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[sil-combine] Fix a couple of oversights in the propagation of concrete types of existentials

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- Do not try to make a lookup type of a witness_method more concrete if it not an opened existential.
- Replace witness_method instruction by a new one with a more concrete type only in the specific apply instruction instead of doing it everywhere. This allows for more optimization opportunities if the same witness_method is used by multiple apply instructions.
This commit is contained in:
Roman Levenstein
2016-10-17 10:41:58 -07:00
parent a4d7b37eec
commit 1e6edcbcc5
2 changed files with 41 additions and 4 deletions
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20
lib/SILOptimizer/SILCombiner/SILCombinerApplyVisitors.cpp
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@@ -871,12 +871,17 @@ SILCombiner::propagateConcreteTypeOfInitExistential(FullApplySite AI,
return nullptr;
}
// Obtain the protocol whose which should be used by the conformance.
// The lookup type is not a opened existential type,
// thus it cannot be made more concrete.
if (!WMI->getLookupType()->isOpenedExistential())
return nullptr;
// Obtain the protocol which should be used by the conformance.
auto *PD = WMI->getLookupProtocol();
// Propagate the concrete type into a callee-operand, which is a
// witness_method instruction.
auto PropagateIntoOperand = [this, &WMI](CanType ConcreteType,
auto PropagateIntoOperand = [this, &WMI, &AI](CanType ConcreteType,
ProtocolConformanceRef Conformance) {
// Keep around the dependence on the open instruction unless we've
// actually eliminated the use.
@@ -885,8 +890,15 @@ SILCombiner::propagateConcreteTypeOfInitExistential(FullApplySite AI,
Conformance, WMI->getMember(),
WMI->getType(),
WMI->isVolatile());
replaceInstUsesWith(*WMI, NewWMI);
eraseInstFromFunction(*WMI);
// Replace only uses of the witness_method in the apply that is going to
// be changed.
MutableArrayRef<Operand> Operands = AI.getInstruction()->getAllOperands();
for (auto &Op : Operands) {
if (Op.get() == WMI)
Op.set(NewWMI);
}
if (WMI->use_empty())
eraseInstFromFunction(*WMI);
};
// Try to perform the propagation.