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authored <ed@FreeBSD.org>2009-06-02 17:52:33 +0000
committered <ed@FreeBSD.org>2009-06-02 17:52:33 +0000
commit3277b69d734b9c90b44ebde4ede005717e2c3b2e (patch)
tree64ba909838c23261cace781ece27d106134ea451 /include/llvm/Use.h
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Import LLVM, at r72732.
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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.
+//
+// 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 "llvm/Support/Casting.h"
+#include "llvm/ADT/iterator.h"
+#include "llvm/ADT/PointerIntPair.h"
+
+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.
+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);
+
+ /// 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 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
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