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Diffstat (limited to 'include/llvm/IR/DataLayout.h')
| -rw-r--r-- | include/llvm/IR/DataLayout.h | 427 |
1 files changed, 427 insertions, 0 deletions
diff --git a/include/llvm/IR/DataLayout.h b/include/llvm/IR/DataLayout.h new file mode 100644 index 0000000000..8d9f543b9f --- /dev/null +++ b/include/llvm/IR/DataLayout.h @@ -0,0 +1,427 @@ +//===--------- llvm/DataLayout.h - Data size & alignment info ---*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file defines layout properties related to datatype size/offset/alignment +// information. It uses lazy annotations to cache information about how +// structure types are laid out and used. +// +// This structure should be created once, filled in if the defaults are not +// correct and then passed around by const&. None of the members functions +// require modification to the object. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_IR_DATALAYOUT_H +#define LLVM_IR_DATALAYOUT_H + +#include "llvm/ADT/DenseMap.h" +#include "llvm/ADT/SmallVector.h" +#include "llvm/Pass.h" +#include "llvm/Support/DataTypes.h" + +namespace llvm { + +class Value; +class Type; +class IntegerType; +class StructType; +class StructLayout; +class GlobalVariable; +class LLVMContext; +template<typename T> +class ArrayRef; + +/// Enum used to categorize the alignment types stored by LayoutAlignElem +enum AlignTypeEnum { + INVALID_ALIGN = 0, ///< An invalid alignment + INTEGER_ALIGN = 'i', ///< Integer type alignment + VECTOR_ALIGN = 'v', ///< Vector type alignment + FLOAT_ALIGN = 'f', ///< Floating point type alignment + AGGREGATE_ALIGN = 'a', ///< Aggregate alignment + STACK_ALIGN = 's' ///< Stack objects alignment +}; + +/// Layout alignment element. +/// +/// Stores the alignment data associated with a given alignment type (integer, +/// vector, float) and type bit width. +/// +/// @note The unusual order of elements in the structure attempts to reduce +/// padding and make the structure slightly more cache friendly. +struct LayoutAlignElem { + unsigned AlignType : 8; ///< Alignment type (AlignTypeEnum) + unsigned TypeBitWidth : 24; ///< Type bit width + unsigned ABIAlign : 16; ///< ABI alignment for this type/bitw + unsigned PrefAlign : 16; ///< Pref. alignment for this type/bitw + + /// Initializer + static LayoutAlignElem get(AlignTypeEnum align_type, unsigned abi_align, + unsigned pref_align, uint32_t bit_width); + /// Equality predicate + bool operator==(const LayoutAlignElem &rhs) const; +}; + +/// Layout pointer alignment element. +/// +/// Stores the alignment data associated with a given pointer and address space. +/// +/// @note The unusual order of elements in the structure attempts to reduce +/// padding and make the structure slightly more cache friendly. +struct PointerAlignElem { + unsigned ABIAlign; ///< ABI alignment for this type/bitw + unsigned PrefAlign; ///< Pref. alignment for this type/bitw + uint32_t TypeBitWidth; ///< Type bit width + uint32_t AddressSpace; ///< Address space for the pointer type + + /// Initializer + static PointerAlignElem get(uint32_t addr_space, unsigned abi_align, + unsigned pref_align, uint32_t bit_width); + /// Equality predicate + bool operator==(const PointerAlignElem &rhs) const; +}; + + +/// DataLayout - This class holds a parsed version of the target data layout +/// string in a module and provides methods for querying it. The target data +/// layout string is specified *by the target* - a frontend generating LLVM IR +/// is required to generate the right target data for the target being codegen'd +/// to. If some measure of portability is desired, an empty string may be +/// specified in the module. +class DataLayout : public ImmutablePass { +private: + bool LittleEndian; ///< Defaults to false + unsigned StackNaturalAlign; ///< Stack natural alignment + + SmallVector<unsigned char, 8> LegalIntWidths; ///< Legal Integers. + + /// Alignments- Where the primitive type alignment data is stored. + /// + /// @sa init(). + /// @note Could support multiple size pointer alignments, e.g., 32-bit + /// pointers vs. 64-bit pointers by extending LayoutAlignment, but for now, + /// we don't. + SmallVector<LayoutAlignElem, 16> Alignments; + DenseMap<unsigned, PointerAlignElem> Pointers; + + /// InvalidAlignmentElem - This member is a signal that a requested alignment + /// type and bit width were not found in the SmallVector. + static const LayoutAlignElem InvalidAlignmentElem; + + /// InvalidPointerElem - This member is a signal that a requested pointer + /// type and bit width were not found in the DenseSet. + static const PointerAlignElem InvalidPointerElem; + + // The StructType -> StructLayout map. + mutable void *LayoutMap; + + //! Set/initialize target alignments + void setAlignment(AlignTypeEnum align_type, unsigned abi_align, + unsigned pref_align, uint32_t bit_width); + unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width, + bool ABIAlign, Type *Ty) const; + + //! Set/initialize pointer alignments + void setPointerAlignment(uint32_t addr_space, unsigned abi_align, + unsigned pref_align, uint32_t bit_width); + + //! Internal helper method that returns requested alignment for type. + unsigned getAlignment(Type *Ty, bool abi_or_pref) const; + + /// Valid alignment predicate. + /// + /// Predicate that tests a LayoutAlignElem reference returned by get() against + /// InvalidAlignmentElem. + bool validAlignment(const LayoutAlignElem &align) const { + return &align != &InvalidAlignmentElem; + } + + /// Valid pointer predicate. + /// + /// Predicate that tests a PointerAlignElem reference returned by get() against + /// InvalidPointerElem. + bool validPointer(const PointerAlignElem &align) const { + return &align != &InvalidPointerElem; + } + + /// Parses a target data specification string. Assert if the string is + /// malformed. + void parseSpecifier(StringRef LayoutDescription); + +public: + /// Default ctor. + /// + /// @note This has to exist, because this is a pass, but it should never be + /// used. + DataLayout(); + + /// Constructs a DataLayout from a specification string. See init(). + explicit DataLayout(StringRef LayoutDescription) + : ImmutablePass(ID) { + init(LayoutDescription); + } + + /// Initialize target data from properties stored in the module. + explicit DataLayout(const Module *M); + + DataLayout(const DataLayout &TD) : + ImmutablePass(ID), + LittleEndian(TD.isLittleEndian()), + LegalIntWidths(TD.LegalIntWidths), + Alignments(TD.Alignments), + Pointers(TD.Pointers), + LayoutMap(0) + { } + + ~DataLayout(); // Not virtual, do not subclass this class + + /// Parse a data layout string (with fallback to default values). Ensure that + /// the data layout pass is registered. + void init(StringRef LayoutDescription); + + /// Layout endianness... + bool isLittleEndian() const { return LittleEndian; } + bool isBigEndian() const { return !LittleEndian; } + + /// getStringRepresentation - Return the string representation of the + /// DataLayout. This representation is in the same format accepted by the + /// string constructor above. + std::string getStringRepresentation() const; + + /// isLegalInteger - This function returns true if the specified type is + /// known to be a native integer type supported by the CPU. For example, + /// i64 is not native on most 32-bit CPUs and i37 is not native on any known + /// one. This returns false if the integer width is not legal. + /// + /// The width is specified in bits. + /// + bool isLegalInteger(unsigned Width) const { + for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i) + if (LegalIntWidths[i] == Width) + return true; + return false; + } + + bool isIllegalInteger(unsigned Width) const { + return !isLegalInteger(Width); + } + + /// Returns true if the given alignment exceeds the natural stack alignment. + bool exceedsNaturalStackAlignment(unsigned Align) const { + return (StackNaturalAlign != 0) && (Align > StackNaturalAlign); + } + + /// fitsInLegalInteger - This function returns true if the specified type fits + /// in a native integer type supported by the CPU. For example, if the CPU + /// only supports i32 as a native integer type, then i27 fits in a legal + // integer type but i45 does not. + bool fitsInLegalInteger(unsigned Width) const { + for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i) + if (Width <= LegalIntWidths[i]) + return true; + return false; + } + + /// Layout pointer alignment + /// FIXME: The defaults need to be removed once all of + /// the backends/clients are updated. + unsigned getPointerABIAlignment(unsigned AS = 0) const { + DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS); + if (val == Pointers.end()) { + val = Pointers.find(0); + } + return val->second.ABIAlign; + } + /// Return target's alignment for stack-based pointers + /// FIXME: The defaults need to be removed once all of + /// the backends/clients are updated. + unsigned getPointerPrefAlignment(unsigned AS = 0) const { + DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS); + if (val == Pointers.end()) { + val = Pointers.find(0); + } + return val->second.PrefAlign; + } + /// Layout pointer size + /// FIXME: The defaults need to be removed once all of + /// the backends/clients are updated. + unsigned getPointerSize(unsigned AS = 0) const { + DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS); + if (val == Pointers.end()) { + val = Pointers.find(0); + } + return val->second.TypeBitWidth; + } + /// Layout pointer size, in bits + /// FIXME: The defaults need to be removed once all of + /// the backends/clients are updated. + unsigned getPointerSizeInBits(unsigned AS = 0) const { + return getPointerSize(AS) * 8; + } + /// Size examples: + /// + /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*] + /// ---- ---------- --------------- --------------- + /// i1 1 8 8 + /// i8 8 8 8 + /// i19 19 24 32 + /// i32 32 32 32 + /// i100 100 104 128 + /// i128 128 128 128 + /// Float 32 32 32 + /// Double 64 64 64 + /// X86_FP80 80 80 96 + /// + /// [*] The alloc size depends on the alignment, and thus on the target. + /// These values are for x86-32 linux. + + /// getTypeSizeInBits - Return the number of bits necessary to hold the + /// specified type. For example, returns 36 for i36 and 80 for x86_fp80. + /// The type passed must have a size (Type::isSized() must return true). + uint64_t getTypeSizeInBits(Type* Ty) const; + + /// getTypeStoreSize - Return the maximum number of bytes that may be + /// overwritten by storing the specified type. For example, returns 5 + /// for i36 and 10 for x86_fp80. + uint64_t getTypeStoreSize(Type *Ty) const { + return (getTypeSizeInBits(Ty)+7)/8; + } + + /// getTypeStoreSizeInBits - Return the maximum number of bits that may be + /// overwritten by storing the specified type; always a multiple of 8. For + /// example, returns 40 for i36 and 80 for x86_fp80. + uint64_t getTypeStoreSizeInBits(Type *Ty) const { + return 8*getTypeStoreSize(Ty); + } + + /// getTypeAllocSize - Return the offset in bytes between successive objects + /// of the specified type, including alignment padding. This is the amount + /// that alloca reserves for this type. For example, returns 12 or 16 for + /// x86_fp80, depending on alignment. + uint64_t getTypeAllocSize(Type* Ty) const { + // Round up to the next alignment boundary. + return RoundUpAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty)); + } + + /// getTypeAllocSizeInBits - Return the offset in bits between successive + /// objects of the specified type, including alignment padding; always a + /// multiple of 8. This is the amount that alloca reserves for this type. + /// For example, returns 96 or 128 for x86_fp80, depending on alignment. + uint64_t getTypeAllocSizeInBits(Type* Ty) const { + return 8*getTypeAllocSize(Ty); + } + + /// getABITypeAlignment - Return the minimum ABI-required alignment for the + /// specified type. + unsigned getABITypeAlignment(Type *Ty) const; + + /// getABIIntegerTypeAlignment - Return the minimum ABI-required alignment for + /// an integer type of the specified bitwidth. + unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const; + + + /// getCallFrameTypeAlignment - Return the minimum ABI-required alignment + /// for the specified type when it is part of a call frame. + unsigned getCallFrameTypeAlignment(Type *Ty) const; + + + /// getPrefTypeAlignment - Return the preferred stack/global alignment for + /// the specified type. This is always at least as good as the ABI alignment. + unsigned getPrefTypeAlignment(Type *Ty) const; + + /// getPreferredTypeAlignmentShift - Return the preferred alignment for the + /// specified type, returned as log2 of the value (a shift amount). + /// + unsigned getPreferredTypeAlignmentShift(Type *Ty) const; + + /// getIntPtrType - Return an integer type with size at least as big as that + /// of a pointer in the given address space. + IntegerType *getIntPtrType(LLVMContext &C, unsigned AddressSpace = 0) const; + + /// getIntPtrType - Return an integer (vector of integer) type with size at + /// least as big as that of a pointer of the given pointer (vector of pointer) + /// type. + Type *getIntPtrType(Type *) const; + + /// getIndexedOffset - return the offset from the beginning of the type for + /// the specified indices. This is used to implement getelementptr. + /// + uint64_t getIndexedOffset(Type *Ty, ArrayRef<Value *> Indices) const; + + /// getStructLayout - Return a StructLayout object, indicating the alignment + /// of the struct, its size, and the offsets of its fields. Note that this + /// information is lazily cached. + const StructLayout *getStructLayout(StructType *Ty) const; + + /// getPreferredAlignment - Return the preferred alignment of the specified + /// global. This includes an explicitly requested alignment (if the global + /// has one). + unsigned getPreferredAlignment(const GlobalVariable *GV) const; + + /// getPreferredAlignmentLog - Return the preferred alignment of the + /// specified global, returned in log form. This includes an explicitly + /// requested alignment (if the global has one). + unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const; + + /// RoundUpAlignment - Round the specified value up to the next alignment + /// boundary specified by Alignment. For example, 7 rounded up to an + /// alignment boundary of 4 is 8. 8 rounded up to the alignment boundary of 4 + /// is 8 because it is already aligned. + template <typename UIntTy> + static UIntTy RoundUpAlignment(UIntTy Val, unsigned Alignment) { + assert((Alignment & (Alignment-1)) == 0 && "Alignment must be power of 2!"); + return (Val + (Alignment-1)) & ~UIntTy(Alignment-1); + } + + static char ID; // Pass identification, replacement for typeid +}; + +/// StructLayout - used to lazily calculate structure layout information for a +/// target machine, based on the DataLayout structure. +/// +class StructLayout { + uint64_t StructSize; + unsigned StructAlignment; + unsigned NumElements; + uint64_t MemberOffsets[1]; // variable sized array! +public: + + uint64_t getSizeInBytes() const { + return StructSize; + } + + uint64_t getSizeInBits() const { + return 8*StructSize; + } + + unsigned getAlignment() const { + return StructAlignment; + } + + /// getElementContainingOffset - Given a valid byte offset into the structure, + /// return the structure index that contains it. + /// + unsigned getElementContainingOffset(uint64_t Offset) const; + + uint64_t getElementOffset(unsigned Idx) const { + assert(Idx < NumElements && "Invalid element idx!"); + return MemberOffsets[Idx]; + } + + uint64_t getElementOffsetInBits(unsigned Idx) const { + return getElementOffset(Idx)*8; + } + +private: + friend class DataLayout; // Only DataLayout can create this class + StructLayout(StructType *ST, const DataLayout &TD); +}; + +} // End llvm namespace + +#endif |