1 //===- llvm/IR/Comdat.h - Comdat definitions --------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 /// @file
10 /// This file contains the declaration of the Comdat class, which represents a
11 /// single COMDAT in LLVM.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_IR_COMDAT_H
16 #define LLVM_IR_COMDAT_H
17 
18 #include "llvm-c/Types.h"
19 #include "llvm/ADT/SmallPtrSet.h"
20 #include "llvm/Support/CBindingWrapping.h"
21 
22 namespace llvm {
23 
24 class GlobalObject;
25 class raw_ostream;
26 class StringRef;
27 template <typename ValueTy> class StringMapEntry;
28 
29 // This is a Name X SelectionKind pair. The reason for having this be an
30 // independent object instead of just adding the name and the SelectionKind
31 // to a GlobalObject is that it is invalid to have two Comdats with the same
32 // name but different SelectionKind. This structure makes that unrepresentable.
33 class Comdat {
34 public:
35   enum SelectionKind {
36     Any,           ///< The linker may choose any COMDAT.
37     ExactMatch,    ///< The data referenced by the COMDAT must be the same.
38     Largest,       ///< The linker will choose the largest COMDAT.
39     NoDeduplicate, ///< No deduplication is performed.
40     SameSize,      ///< The data referenced by the COMDAT must be the same size.
41   };
42 
43   Comdat(const Comdat &) = delete;
44   Comdat(Comdat &&C);
45 
46   SelectionKind getSelectionKind() const { return SK; }
47   void setSelectionKind(SelectionKind Val) { SK = Val; }
48   StringRef getName() const;
49   void print(raw_ostream &OS, bool IsForDebug = false) const;
50   void dump() const;
51   const SmallPtrSetImpl<GlobalObject *> &getUsers() const { return Users; }
52 
53 private:
54   friend class Module;
55   friend class GlobalObject;
56 
57   Comdat();
58   void addUser(GlobalObject *GO);
59   void removeUser(GlobalObject *GO);
60 
61   // Points to the map in Module.
62   StringMapEntry<Comdat> *Name = nullptr;
63   SelectionKind SK = Any;
64   // Globals using this comdat.
65   SmallPtrSet<GlobalObject *, 2> Users;
66 };
67 
68 // Create wrappers for C Binding types (see CBindingWrapping.h).
69 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(Comdat, LLVMComdatRef)
70 
71 inline raw_ostream &operator<<(raw_ostream &OS, const Comdat &C) {
72   C.print(OS);
73   return OS;
74 }
75 
76 } // end namespace llvm
77 
78 #endif // LLVM_IR_COMDAT_H
79