llvm-6502/include/llvm/Use.h

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//===-- llvm/Use.h - Definition of the Use class ----------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This defines the Use class. The Use class represents the operand of an
// instruction or some other User instance which refers to a Value. The Use
// class keeps the "use list" of the referenced value up to date.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_USE_H
#define LLVM_USE_H
#include "llvm/Support/Casting.h"
#include "llvm/ADT/iterator.h"
namespace llvm {
class Value;
class User;
//===----------------------------------------------------------------------===//
// Generic Tagging Functions
//===----------------------------------------------------------------------===//
// We adhere to the following convention: The type of a tagged pointer
// to T is T volatile*. This means that functions that superpose a tag
// on a pointer will be supplied a T* (or T const*) and will return a
// tagged one: T volatile*. Untagging functions do it the other way
// 'round. While this scheme does not prevent dereferencing of tagged
// pointers, proper type annotations do catch most inappropriate uses.
/// Tag - generic tag type for (at least 32 bit) pointers
enum Tag { noTag, tagOne, tagTwo, tagThree };
/// addTag - insert tag bits into an (untagged) pointer
template <typename T, typename TAG>
inline volatile T *addTag(const T *P, TAG Tag) {
return reinterpret_cast<T*>(ptrdiff_t(P) | Tag);
}
/// stripTag - remove tag bits from a pointer,
/// making it dereferencable
template <ptrdiff_t MASK, typename T>
inline T *stripTag(const volatile T *P) {
return reinterpret_cast<T*>(ptrdiff_t(P) & ~MASK);
}
/// extractTag - extract tag bits from a pointer
template <typename TAG, TAG MASK, typename T>
inline TAG extractTag(const volatile T *P) {
return TAG(ptrdiff_t(P) & MASK);
}
/// transferTag - transfer tag bits from a pointer,
/// to an untagged pointer
template <ptrdiff_t MASK, typename T>
inline volatile T *transferTag(const volatile T *From, const T *To) {
return reinterpret_cast<T*>((ptrdiff_t(From) & MASK) | ptrdiff_t(To));
}
//===----------------------------------------------------------------------===//
// Use Class
//===----------------------------------------------------------------------===//
/// Use is here to make keeping the "use" list of a Value up-to-date really
/// easy.
class Use {
public:
/// swap - provide a fast substitute to std::swap<Use>
/// that also works with less standard-compliant compilers
void swap(Use &RHS);
private:
/// Copy ctor - do not implement
Use(const Use &U);
/// Destructor - Only for zap()
inline ~Use() {
if (Val) removeFromList();
}
/// Default ctor - This leaves the Use completely uninitialized. The only
/// thing that is valid to do with this use is to call the "init" method.
inline Use() {}
enum PrevPtrTag { zeroDigitTag = noTag
, oneDigitTag = tagOne
, stopTag = tagTwo
, fullStopTag = tagThree };
public:
/// Normally Use will just implicitly convert to a Value* that it holds.
operator Value*() const { return Val; }
/// If implicit conversion to Value* doesn't work, the get() method returns
/// the Value*.
Value *get() const { return Val; }
/// getUser - This returns the User that contains this Use. For an
/// instruction operand, for example, this will return the instruction.
User *getUser() const;
inline void set(Value *Val);
Value *operator=(Value *RHS) {
set(RHS);
return RHS;
}
const Use &operator=(const Use &RHS) {
set(RHS.Val);
return *this;
}
Value *operator->() { return Val; }
const Value *operator->() const { return Val; }
Use *getNext() const { return Next; }
/// zap - This is used to destroy Use operands when the number of operands of
/// a User changes.
static void zap(Use *Start, const Use *Stop, bool del = false);
private:
const Use* getImpliedUser() const;
static Use *initTags(Use *Start, Use *Stop, ptrdiff_t Done = 0);
Value *Val;
Use *Next, *volatile*Prev;
void setPrev(Use **NewPrev) {
Prev = transferTag<fullStopTag>(Prev, NewPrev);
}
void addToList(Use **List) {
Next = *List;
if (Next) Next->setPrev(&Next);
setPrev(List);
*List = this;
}
void removeFromList() {
Use **StrippedPrev = stripTag<fullStopTag>(Prev);
*StrippedPrev = Next;
if (Next) Next->setPrev(StrippedPrev);
}
friend class Value;
friend class User;
};
// simplify_type - Allow clients to treat uses just like values when using
// casting operators.
template<> struct simplify_type<Use> {
typedef Value* SimpleType;
static SimpleType getSimplifiedValue(const Use &Val) {
return static_cast<SimpleType>(Val.get());
}
};
template<> struct simplify_type<const Use> {
typedef Value* SimpleType;
static SimpleType getSimplifiedValue(const Use &Val) {
return static_cast<SimpleType>(Val.get());
}
};
template<typename UserTy> // UserTy == 'User' or 'const User'
class value_use_iterator : public forward_iterator<UserTy*, ptrdiff_t> {
typedef forward_iterator<UserTy*, ptrdiff_t> super;
typedef value_use_iterator<UserTy> _Self;
Use *U;
explicit value_use_iterator(Use *u) : U(u) {}
friend class Value;
public:
typedef typename super::reference reference;
typedef typename super::pointer pointer;
value_use_iterator(const _Self &I) : U(I.U) {}
value_use_iterator() {}
bool operator==(const _Self &x) const {
return U == x.U;
}
bool operator!=(const _Self &x) const {
return !operator==(x);
}
/// atEnd - return true if this iterator is equal to use_end() on the value.
bool atEnd() const { return U == 0; }
// Iterator traversal: forward iteration only
_Self &operator++() { // Preincrement
assert(U && "Cannot increment end iterator!");
U = U->getNext();
return *this;
}
_Self operator++(int) { // Postincrement
_Self tmp = *this; ++*this; return tmp;
}
// Retrieve a pointer to the current User.
UserTy *operator*() const {
assert(U && "Cannot dereference end iterator!");
return U->getUser();
}
UserTy *operator->() const { return operator*(); }
Use &getUse() const { return *U; }
/// getOperandNo - Return the operand # of this use in its User. Defined in
/// User.h
///
unsigned getOperandNo() const;
};
template<> struct simplify_type<value_use_iterator<User> > {
typedef User* SimpleType;
static SimpleType getSimplifiedValue(const value_use_iterator<User> &Val) {
return *Val;
}
};
template<> struct simplify_type<const value_use_iterator<User> >
: public simplify_type<value_use_iterator<User> > {};
template<> struct simplify_type<value_use_iterator<const User> > {
typedef const User* SimpleType;
static SimpleType getSimplifiedValue(const
value_use_iterator<const User> &Val) {
return *Val;
}
};
template<> struct simplify_type<const value_use_iterator<const User> >
: public simplify_type<value_use_iterator<const User> > {};
} // End llvm namespace
#endif