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[semantic-sil] Make emitEnumElementDispatchWithOwnership conform to ownership.

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This means inserting an eager copy on the switch operand, eliminating the
unforwarding, and destroying the copy in the default case as well as the normal
cases.

I did not refactor this code to use the switch enum builder, but at some point
it should be refactored as such.
This commit is contained in:
Michael Gottesman
2017-03-27 13:12:50 -07:00
parent ba1e9f76d8
commit eaa229b9f8
1 changed files with 11 additions and 25 deletions
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36
lib/SILGen/SILGenPattern.cpp
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@@ -1575,6 +1575,9 @@ void PatternMatchEmission::emitEnumElementDispatchWithOwnership(
ArrayRef<RowToSpecialize> rows, ConsumableManagedValue src,
const SpecializationHandler &handleCase,
const FailureHandler &outerFailure) {
assert(src.getFinalConsumption() != CastConsumptionKind::TakeOnSuccess &&
"SIL ownership does not support TakeOnSuccess");
CanType sourceType = rows[0].Pattern->getType()->getCanonicalType();
struct CaseInfo {
@@ -1675,9 +1678,11 @@ void PatternMatchEmission::emitEnumElementDispatchWithOwnership(
assert(caseBBs.size() == caseInfos.size());
SILValue srcValue = src.getFinalManagedValue().forward(SGF);
SILLocation loc = PatternMatchStmt;
loc.setDebugLoc(rows[0].Pattern);
// SEMANTIC SIL TODO: Once we have the representation of a switch_enum that
// can take a +0 value, this extra copy should be a borrow.
SILValue srcValue = src.getFinalManagedValue().copy(SGF, loc).forward(SGF);
SGF.B.createSwitchEnum(loc, srcValue, defaultBB, caseBBs);
// Okay, now emit all the cases.
@@ -1734,23 +1739,12 @@ void PatternMatchEmission::emitEnumElementDispatchWithOwnership(
} else {
auto *eltTL = &SGF.getTypeLowering(eltTy);
// Normally we'd just use the consumption of the source
// because the difference between TakeOnSuccess and TakeAlways
// doesn't matter for irrefutable rows. But if we need to
// re-abstract, we'll see a lot of benefit from figuring out
// that we can use TakeAlways here.
auto eltConsumption = src.getFinalConsumption();
if (caseInfo.Irrefutable &&
eltConsumption == CastConsumptionKind::TakeOnSuccess) {
assert(!SGF.F.getModule().getOptions().EnableSILOwnership &&
"TakeOnSuccess is not supported when compiling with ownership");
eltConsumption = CastConsumptionKind::TakeAlways;
}
SILValue eltValue =
caseBB->createPHIArgument(eltTy, ValueOwnershipKind::Owned);
origCMV = getManagedSubobject(SGF, eltValue, *eltTL, eltConsumption);
// We performed a copy early, so we get a +1 value here.
origCMV = getManagedSubobject(SGF, eltValue, *eltTL,
CastConsumptionKind::TakeAlways);
eltCMV = origCMV;
// If the payload is boxed, project it.
@@ -1786,22 +1780,14 @@ void PatternMatchEmission::emitEnumElementDispatchWithOwnership(
substEltTy);
}
const FailureHandler *innerFailure = &outerFailure;
FailureHandler specializedFailure = [&](SILLocation loc) {
ArgUnforwarder unforwarder(SGF);
unforwarder.unforwardBorrowedValues(src, origCMV);
outerFailure(loc);
};
if (ArgUnforwarder::requiresUnforwarding(SGF, src))
innerFailure = &specializedFailure;
handleCase(eltCMV, specializedRows, *innerFailure);
handleCase(eltCMV, specializedRows, outerFailure);
assert(!SGF.B.hasValidInsertionPoint() && "did not end block");
}
// Emit the default block if we needed one.
if (defaultBB) {
SGF.B.setInsertionPoint(defaultBB);
SGF.B.createOwnedPHIArgument(src.getType());
outerFailure(rows.back().Pattern);
}
}