X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FMC%2FMCSymbol.h;h=b2910dfccd637abc15622fa3d736f5a252360100;hb=00552e3875ee5f382db6c98286a241a7d0efe1b8;hp=7db5bade8e2449956c44f8112b2a35d4ffa33e6e;hpb=5760c5fe31af0e7afb0d69bb36f36def2a723deb;p=oota-llvm.git diff --git a/include/llvm/MC/MCSymbol.h b/include/llvm/MC/MCSymbol.h index 7db5bade8e2..b2910dfccd6 100644 --- a/include/llvm/MC/MCSymbol.h +++ b/include/llvm/MC/MCSymbol.h @@ -15,11 +15,13 @@ #define LLVM_MC_MCSYMBOL_H #include "llvm/ADT/PointerIntPair.h" +#include "llvm/ADT/PointerUnion.h" #include "llvm/ADT/StringMap.h" -#include "llvm/MC/MCExpr.h" +#include "llvm/MC/MCAssembler.h" #include "llvm/Support/Compiler.h" namespace llvm { +class MCAsmInfo; class MCExpr; class MCSymbol; class MCFragment; @@ -35,22 +37,47 @@ class raw_ostream; /// 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; - /// Name - The name of the symbol. The referred-to string data is actually - /// held by the StringMap that lives in MCContext. - const StringMapEntry *Name; - - /// The section 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. - mutable MCSection *Section; - - /// Value - If non-null, the value for a variable symbol. - const MCExpr *Value; + /// 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 @@ -63,19 +90,40 @@ class MCSymbol { /// IsUsed - True if this symbol has been used. mutable unsigned IsUsed : 1; - mutable bool HasData : 1; + mutable bool IsRegistered : 1; - /// Index field, for use by the object file implementation. - mutable uint64_t Index : 60; + /// This symbol is visible outside this translation unit. + mutable unsigned IsExternal : 1; - /// An expression describing how to calculate the size of a symbol. If a - /// symbol has no size this field will be NULL. - const MCExpr *SymbolSize = nullptr; + /// 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. - // - // FIXME: Pack this in with other fields? - unsigned CommonAlign = -1U; + /// + /// 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. @@ -83,48 +131,89 @@ class MCSymbol { /// The size of the symbol, if it is 'common'. uint64_t CommonSize; - }; - - /// The Flags field is used by object file implementations to store - /// additional per symbol information which is not easily classified. - mutable uint32_t Flags = 0; - /// The fragment this symbol's value is relative to, if any. Also stores if - /// this symbol is visible outside this translation unit (bit 0) or if it is - /// private extern (bit 1). - mutable PointerIntPair Fragment; + /// If non-null, the value for a variable symbol. + const MCExpr *Value; + }; -private: // MCContext creates and uniques these. +protected: // MCContext creates and uniques these. friend class MCExpr; friend class MCContext; - MCSymbol(const StringMapEntry *Name, bool isTemporary) - : Name(Name), Section(nullptr), Value(nullptr), IsTemporary(isTemporary), - IsRedefinable(false), IsUsed(false), HasData(false), Index(0) { + + /// \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; + + 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; + } + + // 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); + +private: + + 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?"); } MCSymbol(const MCSymbol &) = delete; void operator=(const MCSymbol &) = delete; MCSection *getSectionPtr() const { - if (Section || !Value) + 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 = Value->FindAssociatedSection(); + return Section = getVariableValue()->findAssociatedSection(); + } + + /// \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(); } public: /// getName - Get the symbol name. - StringRef getName() const { return Name ? Name->first() : ""; } + StringRef getName() const { + if (!SectionOrFragmentAndHasName.getInt()) + return StringRef(); - bool hasData() const { return HasData; } + return getNameEntryPtr()->first(); + } - MCSymbol &getData() const { return *const_cast(this); } + bool isRegistered() const { return IsRegistered; } + void setIsRegistered(bool Value) const { IsRegistered = Value; } - /// Initialize symbol data. - /// - /// Nothing really to do here, but this is enables an assertion that \a - /// MCAssembler::getOrCreateSymbolData() has actually been called before - /// anyone calls \a getData(). - void initializeData() const { HasData = true; } + void setUsedInReloc() const { IsUsedInReloc = true; } + bool isUsedInReloc() const { return IsUsedInReloc; } /// \name Accessors /// @{ @@ -143,8 +232,11 @@ public: /// \brief Prepare this symbol to be redefined. void redefineIfPossible() { if (IsRedefinable) { - Value = nullptr; - Section = nullptr; + if (SymbolContents == SymContentsVariable) { + Value = nullptr; + SymbolContents = SymContentsUnset; + } + setUndefined(); IsRedefinable = false; } } @@ -177,18 +269,31 @@ public: /// Mark the symbol as defined in the section \p S. void setSection(MCSection &S) { assert(!isVariable() && "Cannot set section of variable"); - Section = &S; + assert(!SectionOrFragmentAndHasName.getPointer().is() && + "Section or null expected"); + SectionOrFragmentAndHasName.setPointer(&S); } - /// setUndefined - Mark the symbol as undefined. - void setUndefined() { Section = nullptr; } + /// 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 Value != nullptr; } + bool isVariable() const { + return SymbolContents == SymContentsVariable; + } /// getVariableValue() - Get the value for variable symbols. const MCExpr *getVariableValue() const { @@ -202,29 +307,27 @@ public: /// @} /// Get the (implementation defined) index. - uint64_t getIndex() const { - assert(HasData && "Uninitialized symbol data"); + uint32_t getIndex() const { return Index; } /// Set the (implementation defined) index. - void setIndex(uint64_t Value) const { - assert(HasData && "Uninitialized symbol data"); - assert(!(Value >> 60) && "Not enough bits for value"); + void setIndex(uint32_t Value) const { Index = Value; } - void setSize(const MCExpr *SS) { SymbolSize = SS; } - - const MCExpr *getSize() const { return SymbolSize; } - uint64_t getOffset() const { - assert(!isCommon()); + assert((SymbolContents == SymContentsUnset || + SymbolContents == SymContentsOffset) && + "Cannot get offset for a common/variable symbol"); return Offset; } void setOffset(uint64_t Value) { - assert(!isCommon()); + assert((SymbolContents == SymContentsUnset || + SymbolContents == SymContentsOffset) && + "Cannot set offset for a common/variable symbol"); Offset = Value; + SymbolContents = SymContentsOffset; } /// Return the size of a 'common' symbol. @@ -240,51 +343,80 @@ public: void setCommon(uint64_t Size, unsigned Align) { assert(getOffset() == 0); CommonSize = Size; - CommonAlign = Align; + 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 CommonAlign; + 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 CommonAlign != -1U; } + 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 { Flags = Value; } + 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; } - - MCFragment *getFragment() const { return Fragment.getPointer(); } - void setFragment(MCFragment *Value) const { Fragment.setPointer(Value); } - - bool isExternal() const { return Fragment.getInt() & 1; } - void setExternal(bool Value) const { - Fragment.setInt((Fragment.getInt() & ~1) | unsigned(Value)); - } - - bool isPrivateExtern() const { return Fragment.getInt() & 2; } - void setPrivateExtern(bool Value) { - Fragment.setInt((Fragment.getInt() & ~2) | (unsigned(Value) << 1)); - } - - /// print - Print the value to the stream \p OS. - void print(raw_ostream &OS) const; - - /// dump - Print the value to stderr. - void dump() const; }; inline raw_ostream &operator<<(raw_ostream &OS, const MCSymbol &Sym) { - Sym.print(OS); + Sym.print(OS, nullptr); return OS; } } // end namespace llvm