#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 MCAsmLayout;
- 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<PointerUnion<MCSection *, MCFragment *>, 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;
-
- /// IsUsed - True if this symbol has been used.
- mutable unsigned IsUsed : 1;
-
- private: // MCContext creates and uniques these.
- friend class MCExpr;
- friend class MCContext;
- MCSymbol(StringRef name, bool isTemporary)
- : Name(name), Section(0), Value(0),
- IsTemporary(isTemporary), IsUsed(false) {}
-
- MCSymbol(const MCSymbol&) LLVM_DELETED_FUNCTION;
- void operator=(const MCSymbol&) LLVM_DELETED_FUNCTION;
- public:
- /// getName - Get the symbol name.
- StringRef getName() const { return Name; }
-
- /// @name Accessors
- /// @{
-
- /// 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; }
-
- /// @}
- /// @name Associated Sections
- /// @{
-
- /// 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;
- }
+protected: // MCContext creates and uniques these.
+ friend class MCExpr;
+ friend class MCContext;
+
+ /// \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<bool> *NameEntry;
+ uint64_t AlignmentPadding;
+ } NameEntryStorageTy;
+
+ MCSymbol(SymbolKind Kind, const StringMapEntry<bool> *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;
+ }
- /// isInSection - Check if this symbol is defined in some section (i.e., it
- /// is defined but not absolute).
- bool isInSection() const {
- return isDefined() && !isAbsolute();
- }
+ // 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<bool> *Name,
+ MCContext &Ctx);
- /// isUndefined - Check if this symbol undefined (i.e., implicitly defined).
- bool isUndefined() const {
- return !isDefined();
- }
+private:
- /// isAbsolute - Check if this is an absolute symbol.
- bool isAbsolute() const {
- return Section == AbsolutePseudoSection;
- }
+ 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?");
+ }
- /// getSection - Get the section associated with a defined, non-absolute
- /// symbol.
- const MCSection &getSection() const {
- assert(isInSection() && "Invalid accessor!");
- return *Section;
- }
+ 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<MCFragment *>() && "Section or null expected");
+ MCSection *Section = SectionOrFragment.dyn_cast<MCSection *>();
+ if (Section || !isVariable())
+ return Section;
+ return Section = getVariableValue(SetUsed)->findAssociatedSection();
+ }
- /// setSection - Mark the symbol as defined in the section \p S.
- void setSection(const MCSection &S) { Section = &S; }
+ /// \brief Get a reference to the name field. Requires that we have a name
+ const StringMapEntry<bool> *&getNameEntryPtr() {
+ assert(SectionOrFragmentAndHasName.getInt() && "Name is required");
+ NameEntryStorageTy *Name = reinterpret_cast<NameEntryStorageTy *>(this);
+ return (*(Name - 1)).NameEntry;
+ }
+ const StringMapEntry<bool> *&getNameEntryPtr() const {
+ return const_cast<MCSymbol*>(this)->getNameEntryPtr();
+ }
- /// setUndefined - Mark the symbol as undefined.
- void setUndefined() {
- Section = 0;
+public:
+ /// getName - Get the symbol name.
+ StringRef getName() const {
+ if (!SectionOrFragmentAndHasName.getInt())
+ return StringRef();
+
+ return getNameEntryPtr()->first();
+ }
+
+ bool isRegistered() const { return IsRegistered; }
+ void setIsRegistered(bool Value) const { IsRegistered = Value; }
+
+ void setUsedInReloc() const { IsUsedInReloc = true; }
+ bool isUsedInReloc() const { return IsUsedInReloc; }
+
+ /// \name Accessors
+ /// @{
+
+ /// 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;
}
+ }
- /// setAbsolute - Mark the symbol as absolute.
- void setAbsolute() { Section = AbsolutePseudoSection; }
+ /// @}
+ /// \name Associated Sections
+ /// @{
- /// @}
- /// @name Variable Symbols
- /// @{
+ /// 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;
+ }
- /// isVariable - Check if this is a variable symbol.
- bool isVariable() const {
- return Value != 0;
- }
+ /// 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);
+ }
- /// getVariableValue() - Get the value for variable symbols.
- const MCExpr *getVariableValue() const {
- assert(isVariable() && "Invalid accessor!");
- IsUsed = true;
- return Value;
- }
+ /// isUndefined - Check if this symbol undefined (i.e., implicitly defined).
+ bool isUndefined(bool SetUsed = true) const { return !isDefined(SetUsed); }
- // AliasedSymbol() - If this is an alias (a = b), return the symbol
- // we ultimately point to. For a non-alias, this just returns the symbol
- // itself.
- const MCSymbol &AliasedSymbol() const;
+ /// isAbsolute - Check if this is an absolute symbol.
+ bool isAbsolute(bool SetUsed = true) const {
+ return getSectionPtr(SetUsed) == AbsolutePseudoSection;
+ }
- // If this symbol is not a variable, return itself. If it is a variable,
- // evaluate it and check if it is of the form Base + ConstantOffset. If so,
- // return Base, if not, return nullptr.
- const MCSymbol *getBaseSymbol(const MCAsmLayout &Layout) const;
+ /// 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<MCFragment *>() &&
+ "Section or null expected");
+ SectionOrFragmentAndHasName.setPointer(&S);
+ }
- void setVariableValue(const MCExpr *Value);
+ /// Mark the symbol as undefined.
+ void setUndefined() {
+ SectionOrFragmentAndHasName.setPointer(
+ PointerUnion<MCSection *, MCFragment *>());
+ }
- /// @}
+ bool isELF() const { return Kind == SymbolKindELF; }
- /// print - Print the value to the stream \p OS.
- void print(raw_ostream &OS) const;
+ bool isCOFF() const { return Kind == SymbolKindCOFF; }
- /// dump - Print the value to stderr.
- void dump() const;
- };
+ 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;
+ }
+
+ /// Return the size of a 'common' symbol.
+ uint64_t getCommonSize() const {
+ assert(isCommon() && "Not a 'common' symbol!");
+ return CommonSize;
+ }
- inline raw_ostream &operator<<(raw_ostream &OS, const MCSymbol &Sym) {
- Sym.print(OS);
- return OS;
+ /// 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<MCFragment *>();
+ }
+ 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
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