gc: implement nil chan support
The spec has defined nil chans this way for months.
I'm behind.
R=ken2
CC=golang-dev
https://golang.org/cl/4897050
diff --git a/src/cmd/gc/builtin.c.boot b/src/cmd/gc/builtin.c.boot
index 84eef69..190c560 100644
--- a/src/cmd/gc/builtin.c.boot
+++ b/src/cmd/gc/builtin.c.boot
@@ -66,15 +66,14 @@
"func \"\".mapiternext (hiter *any)\n"
"func \"\".mapiter1 (hiter *any) any\n"
"func \"\".mapiter2 (hiter *any) (key any, val any)\n"
- "func \"\".makechan (elem *uint8, hint int64) chan any\n"
- "func \"\".chanrecv1 (hchan <-chan any) any\n"
- "func \"\".chanrecv2 (hchan <-chan any) (elem any, received bool)\n"
- "func \"\".chansend1 (hchan chan<- any, elem any)\n"
+ "func \"\".makechan (chanType *uint8, hint int64) chan any\n"
+ "func \"\".chanrecv1 (chanType *uint8, hchan <-chan any) any\n"
+ "func \"\".chanrecv2 (chanType *uint8, hchan <-chan any) (elem any, received bool)\n"
+ "func \"\".chansend1 (chanType *uint8, hchan chan<- any, elem any)\n"
"func \"\".closechan (hchan any)\n"
- "func \"\".closedchan (hchan any) bool\n"
- "func \"\".selectnbsend (hchan chan<- any, elem any) bool\n"
- "func \"\".selectnbrecv (elem *any, hchan <-chan any) bool\n"
- "func \"\".selectnbrecv2 (elem *any, received *bool, hchan <-chan any) bool\n"
+ "func \"\".selectnbsend (chanType *uint8, hchan chan<- any, elem any) bool\n"
+ "func \"\".selectnbrecv (chanType *uint8, elem *any, hchan <-chan any) bool\n"
+ "func \"\".selectnbrecv2 (chanType *uint8, elem *any, received *bool, hchan <-chan any) bool\n"
"func \"\".newselect (size int) *uint8\n"
"func \"\".selectsend (sel *uint8, hchan chan<- any, elem *any) bool\n"
"func \"\".selectrecv (sel *uint8, hchan <-chan any, elem *any) bool\n"
diff --git a/src/cmd/gc/runtime.go b/src/cmd/gc/runtime.go
index 64098ab..549f7ab 100644
--- a/src/cmd/gc/runtime.go
+++ b/src/cmd/gc/runtime.go
@@ -91,16 +91,15 @@
func mapiter2(hiter *any) (key any, val any)
// *byte is really *runtime.Type
-func makechan(elem *byte, hint int64) (hchan chan any)
-func chanrecv1(hchan <-chan any) (elem any)
-func chanrecv2(hchan <-chan any) (elem any, received bool)
-func chansend1(hchan chan<- any, elem any)
+func makechan(chanType *byte, hint int64) (hchan chan any)
+func chanrecv1(chanType *byte, hchan <-chan any) (elem any)
+func chanrecv2(chanType *byte, hchan <-chan any) (elem any, received bool)
+func chansend1(chanType *byte, hchan chan<- any, elem any)
func closechan(hchan any)
-func closedchan(hchan any) bool
-func selectnbsend(hchan chan<- any, elem any) bool
-func selectnbrecv(elem *any, hchan <-chan any) bool
-func selectnbrecv2(elem *any, received *bool, hchan <-chan any) bool
+func selectnbsend(chanType *byte, hchan chan<- any, elem any) bool
+func selectnbrecv(chanType *byte, elem *any, hchan <-chan any) bool
+func selectnbrecv2(chanType *byte, elem *any, received *bool, hchan <-chan any) bool
func newselect(size int) (sel *byte)
func selectsend(sel *byte, hchan chan<- any, elem *any) (selected bool)
diff --git a/src/cmd/gc/select.c b/src/cmd/gc/select.c
index 8395dda..909ad3a 100644
--- a/src/cmd/gc/select.c
+++ b/src/cmd/gc/select.c
@@ -250,9 +250,8 @@
case OSEND:
// if c != nil && selectnbsend(c, v) { body } else { default body }
ch = cheapexpr(n->left, &r->ninit);
- r->ntest = nod(OANDAND, nod(ONE, ch, nodnil()),
- mkcall1(chanfn("selectnbsend", 2, ch->type),
- types[TBOOL], &r->ninit, ch, n->right));
+ r->ntest = mkcall1(chanfn("selectnbsend", 2, ch->type),
+ types[TBOOL], &r->ninit, typename(ch->type), ch, n->right);
break;
case OSELRECV:
@@ -260,9 +259,8 @@
r = nod(OIF, N, N);
r->ninit = cas->ninit;
ch = cheapexpr(n->right->left, &r->ninit);
- r->ntest = nod(OANDAND, nod(ONE, ch, nodnil()),
- mkcall1(chanfn("selectnbrecv", 2, ch->type),
- types[TBOOL], &r->ninit, n->left, ch));
+ r->ntest = mkcall1(chanfn("selectnbrecv", 2, ch->type),
+ types[TBOOL], &r->ninit, typename(ch->type), n->left, ch);
break;
case OSELRECV2:
@@ -270,9 +268,8 @@
r = nod(OIF, N, N);
r->ninit = cas->ninit;
ch = cheapexpr(n->right->left, &r->ninit);
- r->ntest = nod(OANDAND, nod(ONE, ch, nodnil()),
- mkcall1(chanfn("selectnbrecv2", 2, ch->type),
- types[TBOOL], &r->ninit, n->left, n->ntest, ch));
+ r->ntest = mkcall1(chanfn("selectnbrecv2", 2, ch->type),
+ types[TBOOL], &r->ninit, typename(ch->type), n->left, n->ntest, ch);
break;
}
typecheck(&r->ntest, Erv);
diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index 7a39db2..9cd4ee9 100644
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -591,7 +591,7 @@
walkexprlistsafe(n->list, init);
walkexpr(&r->left, init);
fn = chanfn("chanrecv2", 2, r->left->type);
- r = mkcall1(fn, getoutargx(fn->type), init, r->left);
+ r = mkcall1(fn, getoutargx(fn->type), init, typename(r->left->type), r->left);
n->rlist->n = r;
n->op = OAS2FUNC;
goto as2func;
@@ -858,7 +858,7 @@
case ORECV:
walkexpr(&n->left, init);
walkexpr(&n->right, init);
- n = mkcall1(chanfn("chanrecv1", 2, n->left->type), n->type, init, n->left);
+ n = mkcall1(chanfn("chanrecv1", 2, n->left->type), n->type, init, typename(n->left->type), n->left);
goto ret;
case OSLICE:
@@ -1078,7 +1078,7 @@
case OMAKECHAN:
n = mkcall1(chanfn("makechan", 1, n->type), n->type, init,
- typename(n->type->type),
+ typename(n->type),
conv(n->left, types[TINT64]));
goto ret;
@@ -1163,7 +1163,7 @@
goto ret;
case OSEND:
- n = mkcall1(chanfn("chansend1", 2, n->left->type), T, init, n->left, n->right);
+ n = mkcall1(chanfn("chansend1", 2, n->left->type), T, init, typename(n->left->type), n->left, n->right);
goto ret;
case OCLOSURE:
diff --git a/src/pkg/reflect/value.go b/src/pkg/reflect/value.go
index e40b434..d3c510a 100644
--- a/src/pkg/reflect/value.go
+++ b/src/pkg/reflect/value.go
@@ -1162,7 +1162,7 @@
if ch == 0 {
panic("recv on nil channel")
}
- valWord, selected, ok := chanrecv(ch, nb)
+ valWord, selected, ok := chanrecv(iv.typ.runtimeType(), ch, nb)
if selected {
val = valueFromIword(0, t.Elem(), valWord)
}
@@ -1192,7 +1192,7 @@
if ch == 0 {
panic("send on nil channel")
}
- return chansend(ch, ix.word, nb)
+ return chansend(iv.typ.runtimeType(), ch, ix.word, nb)
}
// Set assigns x to the value v.
@@ -1720,8 +1720,8 @@
func chancap(ch iword) int32
func chanclose(ch iword)
func chanlen(ch iword) int32
-func chanrecv(ch iword, nb bool) (val iword, selected, received bool)
-func chansend(ch iword, val iword, nb bool) bool
+func chanrecv(t *runtime.Type, ch iword, nb bool) (val iword, selected, received bool)
+func chansend(t *runtime.Type, ch iword, val iword, nb bool) bool
func makechan(typ *runtime.Type, size uint32) (ch iword)
func makemap(t *runtime.Type) iword
diff --git a/src/pkg/runtime/chan.c b/src/pkg/runtime/chan.c
index ffb3261..ef53423 100644
--- a/src/pkg/runtime/chan.c
+++ b/src/pkg/runtime/chan.c
@@ -81,10 +81,13 @@
static void destroychan(Hchan*);
Hchan*
-runtime·makechan_c(Type *elem, int64 hint)
+runtime·makechan_c(ChanType *t, int64 hint)
{
Hchan *c;
int32 n;
+ Type *elem;
+
+ elem = t->elem;
if(hint < 0 || (int32)hint != hint || (elem->size > 0 && hint > ((uintptr)-1) / elem->size))
runtime·panicstring("makechan: size out of range");
@@ -121,7 +124,7 @@
void
reflect·makechan(ChanType *t, uint32 size, Hchan *c)
{
- c = runtime·makechan_c(t->elem, size);
+ c = runtime·makechan_c(t, size);
FLUSH(&c);
}
@@ -132,11 +135,11 @@
}
-// makechan(elem *Type, hint int64) (hchan *chan any);
+// makechan(t *ChanType, hint int64) (hchan *chan any);
void
-runtime·makechan(Type *elem, int64 hint, Hchan *ret)
+runtime·makechan(ChanType *t, int64 hint, Hchan *ret)
{
- ret = runtime·makechan_c(elem, hint);
+ ret = runtime·makechan_c(t, hint);
FLUSH(&ret);
}
@@ -155,14 +158,22 @@
* the operation; we'll see that it's now closed.
*/
void
-runtime·chansend(Hchan *c, byte *ep, bool *pres)
+runtime·chansend(ChanType *t, Hchan *c, byte *ep, bool *pres)
{
SudoG *sg;
SudoG mysg;
G* gp;
- if(c == nil)
- runtime·panicstring("send to nil channel");
+ if(c == nil) {
+ USED(t);
+ if(pres != nil) {
+ *pres = false;
+ return;
+ }
+ g->status = Gwaiting;
+ runtime·gosched();
+ return; // not reached
+ }
if(runtime·gcwaiting)
runtime·gosched();
@@ -263,21 +274,29 @@
void
-runtime·chanrecv(Hchan* c, byte *ep, bool *selected, bool *received)
+runtime·chanrecv(ChanType *t, Hchan* c, byte *ep, bool *selected, bool *received)
{
SudoG *sg;
SudoG mysg;
G *gp;
- if(c == nil)
- runtime·panicstring("receive from nil channel");
-
if(runtime·gcwaiting)
runtime·gosched();
if(debug)
runtime·printf("chanrecv: chan=%p\n", c);
+ if(c == nil) {
+ USED(t);
+ if(selected != nil) {
+ *selected = false;
+ return;
+ }
+ g->status = Gwaiting;
+ runtime·gosched();
+ return; // not reached
+ }
+
runtime·lock(c);
if(c->dataqsiz > 0)
goto asynch;
@@ -385,50 +404,29 @@
// chansend1(hchan *chan any, elem any);
#pragma textflag 7
void
-runtime·chansend1(Hchan* c, ...)
+runtime·chansend1(ChanType *t, Hchan* c, ...)
{
- int32 o;
- byte *ae;
-
- if(c == nil)
- runtime·panicstring("send to nil channel");
-
- o = runtime·rnd(sizeof(c), c->elemalign);
- ae = (byte*)&c + o;
- runtime·chansend(c, ae, nil);
+ runtime·chansend(t, c, (byte*)(&c+1), nil);
}
// chanrecv1(hchan *chan any) (elem any);
#pragma textflag 7
void
-runtime·chanrecv1(Hchan* c, ...)
+runtime·chanrecv1(ChanType *t, Hchan* c, ...)
{
- int32 o;
- byte *ae;
-
- o = runtime·rnd(sizeof(c), Structrnd);
- ae = (byte*)&c + o;
-
- runtime·chanrecv(c, ae, nil, nil);
+ runtime·chanrecv(t, c, (byte*)(&c+1), nil, nil);
}
// chanrecv2(hchan *chan any) (elem any, received bool);
#pragma textflag 7
void
-runtime·chanrecv2(Hchan* c, ...)
+runtime·chanrecv2(ChanType *t, Hchan* c, ...)
{
- int32 o;
- byte *ae, *ac;
-
- if(c == nil)
- runtime·panicstring("receive from nil channel");
+ byte *ae, *ap;
- o = runtime·rnd(sizeof(c), Structrnd);
- ae = (byte*)&c + o;
- o += c->elemsize;
- ac = (byte*)&c + o;
-
- runtime·chanrecv(c, ae, nil, ac);
+ ae = (byte*)(&c+1);
+ ap = ae + t->elem->size;
+ runtime·chanrecv(t, c, ae, nil, ap);
}
// func selectnbsend(c chan any, elem any) bool
@@ -444,7 +442,7 @@
//
// as
//
-// if c != nil && selectnbsend(c, v) {
+// if selectnbsend(c, v) {
// ... foo
// } else {
// ... bar
@@ -452,17 +450,13 @@
//
#pragma textflag 7
void
-runtime·selectnbsend(Hchan *c, ...)
+runtime·selectnbsend(ChanType *t, Hchan *c, ...)
{
- int32 o;
byte *ae, *ap;
- o = runtime·rnd(sizeof(c), c->elemalign);
- ae = (byte*)&c + o;
- o = runtime·rnd(o+c->elemsize, Structrnd);
- ap = (byte*)&c + o;
-
- runtime·chansend(c, ae, ap);
+ ae = (byte*)(&c + 1);
+ ap = ae + runtime·rnd(t->elem->size, Structrnd);
+ runtime·chansend(t, c, ae, ap);
}
// func selectnbrecv(elem *any, c chan any) bool
@@ -478,7 +472,7 @@
//
// as
//
-// if c != nil && selectnbrecv(&v, c) {
+// if selectnbrecv(&v, c) {
// ... foo
// } else {
// ... bar
@@ -486,9 +480,9 @@
//
#pragma textflag 7
void
-runtime·selectnbrecv(byte *v, Hchan *c, bool selected)
+runtime·selectnbrecv(ChanType *t, byte *v, Hchan *c, bool selected)
{
- runtime·chanrecv(c, v, &selected, nil);
+ runtime·chanrecv(t, c, v, &selected, nil);
}
// func selectnbrecv2(elem *any, ok *bool, c chan any) bool
@@ -512,9 +506,9 @@
//
#pragma textflag 7
void
-runtime·selectnbrecv2(byte *v, bool *received, Hchan *c, bool selected)
+runtime·selectnbrecv2(ChanType *t, byte *v, bool *received, Hchan *c, bool selected)
{
- runtime·chanrecv(c, v, &selected, received);
+ runtime·chanrecv(t, c, v, &selected, received);
}
// For reflect:
@@ -525,14 +519,11 @@
// The "uintptr selected" is really "bool selected" but saying
// uintptr gets us the right alignment for the output parameter block.
void
-reflect·chansend(Hchan *c, uintptr val, bool nb, uintptr selected)
+reflect·chansend(ChanType *t, Hchan *c, uintptr val, bool nb, uintptr selected)
{
bool *sp;
byte *vp;
- if(c == nil)
- runtime·panicstring("send to nil channel");
-
if(nb) {
selected = false;
sp = (bool*)&selected;
@@ -541,11 +532,11 @@
FLUSH(&selected);
sp = nil;
}
- if(c->elemsize <= sizeof(val))
+ if(t->elem->size <= sizeof(val))
vp = (byte*)&val;
else
vp = (byte*)val;
- runtime·chansend(c, vp, sp);
+ runtime·chansend(t, c, vp, sp);
}
// For reflect:
@@ -553,13 +544,10 @@
// where an iword is the same word an interface value would use:
// the actual data if it fits, or else a pointer to the data.
void
-reflect·chanrecv(Hchan *c, bool nb, uintptr val, bool selected, bool received)
+reflect·chanrecv(ChanType *t, Hchan *c, bool nb, uintptr val, bool selected, bool received)
{
byte *vp;
bool *sp;
-
- if(c == nil)
- runtime·panicstring("receive from nil channel");
if(nb) {
selected = false;
@@ -571,15 +559,15 @@
}
received = false;
FLUSH(&received);
- if(c->elemsize <= sizeof(val)) {
+ if(t->elem->size <= sizeof(val)) {
val = 0;
vp = (byte*)&val;
} else {
- vp = runtime·mal(c->elemsize);
+ vp = runtime·mal(t->elem->size);
val = (uintptr)vp;
FLUSH(&val);
}
- runtime·chanrecv(c, vp, sp, &received);
+ runtime·chanrecv(t, c, vp, sp, &received);
}
static void newselect(int32, Select**);
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index 9719c30..526a320 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -62,6 +62,7 @@
typedef struct Itab Itab;
typedef struct Eface Eface;
typedef struct Type Type;
+typedef struct ChanType ChanType;
typedef struct MapType MapType;
typedef struct Defer Defer;
typedef struct Panic Panic;
@@ -624,9 +625,9 @@
void runtime·mapiterkeyvalue(struct hash_iter*, void*, void*);
Hmap* runtime·makemap_c(MapType*, int64);
-Hchan* runtime·makechan_c(Type*, int64);
-void runtime·chansend(Hchan*, void*, bool*);
-void runtime·chanrecv(Hchan*, void*, bool*, bool*);
+Hchan* runtime·makechan_c(ChanType*, int64);
+void runtime·chansend(ChanType*, Hchan*, void*, bool*);
+void runtime·chanrecv(ChanType*, Hchan*, void*, bool*, bool*);
int32 runtime·chanlen(Hchan*);
int32 runtime·chancap(Hchan*);
diff --git a/src/pkg/runtime/type.h b/src/pkg/runtime/type.h
index d406755..8c80c62 100644
--- a/src/pkg/runtime/type.h
+++ b/src/pkg/runtime/type.h
@@ -16,7 +16,6 @@
typedef struct InterfaceType InterfaceType;
typedef struct Method Method;
typedef struct IMethod IMethod;
-typedef struct ChanType ChanType;
typedef struct SliceType SliceType;
typedef struct FuncType FuncType;
diff --git a/test/chan/select3.go b/test/chan/select3.go
index b4e8f8e..d919de3e 100644
--- a/test/chan/select3.go
+++ b/test/chan/select3.go
@@ -58,15 +58,15 @@
closedch := make(chan int)
close(closedch)
- // sending/receiving from a nil channel outside a select panics
- testPanic(always, func() {
+ // sending/receiving from a nil channel blocks
+ testBlock(always, func() {
nilch <- 7
})
- testPanic(always, func() {
+ testBlock(always, func() {
<-nilch
})
- // sending/receiving from a nil channel inside a select never panics
+ // sending/receiving from a nil channel inside a select is never selected
testPanic(never, func() {
select {
case nilch <- 7:
