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Merged
ASDAlexander77 merged 1 commit into from
Oct 1, 2026
Merged

?? takes the right side only for null or undefined, and a number never equals null #431

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14 changes: 13 additions & 1 deletion tslang/lib/TypeScript/MLIRGenExpressions.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -824,7 +824,19 @@ namespace mlirgen
}
}

auto resultReturnUnions =
return mlirGenBinaryValues(location, opCode, leftExpressionValue, rightExpressionValue, genContext, saveResult);
}

ValueOrLogicalResult MLIRGenImpl::mlirGenBinaryValues(mlir::Location location, SyntaxKind opCode, mlir::Value leftExpressionValue,
mlir::Value rightExpressionValue, const GenContext &genContext,
bool saveResult)
{
if (auto folded = foldNullishCompare(location, opCode, leftExpressionValue, rightExpressionValue))
{
return *folded;
}

auto resultReturnUnions =
binaryOpLogicForUnions(location, opCode, leftExpressionValue, rightExpressionValue, genContext);
if (resultReturnUnions.value || resultReturnUnions.failed())
{
Expand Down
277 changes: 243 additions & 34 deletions tslang/lib/TypeScript/MLIRGenImpl.h
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Expand Up @@ -3055,6 +3055,11 @@ class MLIRGenImpl
auto doneIdent = nf.createIdentifier(S("done"));

NodeArray<ObjectLiteralElementLike> retObjectProperties;
if (stop && expr == SyntaxKind::Identifier && expr.as<Identifier>()->escapedText == S(UNDEFINED_NAME))
{
expr->internalFlags |= InternalFlags::GeneratorDoneValue;
}

auto valueProp = nf.createPropertyAssignment(valueIdent, expr);
retObjectProperties.push_back(valueProp);

Expand Down Expand Up @@ -4757,6 +4762,122 @@ class MLIRGenImpl
return resultFirst;
}

// a type whose values are never null or undefined: a value type - a number, a boolean, a tuple - or a union
// of them only, such as `0 | 1 | 42`
bool isNeverNullish(mlir::Type type)
{
if (auto unionType = dyn_cast<mlir_ts::UnionType>(type))
{
return llvm::all_of(unionType.getTypes(), [&](mlir::Type subType) { return isNeverNullish(subType); });
}

return mth.isValueType(type);
}

// the type without null and undefined: what is left once `?? b` did not take `b`
mlir::Type getNonNullishType(mlir::Type type)
{
if (auto optType = dyn_cast<mlir_ts::OptionalType>(type))
{
return getNonNullishType(optType.getElementType());
}

if (auto unionType = dyn_cast<mlir_ts::UnionType>(type))
{
mlir::SmallVector<mlir::Type> types;
for (auto subType : unionType.getTypes())
{
if (!isa<mlir_ts::NullType>(subType) && !isa<mlir_ts::UndefinedType>(subType))
{
types.push_back(subType);
}
}

if (types.size() > 0 && types.size() < unionType.getTypes().size())
{
return getUnionType(types);
}
}

return type;
}

// whether `value` is null or undefined, by its type: an optional only when it has no value or its value is,
// a value type never; anything else - a union, any, a reference - is compared with null and with undefined
mlir::Value mlirGenIsNullish(mlir::Location location, mlir::Value value, const GenContext &genContext)
{
auto toBoolean = [&](mlir::Value boolValue) -> mlir::Value {
if (boolValue && boolValue.getType() != getBooleanType())
{
auto result = cast(location, getBooleanType(), boolValue, genContext);
return result.failed_or_no_value() ? mlir::Value() : V(result);
}

return boolValue;
};

auto type = value.getType();
if (isa<mlir_ts::NullType>(type) || isa<mlir_ts::UndefinedType>(type))
{
return toBoolean(V(mlirGenBooleanValue(location, true)));
}

if (auto optType = dyn_cast<mlir_ts::OptionalType>(type))
{
auto hasValue = builder.create<mlir_ts::HasValueOp>(location, getBooleanType(), value);
auto elementType = optType.getElementType();

// the value is tested only when there is one
auto ifOp = builder.create<mlir_ts::IfOp>(location, mlir::TypeRange{getBooleanType()}, hasValue, true);
builder.setInsertionPointToStart(&ifOp.getThenRegion().front());
mlir::Value valueIsNullish;
if (isNeverNullish(elementType))
{
valueIsNullish = toBoolean(V(mlirGenBooleanValue(location, false)));
}
else
{
auto innerValue = builder.create<mlir_ts::ValueOp>(location, elementType, value);
valueIsNullish = mlirGenIsNullish(location, innerValue, genContext);
if (!valueIsNullish)
{
return mlir::Value();
}
}

builder.create<mlir_ts::ResultOp>(location, mlir::ValueRange{valueIsNullish});

builder.setInsertionPointToStart(&ifOp.getElseRegion().front());
builder.create<mlir_ts::ResultOp>(location, mlir::ValueRange{toBoolean(V(mlirGenBooleanValue(location, true)))});

builder.setInsertionPointAfter(ifOp);
return ifOp.getResult(0);
}

if (isNeverNullish(type))
{
return toBoolean(V(mlirGenBooleanValue(location, false)));
}

auto isNull = mlirGenBinaryValues(location, SyntaxKind::EqualsEqualsEqualsToken, value,
builder.create<mlir_ts::NullOp>(location, getNullType()), genContext);
if (isNull.failed_or_no_value())
{
return mlir::Value();
}

auto isUndefined = mlirGenBinaryValues(location, SyntaxKind::EqualsEqualsEqualsToken, value,
builder.create<mlir_ts::UndefOp>(location, getUndefinedType()), genContext);
if (isUndefined.failed_or_no_value())
{
return mlir::Value();
}

return builder.create<mlir_ts::ArithmeticBinaryOp>(
location, getBooleanType(), builder.getI32IntegerAttr((int)SyntaxKind::BarToken), toBoolean(V(isNull)),
toBoolean(V(isUndefined)));
}

ValueOrLogicalResult mlirGenQuestionQuestionLogic(BinaryExpression binaryExpressionAST, bool saveResult,
const GenContext &genContext)
{
Expand All @@ -4770,42 +4891,22 @@ class MLIRGenImpl
EXIT_IF_FAILED_OR_NO_VALUE(result)
auto leftExpressionValue = V(result);

// `a ?? b` is `b` only when `a` is null or undefined, so its type is `a`'s without them, or `b`'s
auto leftNonNullishType = getNonNullishType(leftExpressionValue.getType());
// `a` that is only null or undefined - `x` narrowed so by `x = null` - always gives `b`
auto leftAlwaysNullish =
isa<mlir_ts::NullType>(leftNonNullishType) || isa<mlir_ts::UndefinedType>(leftNonNullishType);
auto resultWhenFalseType = evaluate(rightExpression, genContext);
auto defaultUnionType = getUnionType(location, leftExpressionValue.getType(), resultWhenFalseType);
auto defaultUnionType = getUnionType(location, leftNonNullishType, resultWhenFalseType);
auto merged = false;
auto resultType = mth.findBaseType(resultWhenFalseType, leftExpressionValue.getType(), merged, defaultUnionType);
auto resultType = leftAlwaysNullish
? resultWhenFalseType
: mth.findBaseType(resultWhenFalseType, leftNonNullishType, merged, defaultUnionType);

// extarct value from optional type
auto actualLeftValue = leftExpressionValue;
auto hasOptional = false;
if (auto optType = dyn_cast<mlir_ts::OptionalType>(actualLeftValue.getType()))
auto ifCond = mlirGenIsNullish(location, leftExpressionValue, genContext);
if (!ifCond)
{
hasOptional = true;
CAST(actualLeftValue, location, optType.getElementType(), leftExpressionValue, genContext);
}

CAST_A(opaqueValueOfLeftValue, location, getOpaqueType(), actualLeftValue, genContext);

auto nullVal = builder.create<mlir_ts::NullOp>(location, getNullType());

auto compareToNull = builder.create<mlir_ts::LogicalBinaryOp>(
location, getBooleanType(), builder.getI32IntegerAttr((int)SyntaxKind::EqualsEqualsEqualsToken), opaqueValueOfLeftValue,
nullVal);

mlir::Value ifCond = compareToNull;
if (hasOptional)
{
CAST_A(hasValue, location, getBooleanType(), leftExpressionValue, genContext);
CAST_A(isFalse, location, getBooleanType(), mlirGenBooleanValue(location, false), genContext);
auto compareToFalse = builder.create<mlir_ts::LogicalBinaryOp>(
location, getBooleanType(), builder.getI32IntegerAttr((int)SyntaxKind::EqualsEqualsEqualsToken), isFalse,
hasValue);

auto orOp = builder.create<mlir_ts::ArithmeticBinaryOp>(
location, getBooleanType(), builder.getI32IntegerAttr((int)SyntaxKind::BarToken), compareToFalse,
compareToNull);

ifCond = orOp;
return mlir::failure();
}

auto ifOp = builder.create<mlir_ts::IfOp>(location, mlir::TypeRange{resultType}, ifCond, true);
Expand All @@ -4829,9 +4930,34 @@ class MLIRGenImpl
builder.create<mlir_ts::ResultOp>(location, mlir::ValueRange{resultTrue});

builder.setInsertionPointToStart(&ifOp.getElseRegion().front());
auto resultFalse = leftExpressionValue;
if (leftAlwaysNullish)
{
// never taken
builder.create<mlir_ts::ResultOp>(location, mlir::ValueRange{builder.create<mlir_ts::UndefOp>(location, resultType)});
builder.setInsertionPointAfter(ifOp);
auto ifResult = ifOp.getResults().front();
if (saveResult)
{
return mlirGenSaveLogicOneItem(location, leftExpressionValue, ifResult, genContext);
}

if (mlir::failed(instantiateGenericsForBinaryOp(location, leftExpressionValue, resultFalse, genContext)))
return ifResult;
}

// here `a` is neither null nor undefined: take it as such
mlir::Value resultFalse = leftExpressionValue;
if (auto optType = dyn_cast<mlir_ts::OptionalType>(resultFalse.getType()))
{
resultFalse = builder.create<mlir_ts::ValueOp>(location, optType.getElementType(), resultFalse);
}

if (isa<mlir_ts::UnionType>(resultFalse.getType()) && resultFalse.getType() != leftNonNullishType)
{
resultFalse = castToNarrowedType(location, resultFalse, leftNonNullishType, genContext);
VALIDATE(resultFalse, location)
}

if (mlir::failed(instantiateGenericsForBinaryOp(location, leftExpressionValue, resultFalse, genContext)))
{
return mlir::failure();
}
Expand Down Expand Up @@ -8520,6 +8646,79 @@ class MLIRGenImpl
return mlirGenBooleanValue(location, isEquals ? namesMatch : !namesMatch);
}

// A compare with null or undefined whose answer the type gives: a value type - a number, a boolean, a tuple -
// is neither, and an optional of one holds undefined or a value, never null. Lowered as they were, `0 === null`
// compared the number with null read as 0, and was true.
std::optional<ValueOrLogicalResult> foldNullishCompare(mlir::Location location, SyntaxKind opCode,
mlir::Value leftValue, mlir::Value rightValue)
{
auto isEquals = opCode == SyntaxKind::EqualsEqualsToken || opCode == SyntaxKind::EqualsEqualsEqualsToken;
auto isNotEquals = opCode == SyntaxKind::ExclamationEqualsToken || opCode == SyntaxKind::ExclamationEqualsEqualsToken;
if (!isEquals && !isNotEquals)
{
return std::nullopt;
}

auto isLoose = opCode == SyntaxKind::EqualsEqualsToken || opCode == SyntaxKind::ExclamationEqualsToken;
auto isNullish = [](mlir::Type type) { return isa<mlir_ts::NullType>(type) || isa<mlir_ts::UndefinedType>(type); };

mlir::Value otherValue;
mlir::Type nullishType;
if (isNullish(rightValue.getType()) && !isNullish(leftValue.getType()))
{
otherValue = leftValue;
nullishType = rightValue.getType();
}
else if (isNullish(leftValue.getType()) && !isNullish(rightValue.getType()))
{
otherValue = rightValue;
nullishType = leftValue.getType();
}
else
{
return std::nullopt;
}

auto otherType = otherValue.getType();
if (isNeverNullish(otherType))
{
return mlirGenBooleanValue(location, isNotEquals);
}

auto optType = dyn_cast<mlir_ts::OptionalType>(otherType);
if (!optType || !isNeverNullish(optType.getElementType()))
{
return std::nullopt;
}

if (isa<mlir_ts::NullType>(nullishType))
{
if (!isLoose)
{
return mlirGenBooleanValue(location, isNotEquals);
}

// `== null` matches undefined too: the optional has no value
mlir::Value hasValue = builder.create<mlir_ts::HasValueOp>(location, getBooleanType(), otherValue);
if (isNotEquals)
{
return hasValue;
}

auto falseValue = builder.create<mlir_ts::ConstantOp>(location, getBooleanType(), builder.getBoolAttr(false));
return V(builder.create<mlir_ts::LogicalBinaryOp>(
location, getBooleanType(), builder.getI32IntegerAttr((int)SyntaxKind::EqualsEqualsEqualsToken), hasValue,
falseValue));
}

// an optional compared with undefined is handled as it was
return std::nullopt;
}

ValueOrLogicalResult mlirGenBinaryValues(mlir::Location location, SyntaxKind opCode, mlir::Value leftExpressionValue,
mlir::Value rightExpressionValue, const GenContext &genContext,
bool saveResult = false);

ValueOrLogicalResult mlirGen(TrueLiteral trueLiteral, const GenContext &genContext);

ValueOrLogicalResult mlirGen(FalseLiteral falseLiteral, const GenContext &genContext);
Expand Down Expand Up @@ -9557,6 +9756,16 @@ class MLIRGenImpl
EXIT_IF_FAILED_OR_NO_VALUE(result)
itemValue = V(result);

// a finished generator's value, of a value type - a number, a boolean, a tuple: its zero, as the cast
// of undefined to it lowers to (see UndefOpLowering), without that cast's warning in every generator
// of such a T. Other types keep the cast: to a string it is the text "undefined".
if (!!(propertyAssignment->initializer->internalFlags & InternalFlags::GeneratorDoneValue)
&& receiverElementType && isa<mlir_ts::UndefinedType>(itemValue.getType())
&& mth.isValueType(receiverElementType))
{
itemValue = builder.create<mlir_ts::UndefOp>(location, receiverElementType);
}

// in case of Union type
if (oli.receiverType && !receiverElementType)
{
Expand Down
2 changes: 2 additions & 0 deletions tslang/test/tester/CMakeLists.txt
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Expand Up @@ -397,6 +397,7 @@ tslang_add_test(NAME test-compile-00-optional-fields COMMAND test-runner "${PROJ
tslang_add_test(NAME test-compile-00-generator-return COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00generator_return.ts")
tslang_add_test(NAME test-compile-00-return-inference-undefined COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00return_inference_undefined.ts")
tslang_add_test(NAME test-compile-00-return-falls-off-end COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00return_falls_off_end.ts")
tslang_add_test(NAME test-compile-00-nullish-values COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00nullish_values.ts")
tslang_add_test(NAME test-compile-00-intersection-type COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00intersection_type.ts")
tslang_add_test(NAME test-compile-00-intersection-type-generic COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00intersection_type_generic.ts")
tslang_add_test(NAME test-compile-00-length COMMAND test-runner "${PROJECT_SOURCE_DIR}/test/tester/tests/00length.ts")
Expand Down Expand Up @@ -877,6 +878,7 @@ tslang_add_test(NAME test-jit-00-optional-fields COMMAND test-runner -jit "${PRO
tslang_add_test(NAME test-jit-00-generator-return COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00generator_return.ts")
tslang_add_test(NAME test-jit-00-return-inference-undefined COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00return_inference_undefined.ts")
tslang_add_test(NAME test-jit-00-return-falls-off-end COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00return_falls_off_end.ts")
tslang_add_test(NAME test-jit-00-nullish-values COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00nullish_values.ts")
tslang_add_test(NAME test-jit-00-union-global-init COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00union_global_init.ts")
tslang_add_test(NAME test-jit-00-intersection-type COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00intersection_type.ts")
tslang_add_test(NAME test-jit-00-intersection-type-generic COMMAND test-runner -jit "${PROJECT_SOURCE_DIR}/test/tester/tests/00intersection_type_generic.ts")
Expand Down
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