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[flang][runtime] Further work on speeding up work queue operations #149189

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Jul 18, 2025
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[flang][runtime] Further work on speeding up work queue operations #149189

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12 changes: 9 additions & 3 deletions flang-rt/lib/runtime/assign.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -279,13 +279,15 @@ RT_API_ATTRS int AssignTicket::Begin(WorkQueue &workQueue) {
if (mustDeallocateLHS) {
// Convert the LHS into a temporary, then make it look deallocated.
toDeallocate_ = &tempDescriptor_.descriptor();
persist_ = true; // tempDescriptor_ state must outlive child tickets
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@akuhlens akuhlens Jul 16, 2025

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The general idea here is that by delaying conditionally setting persist, we can avoid persisting the allocation under some conditions and avoid the overhead of a trip through the work queue in those cases, correct?

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@klausler klausler Jul 16, 2025

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Actually, it was being set unconditionally, so it would be true even when the child task was run immediately as BeginDestroy or whatever, and that caused a later no-op suspension and resumption.

std::memcpy(
reinterpret_cast<void *>(toDeallocate_), &to_, to_.SizeInBytes());
to_.set_base_addr(nullptr);
if (toDerived_ && (flags_ & NeedFinalization)) {
if (int status{workQueue.BeginFinalize(*toDeallocate_, *toDerived_)};
status != StatOk && status != StatContinue) {
int status{workQueue.BeginFinalize(*toDeallocate_, *toDerived_)};
if (status == StatContinue) {
// tempDescriptor_ state must outlive pending child ticket
persist_ = true;
} else if (status != StatOk) {
return status;
}
flags_ &= ~NeedFinalization;
Expand All @@ -304,6 +306,9 @@ RT_API_ATTRS int AssignTicket::Begin(WorkQueue &workQueue) {
if (int stat{ReturnError(
workQueue.terminator(), newFrom.Allocate(kNoAsyncObject))};
stat != StatOk) {
if (stat == StatContinue) {
persist_ = true;
}
return stat;
}
if (HasDynamicComponent(*from_)) {
Expand Down Expand Up @@ -507,6 +512,7 @@ RT_API_ATTRS int AssignTicket::Continue(WorkQueue &workQueue) {
}
}
if (persist_) {
// tempDescriptor_ must outlive pending child ticket(s)
done_ = true;
return StatContinue;
} else {
Expand Down
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