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SILGen OSSA support for switch_enum/checked_cast_br, related cleanup

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Use APIs for creating terminator results that handle forwarding
ownership consistently.

Add ManagedValue::forForwardedRValue(SILValue) to handle cleanups
consistently based on ownership forwarding.

Add SILGenBuilder::createForwardedTermResult(SILType type) for
creating termator results with the correct ownership and cleanups.

Add SILGenBuilder::createTermResult(SILType type, ValueOwnershipKind
ownership) that handles cleanup based on terminator result ownership.

Add SILGenBuilder::createOptionalSomeResult(SwitchEnumInst) so a lot
of code doesn't need to deal with unwrapping Optional types,
terminator results, and ownership rules.

Replace the existing "phi" APIs with a single
SILGenBuilder::createPhi(SILType, ValueOwnershipKind) that handles
cleanup based on phi ownership.

Phis and terminator results are fundamentally different and need to be handled differently everywhere. Remove the confusion where terminator results were generated with a "phi argument" API.
This commit is contained in:
Andrew Trick
2021-09-06 12:31:35 -07:00
parent 86c6a46063
commit 8f53a927b0
16 changed files with 200 additions and 139 deletions
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44
lib/SILGen/SILGenPattern.cpp
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@@ -1896,12 +1896,10 @@ void PatternMatchEmission::emitEnumElementObjectDispatch(
CaseBlocks blocks{SGF, rows, sourceType, SGF.B.getInsertionBB()};
RegularLocation loc(PatternMatchStmt, rows[0].Pattern, SGF.SGM.M);
bool isPlusZero =
src.getFinalConsumption() == CastConsumptionKind::BorrowAlways;
SILValue srcValue = src.getFinalManagedValue().forward(SGF);
SGF.B.createSwitchEnum(loc, srcValue, blocks.getDefaultBlock(),
blocks.getCaseBlocks(), blocks.getCounts(),
defaultCastCount);
auto *sei = SGF.B.createSwitchEnum(loc, srcValue, blocks.getDefaultBlock(),
blocks.getCaseBlocks(), blocks.getCounts(),
defaultCastCount);
// Okay, now emit all the cases.
blocks.forEachCase([&](EnumElementDecl *elt, SILBasicBlock *caseBB,
@@ -1920,13 +1918,25 @@ void PatternMatchEmission::emitEnumElementObjectDispatch(
SILType eltTy;
bool hasNonVoidAssocValue = false;
bool hasAssocValue = elt->hasAssociatedValues();
ManagedValue caseResult;
auto caseConsumption = CastConsumptionKind::BorrowAlways;
if (hasAssocValue) {
eltTy = src.getType().getEnumElementType(elt, SGF.SGM.M,
SGF.getTypeExpansionContext());
hasNonVoidAssocValue = !eltTy.getASTType()->isVoid();
caseResult = SGF.B.createForwardedTermResult(eltTy);
// The consumption kind of a switch enum's source and its case result can
// differ. For example, a TakeAlways source may have no ownership because
// it holds a trivial value, but its nontrivial result may be
// Guaranteed. For valid OSSA, we reconcile it with the case result
// value's ownership here.
if (caseResult.getOwnershipKind() == OwnershipKind::Owned)
caseConsumption = CastConsumptionKind::TakeAlways;
}
ConsumableManagedValue eltCMV, origCMV;
ConsumableManagedValue eltCMV;
// Void (i.e. empty) cases.
//
@@ -1937,8 +1947,7 @@ void PatternMatchEmission::emitEnumElementObjectDispatch(
// still need to create the argument. So do that instead of creating the
// empty-tuple. Otherwise, we need to create undef or the empty-tuple.
if (hasAssocValue) {
return {SGF.B.createOwnedPhiArgument(eltTy),
CastConsumptionKind::TakeAlways};
return {caseResult, caseConsumption};
}
// Otherwise, try to avoid making an empty tuple value if it's obviously
@@ -1962,21 +1971,12 @@ void PatternMatchEmission::emitEnumElementObjectDispatch(
} else {
auto *eltTL = &SGF.getTypeLowering(eltTy);
SILValue eltValue;
if (isPlusZero) {
origCMV = {SGF.B.createGuaranteedTransformingTerminatorArgument(eltTy),
CastConsumptionKind::BorrowAlways};
} else {
origCMV = {SGF.B.createOwnedPhiArgument(eltTy),
CastConsumptionKind::TakeAlways};
}
eltCMV = origCMV;
eltCMV = {caseResult, caseConsumption};
// If the payload is boxed, project it.
if (elt->isIndirect() || elt->getParentEnum()->isIndirect()) {
ManagedValue boxedValue =
SGF.B.createProjectBox(loc, origCMV.getFinalManagedValue(), 0);
SGF.B.createProjectBox(loc, eltCMV.getFinalManagedValue(), 0);
eltTL = &SGF.getTypeLowering(boxedValue.getType());
if (eltTL->isLoadable()) {
boxedValue = SGF.B.createLoadBorrow(loc, boxedValue);
@@ -2013,11 +2013,7 @@ void PatternMatchEmission::emitEnumElementObjectDispatch(
// Emit the default block if we needed one.
if (SILBasicBlock *defaultBB = blocks.getDefaultBlock()) {
SGF.B.setInsertionPoint(defaultBB);
if (isPlusZero) {
SGF.B.createGuaranteedTransformingTerminatorArgument(src.getType());
} else {
SGF.B.createOwnedPhiArgument(src.getType());
}
ManagedValue::forForwardedRValue(SGF, sei->createDefaultResult());
outerFailure(rows.back().Pattern);
}
}