Пример #1
0
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
}
Пример #2
0
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
		}
	}
}