lib/Object/RecordStreamer.h

//===- RecordStreamer.h - Record asm defined and used symbols ---*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_LIB_OBJECT_RECORDSTREAMER_H
#define LLVM_LIB_OBJECT_RECORDSTREAMER_H

#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/MC/MCDirectives.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/SMLoc.h"
#include <vector>

namespace llvm {

class RecordStreamer : public MCStreamer {
public:
  enum State { NeverSeen, Global, Defined, DefinedGlobal, DefinedWeak, Used,
               UndefinedWeak};

private:
  StringMap<State> Symbols;
  // Map of aliases created by .symver directives, saved so we can update
  // their symbol binding after parsing complete. This maps from each
  // aliasee to its list of aliases.
  DenseMap<const MCSymbol *, std::vector<MCSymbol *>> SymverAliasMap;

  void markDefined(const MCSymbol &Symbol);
  void markGlobal(const MCSymbol &Symbol, MCSymbolAttr Attribute);
  void markUsed(const MCSymbol &Symbol);
  void visitUsedSymbol(const MCSymbol &Sym) override;

public:
  RecordStreamer(MCContext &Context);

  using const_iterator = StringMap<State>::const_iterator;

  const_iterator begin();
  const_iterator end();
  void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI,
                       bool) override;
  void EmitLabel(MCSymbol *Symbol, SMLoc Loc = SMLoc()) override;
  void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) override;
  bool EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) override;
  void EmitZerofill(MCSection *Section, MCSymbol *Symbol, uint64_t Size,
                    unsigned ByteAlignment) override;
  void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
                        unsigned ByteAlignment) override;
  /// Record .symver aliases for later processing.
  void emitELFSymverDirective(MCSymbol *Alias,
                              const MCSymbol *Aliasee) override;
  /// Return the map of .symver aliasee to associated aliases.
  DenseMap<const MCSymbol *, std::vector<MCSymbol *>> &symverAliases() {
    return SymverAliasMap;
  }

  /// Get the state recorded for the given symbol.
  State getSymbolState(const MCSymbol *Sym) {
    auto SI = Symbols.find(Sym->getName());
    if (SI == Symbols.end())
      return NeverSeen;
    return SI->second;
  }
};

} // end namespace llvm

#endif // LLVM_LIB_OBJECT_RECORDSTREAMER_H