//===-- llvm/Constant.h - Constant class definition -------------*- C++ -*-===//
-//
+//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
-//
+//
//===----------------------------------------------------------------------===//
//
// This file contains the declaration of the Constant class.
namespace llvm {
+/// 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.
+/// Constant's are created on demand as needed and never deleted: thus clients
+/// don't have to worry about the lifetime of the objects.
+/// @brief LLVM Constant Representation
class Constant : public User {
+ void operator=(const Constant &); // Do not implement
+ Constant(const Constant &); // Do not implement
protected:
- inline Constant(const Type *Ty) : User(Ty, Value::ConstantVal) {}
- ~Constant() {}
+ Constant(const Type *Ty, ValueTy vty, Use *Ops, unsigned NumOps)
+ : User(Ty, vty, Ops, NumOps) {}
void destroyConstantImpl();
public:
- // setName - Specialize setName to handle symbol table majik...
- virtual void setName(const std::string &name, SymbolTable *ST = 0);
-
/// Static constructor to get a '0' constant of arbitrary type...
///
static Constant *getNullValue(const Type *Ty);
+ /// Static constructor to get a '-1' constant. This supports integers and
+ /// vectors.
+ ///
+ static Constant *getAllOnesValue(const Type *Ty);
+
/// isNullValue - Return true if this is the value that would be returned by
/// getNullValue.
virtual bool isNullValue() const = 0;
virtual void print(std::ostream &O) const;
+ void print(std::ostream *O) const { if (O) print(*O); }
+
+ /// canTrap - 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;
- /// isConstantExpr - Return true if this is a ConstantExpr
- ///
- virtual bool isConstantExpr() const { return false; }
+ /// ContaintsRelocations - Return true if the constant value contains
+ /// relocations which cannot be resolved at compile time.
+ bool ContainsRelocations() const;
+ // Specialize get/setOperand for Constant's as their operands are always
+ // constants as well.
+ Constant *getOperand(unsigned i) {
+ return static_cast<Constant*>(User::getOperand(i));
+ }
+ const Constant *getOperand(unsigned i) const {
+ return static_cast<const Constant*>(User::getOperand(i));
+ }
+ void setOperand(unsigned i, Constant *C) {
+ User::setOperand(i, C);
+ }
/// destroyConstant - 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
/// available cached constants. Implementations should call
/// destroyConstantImpl as the last thing they do, to destroy all users and
/// delete this.
- ///
- /// Note that this call is only valid on non-primitive constants: You cannot
- /// destroy an integer constant for example. This API is used to delete
- /// constants that have ConstantPointerRef's embeded in them when the module
- /// is deleted, and it is used by GlobalDCE to remove ConstantPointerRefs that
- /// are unneeded, allowing globals to be DCE'd.
- ///
virtual void destroyConstant() { assert(0 && "Not reached!"); }
-
//// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const Constant *) { return true; }
+ static inline bool classof(const GlobalValue *) { return true; }
static inline bool classof(const Value *V) {
- return V->getValueType() == Value::ConstantVal;
+ return V->getValueID() >= ConstantFirstVal &&
+ V->getValueID() <= ConstantLastVal;
}
/// replaceUsesOfWithOnConstant - This method is a special form of
/// use Value::replaceAllUsesWith, which automatically dispatches to this
/// method as needed.
///
- virtual void replaceUsesOfWithOnConstant(Value *From, Value *To,
- bool DisableChecking = false) {
+ virtual void replaceUsesOfWithOnConstant(Value *, Value *, Use *) {
// Provide a default implementation for constants (like integers) that
// cannot use any other values. This cannot be called at runtime, but needs
// to be here to avoid link errors.
"implemented for all constants that have operands!");
assert(0 && "Constants that do not have operands cannot be using 'From'!");
}
+
+ /// getStringValue - Turn an LLVM constant pointer that eventually points to a
+ /// global into a string value. Return an empty string if we can't do it.
+ /// Parameter Chop determines if the result is chopped at the first null
+ /// terminator.
+ ///
+ std::string getStringValue(bool Chop = true, unsigned Offset = 0);
};
} // End llvm namespace
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