1 //===- RecordStreamer.h - Record asm defined and used symbols ---*- 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 #ifndef LLVM_LIB_OBJECT_RECORDSTREAMER_H
10 #define LLVM_LIB_OBJECT_RECORDSTREAMER_H
11 
12 #include "llvm/ADT/DenseMap.h"
13 #include "llvm/ADT/StringMap.h"
14 #include "llvm/MC/MCDirectives.h"
15 #include "llvm/MC/MCStreamer.h"
16 #include "llvm/MC/MCSymbol.h"
17 #include "llvm/Support/SMLoc.h"
18 #include <vector>
19 
20 namespace llvm {
21 
22 class GlobalValue;
23 class Module;
24 
25 class RecordStreamer : public MCStreamer {
26 public:
27   enum State { NeverSeen, Global, Defined, DefinedGlobal, DefinedWeak, Used,
28                UndefinedWeak};
29 
30 private:
31   const Module &M;
32   StringMap<State> Symbols;
33   // Map of aliases created by .symver directives, saved so we can update
34   // their symbol binding after parsing complete. This maps from each
35   // aliasee to its list of aliases.
36   DenseMap<const MCSymbol *, std::vector<StringRef>> SymverAliasMap;
37 
38   /// Get the state recorded for the given symbol.
39   State getSymbolState(const MCSymbol *Sym);
40 
41   void markDefined(const MCSymbol &Symbol);
42   void markGlobal(const MCSymbol &Symbol, MCSymbolAttr Attribute);
43   void markUsed(const MCSymbol &Symbol);
44   void visitUsedSymbol(const MCSymbol &Sym) override;
45 
46 public:
47   RecordStreamer(MCContext &Context, const Module &M);
48 
49   void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI) override;
50   void EmitLabel(MCSymbol *Symbol, SMLoc Loc = SMLoc()) override;
51   void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) override;
52   bool EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) override;
53   void EmitZerofill(MCSection *Section, MCSymbol *Symbol, uint64_t Size,
54                     unsigned ByteAlignment, SMLoc Loc = SMLoc()) override;
55   void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
56                         unsigned ByteAlignment) override;
57 
58   // Ignore COFF-specific directives; we do not need any information from them,
59   // but the default implementation of these methods crashes, so we override
60   // them with versions that do nothing.
61   void BeginCOFFSymbolDef(const MCSymbol *Symbol) override {}
62   void EmitCOFFSymbolStorageClass(int StorageClass) override {}
63   void EmitCOFFSymbolType(int Type) override {}
64   void EndCOFFSymbolDef() override {}
65 
66   /// Record .symver aliases for later processing.
67   void emitELFSymverDirective(StringRef AliasName,
68                               const MCSymbol *Aliasee) override;
69 
70   // Emit ELF .symver aliases and ensure they have the same binding as the
71   // defined symbol they alias with.
72   void flushSymverDirectives();
73 
74   // Symbols iterators
75   using const_iterator = StringMap<State>::const_iterator;
76   const_iterator begin();
77   const_iterator end();
78 
79   // SymverAliasMap iterators
80   using const_symver_iterator = decltype(SymverAliasMap)::const_iterator;
81   iterator_range<const_symver_iterator> symverAliases();
82 };
83 
84 } // end namespace llvm
85 
86 #endif // LLVM_LIB_OBJECT_RECORDSTREAMER_H
87