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compiler/runtime: move the channel blocked list onto the stack #1144

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Merged
merged 1 commit into from
Jun 8, 2020
Merged

compiler/runtime: move the channel blocked list onto the stack #1144

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16 changes: 13 additions & 3 deletions compiler/channel.go
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Original file line number Diff line number Diff line change
Expand Up @@ -35,12 +35,17 @@ func (b *builder) createChanSend(instr *ssa.Send) {
valueAlloca, valueAllocaCast, valueAllocaSize := b.createTemporaryAlloca(valueType, "chan.value")
b.CreateStore(chanValue, valueAlloca)

// Allocate blockedlist buffer.
channelBlockedList := b.mod.GetTypeByName("runtime.channelBlockedList")
channelBlockedListAlloca, channelBlockedListAllocaCast, channelBlockedListAllocaSize := b.createTemporaryAlloca(channelBlockedList, "chan.blockedList")

// Do the send.
b.createRuntimeCall("chanSend", []llvm.Value{ch, valueAllocaCast}, "")
b.createRuntimeCall("chanSend", []llvm.Value{ch, valueAllocaCast, channelBlockedListAlloca}, "")

// End the lifetime of the alloca.
// End the lifetime of the allocas.
// This also works around a bug in CoroSplit, at least in LLVM 8:
// https://bugs.llvm.org/show_bug.cgi?id=41742
b.emitLifetimeEnd(channelBlockedListAllocaCast, channelBlockedListAllocaSize)
b.emitLifetimeEnd(valueAllocaCast, valueAllocaSize)
}

Expand All @@ -53,9 +58,14 @@ func (b *builder) createChanRecv(unop *ssa.UnOp) llvm.Value {
// Allocate memory to receive into.
valueAlloca, valueAllocaCast, valueAllocaSize := b.createTemporaryAlloca(valueType, "chan.value")

// Allocate blockedlist buffer.
channelBlockedList := b.mod.GetTypeByName("runtime.channelBlockedList")
channelBlockedListAlloca, channelBlockedListAllocaCast, channelBlockedListAllocaSize := b.createTemporaryAlloca(channelBlockedList, "chan.blockedList")

// Do the receive.
commaOk := b.createRuntimeCall("chanRecv", []llvm.Value{ch, valueAllocaCast}, "")
commaOk := b.createRuntimeCall("chanRecv", []llvm.Value{ch, valueAllocaCast, channelBlockedListAlloca}, "")
received := b.CreateLoad(valueAlloca, "chan.received")
b.emitLifetimeEnd(channelBlockedListAllocaCast, channelBlockedListAllocaSize)
b.emitLifetimeEnd(valueAllocaCast, valueAllocaSize)

if unop.CommaOk {
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10 changes: 6 additions & 4 deletions src/runtime/chan.go
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Original file line number Diff line number Diff line change
Expand Up @@ -446,7 +446,7 @@ type chanSelectState struct {
// chanSend sends a single value over the channel.
// This operation will block unless a value is immediately available.
// May panic if the channel is closed.
func chanSend(ch *channel, value unsafe.Pointer) {
func chanSend(ch *channel, value unsafe.Pointer, blockedlist *channelBlockedList) {
if ch.trySend(value) {
// value immediately sent
chanDebug(ch)
Expand All @@ -462,10 +462,11 @@ func chanSend(ch *channel, value unsafe.Pointer) {
sender := task.Current()
ch.state = chanStateSend
sender.Ptr = value
ch.blocked = &channelBlockedList{
*blockedlist = channelBlockedList{
next: ch.blocked,
t: sender,
}
ch.blocked = blockedlist
chanDebug(ch)
task.Pause()
sender.Ptr = nil
Expand All @@ -475,7 +476,7 @@ func chanSend(ch *channel, value unsafe.Pointer) {
// It blocks if there is no available value to recieve.
// The recieved value is copied into the value pointer.
// Returns the comma-ok value.
func chanRecv(ch *channel, value unsafe.Pointer) bool {
func chanRecv(ch *channel, value unsafe.Pointer, blockedlist *channelBlockedList) bool {
if rx, ok := ch.tryRecv(value); rx {
// value immediately available
chanDebug(ch)
Expand All @@ -491,10 +492,11 @@ func chanRecv(ch *channel, value unsafe.Pointer) bool {
receiver := task.Current()
ch.state = chanStateRecv
receiver.Ptr, receiver.Data = value, 1
ch.blocked = &channelBlockedList{
*blockedlist = channelBlockedList{
next: ch.blocked,
t: receiver,
}
ch.blocked = blockedlist
chanDebug(ch)
task.Pause()
ok := receiver.Data == 1
Expand Down