| //===-- llvm/Constant.h - Constant class definition -------------*- C++ -*-===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file contains the declaration of the Constant class. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_IR_CONSTANT_H |
| #define LLVM_IR_CONSTANT_H |
| |
| #include "llvm/IR/User.h" |
| #include "llvm/IR/Value.h" |
| #include "llvm/Support/Casting.h" |
| |
| namespace llvm { |
| |
| class APInt; |
| |
| /// This is an important base class in LLVM. It provides the common facilities |
| /// of all constant values in an LLVM program. A constant is a value that is |
| /// immutable at runtime. Functions are constants because their address is |
| /// immutable. Same with global variables. |
| /// |
| /// All constants share the capabilities provided in this class. All constants |
| /// can have a null value. They can have an operand list. Constants can be |
| /// simple (integer and floating point values), complex (arrays and structures), |
| /// or expression based (computations yielding a constant value composed of |
| /// only certain operators and other constant values). |
| /// |
| /// Note that Constants are immutable (once created they never change) |
| /// and are fully shared by structural equivalence. This means that two |
| /// structurally equivalent constants will always have the same address. |
| /// Constants are created on demand as needed and never deleted: thus clients |
| /// don't have to worry about the lifetime of the objects. |
| /// LLVM Constant Representation |
| class Constant : public User { |
| protected: |
| Constant(Type *ty, ValueTy vty, Use *Ops, unsigned NumOps) |
| : User(ty, vty, Ops, NumOps) {} |
| |
| public: |
| void operator=(const Constant &) = delete; |
| Constant(const Constant &) = delete; |
| |
| /// Return true if this is the value that would be returned by getNullValue. |
| bool isNullValue() const; |
| |
| /// Returns true if the value is one. |
| bool isOneValue() const; |
| |
| /// Return true if this is the value that would be returned by |
| /// getAllOnesValue. |
| bool isAllOnesValue() const; |
| |
| /// Return true if the value is what would be returned by |
| /// getZeroValueForNegation. |
| bool isNegativeZeroValue() const; |
| |
| /// Return true if the value is negative zero or null value. |
| bool isZeroValue() const; |
| |
| /// Return true if the value is not the smallest signed value. |
| bool isNotMinSignedValue() const; |
| |
| /// Return true if the value is the smallest signed value. |
| bool isMinSignedValue() const; |
| |
| /// Return true if this is a finite and non-zero floating-point scalar |
| /// constant or a vector constant with all finite and non-zero elements. |
| bool isFiniteNonZeroFP() const; |
| |
| /// Return true if this is a normal (as opposed to denormal) floating-point |
| /// scalar constant or a vector constant with all normal elements. |
| bool isNormalFP() const; |
| |
| /// Return true if this scalar has an exact multiplicative inverse or this |
| /// vector has an exact multiplicative inverse for each element in the vector. |
| bool hasExactInverseFP() const; |
| |
| /// Return true if this is a floating-point NaN constant or a vector |
| /// floating-point constant with all NaN elements. |
| bool isNaN() const; |
| |
| /// Return true if this is a vector constant that includes any undefined |
| /// elements. |
| bool containsUndefElement() const; |
| |
| /// Return true if this is a vector constant that includes any constant |
| /// expressions. |
| bool containsConstantExpression() const; |
| |
| /// Return true if evaluation of this constant could trap. This is true for |
| /// things like constant expressions that could divide by zero. |
| bool canTrap() const; |
| |
| /// Return true if the value can vary between threads. |
| bool isThreadDependent() const; |
| |
| /// Return true if the value is dependent on a dllimport variable. |
| bool isDLLImportDependent() const; |
| |
| /// Return true if the constant has users other than constant expressions and |
| /// other dangling things. |
| bool isConstantUsed() const; |
| |
| /// This method classifies the entry according to whether or not it may |
| /// generate a relocation entry. This must be conservative, so if it might |
| /// codegen to a relocatable entry, it should say so. |
| /// |
| /// FIXME: This really should not be in IR. |
| bool needsRelocation() const; |
| |
| /// For aggregates (struct/array/vector) return the constant that corresponds |
| /// to the specified element if possible, or null if not. This can return null |
| /// if the element index is a ConstantExpr, if 'this' is a constant expr or |
| /// if the constant does not fit into an uint64_t. |
| Constant *getAggregateElement(unsigned Elt) const; |
| Constant *getAggregateElement(Constant *Elt) const; |
| |
| /// If this is a splat vector constant, meaning that all of the elements have |
| /// the same value, return that value. Otherwise return 0. |
| Constant *getSplatValue() const; |
| |
| /// If C is a constant integer then return its value, otherwise C must be a |
| /// vector of constant integers, all equal, and the common value is returned. |
| const APInt &getUniqueInteger() const; |
| |
| /// Called if some element of this constant is no longer valid. |
| /// At this point only other constants may be on the use_list for this |
| /// constant. Any constants on our Use list must also be destroy'd. The |
| /// implementation must be sure to remove the constant from the list of |
| /// available cached constants. Implementations should implement |
| /// destroyConstantImpl to remove constants from any pools/maps they are |
| /// contained it. |
| void destroyConstant(); |
| |
| //// Methods for support type inquiry through isa, cast, and dyn_cast: |
| static bool classof(const Value *V) { |
| static_assert(ConstantFirstVal == 0, "V->getValueID() >= ConstantFirstVal always succeeds"); |
| return V->getValueID() <= ConstantLastVal; |
| } |
| |
| /// This method is a special form of User::replaceUsesOfWith |
| /// (which does not work on constants) that does work |
| /// on constants. Basically this method goes through the trouble of building |
| /// a new constant that is equivalent to the current one, with all uses of |
| /// From replaced with uses of To. After this construction is completed, all |
| /// of the users of 'this' are replaced to use the new constant, and then |
| /// 'this' is deleted. In general, you should not call this method, instead, |
| /// use Value::replaceAllUsesWith, which automatically dispatches to this |
| /// method as needed. |
| /// |
| void handleOperandChange(Value *, Value *); |
| |
| static Constant *getNullValue(Type* Ty); |
| |
| /// @returns the value for an integer or vector of integer constant of the |
| /// given type that has all its bits set to true. |
| /// Get the all ones value |
| static Constant *getAllOnesValue(Type* Ty); |
| |
| /// Return the value for an integer or pointer constant, or a vector thereof, |
| /// with the given scalar value. |
| static Constant *getIntegerValue(Type *Ty, const APInt &V); |
| |
| /// If there are any dead constant users dangling off of this constant, remove |
| /// them. This method is useful for clients that want to check to see if a |
| /// global is unused, but don't want to deal with potentially dead constants |
| /// hanging off of the globals. |
| void removeDeadConstantUsers() const; |
| |
| const Constant *stripPointerCasts() const { |
| return cast<Constant>(Value::stripPointerCasts()); |
| } |
| |
| Constant *stripPointerCasts() { |
| return const_cast<Constant*>( |
| static_cast<const Constant *>(this)->stripPointerCasts()); |
| } |
| }; |
| |
| } // end namespace llvm |
| |
| #endif // LLVM_IR_CONSTANT_H |