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[pred-memopt] Simplify logic around lifetime extending a value that is consumed in a loop. #30619

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Merged
merged 1 commit into from
Mar 24, 2020
Merged

[pred-memopt] Simplify logic around lifetime extending a value that is consumed in a loop. #30619

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57 changes: 10 additions & 47 deletions lib/SILOptimizer/Mandatory/PredictableMemOpt.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1199,46 +1199,25 @@ void AvailableValueAggregator::addHandOffCopyDestroysForPhis(
// no further work to do.
auto *loadOperand = &load->getAllOperands()[0];
LinearLifetimeChecker checker(visitedBlocks, deadEndBlocks);
bool didInsertDestroy = false;
bool consumedInLoop = checker.completeConsumingUseSet(
phi, loadOperand, leakingBlocks, [&](SILBasicBlock::iterator iter) {
SILBuilderWithScope builder(iter);
builder.emitDestroyValueOperation(loc, phi);
didInsertDestroy = true;
});

// If we did not insert any destroy_values, we either:
//
// 1. Are consuming the value in a loop, but the loop is an infinite loop
// so we shouldn't insert a destroy.
//
// 2. Are not consuming the value in the loop and our phi is strongly
// control equivalent with the load_borrow, so we insert a destroy
// /after/ the load_borrow.
if (!didInsertDestroy) {
if (!consumedInLoop) {
auto next = std::next(load->getIterator());
SILBuilderWithScope builder(next);
builder.emitDestroyValueOperation(next->getLoc(), phi);
}
continue;
}

// Ok, we found some leaking blocks and potentially that our load is
// "consumed" inside a different loop in the loop nest from cvi. If we are
// consumed in the loop, then our visit should have inserted all of the
// necessary destroys for us by inserting the destroys on the loop
// boundaries. So, exit now.
// Ok, we found some leaking blocks and potentially that our load is
// "consumed" inside a different loop in the loop nest from cvi. If we are
// consumed in the loop, then our visit should have inserted all of the
// necessary destroys for us by inserting the destroys on the loop
// boundaries. So, exit now.
// boundaries. So, continue.
//
// NOTE: This includes cases where due to an infinite loop, we did not
// insert /any/ destroys since the loop has no boundary in a certain sense.
if (consumedInLoop) {
continue;
}

// Otherwise, we had a branching case,
// Otherwise, we need to insert one last destroy after the load for our phi.
auto next = std::next(load->getIterator());
SILBuilderWithScope builder(next);
builder.emitDestroyValueOperation(next->getLoc(), phi);
Expand Down Expand Up @@ -1304,41 +1283,25 @@ void AvailableValueAggregator::addMissingDestroysForCopiedValues(
// no further work to do.
auto *loadOperand = &load->getAllOperands()[0];
LinearLifetimeChecker checker(visitedBlocks, deadEndBlocks);
bool didInsertDestroy = false;
bool consumedInLoop = checker.completeConsumingUseSet(
cvi, loadOperand, leakingBlocks, [&](SILBasicBlock::iterator iter) {
SILBuilderWithScope builder(iter);
builder.emitDestroyValueOperation(loc, cvi);
didInsertDestroy = true;
});

// If we did not insert any destroy_values, we either:
//
// 1. Are consuming the value in a loop, but the loop is an infinite loop
// so we shouldn't insert a destroy.
//
// 2. Are not consuming the value in the loop and our phi is strongly
// control equivalent with the load_borrow, so we insert a destroy
// /after/ the load_borrow.
if (!didInsertDestroy) {
if (!consumedInLoop) {
auto next = std::next(load->getIterator());
SILBuilderWithScope builder(next);
builder.emitDestroyValueOperation(next->getLoc(), cvi);
}
continue;
}

// Ok, we found some leaking blocks and potentially that our load is
// "consumed" inside a different loop in the loop nest from cvi. If we are
// consumed in the loop, then our visit should have inserted all of the
// necessary destroys for us by inserting the destroys on the loop
// boundaries. So, exit now.
// boundaries. So, continue.
//
// NOTE: This includes cases where due to an infinite loop, we did not
// insert /any/ destroys since the loop has no boundary in a certain sense.
if (consumedInLoop) {
continue;
}

// Otherwise, we had a branching case,
// Otherwise, we need to insert one last destroy after the load for our phi.
auto next = std::next(load->getIterator());
SILBuilderWithScope builder(next);
builder.emitDestroyValueOperation(next->getLoc(), cvi);
Expand Down