static bool partialApplyEscapes(SILValue V, bool examineApply) {
SILModuleConventions ModConv(*V->getModule());
llvm::SmallVector<Operand *, 32> Worklist(V->use_begin(), V->use_end());
while (!Worklist.empty()) {
auto *Op = Worklist.pop_back_val();
// These instructions do not cause the address to escape.
if (!useCaptured(Op))
continue;
auto *User = Op->getUser();
// If we have a copy_value, the copy value does not cause an escape, but its
// uses might do so... so add the copy_value's uses to the worklist and
// continue.
if (auto CVI = dyn_cast<CopyValueInst>(User)) {
copy(CVI->getUses(), std::back_inserter(Worklist));
continue;
}
if (auto *Apply = dyn_cast<ApplyInst>(User)) {
// Applying a function does not cause the function to escape.
if (Op->getOperandNumber() == 0)
continue;
// apply instructions do not capture the pointer when it is passed
// indirectly
if (Apply->getArgumentConvention(Op->getOperandNumber() - 1)
.isIndirectConvention())
continue;
// Optionally drill down into an apply to see if the operand is
// captured in or returned from the apply.
if (examineApply && !partialApplyArgumentEscapes(Op))
continue;
}
// partial_apply instructions do not allow the pointer to escape
// when it is passed indirectly, unless the partial_apply itself
// escapes
if (auto *PartialApply = dyn_cast<PartialApplyInst>(User)) {
auto Args = PartialApply->getArguments();
auto Params = PartialApply->getSubstCalleeType()->getParameters();
Params = Params.slice(Params.size() - Args.size(), Args.size());
if (ModConv.isSILIndirect(Params[Op->getOperandNumber() - 1])) {
if (partialApplyEscapes(PartialApply, /*examineApply = */ true))
return true;
continue;
}
}
return true;
}
return false;
}
