#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;
/// 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<bool> *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<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
/// 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.
/// 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<MCFragment *, 2> 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<bool> *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<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;
+ }
+
+ // 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);
+
+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)
+ 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 = Value->FindAssociatedSection();
+ return Section = getVariableValue(SetUsed)->findAssociatedSection();
+ }
+
+ /// \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();
}
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<MCSymbol *>(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
/// @{
/// isUsed - Check if this is used.
bool isUsed() const { return IsUsed; }
- void setUsed(bool Value) const { IsUsed = Value; }
+ void setUsed(bool Value) const { IsUsed |= Value; }
/// \brief Check if this symbol is redefinable.
bool isRedefinable() const { return IsRedefinable; }
/// \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;
}
}
/// 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 getSectionPtr() != nullptr; }
+ bool isDefined(bool SetUsed = true) const {
+ return getSectionPtr(SetUsed) != nullptr;
+ }
/// isInSection - Check if this symbol is defined in some section (i.e., it
/// is defined but not absolute).
- bool isInSection() const { return isDefined() && !isAbsolute(); }
+ bool isInSection(bool SetUsed = true) const {
+ return isDefined(SetUsed) && !isAbsolute(SetUsed);
+ }
/// isUndefined - Check if this symbol undefined (i.e., implicitly defined).
- bool isUndefined() const { return !isDefined(); }
+ bool isUndefined(bool SetUsed = true) const { return !isDefined(SetUsed); }
/// isAbsolute - Check if this is an absolute symbol.
- bool isAbsolute() const { return getSectionPtr() == AbsolutePseudoSection; }
+ bool isAbsolute(bool SetUsed = true) const {
+ return getSectionPtr(SetUsed) == AbsolutePseudoSection;
+ }
/// Get the section associated with a defined, non-absolute symbol.
- MCSection &getSection() const {
- assert(isInSection() && "Invalid accessor!");
- return *getSectionPtr();
+ 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");
- Section = &S;
+ assert(!SectionOrFragmentAndHasName.getPointer().is<MCFragment *>() &&
+ "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<MCSection *, MCFragment *>());
+ }
+
+ 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 {
+ /// getVariableValue - Get the value for variable symbols.
+ const MCExpr *getVariableValue(bool SetUsed = true) const {
assert(isVariable() && "Invalid accessor!");
- IsUsed = true;
+ IsUsed |= SetUsed;
return Value;
}
/// @}
/// 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.
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<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 { 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
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