//===-- 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 constant and a constant 'Y' are element-wise equal. | |

/// This is identical to just comparing the pointers, with the exception that | |

/// for vectors, if only one of the constants has an `undef` element in some | |

/// lane, the constants still match. | |

bool isElementWiseEqual(Value *Y) 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 |