//===-- llvm/Use.h - Definition of the Use class ----------------*- 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 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.
//
+// Pointer tagging is used to efficiently find the User corresponding
+// to a Use without having to store a User pointer in every Use. A
+// User is preceded in memory by all the Uses corresponding to its
+// operands, and the low bits of one of the fields (Prev) of the Use
+// class are used to encode offsets to be able to find that User given
+// a pointer to any Use. For details, see:
+//
+// http://www.llvm.org/docs/ProgrammersManual.html#UserLayout
+//
//===----------------------------------------------------------------------===//
#ifndef LLVM_USE_H
#define LLVM_USE_H
-#include "Support/ilist"
-template<typename NodeTy> struct ilist_traits;
+#include "llvm/Support/Casting.h"
+#include "llvm/ADT/PointerIntPair.h"
+#include <cstddef>
+#include <iterator>
+
+namespace llvm {
+
class Value;
class User;
+class Use;
+
+/// Tag - generic tag type for (at least 32 bit) pointers
+enum Tag { noTag, tagOne, tagTwo, tagThree };
+// Use** is only 4-byte aligned.
+template<>
+class PointerLikeTypeTraits<Use**> {
+public:
+ static inline void *getAsVoidPointer(Use** P) { return P; }
+ static inline Use **getFromVoidPointer(void *P) {
+ return static_cast<Use**>(P);
+ }
+ enum { NumLowBitsAvailable = 2 };
+};
//===----------------------------------------------------------------------===//
// Use Class
//===----------------------------------------------------------------------===//
-// Use is here to make keeping the "use" list of a Value up-to-date really easy.
-//
+/// Use is here to make keeping the "use" list of a Value up-to-date really
+/// easy.
class Use {
- Value *Val;
- User *U;
- Use *Prev, *Next;
- friend class ilist_traits<Use>;
public:
- inline Use(Value *v, User *user);
- inline Use(const Use &u);
- inline ~Use();
+ /// 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; }
- User *getUser() const { return U; }
+
+ /// 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->() { return Val; }
const Value *operator->() const { return Val; }
-};
-template<>
-struct ilist_traits<Use> {
- static Use *getPrev(Use *N) { return N->Prev; }
- static Use *getNext(Use *N) { return N->Next; }
- static const Use *getPrev(const Use *N) { return N->Prev; }
- static const Use *getNext(const Use *N) { return N->Next; }
- static void setPrev(Use *N, Use *Prev) { N->Prev = Prev; }
- static void setNext(Use *N, Use *Next) { N->Next = Next; }
-
- // createNode - this is used to create the end marker for the use list
- static Use *createNode() { return new Use(0,0); }
-
- void addNodeToList(Use *NTy) {}
- void removeNodeFromList(Use *NTy) {}
- void transferNodesFromList(iplist<Use, ilist_traits> &L2,
- ilist_iterator<Use> first,
- ilist_iterator<Use> last) {}
-};
+ 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);
+
+ /// getPrefix - Return deletable pointer if appropriate
+ Use *getPrefix();
+private:
+ const Use* getImpliedUser() const;
+ static Use *initTags(Use *Start, Use *Stop, ptrdiff_t Done = 0);
+
+ Value *Val;
+ Use *Next;
+ PointerIntPair<Use**, 2, PrevPtrTag> Prev;
+
+ void setPrev(Use **NewPrev) {
+ Prev.setPointer(NewPrev);
+ }
+ void addToList(Use **List) {
+ Next = *List;
+ if (Next) Next->setPrev(&Next);
+ setPrev(List);
+ *List = this;
+ }
+ void removeFromList() {
+ Use **StrippedPrev = Prev.getPointer();
+ *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 (SimpleType)Val.get();
+ return static_cast<SimpleType>(Val.get());
}
};
template<> struct simplify_type<const Use> {
typedef Value* SimpleType;
static SimpleType getSimplifiedValue(const Use &Val) {
- return (SimpleType)Val.get();
+ return static_cast<SimpleType>(Val.get());
}
};
-struct UseListIteratorWrapper : public iplist<Use>::iterator {
- typedef iplist<Use>::iterator Super;
- UseListIteratorWrapper() {}
- UseListIteratorWrapper(const Super &RHS) : Super(RHS) {}
- UseListIteratorWrapper &operator=(const Super &RHS) {
- Super::operator=(RHS);
- return *this;
- }
- inline User *operator*() const;
- User *operator->() const { return operator*(); }
+template<typename UserTy> // UserTy == 'User' or 'const User'
+class value_use_iterator : public std::iterator<std::forward_iterator_tag,
+ UserTy*, ptrdiff_t> {
+ typedef std::iterator<std::forward_iterator_tag, 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;
- UseListIteratorWrapper operator--() { return Super::operator--(); }
- UseListIteratorWrapper operator++() { return Super::operator++(); }
+ value_use_iterator(const _Self &I) : U(I.U) {}
+ value_use_iterator() {}
- UseListIteratorWrapper operator--(int) { // postdecrement operators...
- UseListIteratorWrapper tmp = *this;
- --*this;
- return tmp;
+ bool operator==(const _Self &x) const {
+ return U == x.U;
}
- UseListIteratorWrapper operator++(int) { // postincrement operators...
- UseListIteratorWrapper tmp = *this;
- ++*this;
- return tmp;
+ bool operator!=(const _Self &x) const {
+ return !operator==(x);
}
-};
-
-struct UseListConstIteratorWrapper : public iplist<Use>::const_iterator {
- typedef iplist<Use>::const_iterator Super;
- UseListConstIteratorWrapper() {}
- UseListConstIteratorWrapper(const Super &RHS) : Super(RHS) {}
- // Allow conversion from non-const to const iterators
- UseListConstIteratorWrapper(const UseListIteratorWrapper &RHS) : Super(RHS) {}
- UseListConstIteratorWrapper(const iplist<Use>::iterator &RHS) : Super(RHS) {}
+ /// atEnd - return true if this iterator is equal to use_end() on the value.
+ bool atEnd() const { return U == 0; }
- UseListConstIteratorWrapper &operator=(const Super &RHS) {
- Super::operator=(RHS);
+ // 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;
+ }
- inline const User *operator*() const;
- const User *operator->() const { return operator*(); }
+ // Retrieve a pointer to the current User.
+ UserTy *operator*() const {
+ assert(U && "Cannot dereference end iterator!");
+ return U->getUser();
+ }
- UseListConstIteratorWrapper operator--() { return Super::operator--(); }
- UseListConstIteratorWrapper operator++() { return Super::operator++(); }
+ UserTy *operator->() const { return operator*(); }
- UseListConstIteratorWrapper operator--(int) { // postdecrement operators...
- UseListConstIteratorWrapper tmp = *this;
- --*this;
- return tmp;
- }
- UseListConstIteratorWrapper operator++(int) { // postincrement operators...
- UseListConstIteratorWrapper tmp = *this;
- ++*this;
- return tmp;
- }
+ Use &getUse() const { return *U; }
+
+ /// getOperandNo - Return the operand # of this use in its User. Defined in
+ /// User.h
+ ///
+ unsigned getOperandNo() const;
};
+} // End llvm namespace
+
#endif
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