142 lines
3.7 KiB
C++
142 lines
3.7 KiB
C++
//===- llvm/Use.h - Definition of the Use class -----------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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/// \file
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///
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/// This defines the Use class. The Use class represents the operand of an
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/// instruction or some other User instance which refers to a Value. The Use
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/// class keeps the "use list" of the referenced value up to date.
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///
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_IR_USE_H
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#define LLVM_IR_USE_H
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#include "llvm-c/Types.h"
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#include "llvm/Support/CBindingWrapping.h"
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#include "llvm/Support/Compiler.h"
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namespace llvm {
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template <typename> struct simplify_type;
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class User;
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class Value;
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/// A Use represents the edge between a Value definition and its users.
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///
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/// This is notionally a two-dimensional linked list. It supports traversing
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/// all of the uses for a particular value definition. It also supports jumping
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/// directly to the used value when we arrive from the User's operands, and
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/// jumping directly to the User when we arrive from the Value's uses.
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class Use {
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public:
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Use(const Use &U) = delete;
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/// Provide a fast substitute to std::swap<Use>
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/// that also works with less standard-compliant compilers
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LLVM_ABI void swap(Use &RHS);
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private:
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/// Destructor - Only for zap()
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~Use() { removeFromList(); }
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/// Constructor
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Use(User *Parent) : Parent(Parent) {}
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public:
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friend class Value;
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friend class User;
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operator Value *() const { return Val; }
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Value *get() const { return Val; }
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/// Returns the User that contains this Use.
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///
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/// For an instruction operand, for example, this will return the
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/// instruction.
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User *getUser() const { return Parent; };
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LLVM_ABI inline void set(Value *Val);
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LLVM_ABI inline Value *operator=(Value *RHS);
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LLVM_ABI inline const Use &operator=(const Use &RHS);
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Value *operator->() { return Val; }
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const Value *operator->() const { return Val; }
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Use *getNext() const { return Next; }
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/// Return the operand # of this use in its User.
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LLVM_ABI unsigned getOperandNo() const;
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/// Destroys Use operands when the number of operands of
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/// a User changes.
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LLVM_ABI static void zap(Use *Start, const Use *Stop, bool del = false);
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private:
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Value *Val = nullptr;
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Use *Next = nullptr;
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Use **Prev = nullptr;
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User *Parent = nullptr;
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void addToList(Use **List) {
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Next = *List;
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if (Next)
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Next->Prev = &Next;
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Prev = List;
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*Prev = this;
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}
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void removeFromList() {
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if (Prev) {
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*Prev = Next;
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if (Next) {
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Next->Prev = Prev;
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Next = nullptr;
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}
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Prev = nullptr;
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}
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}
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};
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/// Allow clients to treat uses just like values when using
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/// casting operators.
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template <> struct simplify_type<Use> {
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using SimpleType = Value *;
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static SimpleType getSimplifiedValue(Use &Val) { return Val.get(); }
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};
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template <> struct simplify_type<const Use> {
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using SimpleType = /*const*/ Value *;
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static SimpleType getSimplifiedValue(const Use &Val) { return Val.get(); }
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};
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template <> struct simplify_type<Use *> {
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using SimpleType = Value *;
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static SimpleType getSimplifiedValue(Use *Val) {
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return Val ? Val->get() : nullptr;
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}
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};
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template <> struct simplify_type<const Use *> {
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using SimpleType = /*const*/ Value *;
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static SimpleType getSimplifiedValue(const Use *Val) {
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return Val ? Val->get() : nullptr;
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}
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};
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// Create wrappers for C Binding types (see CBindingWrapping.h).
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DEFINE_SIMPLE_CONVERSION_FUNCTIONS(Use, LLVMUseRef)
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} // end namespace llvm
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#endif // LLVM_IR_USE_H
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