| //===--- SILConstants.h - SIL constant representation -----------*- C++ -*-===// |
| // |
| // This source file is part of the Swift.org open source project |
| // |
| // Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors |
| // Licensed under Apache License v2.0 with Runtime Library Exception |
| // |
| // See https://swift.org/LICENSE.txt for license information |
| // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This defines an interface to represent SIL level structured constants in a |
| // memory efficient way. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef SWIFT_SIL_CONSTANTS_H |
| #define SWIFT_SIL_CONSTANTS_H |
| |
| #include "swift/SIL/SILValue.h" |
| #include "llvm/Support/CommandLine.h" |
| |
| |
| namespace swift { |
| class SingleValueInstruction; |
| class SILValue; |
| class SILBuilder; |
| class SerializedSILLoader; |
| |
| struct APIntSymbolicValue; |
| struct ArraySymbolicValue; |
| struct EnumWithPayloadSymbolicValue; |
| struct UnknownSymbolicValue; |
| |
| extern llvm::cl::opt<unsigned> ConstExprLimit; |
| |
| /// When we fail to constant fold a value, this captures a reason why, |
| /// allowing the caller to produce a specific diagnostic. The "Unknown" |
| /// SymbolicValue representation also includes a pointer to the SILNode in |
| /// question that was problematic. |
| enum class UnknownReason { |
| // TODO: Eliminate the default code, by making classifications for each |
| // failure mode. |
| Default, |
| |
| /// The constant expression was too big. This is reported on a random |
| /// instruction within the constexpr that triggered the issue. |
| TooManyInstructions, |
| |
| /// A control flow loop was found. |
| Loop, |
| |
| /// Integer overflow detected. |
| Overflow, |
| |
| /// Unspecified trap detected. |
| Trap, |
| }; |
| |
| /// This is the symbolic value tracked for each SILValue in a scope. We |
| /// support multiple representational forms for the constant node in order to |
| /// avoid pointless memory bloat + copying. This is intended to be a |
| /// light-weight POD type we can put in hash tables and pass around by-value. |
| /// |
| /// Internally, this value has multiple ways to represent the same sorts of |
| /// symbolic values (e.g. to save memory). It provides a simpler public |
| /// interface though. |
| class SymbolicValue { |
| private: |
| enum RepresentationKind { |
| /// This symbolic value cannot be determined, carries multiple values |
| /// (i.e., varies dynamically at the top level), or is of some type that |
| /// we cannot analyze and propagate (e.g. NSObject). |
| /// |
| RK_Unknown, |
| |
| /// This value is known to be a metatype reference. The type is stored |
| /// in the "metatype" member. |
| RK_Metatype, |
| |
| /// This value is known to be a function reference, e.g. through |
| /// function_ref directly, or a devirtualized method reference. |
| RK_Function, |
| |
| /// This value is represented with a bump-pointer allocated APInt. |
| RK_Integer, |
| |
| /// This value is represented with an inline integer representation. |
| RK_IntegerInline, |
| |
| /// This value is a struct or tuple of constants. This is tracked by the |
| /// "aggregate" member of the value union. |
| RK_Aggregate, |
| }; |
| |
| union { |
| /// When the value is Unknown, this contains information about the |
| /// unfoldable part of the computation. |
| UnknownSymbolicValue *unknown; |
| |
| /// This is always a SILType with an object category. This is the value |
| /// of the underlying instance type, not the MetatypeType. |
| TypeBase *metatype; |
| |
| SILFunction *function; |
| |
| /// When this SymbolicValue is of "Integer" kind, this pointer stores |
| /// the words of the APInt value it holds. |
| uint64_t *integer; |
| |
| /// This holds the bits of an integer for an inline representation. |
| uint64_t integerInline; |
| |
| /// When this SymbolicValue is of "Aggregate" kind, this pointer stores |
| /// information about the array elements and count. |
| const SymbolicValue *aggregate; |
| } value; |
| |
| RepresentationKind representationKind : 8; |
| |
| union { |
| /// This is the reason code for RK_Unknown values. |
| UnknownReason unknownReason : 32; |
| |
| /// This is the number of bits in an RK_Integer or RK_IntegerInline |
| /// representation, which makes the number of entries in the list derivable. |
| unsigned integerBitwidth; |
| |
| /// This is the number of elements for an RK_Aggregate representation. |
| unsigned aggregateNumElements; |
| } auxInfo; |
| |
| public: |
| /// This enum is used to indicate the sort of value held by a SymbolicValue |
| /// independent of its concrete representation. This is the public |
| /// interface to SymbolicValue. |
| enum Kind { |
| /// This is a value that isn't a constant. |
| Unknown, |
| |
| /// This is a known metatype value. |
| Metatype, |
| |
| /// This is a function, represented as a SILFunction. |
| Function, |
| |
| /// This is an integer constant. |
| Integer, |
| |
| /// This can be an array, struct, tuple, etc. |
| Aggregate, |
| }; |
| |
| /// For constant values, return the type classification of this value. |
| Kind getKind() const; |
| |
| /// Return true if this represents a constant value. |
| bool isConstant() const { |
| auto kind = getKind(); |
| return kind != Unknown; |
| } |
| |
| static SymbolicValue getUnknown(SILNode *node, UnknownReason reason, |
| llvm::ArrayRef<SourceLoc> callStack, |
| ASTContext &astContext); |
| |
| /// Return true if this represents an unknown result. |
| bool isUnknown() const { return getKind() == Unknown; } |
| |
| /// Return the call stack for an unknown result. |
| ArrayRef<SourceLoc> getUnknownCallStack() const; |
| |
| /// Return the node that triggered an unknown result. |
| SILNode *getUnknownNode() const; |
| |
| /// Return the reason an unknown result was generated. |
| UnknownReason getUnknownReason() const; |
| |
| static SymbolicValue getMetatype(CanType type) { |
| SymbolicValue result; |
| result.representationKind = RK_Metatype; |
| result.value.metatype = type.getPointer(); |
| return result; |
| } |
| |
| CanType getMetatypeValue() const { |
| assert(representationKind == RK_Metatype); |
| return CanType(value.metatype); |
| } |
| |
| static SymbolicValue getFunction(SILFunction *fn) { |
| assert(fn && "Function cannot be null"); |
| SymbolicValue result; |
| result.representationKind = RK_Function; |
| result.value.function = fn; |
| return result; |
| } |
| |
| SILFunction *getFunctionValue() const { |
| assert(getKind() == Function); |
| return value.function; |
| } |
| |
| static SymbolicValue getInteger(int64_t value, unsigned bitWidth); |
| static SymbolicValue getInteger(const APInt &value, |
| ASTContext &astContext); |
| |
| APInt getIntegerValue() const; |
| unsigned getIntegerValueBitWidth() const; |
| |
| /// This returns an aggregate value with the specified elements in it. This |
| /// copies the elements into the specified ASTContext. |
| static SymbolicValue getAggregate(ArrayRef<SymbolicValue> elements, |
| ASTContext &astContext); |
| |
| ArrayRef<SymbolicValue> getAggregateValue() const; |
| |
| //===--------------------------------------------------------------------===// |
| // Helpers |
| |
| /// Dig through single element aggregates, return the ultimate thing inside of |
| /// it. This is useful when dealing with integers and floats, because they |
| /// are often wrapped in single-element struct wrappers. |
| SymbolicValue lookThroughSingleElementAggregates() const; |
| |
| /// Given that this is an 'Unknown' value, emit diagnostic notes providing |
| /// context about what the problem is. If there is no location for some |
| /// reason, we fall back to using the specified location. |
| void emitUnknownDiagnosticNotes(SILLocation fallbackLoc); |
| |
| /// Clone this SymbolicValue into the specified ASTContext and return the new |
| /// version. This only works for valid constants. |
| SymbolicValue cloneInto(ASTContext &astContext) const; |
| |
| void print(llvm::raw_ostream &os, unsigned indent = 0) const; |
| void dump() const; |
| }; |
| |
| static_assert(sizeof(SymbolicValue) == 2 * sizeof(void *), |
| "SymbolicValue should stay small"); |
| static_assert(std::is_pod<SymbolicValue>::value, |
| "SymbolicValue should stay POD"); |
| |
| inline llvm::raw_ostream &operator<<(llvm::raw_ostream &os, SymbolicValue val) { |
| val.print(os); |
| return os; |
| } |
| |
| } // end namespace swift |
| |
| #endif |