X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FMC%2FMCSymbol.h;h=b2910dfccd637abc15622fa3d736f5a252360100;hb=00552e3875ee5f382db6c98286a241a7d0efe1b8;hp=0acf6e50ba48e9bd7aaa8d0935841b599cd8a032;hpb=a1e31b45cceac55344ab94e19a7b9249b92a2f39;p=oota-llvm.git diff --git a/include/llvm/MC/MCSymbol.h b/include/llvm/MC/MCSymbol.h index 0acf6e50ba4..b2910dfccd6 100644 --- a/include/llvm/MC/MCSymbol.h +++ b/include/llvm/MC/MCSymbol.h @@ -14,6 +14,7 @@ #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" @@ -46,6 +47,15 @@ protected: 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? @@ -62,10 +72,12 @@ protected: /// /// If this is a fragment, then it gives the fragment this symbol's value is /// relative to, if any. - mutable PointerUnion 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, 1> + SectionOrFragmentAndHasName; /// IsTemporary - True if this is an assembler temporary label, which /// typically does not survive in the .o file's symbol table. Usually @@ -86,11 +98,6 @@ protected: /// 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; @@ -98,6 +105,23 @@ protected: /// 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; @@ -107,16 +131,10 @@ protected: /// 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; @@ -132,11 +150,12 @@ protected: // MCContext creates and uniques these. } NameEntryStorageTy; MCSymbol(SymbolKind Kind, const StringMapEntry *Name, bool isTemporary) - : Value(nullptr), IsTemporary(isTemporary), IsRedefinable(false), - IsUsed(false), IsRegistered(false), IsExternal(false), - IsPrivateExtern(false), HasName(!!Name), Kind(Kind), - IsUsedInReloc(false) { + : 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; } @@ -163,16 +182,17 @@ private: MCSection *getSectionPtr() 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 || !Value) + 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(HasName && "Name is required"); + assert(SectionOrFragmentAndHasName.getInt() && "Name is required"); NameEntryStorageTy *Name = reinterpret_cast(this); return (*(Name - 1)).NameEntry; } @@ -183,7 +203,7 @@ private: public: /// getName - Get the symbol name. StringRef getName() const { - if (!HasName) + if (!SectionOrFragmentAndHasName.getInt()) return StringRef(); return getNameEntryPtr()->first(); @@ -212,8 +232,11 @@ public: /// \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; } } @@ -246,13 +269,15 @@ public: /// Mark the symbol as defined in the section \p S. void setSection(MCSection &S) { assert(!isVariable() && "Cannot set section of variable"); - assert(!SectionOrFragment.is() && "Section or null expected"); - SectionOrFragment = &S; + assert(!SectionOrFragmentAndHasName.getPointer().is() && + "Section or null expected"); + SectionOrFragmentAndHasName.setPointer(&S); } /// Mark the symbol as undefined. void setUndefined() { - SectionOrFragment = nullptr; + SectionOrFragmentAndHasName.setPointer( + PointerUnion()); } bool isELF() const { return Kind == SymbolKindELF; } @@ -266,7 +291,9 @@ public: /// @{ /// 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 { @@ -290,12 +317,17 @@ public: } 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. @@ -311,13 +343,20 @@ 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'. @@ -328,7 +367,7 @@ public: 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); @@ -336,13 +375,15 @@ public: } /// Is this a 'common' symbol. - bool isCommon() const { return CommonAlign != -1U; } + bool isCommon() const { + return SymbolContents == SymContentsCommon; + } MCFragment *getFragment() const { - return SectionOrFragment.dyn_cast(); + return SectionOrFragmentAndHasName.getPointer().dyn_cast(); } void setFragment(MCFragment *Value) const { - SectionOrFragment = Value; + SectionOrFragmentAndHasName.setPointer(Value); } bool isExternal() const { return IsExternal; } @@ -362,10 +403,14 @@ protected: 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; } };