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bce1b9a58d
Summary: In a .symver assembler directive like: .symver name, name2@@nodename "name2@@nodename" should get the same symbol binding as "name". While the ELF object writer is updating the symbol binding for .symver aliases before emitting the object file, not doing so when the module inline assembly is handled by the RecordStreamer is causing the wrong behavior in *LTO mode. E.g. when "name" is global, "name2@@nodename" must also be marked as global. Otherwise, the symbol is skipped when iterating over the LTO InputFile symbols (InputFile::Symbol::shouldSkip). So, for example, when performing any *LTO via the gold-plugin, the versioned symbol definition is not recorded by the plugin and passed back to the linker. If the object was in an archive, and there were no other symbols needed from that object, the object would not be included in the final link and references to the versioned symbol are undefined. The llvm-lto2 tests added will give an error about an unused symbol resolution without the fix. Reviewers: rafael, pcc Reviewed By: pcc Subscribers: mehdi_amini, llvm-commits Differential Revision: https://reviews.llvm.org/D30485 llvm-svn: 297332
62 lines
2.3 KiB
C++
62 lines
2.3 KiB
C++
//===-- RecordStreamer.h - Record asm defined and used symbols ---*- C++ -*===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_OBJECT_RECORDSTREAMER_H
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#define LLVM_LIB_OBJECT_RECORDSTREAMER_H
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#include "llvm/MC/MCStreamer.h"
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namespace llvm {
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class RecordStreamer : public MCStreamer {
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public:
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enum State { NeverSeen, Global, Defined, DefinedGlobal, DefinedWeak, Used,
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UndefinedWeak};
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private:
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StringMap<State> Symbols;
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// Map of aliases created by .symver directives, saved so we can update
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// their symbol binding after parsing complete. This maps from each
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// aliasee to its list of aliases.
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DenseMap<const MCSymbol *, std::vector<MCSymbol *>> SymverAliasMap;
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void markDefined(const MCSymbol &Symbol);
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void markGlobal(const MCSymbol &Symbol, MCSymbolAttr Attribute);
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void markUsed(const MCSymbol &Symbol);
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void visitUsedSymbol(const MCSymbol &Sym) override;
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public:
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typedef StringMap<State>::const_iterator const_iterator;
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const_iterator begin();
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const_iterator end();
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RecordStreamer(MCContext &Context);
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void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI) override;
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void EmitLabel(MCSymbol *Symbol, SMLoc Loc = SMLoc()) override;
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void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) override;
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bool EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) override;
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void EmitZerofill(MCSection *Section, MCSymbol *Symbol, uint64_t Size,
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unsigned ByteAlignment) override;
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void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
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unsigned ByteAlignment) override;
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/// Record .symver aliases for later processing.
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void emitELFSymverDirective(MCSymbol *Alias,
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const MCSymbol *Aliasee) override;
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/// Return the map of .symver aliasee to associated aliases.
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DenseMap<const MCSymbol *, std::vector<MCSymbol *>> &symverAliases() {
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return SymverAliasMap;
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}
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/// Get the state recorded for the given symbol.
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State getSymbolState(const MCSymbol *Sym) {
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auto SI = Symbols.find(Sym->getName());
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if (SI == Symbols.end())
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return NeverSeen;
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return SI->second;
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}
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};
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}
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#endif
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