched(ctxt, q1, q)
			}
			for ; p != nil; p = p.Link {
				if p.Mark&NOSCHED == 0 {
					break
				}
				q = p
			}
			p1 = p
			q1 = p
			o = 0
			continue
		}
		if p.Mark&(LABEL|SYNC) != 0 {
			if q1 != p {
				sched(ctxt, q1, q)
			}
			q1 = p
			o = 1
		}
		if p.Mark&(BRANCH|SYNC) != 0 {
			sched(ctxt, q1, p)
			q1 = p1
			o = 0
		}
		if o >= NSCHED {
			sched(ctxt, q1, p)
			q1 = p1
			o = 0
		}
		q = p
	}
}