go/src/cmd/compile/internal/gc/select.go
Dave Cheney d7012ca282 cmd/compile/internal/gc: unexport more helper functions
After the removal of the old backend many types are no longer referenced
outside internal/gc. Make these functions private so that tools like
honnef.co/go/unused can spot when they become dead code. In doing so
this CL identified several previously public helpers which are no longer
used, so removes them.

This should be the last of the public functions.

Change-Id: I7e9c4e72f86f391b428b9dddb6f0d516529706c3
Reviewed-on: https://go-review.googlesource.com/29134
Run-TryBot: Dave Cheney <dave@cheney.net>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2016-09-15 13:57:42 +00:00

355 lines
9.3 KiB
Go

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package gc
// select
func typecheckselect(sel *Node) {
var ncase *Node
var n *Node
var def *Node
lno := setlineno(sel)
count := 0
typecheckslice(sel.Ninit.Slice(), Etop)
for _, n1 := range sel.List.Slice() {
count++
ncase = n1
setlineno(ncase)
if ncase.Op != OXCASE {
Fatalf("typecheckselect %v", ncase.Op)
}
if ncase.List.Len() == 0 {
// default
if def != nil {
yyerror("multiple defaults in select (first at %v)", def.Line())
} else {
def = ncase
}
} else if ncase.List.Len() > 1 {
yyerror("select cases cannot be lists")
} else {
ncase.List.SetIndex(0, typecheck(ncase.List.Index(0), Etop))
n = ncase.List.Index(0)
ncase.Left = n
ncase.List.Set(nil)
setlineno(n)
switch n.Op {
default:
yyerror("select case must be receive, send or assign recv")
// convert x = <-c into OSELRECV(x, <-c).
// remove implicit conversions; the eventual assignment
// will reintroduce them.
case OAS:
if (n.Right.Op == OCONVNOP || n.Right.Op == OCONVIFACE) && n.Right.Implicit {
n.Right = n.Right.Left
}
if n.Right.Op != ORECV {
yyerror("select assignment must have receive on right hand side")
break
}
n.Op = OSELRECV
// convert x, ok = <-c into OSELRECV2(x, <-c) with ntest=ok
case OAS2RECV:
if n.Rlist.First().Op != ORECV {
yyerror("select assignment must have receive on right hand side")
break
}
n.Op = OSELRECV2
n.Left = n.List.First()
n.List.Set1(n.List.Second())
n.Right = n.Rlist.First()
n.Rlist.Set(nil)
// convert <-c into OSELRECV(N, <-c)
case ORECV:
n = Nod(OSELRECV, nil, n)
n.Typecheck = 1
ncase.Left = n
case OSEND:
break
}
}
typecheckslice(ncase.Nbody.Slice(), Etop)
}
sel.Xoffset = int64(count)
lineno = lno
}
func walkselect(sel *Node) {
if sel.List.Len() == 0 && sel.Xoffset != 0 {
Fatalf("double walkselect") // already rewrote
}
lno := setlineno(sel)
i := sel.List.Len()
// optimization: zero-case select
var init []*Node
var r *Node
var n *Node
var var_ *Node
var selv *Node
if i == 0 {
sel.Nbody.Set1(mkcall("block", nil, nil))
goto out
}
// optimization: one-case select: single op.
// TODO(rsc): Reenable optimization once order.go can handle it.
// golang.org/issue/7672.
if i == 1 {
cas := sel.List.First()
setlineno(cas)
l := cas.Ninit.Slice()
if cas.Left != nil { // not default:
n := cas.Left
l = append(l, n.Ninit.Slice()...)
n.Ninit.Set(nil)
var ch *Node
switch n.Op {
default:
Fatalf("select %v", n.Op)
// ok already
case OSEND:
ch = n.Left
case OSELRECV, OSELRECV2:
ch = n.Right.Left
if n.Op == OSELRECV || n.List.Len() == 0 {
if n.Left == nil {
n = n.Right
} else {
n.Op = OAS
}
break
}
if n.Left == nil {
nblank = typecheck(nblank, Erv|Easgn)
n.Left = nblank
}
n.Op = OAS2
n.List.Prepend(n.Left)
n.Rlist.Set1(n.Right)
n.Right = nil
n.Left = nil
n.Typecheck = 0
n = typecheck(n, Etop)
}
// if ch == nil { block() }; n;
a := Nod(OIF, nil, nil)
a.Left = Nod(OEQ, ch, nodnil())
var ln Nodes
ln.Set(l)
a.Nbody.Set1(mkcall("block", nil, &ln))
l = ln.Slice()
a = typecheck(a, Etop)
l = append(l, a)
l = append(l, n)
}
l = append(l, cas.Nbody.Slice()...)
sel.Nbody.Set(l)
goto out
}
// convert case value arguments to addresses.
// this rewrite is used by both the general code and the next optimization.
for _, cas := range sel.List.Slice() {
setlineno(cas)
n = cas.Left
if n == nil {
continue
}
switch n.Op {
case OSEND:
n.Right = Nod(OADDR, n.Right, nil)
n.Right = typecheck(n.Right, Erv)
case OSELRECV, OSELRECV2:
if n.Op == OSELRECV2 && n.List.Len() == 0 {
n.Op = OSELRECV
}
if n.Op == OSELRECV2 {
n.List.SetIndex(0, Nod(OADDR, n.List.First(), nil))
n.List.SetIndex(0, typecheck(n.List.Index(0), Erv))
}
if n.Left == nil {
n.Left = nodnil()
} else {
n.Left = Nod(OADDR, n.Left, nil)
n.Left = typecheck(n.Left, Erv)
}
}
}
// optimization: two-case select but one is default: single non-blocking op.
if i == 2 && (sel.List.First().Left == nil || sel.List.Second().Left == nil) {
var cas *Node
var dflt *Node
if sel.List.First().Left == nil {
cas = sel.List.Second()
dflt = sel.List.First()
} else {
dflt = sel.List.Second()
cas = sel.List.First()
}
n := cas.Left
setlineno(n)
r := Nod(OIF, nil, nil)
r.Ninit.Set(cas.Ninit.Slice())
switch n.Op {
default:
Fatalf("select %v", n.Op)
// if selectnbsend(c, v) { body } else { default body }
case OSEND:
ch := n.Left
r.Left = mkcall1(chanfn("selectnbsend", 2, ch.Type), Types[TBOOL], &r.Ninit, typename(ch.Type), ch, n.Right)
// if c != nil && selectnbrecv(&v, c) { body } else { default body }
case OSELRECV:
r = Nod(OIF, nil, nil)
r.Ninit.Set(cas.Ninit.Slice())
ch := n.Right.Left
r.Left = mkcall1(chanfn("selectnbrecv", 2, ch.Type), Types[TBOOL], &r.Ninit, typename(ch.Type), n.Left, ch)
// if c != nil && selectnbrecv2(&v, c) { body } else { default body }
case OSELRECV2:
r = Nod(OIF, nil, nil)
r.Ninit.Set(cas.Ninit.Slice())
ch := n.Right.Left
r.Left = mkcall1(chanfn("selectnbrecv2", 2, ch.Type), Types[TBOOL], &r.Ninit, typename(ch.Type), n.Left, n.List.First(), ch)
}
r.Left = typecheck(r.Left, Erv)
r.Nbody.Set(cas.Nbody.Slice())
r.Rlist.Set(append(dflt.Ninit.Slice(), dflt.Nbody.Slice()...))
sel.Nbody.Set1(r)
goto out
}
init = sel.Ninit.Slice()
sel.Ninit.Set(nil)
// generate sel-struct
setlineno(sel)
selv = temp(selecttype(int32(sel.Xoffset)))
r = Nod(OAS, selv, nil)
r = typecheck(r, Etop)
init = append(init, r)
var_ = conv(conv(Nod(OADDR, selv, nil), Types[TUNSAFEPTR]), ptrto(Types[TUINT8]))
r = mkcall("newselect", nil, nil, var_, nodintconst(selv.Type.Width), nodintconst(sel.Xoffset))
r = typecheck(r, Etop)
init = append(init, r)
// register cases
for _, cas := range sel.List.Slice() {
setlineno(cas)
n = cas.Left
r = Nod(OIF, nil, nil)
r.Ninit.Set(cas.Ninit.Slice())
cas.Ninit.Set(nil)
if n != nil {
r.Ninit.AppendNodes(&n.Ninit)
n.Ninit.Set(nil)
}
if n == nil {
// selectdefault(sel *byte);
r.Left = mkcall("selectdefault", Types[TBOOL], &r.Ninit, var_)
} else {
switch n.Op {
default:
Fatalf("select %v", n.Op)
// selectsend(sel *byte, hchan *chan any, elem *any) (selected bool);
case OSEND:
r.Left = mkcall1(chanfn("selectsend", 2, n.Left.Type), Types[TBOOL], &r.Ninit, var_, n.Left, n.Right)
// selectrecv(sel *byte, hchan *chan any, elem *any) (selected bool);
case OSELRECV:
r.Left = mkcall1(chanfn("selectrecv", 2, n.Right.Left.Type), Types[TBOOL], &r.Ninit, var_, n.Right.Left, n.Left)
// selectrecv2(sel *byte, hchan *chan any, elem *any, received *bool) (selected bool);
case OSELRECV2:
r.Left = mkcall1(chanfn("selectrecv2", 2, n.Right.Left.Type), Types[TBOOL], &r.Ninit, var_, n.Right.Left, n.Left, n.List.First())
}
}
// selv is no longer alive after use.
r.Nbody.Append(Nod(OVARKILL, selv, nil))
r.Nbody.AppendNodes(&cas.Nbody)
r.Nbody.Append(Nod(OBREAK, nil, nil))
init = append(init, r)
}
// run the select
setlineno(sel)
init = append(init, mkcall("selectgo", nil, nil, var_))
sel.Nbody.Set(init)
out:
sel.List.Set(nil)
walkstmtlist(sel.Nbody.Slice())
lineno = lno
}
// Keep in sync with src/runtime/select.go.
func selecttype(size int32) *Type {
// TODO(dvyukov): it's possible to generate Scase only once
// and then cache; and also cache Select per size.
scase := Nod(OTSTRUCT, nil, nil)
scase.List.Append(Nod(ODCLFIELD, newname(lookup("elem")), typenod(ptrto(Types[TUINT8]))))
scase.List.Append(Nod(ODCLFIELD, newname(lookup("chan")), typenod(ptrto(Types[TUINT8]))))
scase.List.Append(Nod(ODCLFIELD, newname(lookup("pc")), typenod(Types[TUINTPTR])))
scase.List.Append(Nod(ODCLFIELD, newname(lookup("kind")), typenod(Types[TUINT16])))
scase.List.Append(Nod(ODCLFIELD, newname(lookup("so")), typenod(Types[TUINT16])))
scase.List.Append(Nod(ODCLFIELD, newname(lookup("receivedp")), typenod(ptrto(Types[TUINT8]))))
scase.List.Append(Nod(ODCLFIELD, newname(lookup("releasetime")), typenod(Types[TUINT64])))
scase = typecheck(scase, Etype)
scase.Type.Noalg = true
scase.Type.Local = true
sel := Nod(OTSTRUCT, nil, nil)
sel.List.Append(Nod(ODCLFIELD, newname(lookup("tcase")), typenod(Types[TUINT16])))
sel.List.Append(Nod(ODCLFIELD, newname(lookup("ncase")), typenod(Types[TUINT16])))
sel.List.Append(Nod(ODCLFIELD, newname(lookup("pollorder")), typenod(ptrto(Types[TUINT8]))))
sel.List.Append(Nod(ODCLFIELD, newname(lookup("lockorder")), typenod(ptrto(Types[TUINT8]))))
arr := Nod(OTARRAY, nodintconst(int64(size)), scase)
sel.List.Append(Nod(ODCLFIELD, newname(lookup("scase")), arr))
arr = Nod(OTARRAY, nodintconst(int64(size)), typenod(Types[TUINT16]))
sel.List.Append(Nod(ODCLFIELD, newname(lookup("lockorderarr")), arr))
arr = Nod(OTARRAY, nodintconst(int64(size)), typenod(Types[TUINT16]))
sel.List.Append(Nod(ODCLFIELD, newname(lookup("pollorderarr")), arr))
sel = typecheck(sel, Etype)
sel.Type.Noalg = true
sel.Type.Local = true
return sel.Type
}