func follow(ctxt *liblink.Link, s *liblink.LSym) {
var firstp *liblink.Prog
var lastp *liblink.Prog
ctxt.Cursym = s
firstp = ctxt.Prg()
lastp = firstp
xfol(ctxt, s.Text, &lastp)
lastp.Link = nil
s.Text = firstp.Link
}
func addstacksplit(ctxt *liblink.Link, cursym *liblink.LSym) {
var p *liblink.Prog
var q *liblink.Prog
var autoffset int64
var deltasp int64
var a int
if ctxt.Symmorestack[0] == nil {
ctxt.Symmorestack[0] = liblink.Linklookup(ctxt, "runtime.morestack", 0)
ctxt.Symmorestack[1] = liblink.Linklookup(ctxt, "runtime.morestack_noctxt", 0)
}
if ctxt.Headtype == liblink.Hplan9 && ctxt.Plan9privates == nil {
ctxt.Plan9privates = liblink.Linklookup(ctxt, "_privates", 0)
}
ctxt.Cursym = cursym
if cursym.Text == nil || cursym.Text.Link == nil {
return
}
p = cursym.Text
autoffset = p.To.Offset
if autoffset < 0 {
autoffset = 0
}
cursym.Locals = autoffset
cursym.Args = p.To.Offset2
q = nil
if p.From.Scale&liblink.NOSPLIT == 0 || (p.From.Scale&liblink.WRAPPER != 0) {
p = liblink.Appendp(ctxt, p)
p = load_g_cx(ctxt, p) // load g into CX
}
if cursym.Text.From.Scale&liblink.NOSPLIT == 0 {
p = stacksplit(ctxt, p, autoffset, bool2int(cursym.Text.From.Scale&liblink.NEEDCTXT == 0), &q) // emit split check
}
if autoffset != 0 {
p = liblink.Appendp(ctxt, p)
p.As = AADJSP
p.From.Typ = D_CONST
p.From.Offset = 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 = liblink.Appendp(ctxt, p)
p.As = ANOP
p.Spadj = -ctxt.Arch.Ptrsize
p = liblink.Appendp(ctxt, p)
p.As = ANOP
p.Spadj = ctxt.Arch.Ptrsize
}
if q != nil {
q.Pcond = p
}
deltasp = autoffset
if cursym.Text.From.Scale&liblink.WRAPPER != 0 {
// g->panicwrap += autoffset + ctxt->arch->ptrsize;
p = liblink.Appendp(ctxt, p)
p.As = AADDL
p.From.Typ = D_CONST
p.From.Offset = autoffset + ctxt.Arch.Ptrsize
p.To.Typ = D_INDIR + D_CX
p.To.Offset = 2 * ctxt.Arch.Ptrsize
}
if ctxt.Debugzerostack != 0 && autoffset != 0 && cursym.Text.From.Scale&liblink.NOSPLIT == 0 {
// 8l -Z means zero the stack frame on entry.
// This slows down function calls but can help avoid
// false positives in garbage collection.
p = liblink.Appendp(ctxt, p)
p.As = AMOVL
p.From.Typ = D_SP
p.To.Typ = D_DI
p = liblink.Appendp(ctxt, p)
p.As = AMOVL
p.From.Typ = D_CONST
p.From.Offset = autoffset / 4
p.To.Typ = D_CX
p = liblink.Appendp(ctxt, p)
p.As = AMOVL
p.From.Typ = D_CONST
p.From.Offset = 0
p.To.Typ = D_AX
p = liblink.Appendp(ctxt, p)
p.As = AREP
p = liblink.Appendp(ctxt, p)
p.As = ASTOSL
}
for ; p != nil; p = p.Link {
a = p.From.Typ
if a == D_AUTO {
p.From.Offset += deltasp
}
if a == D_PARAM {
p.From.Offset += deltasp + 4
}
a = p.To.Typ
if a == D_AUTO {
p.To.Offset += deltasp
}
if a == D_PARAM {
p.To.Offset += deltasp + 4
}
switch p.As {
default:
continue
case APUSHL,
APUSHFL:
deltasp += 4
p.Spadj = 4
continue
case APUSHW,
APUSHFW:
deltasp += 2
p.Spadj = 2
continue
case APOPL,
APOPFL:
deltasp -= 4
p.Spadj = -4
continue
case APOPW,
APOPFW:
deltasp -= 2
p.Spadj = -2
continue
case ARET:
break
}
if autoffset != deltasp {
ctxt.Diag("unbalanced PUSH/POP")
}
if cursym.Text.From.Scale&liblink.WRAPPER != 0 {
p = load_g_cx(ctxt, p)
p = liblink.Appendp(ctxt, p)
// g->panicwrap -= autoffset + ctxt->arch->ptrsize;
p.As = ASUBL
p.From.Typ = D_CONST
p.From.Offset = autoffset + ctxt.Arch.Ptrsize
p.To.Typ = D_INDIR + D_CX
p.To.Offset = 2 * ctxt.Arch.Ptrsize
p = liblink.Appendp(ctxt, p)
p.As = ARET
}
if autoffset != 0 {
p.As = AADJSP
p.From.Typ = D_CONST
p.From.Offset = -autoffset
p.Spadj = -autoffset
p = liblink.Appendp(ctxt, p)
p.As = 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 = AJMP
}
}
}
func addstacksplit(ctxt *liblink.Link, cursym *liblink.LSym) {
var p *liblink.Prog
var pl *liblink.Prog
var q *liblink.Prog
var q1 *liblink.Prog
var q2 *liblink.Prog
var o int
var autosize int64
var autoffset int64
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 = 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.Typ = D_CONST
p.From.Reg = 13
p.From.Offset = 4
p.To.Typ = D_REG
p.To.Reg = 1
// MOVW $n(R13), R2
p = liblink.Appendp(ctxt, p)
p.As = AMOVW
p.From.Typ = D_CONST
p.From.Reg = 13
p.From.Offset = 4 + autoffset
p.To.Typ = D_REG
p.To.Reg = 2
// MOVW $0, R3
p = liblink.Appendp(ctxt, p)
p.As = AMOVW
p.From.Typ = D_CONST
p.From.Offset = 0
p.To.Typ = D_REG
p.To.Reg = 3
// L:
// MOVW.nil R3, 0(R1) +4
// CMP R1, R2
// BNE L
pl = liblink.Appendp(ctxt, p)
p = pl
p.As = AMOVW
p.From.Typ = D_REG
p.From.Reg = 3
p.To.Typ = D_OREG
p.To.Reg = 1
p.To.Offset = 4
p.Scond |= C_PBIT
p = liblink.Appendp(ctxt, p)
p.As = ACMP
p.From.Typ = D_REG
p.From.Reg = 1
p.Reg = 2
p = liblink.Appendp(ctxt, p)
p.As = ABNE
p.To.Typ = D_BRANCH
p.Pcond = pl
}
}
/*
* find leaf subroutines
* strip NOPs
* expand RET
* expand BECOME pseudo
*/
for p = cursym.Text; p != nil; p = p.Link {
switch p.As {
case ACASE:
if ctxt.Flag_shared != 0 {
linkcase(p)
}
case ATEXT:
p.Mark |= LEAF
case ARET:
break
case ADIV,
ADIVU,
AMOD,
AMODU:
q = p
if ctxt.Sym_div == nil {
initdiv(ctxt)
}
cursym.Text.Mark &^= LEAF
continue
case ANOP:
q1 = p.Link
q.Link = q1 /* q is non-nop */
if q1 != nil {
q1.Mark |= p.Mark
}
continue
case ABL,
ABX,
ADUFFZERO,
ADUFFCOPY:
cursym.Text.Mark &^= LEAF
fallthrough
case ABCASE,
AB,
ABEQ,
ABNE,
ABCS,
ABHS,
ABCC,
ABLO,
ABMI,
ABPL,
ABVS,
ABVC,
ABHI,
ABLS,
ABGE,
ABLT,
ABGT,
ABLE:
q1 = p.Pcond
if q1 != nil {
for q1.As == ANOP {
q1 = q1.Link
p.Pcond = q1
}
}
break
}
q = p
}
for p = cursym.Text; p != nil; p = p.Link {
o = p.As
switch o {
case ATEXT:
autosize = p.To.Offset + 4
if autosize <= 4 {
if cursym.Text.Mark&LEAF != 0 {
p.To.Offset = -4
autosize = 0
}
}
if autosize == 0 && cursym.Text.Mark&LEAF == 0 {
if ctxt.Debugvlog != 0 {
fmt.Fprintf(ctxt.Bso, "save suppressed in: %s\n", cursym.Name)
liblink.Bflush(ctxt.Bso)
}
cursym.Text.Mark |= LEAF
}
if cursym.Text.Mark&LEAF != 0 {
cursym.Leaf = 1
if autosize == 0 {
break
}
}
if p.Reg&liblink.NOSPLIT == 0 {
p = stacksplit(ctxt, p, autosize, bool2int(cursym.Text.Reg&liblink.NEEDCTXT == 0)) // emit split check
}
// MOVW.W R14,$-autosize(SP)
p = liblink.Appendp(ctxt, p)
p.As = AMOVW
p.Scond |= C_WBIT
p.From.Typ = D_REG
p.From.Reg = REGLINK
p.To.Typ = D_OREG
p.To.Offset = -autosize
p.To.Reg = REGSP
p.Spadj = autosize
if cursym.Text.Reg&liblink.WRAPPER != 0 {
// g->panicwrap += autosize;
// MOVW panicwrap_offset(g), R3
// ADD $autosize, R3
// MOVW R3 panicwrap_offset(g)
p = liblink.Appendp(ctxt, p)
p.As = AMOVW
p.From.Typ = D_OREG
p.From.Reg = REGG
p.From.Offset = 2 * ctxt.Arch.Ptrsize
p.To.Typ = D_REG
p.To.Reg = 3
p = liblink.Appendp(ctxt, p)
p.As = AADD
p.From.Typ = D_CONST
p.From.Offset = autosize
p.To.Typ = D_REG
p.To.Reg = 3
p = liblink.Appendp(ctxt, p)
p.As = AMOVW
p.From.Typ = D_REG
p.From.Reg = 3
p.To.Typ = D_OREG
p.To.Reg = REGG
p.To.Offset = 2 * ctxt.Arch.Ptrsize
}
case ARET:
nocache_obj5(p)
if cursym.Text.Mark&LEAF != 0 {
if autosize == 0 {
p.As = AB
p.From = zprg_obj5.From
if p.To.Sym != nil { // retjmp
p.To.Typ = D_BRANCH
} else {
p.To.Typ = D_OREG
p.To.Offset = 0
p.To.Reg = REGLINK
}
break
}
}
if cursym.Text.Reg&liblink.WRAPPER != 0 {
var scond int
// Preserve original RET's cond, to allow RET.EQ
// in the implementation of reflect.call.
scond = p.Scond
p.Scond = C_SCOND_NONE
// g->panicwrap -= autosize;
// MOVW panicwrap_offset(g), R3
// SUB $autosize, R3
// MOVW R3 panicwrap_offset(g)
p.As = AMOVW
p.From.Typ = D_OREG
p.From.Reg = REGG
p.From.Offset = 2 * ctxt.Arch.Ptrsize
p.To.Typ = D_REG
p.To.Reg = 3
p = liblink.Appendp(ctxt, p)
p.As = ASUB
p.From.Typ = D_CONST
p.From.Offset = autosize
p.To.Typ = D_REG
p.To.Reg = 3
p = liblink.Appendp(ctxt, p)
p.As = AMOVW
p.From.Typ = D_REG
p.From.Reg = 3
p.To.Typ = D_OREG
p.To.Reg = REGG
p.To.Offset = 2 * ctxt.Arch.Ptrsize
p = liblink.Appendp(ctxt, p)
p.Scond = scond
}
p.As = AMOVW
p.Scond |= C_PBIT
p.From.Typ = D_OREG
p.From.Offset = autosize
p.From.Reg = REGSP
p.To.Typ = 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.Typ = D_BRANCH
q2.To.Sym = p.To.Sym
p.To.Sym = nil
p = q2
}
case AADD:
if p.From.Typ == D_CONST && p.From.Reg == NREG && p.To.Typ == D_REG && p.To.Reg == REGSP {
p.Spadj = -p.From.Offset
}
case ASUB:
if p.From.Typ == D_CONST && p.From.Reg == NREG && p.To.Typ == D_REG && p.To.Reg == REGSP {
p.Spadj = p.From.Offset
}
case ADIV,
ADIVU,
AMOD,
AMODU:
if ctxt.Debugdivmod != 0 {
break
}
if p.From.Typ != D_REG {
break
}
if p.To.Typ != D_REG {
break
}
q1 = p
/* MOV a,4(SP) */
p = liblink.Appendp(ctxt, p)
p.As = AMOVW
p.Lineno = q1.Lineno
p.From.Typ = D_REG
p.From.Reg = q1.From.Reg
p.To.Typ = 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.Typ = D_REG
p.From.Reg = q1.Reg
if q1.Reg == NREG {
p.From.Reg = q1.To.Reg
}
p.To.Typ = 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.Typ = 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.Typ = D_REG
p.From.Reg = REGTMP
p.From.Offset = 0
p.To.Typ = 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.Typ = D_CONST
p.From.Reg = NREG
p.From.Offset = 8
p.Reg = NREG
p.To.Typ = 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.Typ = D_OREG
q1.From.Reg = REGSP
q1.From.Offset = 0
q1.Reg = NREG
q1.To.Typ = D_REG
q1.To.Reg = REGTMP
/* SUB $8,SP */
q1 = liblink.Appendp(ctxt, q1)
q1.As = AMOVW
q1.From.Typ = D_REG
q1.From.Reg = REGTMP
q1.Reg = NREG
q1.To.Typ = 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.Typ == D_OREG && p.To.Reg == REGSP {
p.Spadj = -p.To.Offset
}
if (p.Scond&C_PBIT != 0) && p.From.Typ == D_OREG && p.From.Reg == REGSP && p.To.Reg != REGPC {
p.Spadj = -p.From.Offset
}
if p.From.Typ == D_CONST && p.From.Reg == REGSP && p.To.Typ == D_REG && p.To.Reg == REGSP {
p.Spadj = -p.From.Offset
}
break
}
}
}