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llvm-mirror/lib/Object/RecordStreamer.h
Fangrui Song 7517775e7d [MC] Support .symver *, *, remove
As a resolution to https://sourceware.org/bugzilla/show_bug.cgi?id=25295 , GNU as
from binutils 2.35 supports the optional third argument for the .symver directive.

'remove' for a non-default version is useful:
`.symver def_v1, def@v1, remove` => def_v1 is not retained in the symbol table.
Previously the user has to strip the original symbol or specify a `local:`
version node in a version script to localize the symbol.

`.symver def, def@@v1, remove` and `.symver def, def@@@v1, remove` are supported
as well, though they are identical to `.symver def, def@@@v1`.

local/hidden are not useful so this patch does not implement them.
2021-03-06 15:23:02 -08:00

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3.1 KiB
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//===- RecordStreamer.h - Record asm defined and used symbols ---*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#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/Support/SMLoc.h"
#include <vector>
namespace llvm {
class MCSymbol;
class Module;
class RecordStreamer : public MCStreamer {
public:
enum State { NeverSeen, Global, Defined, DefinedGlobal, DefinedWeak, Used,
UndefinedWeak};
private:
const Module &M;
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<StringRef>> SymverAliasMap;
/// Get the state recorded for the given symbol.
State getSymbolState(const MCSymbol *Sym);
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, const Module &M);
void emitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI) 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, SMLoc Loc = SMLoc()) override;
void emitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment) override;
// Ignore COFF-specific directives; we do not need any information from them,
// but the default implementation of these methods crashes, so we override
// them with versions that do nothing.
void BeginCOFFSymbolDef(const MCSymbol *Symbol) override {}
void EmitCOFFSymbolStorageClass(int StorageClass) override {}
void EmitCOFFSymbolType(int Type) override {}
void EndCOFFSymbolDef() override {}
/// Record .symver aliases for later processing.
void emitELFSymverDirective(const MCSymbol *OriginalSym, StringRef Name,
bool KeepOriginalSym) override;
// Emit ELF .symver aliases and ensure they have the same binding as the
// defined symbol they alias with.
void flushSymverDirectives();
// Symbols iterators
using const_iterator = StringMap<State>::const_iterator;
const_iterator begin();
const_iterator end();
// SymverAliasMap iterators
using const_symver_iterator = decltype(SymverAliasMap)::const_iterator;
iterator_range<const_symver_iterator> symverAliases();
};
} // end namespace llvm
#endif // LLVM_LIB_OBJECT_RECORDSTREAMER_H