#ifndef LLVM_MC_MCSYMBOL_H
#define LLVM_MC_MCSYMBOL_H
+#include "llvm/ADT/PointerIntPair.h"
#include "llvm/ADT/PointerUnion.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/MC/MCAssembler.h"
-#include "llvm/MC/MCExpr.h"
#include "llvm/Support/Compiler.h"
namespace llvm {
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?
///
/// If this is a fragment, then it gives the fragment this symbol's value is
/// relative to, if any.
- mutable PointerUnion<MCSection *, MCFragment *> SectionOrFragment;
-
- /// Value - If non-null, the value for a variable symbol.
- const MCExpr *Value;
+ ///
+ /// 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
/// This symbol is private extern.
mutable unsigned IsPrivateExtern : 1;
- /// 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.
- unsigned HasName : 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.
+ ///
+ /// 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;
/// The size of the symbol, if it is 'common'.
uint64_t CommonSize;
- };
-
- /// The alignment of the symbol, if it is 'common', or -1.
- //
- // FIXME: Pack this in with other fields?
- unsigned CommonAlign = -1U;
- /// 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;
+ /// If non-null, the value for a variable symbol.
+ const MCExpr *Value;
+ };
protected: // MCContext creates and uniques these.
friend class MCExpr;
} NameEntryStorageTy;
MCSymbol(SymbolKind Kind, const StringMapEntry<bool> *Name, bool isTemporary)
- : Value(nullptr), IsTemporary(isTemporary),
- IsRedefinable(false), IsUsed(false), IsRegistered(false),
- IsExternal(false), IsPrivateExtern(false), HasName(!!Name),
- Kind(Kind) {
+ : 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;
}
MCSymbol(const MCSymbol &) = delete;
void operator=(const MCSymbol &) = delete;
- MCSection *getSectionPtr() const {
+ 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 || !Value)
+ 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(HasName && "Name is required");
+ assert(SectionOrFragmentAndHasName.getInt() && "Name is required");
NameEntryStorageTy *Name = reinterpret_cast<NameEntryStorageTy *>(this);
return (*(Name - 1)).NameEntry;
}
public:
/// getName - Get the symbol name.
StringRef getName() const {
- if (!HasName)
+ 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
/// @{
/// 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;
- SectionOrFragment = 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");
- assert(!SectionOrFragment.is<MCFragment *>() && "Section or null expected");
- SectionOrFragment = &S;
+ assert(!SectionOrFragmentAndHasName.getPointer().is<MCFragment *>() &&
+ "Section or null expected");
+ SectionOrFragmentAndHasName.setPointer(&S);
}
/// Mark the symbol as undefined.
void setUndefined() {
- SectionOrFragment = nullptr;
+ SectionOrFragmentAndHasName.setPointer(
+ PointerUnion<MCSection *, MCFragment *>());
}
bool isELF() const { return Kind == SymbolKindELF; }
/// @{
/// 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;
}
}
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'.
bool declareCommon(uint64_t Size, unsigned Align) {
assert(isCommon() || getOffset() == 0);
if(isCommon()) {
- if(CommonSize != Size || CommonAlign != Align)
+ if(CommonSize != Size || getCommonAlignment() != Align)
return true;
} else
setCommon(Size, Align);
}
/// Is this a 'common' symbol.
- bool isCommon() const { return CommonAlign != -1U; }
+ bool isCommon() const {
+ return SymbolContents == SymContentsCommon;
+ }
MCFragment *getFragment() const {
- return SectionOrFragment.dyn_cast<MCFragment *>();
+ return SectionOrFragmentAndHasName.getPointer().dyn_cast<MCFragment *>();
}
void setFragment(MCFragment *Value) const {
- SectionOrFragment = Value;
+ SectionOrFragmentAndHasName.setPointer(Value);
}
bool isExternal() const { return IsExternal; }
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;
}
};
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