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runtime: eliminate scase.receivedp

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Make selectgo return recvOK as a result parameter instead.

Change-Id: Iffd436371d360bf666b76d4d7503e7c3037a9f1d
Reviewed-on: https://go-review.googlesource.com/37935
Reviewed-by: Austin Clements <austin@google.com>
This commit is contained in:
Matthew Dempsky 2017-03-07 15:12:11 -08:00
parent 004260afde
commit 6658219b7e
4 changed files with 34 additions and 43 deletions
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2
src/cmd/compile/internal/gc/builtin.go
View File

@ -242,7 +242,7 @@ func runtimeTypes() []*types.Type {
typs[88] = functype(nil, []*Node{anonfield(typs[3]), anonfield(typs[77])}, []*Node{anonfield(typs[11])})
typs[89] = types.NewPtr(typs[11])
typs[90] = functype(nil, []*Node{anonfield(typs[3]), anonfield(typs[89]), anonfield(typs[77])}, []*Node{anonfield(typs[11])})
typs[91] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[1]), anonfield(typs[32])}, []*Node{anonfield(typs[32])})
typs[91] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[1]), anonfield(typs[32])}, []*Node{anonfield(typs[32]), anonfield(typs[11])})
typs[92] = types.NewSlice(typs[2])
typs[93] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[32]), anonfield(typs[32])}, []*Node{anonfield(typs[92])})
typs[94] = functype(nil, []*Node{anonfield(typs[1]), anonfield(typs[15]), anonfield(typs[15])}, []*Node{anonfield(typs[92])})

2
src/cmd/compile/internal/gc/builtin/runtime.go
View File

@ -146,7 +146,7 @@ func selectnbrecv(elem *any, hchan <-chan any) bool
func selectnbrecv2(elem *any, received *bool, hchan <-chan any) bool
func selectsetpc(cas *byte)
func selectgo(cas0 *byte, order0 *byte, ncases int) int
func selectgo(cas0 *byte, order0 *byte, ncases int) (int, bool)
func block()
func makeslice(typ *byte, len int, cap int) (ary []any)

40
src/cmd/compile/internal/gc/select.go
View File

@ -187,10 +187,6 @@ func walkselectcases(cases *Nodes) []*Node {
if n.Op == OSELRECV2 && n.List.Len() == 0 {
n.Op = OSELRECV
}
if n.Op == OSELRECV2 {
n.List.SetFirst(nod(OADDR, n.List.First(), nil))
n.List.SetFirst(typecheck(n.List.First(), Erv))
}
if n.Left != nil {
n.Left = nod(OADDR, n.Left, nil)
@ -225,7 +221,7 @@ func walkselectcases(cases *Nodes) []*Node {
r.Left = mkcall1(chanfn("selectnbsend", 2, ch.Type), types.Types[TBOOL], &r.Ninit, ch, n.Right)
case OSELRECV:
// if c != nil && selectnbrecv(&v, c) { body } else { default body }
// if selectnbrecv(&v, c) { body } else { default body }
r = nod(OIF, nil, nil)
r.Ninit.Set(cas.Ninit.Slice())
ch := n.Right.Left
@ -236,7 +232,7 @@ func walkselectcases(cases *Nodes) []*Node {
r.Left = mkcall1(chanfn("selectnbrecv", 2, ch.Type), types.Types[TBOOL], &r.Ninit, elem, ch)
case OSELRECV2:
// if c != nil && selectnbrecv2(&v, c) { body } else { default body }
// if selectnbrecv2(&v, &received, c) { body } else { default body }
r = nod(OIF, nil, nil)
r.Ninit.Set(cas.Ninit.Slice())
ch := n.Right.Left
@ -244,7 +240,9 @@ func walkselectcases(cases *Nodes) []*Node {
if elem == nil {
elem = nodnil()
}
r.Left = mkcall1(chanfn("selectnbrecv2", 2, ch.Type), types.Types[TBOOL], &r.Ninit, elem, n.List.First(), ch)
receivedp := nod(OADDR, n.List.First(), nil)
receivedp = typecheck(receivedp, Erv)
r.Left = mkcall1(chanfn("selectnbrecv2", 2, ch.Type), types.Types[TBOOL], &r.Ninit, elem, receivedp, ch)
}
r.Left = typecheck(r.Left, Erv)
@ -282,7 +280,7 @@ func walkselectcases(cases *Nodes) []*Node {
caseDefault
)
var c, elem, receivedp *Node
var c, elem *Node
var kind int64 = caseDefault
if n := cas.Left; n != nil {
@ -295,15 +293,10 @@ func walkselectcases(cases *Nodes) []*Node {
kind = caseSend
c = n.Left
elem = n.Right
case OSELRECV:
case OSELRECV, OSELRECV2:
kind = caseRecv
c = n.Right.Left
elem = n.Left
case OSELRECV2:
kind = caseRecv
c = n.Right.Left
elem = n.Left
receivedp = n.List.First()
}
}
@ -324,11 +317,6 @@ func walkselectcases(cases *Nodes) []*Node {
elem.Type = types.Types[TUNSAFEPTR]
setField("elem", elem)
}
if receivedp != nil {
receivedp = nod(OCONVNOP, receivedp, nil)
receivedp.Type = types.NewPtr(types.Types[TBOOL])
setField("receivedp", receivedp)
}
// TODO(mdempsky): There should be a cleaner way to
// handle this.
@ -341,7 +329,11 @@ func walkselectcases(cases *Nodes) []*Node {
// run the select
lineno = sellineno
chosen := temp(types.Types[TINT])
r = nod(OAS, chosen, mkcall("selectgo", types.Types[TINT], nil, bytePtrToIndex(selv, 0), bytePtrToIndex(order, 0), nodintconst(int64(n))))
recvOK := temp(types.Types[TBOOL])
r = nod(OAS2, nil, nil)
r.List.Set2(chosen, recvOK)
fn := syslook("selectgo")
r.Rlist.Set1(mkcall1(fn, fn.Type.Results(), nil, bytePtrToIndex(selv, 0), bytePtrToIndex(order, 0), nodintconst(int64(n))))
r = typecheck(r, Etop)
init = append(init, r)
@ -358,6 +350,13 @@ func walkselectcases(cases *Nodes) []*Node {
cond = defaultlit(cond, nil)
r = nod(OIF, cond, nil)
if n := cas.Left; n != nil && n.Op == OSELRECV2 {
x := nod(OAS, n.List.First(), recvOK)
x = typecheck(x, Etop)
r.Nbody.Append(x)
}
r.Nbody.AppendNodes(&cas.Nbody)
r.Nbody.Append(nod(OBREAK, nil, nil))
init = append(init, r)
@ -382,7 +381,6 @@ func scasetype() *types.Type {
scase = tostruct([]*Node{
namedfield("c", types.Types[TUNSAFEPTR]),
namedfield("elem", types.Types[TUNSAFEPTR]),
namedfield("receivedp", types.NewPtr(types.Types[TBOOL])),
namedfield("kind", types.Types[TUINT16]),
namedfield("pc", types.Types[TUINTPTR]),
namedfield("releasetime", types.Types[TUINT64]),

33
src/runtime/select.go
View File

@ -28,7 +28,6 @@ const (
type scase struct {
c *hchan // chan
elem unsafe.Pointer // data element
receivedp *bool // pointer to received bool, if any
kind uint16
pc uintptr // race pc (for race detector / msan)
releasetime int64
@ -111,7 +110,9 @@ func block() {
//
// selectgo returns the index of the chosen scase, which matches the
// ordinal position of its respective select{recv,send,default} call.
func selectgo(cas0 *scase, order0 *uint16, ncases int) int {
// Also, if the chosen scase was a receive operation, it returns whether
// a value was received.
func selectgo(cas0 *scase, order0 *uint16, ncases int) (int, bool) {
if debugSelect {
print("select: cas0=", cas0, "\n")
}
@ -219,6 +220,7 @@ loop:
var dfl *scase
var casi int
var cas *scase
var recvOK bool
for i := 0; i < ncases; i++ {
casi = int(pollorder[i])
cas = &scases[casi]
@ -375,8 +377,8 @@ loop:
print("wait-return: cas0=", cas0, " c=", c, " cas=", cas, " kind=", cas.kind, "\n")
}
if cas.kind == caseRecv && cas.receivedp != nil {
*cas.receivedp = true
if cas.kind == caseRecv {
recvOK = true
}
if raceenabled {
@ -409,9 +411,7 @@ bufrecv:
if msanenabled && cas.elem != nil {
msanwrite(cas.elem, c.elemtype.size)
}
if cas.receivedp != nil {
*cas.receivedp = true
}
recvOK = true
qp = chanbuf(c, c.recvx)
if cas.elem != nil {
typedmemmove(c.elemtype, cas.elem, qp)
@ -450,17 +450,13 @@ recv:
if debugSelect {
print("syncrecv: cas0=", cas0, " c=", c, "\n")
}
if cas.receivedp != nil {
*cas.receivedp = true
}
recvOK = true
goto retc
rclose:
// read at end of closed channel
selunlock(scases, lockorder)
if cas.receivedp != nil {
*cas.receivedp = false
}
recvOK = false
if cas.elem != nil {
typedmemclr(c.elemtype, cas.elem)
}
@ -487,7 +483,7 @@ retc:
if cas.releasetime > 0 {
blockevent(cas.releasetime-t0, 1)
}
return casi
return casi, recvOK
sclose:
// send on closed channel
@ -521,13 +517,12 @@ const (
)
//go:linkname reflect_rselect reflect.rselect
func reflect_rselect(cases []runtimeSelect) (chosen int, recvOK bool) {
func reflect_rselect(cases []runtimeSelect) (int, bool) {
if len(cases) == 0 {
block()
}
sel := make([]scase, len(cases))
order := make([]uint16, 2*len(cases))
r := new(bool)
for i := range cases {
rc := &cases[i]
switch rc.dir {
@ -536,16 +531,14 @@ func reflect_rselect(cases []runtimeSelect) (chosen int, recvOK bool) {
case selectSend:
sel[i] = scase{kind: caseSend, c: rc.ch, elem: rc.val}
case selectRecv:
sel[i] = scase{kind: caseRecv, c: rc.ch, elem: rc.val, receivedp: r}
sel[i] = scase{kind: caseRecv, c: rc.ch, elem: rc.val}
}
if raceenabled || msanenabled {
selectsetpc(&sel[i])
}
}
chosen = selectgo(&sel[0], &order[0], len(cases))
recvOK = *r
return
return selectgo(&sel[0], &order[0], len(cases))
}
func (q *waitq) dequeueSudoG(sgp *sudog) {