X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=blobdiff_plain;f=include%2Fllvm%2FMC%2FMCSymbol.h;h=563fa803b0e4b2bc1f30d41891babae3585f1727;hp=e41eb2ab885909ac34aaa3c5b884925121cc2a15;hb=ae65a7a88e8cf63c9ad01e1483181cb7e7bf6f55;hpb=c28cc093e3b5b8601cb5024a5365a6f31f49839a diff --git a/include/llvm/MC/MCSymbol.h b/include/llvm/MC/MCSymbol.h index e41eb2ab885..563fa803b0e 100644 --- a/include/llvm/MC/MCSymbol.h +++ b/include/llvm/MC/MCSymbol.h @@ -14,133 +14,417 @@ #ifndef LLVM_MC_MCSYMBOL_H #define LLVM_MC_MCSYMBOL_H -#include "llvm/ADT/StringRef.h" +#include "llvm/ADT/PointerIntPair.h" +#include "llvm/ADT/PointerUnion.h" +#include "llvm/ADT/StringMap.h" +#include "llvm/MC/MCAssembler.h" +#include "llvm/Support/Compiler.h" namespace llvm { - class MCExpr; - class MCSection; - class MCContext; - class raw_ostream; - - /// MCSymbol - Instances of this class represent a symbol name in the MC file, - /// and MCSymbols are created and unique'd by the MCContext class. MCSymbols - /// should only be constructed with valid names for the object file. +class MCAsmInfo; +class MCExpr; +class MCSymbol; +class MCFragment; +class MCSection; +class MCContext; +class raw_ostream; + +/// MCSymbol - Instances of this class represent a symbol name in the MC file, +/// and MCSymbols are created and uniqued by the MCContext class. MCSymbols +/// should only be constructed with valid names for the object file. +/// +/// If the symbol is defined/emitted into the current translation unit, the +/// Section member is set to indicate what section it lives in. Otherwise, if +/// it is a reference to an external entity, it has a null section. +class MCSymbol { +protected: + /// The kind of the symbol. If it is any value other than unset then this + /// class is actually one of the appropriate subclasses of MCSymbol. + enum SymbolKind { + SymbolKindUnset, + SymbolKindCOFF, + SymbolKindELF, + SymbolKindMachO, + }; + + /// A symbol can contain an Offset, or Value, or be Common, but never more + /// than one of these. + enum Contents : uint8_t { + SymContentsUnset, + SymContentsOffset, + SymContentsVariable, + SymContentsCommon, + }; + + // Special sentinal value for the absolute pseudo section. + // + // FIXME: Use a PointerInt wrapper for this? + static MCSection *AbsolutePseudoSection; + + /// If a symbol has a Fragment, the section is implied, so we only need + /// one pointer. + /// FIXME: We might be able to simplify this by having the asm streamer create + /// dummy fragments. + /// If this is a section, then it gives the symbol is defined in. This is null + /// for undefined symbols, and the special AbsolutePseudoSection value for + /// absolute symbols. If this is a variable symbol, this caches the variable + /// value's section. + /// + /// If this is a fragment, then it gives the fragment this symbol's value is + /// relative to, if any. + /// + /// For the 'HasName' integer, this is true if this symbol is named. + /// A named symbol will have a pointer to the name allocated in the bytes + /// immediately prior to the MCSymbol. + mutable PointerIntPair, 1> + SectionOrFragmentAndHasName; + + /// IsTemporary - True if this is an assembler temporary label, which + /// typically does not survive in the .o file's symbol table. Usually + /// "Lfoo" or ".foo". + unsigned IsTemporary : 1; + + /// \brief True if this symbol can be redefined. + unsigned IsRedefinable : 1; + + /// IsUsed - True if this symbol has been used. + mutable unsigned IsUsed : 1; + + mutable bool IsRegistered : 1; + + /// This symbol is visible outside this translation unit. + mutable unsigned IsExternal : 1; + + /// This symbol is private extern. + mutable unsigned IsPrivateExtern : 1; + + /// LLVM RTTI discriminator. This is actually a SymbolKind enumerator, but is + /// unsigned to avoid sign extension and achieve better bitpacking with MSVC. + unsigned Kind : 2; + + /// True if we have created a relocation that uses this symbol. + mutable unsigned IsUsedInReloc : 1; + + /// This is actually a Contents enumerator, but is unsigned to avoid sign + /// extension and achieve better bitpacking with MSVC. + unsigned SymbolContents : 2; + + /// The alignment of the symbol, if it is 'common', or -1. /// - /// If the symbol is defined/emitted into the current translation unit, the - /// Section member is set to indicate what section it lives in. Otherwise, if - /// it is a reference to an external entity, it has a null section. - /// - class MCSymbol { - // Special sentinal value for the absolute pseudo section. - // - // FIXME: Use a PointerInt wrapper for this? - static const MCSection *AbsolutePseudoSection; - - /// Name - The name of the symbol. The referred-to string data is actually - /// held by the StringMap that lives in MCContext. - StringRef Name; - - /// Section - The section the symbol is defined in. This is null for - /// undefined symbols, and the special AbsolutePseudoSection value for - /// absolute symbols. - const MCSection *Section; - - /// Value - If non-null, the value for a variable symbol. + /// The alignment is stored as log2(align) + 1. This allows all values from + /// 0 to 2^31 to be stored which is every power of 2 representable by an + /// unsigned. + enum : unsigned { NumCommonAlignmentBits = 5 }; + unsigned CommonAlignLog2 : NumCommonAlignmentBits; + + /// The Flags field is used by object file implementations to store + /// additional per symbol information which is not easily classified. + enum : unsigned { NumFlagsBits = 16 }; + mutable uint32_t Flags : NumFlagsBits; + + /// Index field, for use by the object file implementation. + mutable uint32_t Index = 0; + + union { + /// The offset to apply to the fragment address to form this symbol's value. + uint64_t Offset; + + /// The size of the symbol, if it is 'common'. + uint64_t CommonSize; + + /// If non-null, the value for a variable symbol. const MCExpr *Value; + }; - /// IsTemporary - True if this is an assembler temporary label, which - /// typically does not survive in the .o file's symbol table. Usually - /// "Lfoo" or ".foo". - unsigned IsTemporary : 1; - - private: // MCContext creates and uniques these. - friend class MCContext; - MCSymbol(StringRef name, bool isTemporary) - : Name(name), Section(0), Value(0), IsTemporary(isTemporary) {} - - MCSymbol(const MCSymbol&); // DO NOT IMPLEMENT - void operator=(const MCSymbol&); // DO NOT IMPLEMENT - public: - /// getName - Get the symbol name. - StringRef getName() const { return Name; } - - /// @name Symbol Type - /// @{ - - /// isTemporary - Check if this is an assembler temporary symbol. - bool isTemporary() const { - return IsTemporary; - } +protected: // MCContext creates and uniques these. + friend class MCExpr; + friend class MCContext; - /// @} - /// @name Associated Sections - /// @{ + /// \brief The name for a symbol. + /// MCSymbol contains a uint64_t so is probably aligned to 8. On a 32-bit + /// system, the name is a pointer so isn't going to satisfy the 8 byte + /// alignment of uint64_t. Account for that here. + typedef union { + const StringMapEntry *NameEntry; + uint64_t AlignmentPadding; + } NameEntryStorageTy; - /// isDefined - Check if this symbol is defined (i.e., it has an address). - /// - /// Defined symbols are either absolute or in some section. - bool isDefined() const { - return Section != 0; - } + MCSymbol(SymbolKind Kind, const StringMapEntry *Name, bool isTemporary) + : IsTemporary(isTemporary), IsRedefinable(false), IsUsed(false), + IsRegistered(false), IsExternal(false), IsPrivateExtern(false), + Kind(Kind), IsUsedInReloc(false), SymbolContents(SymContentsUnset), + CommonAlignLog2(0), Flags(0) { + Offset = 0; + SectionOrFragmentAndHasName.setInt(!!Name); + if (Name) + getNameEntryPtr() = Name; + } - /// isUndefined - Check if this symbol undefined (i.e., implicitly defined). - bool isUndefined() const { - return !isDefined(); - } + // Provide custom new/delete as we will only allocate space for a name + // if we need one. + void *operator new(size_t s, const StringMapEntry *Name, + MCContext &Ctx); - /// isAbsolute - Check if this is an absolute symbol. - bool isAbsolute() const { - return Section == AbsolutePseudoSection; - } +private: - /// getSection - Get the section associated with a defined, non-absolute - /// symbol. - const MCSection &getSection() const { - assert(!isUndefined() && !isAbsolute() && "Invalid accessor!"); - return *Section; - } + void operator delete(void *); + /// \brief Placement delete - required by std, but never called. + void operator delete(void*, unsigned) { + llvm_unreachable("Constructor throws?"); + } + /// \brief Placement delete - required by std, but never called. + void operator delete(void*, unsigned, bool) { + llvm_unreachable("Constructor throws?"); + } - /// setSection - Mark the symbol as defined in the section \arg S. - void setSection(const MCSection &S) { Section = &S; } + MCSymbol(const MCSymbol &) = delete; + void operator=(const MCSymbol &) = delete; + MCSection *getSectionPtr(bool SetUsed = true) const { + if (MCFragment *F = getFragment()) + return F->getParent(); + const auto &SectionOrFragment = SectionOrFragmentAndHasName.getPointer(); + assert(!SectionOrFragment.is() && "Section or null expected"); + MCSection *Section = SectionOrFragment.dyn_cast(); + if (Section || !isVariable()) + return Section; + return Section = getVariableValue(SetUsed)->findAssociatedSection(); + } - /// setUndefined - Mark the symbol as undefined. - void setUndefined() { - Section = 0; - } + /// \brief Get a reference to the name field. Requires that we have a name + const StringMapEntry *&getNameEntryPtr() { + assert(SectionOrFragmentAndHasName.getInt() && "Name is required"); + NameEntryStorageTy *Name = reinterpret_cast(this); + return (*(Name - 1)).NameEntry; + } + const StringMapEntry *&getNameEntryPtr() const { + return const_cast(this)->getNameEntryPtr(); + } - /// setAbsolute - Mark the symbol as absolute. - void setAbsolute() { Section = AbsolutePseudoSection; } +public: + /// getName - Get the symbol name. + StringRef getName() const { + if (!SectionOrFragmentAndHasName.getInt()) + return StringRef(); - /// @} - /// @name Variable Symbols - /// @{ + return getNameEntryPtr()->first(); + } - /// isVariable - Check if this is a variable symbol. - bool isVariable() const { - return Value != 0; - } + bool isRegistered() const { return IsRegistered; } + void setIsRegistered(bool Value) const { IsRegistered = Value; } + + void setUsedInReloc() const { IsUsedInReloc = true; } + bool isUsedInReloc() const { return IsUsedInReloc; } - /// getValue() - Get the value for variable symbols, or null if the symbol - /// is not a variable. - const MCExpr *getValue() const { return Value; } + /// \name Accessors + /// @{ - void setValue(const MCExpr *Value) { - this->Value = Value; + /// isTemporary - Check if this is an assembler temporary symbol. + bool isTemporary() const { return IsTemporary; } + + /// isUsed - Check if this is used. + bool isUsed() const { return IsUsed; } + void setUsed(bool Value) const { IsUsed |= Value; } + + /// \brief Check if this symbol is redefinable. + bool isRedefinable() const { return IsRedefinable; } + /// \brief Mark this symbol as redefinable. + void setRedefinable(bool Value) { IsRedefinable = Value; } + /// \brief Prepare this symbol to be redefined. + void redefineIfPossible() { + if (IsRedefinable) { + if (SymbolContents == SymContentsVariable) { + Value = nullptr; + SymbolContents = SymContentsUnset; + } + setUndefined(); + IsRedefinable = false; } + } - /// @} + /// @} + /// \name Associated Sections + /// @{ - /// print - Print the value to the stream \arg OS. - void print(raw_ostream &OS) const; + /// isDefined - Check if this symbol is defined (i.e., it has an address). + /// + /// Defined symbols are either absolute or in some section. + bool isDefined(bool SetUsed = true) const { + return getSectionPtr(SetUsed) != nullptr; + } - /// dump - Print the value to stderr. - void dump() const; - }; + /// isInSection - Check if this symbol is defined in some section (i.e., it + /// is defined but not absolute). + bool isInSection(bool SetUsed = true) const { + return isDefined(SetUsed) && !isAbsolute(SetUsed); + } + + /// isUndefined - Check if this symbol undefined (i.e., implicitly defined). + bool isUndefined(bool SetUsed = true) const { return !isDefined(SetUsed); } + + /// isAbsolute - Check if this is an absolute symbol. + bool isAbsolute(bool SetUsed = true) const { + return getSectionPtr(SetUsed) == AbsolutePseudoSection; + } + + /// Get the section associated with a defined, non-absolute symbol. + MCSection &getSection(bool SetUsed = true) const { + assert(isInSection(SetUsed) && "Invalid accessor!"); + return *getSectionPtr(SetUsed); + } + + /// Mark the symbol as defined in the section \p S. + void setSection(MCSection &S) { + assert(!isVariable() && "Cannot set section of variable"); + assert(!SectionOrFragmentAndHasName.getPointer().is() && + "Section or null expected"); + SectionOrFragmentAndHasName.setPointer(&S); + } + + /// Mark the symbol as undefined. + void setUndefined() { + SectionOrFragmentAndHasName.setPointer( + PointerUnion()); + } + + bool isELF() const { return Kind == SymbolKindELF; } + + bool isCOFF() const { return Kind == SymbolKindCOFF; } + + bool isMachO() const { return Kind == SymbolKindMachO; } + + /// @} + /// \name Variable Symbols + /// @{ + + /// isVariable - Check if this is a variable symbol. + bool isVariable() const { + return SymbolContents == SymContentsVariable; + } + + /// getVariableValue - Get the value for variable symbols. + const MCExpr *getVariableValue(bool SetUsed = true) const { + assert(isVariable() && "Invalid accessor!"); + IsUsed |= SetUsed; + return Value; + } + + void setVariableValue(const MCExpr *Value); + + /// @} + + /// Get the (implementation defined) index. + uint32_t getIndex() const { + return Index; + } + + /// Set the (implementation defined) index. + void setIndex(uint32_t Value) const { + Index = Value; + } + + uint64_t getOffset() const { + assert((SymbolContents == SymContentsUnset || + SymbolContents == SymContentsOffset) && + "Cannot get offset for a common/variable symbol"); + return Offset; + } + void setOffset(uint64_t Value) { + assert((SymbolContents == SymContentsUnset || + SymbolContents == SymContentsOffset) && + "Cannot set offset for a common/variable symbol"); + Offset = Value; + SymbolContents = SymContentsOffset; + } - inline raw_ostream &operator<<(raw_ostream &OS, const MCSymbol &Sym) { - Sym.print(OS); - return OS; + /// Return the size of a 'common' symbol. + uint64_t getCommonSize() const { + assert(isCommon() && "Not a 'common' symbol!"); + return CommonSize; } + + /// Mark this symbol as being 'common'. + /// + /// \param Size - The size of the symbol. + /// \param Align - The alignment of the symbol. + void setCommon(uint64_t Size, unsigned Align) { + assert(getOffset() == 0); + CommonSize = Size; + SymbolContents = SymContentsCommon; + + assert((!Align || isPowerOf2_32(Align)) && + "Alignment must be a power of 2"); + unsigned Log2Align = Log2_32(Align) + 1; + assert(Log2Align < (1U << NumCommonAlignmentBits) && + "Out of range alignment"); + CommonAlignLog2 = Log2Align; + } + + /// Return the alignment of a 'common' symbol. + unsigned getCommonAlignment() const { + assert(isCommon() && "Not a 'common' symbol!"); + return CommonAlignLog2 ? (1U << (CommonAlignLog2 - 1)) : 0; + } + + /// Declare this symbol as being 'common'. + /// + /// \param Size - The size of the symbol. + /// \param Align - The alignment of the symbol. + /// \return True if symbol was already declared as a different type + bool declareCommon(uint64_t Size, unsigned Align) { + assert(isCommon() || getOffset() == 0); + if(isCommon()) { + if(CommonSize != Size || getCommonAlignment() != Align) + return true; + } else + setCommon(Size, Align); + return false; + } + + /// Is this a 'common' symbol. + bool isCommon() const { + return SymbolContents == SymContentsCommon; + } + + MCFragment *getFragment() const { + return SectionOrFragmentAndHasName.getPointer().dyn_cast(); + } + void setFragment(MCFragment *Value) const { + SectionOrFragmentAndHasName.setPointer(Value); + } + + bool isExternal() const { return IsExternal; } + void setExternal(bool Value) const { IsExternal = Value; } + + bool isPrivateExtern() const { return IsPrivateExtern; } + void setPrivateExtern(bool Value) { IsPrivateExtern = Value; } + + /// print - Print the value to the stream \p OS. + void print(raw_ostream &OS, const MCAsmInfo *MAI) const; + + /// dump - Print the value to stderr. + void dump() const; + +protected: + /// Get the (implementation defined) symbol flags. + uint32_t getFlags() const { return Flags; } + + /// Set the (implementation defined) symbol flags. + void setFlags(uint32_t Value) const { + assert(Value < (1U << NumFlagsBits) && "Out of range flags"); + Flags = Value; + } + + /// Modify the flags via a mask + void modifyFlags(uint32_t Value, uint32_t Mask) const { + assert(Value < (1U << NumFlagsBits) && "Out of range flags"); + Flags = (Flags & ~Mask) | Value; + } +}; + +inline raw_ostream &operator<<(raw_ostream &OS, const MCSymbol &Sym) { + Sym.print(OS, nullptr); + return OS; +} } // end namespace llvm #endif