SILInstruction *SILCombiner::visitSelectEnumInst(SelectEnumInst *SEI) {
// Canonicalize a select_enum: if the default refers to exactly one case, then
// replace the default with that case.
if (SEI->hasDefault()) {
NullablePtr<EnumElementDecl> elementDecl = SEI->getUniqueCaseForDefault();
if (elementDecl.isNonNull()) {
// Construct a new instruction by copying all the case entries.
SmallVector<std::pair<EnumElementDecl *, SILValue>, 4> CaseValues;
for (int idx = 0, numIdcs = SEI->getNumCases(); idx < numIdcs; idx++) {
CaseValues.push_back(SEI->getCase(idx));
}
// Add the default-entry of the original instruction as case-entry.
CaseValues.push_back(
std::make_pair(elementDecl.get(), SEI->getDefaultResult()));
return Builder.createSelectEnum(SEI->getLoc(), SEI->getEnumOperand(),
SEI->getType(), SILValue(), CaseValues);
}
}
// TODO: We should be able to flat-out replace the select_enum instruction
// with the selected value in another pass. For parity with the enum_is_tag
// combiner pass, handle integer literals for now.
auto *EI = dyn_cast<EnumInst>(SEI->getEnumOperand());
if (!EI)
return nullptr;
SILValue selected;
for (unsigned i = 0, e = SEI->getNumCases(); i < e; ++i) {
auto casePair = SEI->getCase(i);
if (casePair.first == EI->getElement()) {
selected = casePair.second;
break;
}
}
if (!selected)
selected = SEI->getDefaultResult();
if (auto *ILI = dyn_cast<IntegerLiteralInst>(selected)) {
return Builder.createIntegerLiteral(ILI->getLoc(), ILI->getType(),
ILI->getValue());
}
return nullptr;
}
SILInstruction *SILCombiner::visitSelectEnumAddrInst(SelectEnumAddrInst *SEAI) {
// Canonicalize a select_enum_addr: if the default refers to exactly one case,
// then replace the default with that case.
Builder.setCurrentDebugScope(SEAI->getDebugScope());
if (SEAI->hasDefault()) {
NullablePtr<EnumElementDecl> elementDecl = SEAI->getUniqueCaseForDefault();
if (elementDecl.isNonNull()) {
// Construct a new instruction by copying all the case entries.
SmallVector<std::pair<EnumElementDecl *, SILValue>, 4> CaseValues;
for (int idx = 0, numIdcs = SEAI->getNumCases(); idx < numIdcs; idx++) {
CaseValues.push_back(SEAI->getCase(idx));
}
// Add the default-entry of the original instruction as case-entry.
CaseValues.push_back(
std::make_pair(elementDecl.get(), SEAI->getDefaultResult()));
return Builder.createSelectEnumAddr(SEAI->getLoc(),
SEAI->getEnumOperand(),
SEAI->getType(), SILValue(),
CaseValues);
}
}
// Promote select_enum_addr to select_enum if the enum is loadable.
// = select_enum_addr %ptr : $*Optional<SomeClass>, case ...
// ->
// %value = load %ptr
// = select_enum %value
SILType Ty = SEAI->getEnumOperand().getType();
if (!Ty.isLoadable(SEAI->getModule()))
return nullptr;
SmallVector<std::pair<EnumElementDecl*, SILValue>, 8> Cases;
for (int i = 0, e = SEAI->getNumCases(); i < e; ++i)
Cases.push_back(SEAI->getCase(i));
SILValue Default = SEAI->hasDefault() ? SEAI->getDefaultResult() : SILValue();
LoadInst *EnumVal = Builder.createLoad(SEAI->getLoc(),
SEAI->getEnumOperand());
auto *I = Builder.createSelectEnum(SEAI->getLoc(), EnumVal, SEAI->getType(),
Default, Cases);
return I;
}