//===--------- 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/SmallVector.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Type.h"
#include "llvm/Pass.h"
#include "llvm/Support/DataTypes.h"
// This needs to be outside of the namespace, to avoid conflict with llvm-c
// decl.
typedef struct LLVMOpaqueTargetData *LLVMTargetDataRef;
namespace llvm {
class Value;
class StructType;
class StructLayout;
class Triple;
class GlobalVariable;
class LLVMContext;
template<typename T>
class ArrayRef;
/// Enum used to categorize the alignment types stored by LayoutAlignElem
enum AlignTypeEnum {
INVALID_ALIGN = 0,
INTEGER_ALIGN = 'i',
VECTOR_ALIGN = 'v',
FLOAT_ALIGN = 'f',
AGGREGATE_ALIGN = 'a'
};
// FIXME: Currently the DataLayout string carries a "preferred alignment"
// for types. As the DataLayout is module/global, this should likely be
// sunk down to an FTTI element that is queried rather than a global
// preference.
/// \brief 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 {
/// \brief Alignment type from \c AlignTypeEnum
unsigned AlignType : 8;
unsigned TypeBitWidth : 24;
unsigned ABIAlign : 16;
unsigned PrefAlign : 16;
static LayoutAlignElem get(AlignTypeEnum align_type, unsigned abi_align,
unsigned pref_align, uint32_t bit_width);
bool operator==(const LayoutAlignElem &rhs) const;
};
/// \brief 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;
unsigned PrefAlign;
uint32_t TypeByteWidth;
uint32_t AddressSpace;
/// Initializer
static PointerAlignElem get(uint32_t AddressSpace, unsigned ABIAlign,
unsigned PrefAlign, uint32_t TypeByteWidth);
bool operator==(const PointerAlignElem &rhs) const;
};
/// \brief A parsed version of the target data layout string in and 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.
class DataLayout {
private:
/// Defaults to false.
bool BigEndian;
unsigned StackNaturalAlign;
enum ManglingModeT {
MM_None,
MM_ELF,
MM_MachO,
MM_WinCOFF,
MM_WinCOFFX86,
MM_Mips
};
ManglingModeT ManglingMode;
SmallVector<unsigned char, 8> LegalIntWidths;
/// \brief Primitive type alignment data.
SmallVector<LayoutAlignElem, 16> Alignments;
/// \brief The string representation used to create this DataLayout
std::string StringRepresentation;
typedef SmallVector<PointerAlignElem, 8> PointersTy;
PointersTy Pointers;
PointersTy::const_iterator
findPointerLowerBound(uint32_t AddressSpace) const {
return const_cast<DataLayout *>(this)->findPointerLowerBound(AddressSpace);
}
PointersTy::iterator findPointerLowerBound(uint32_t AddressSpace);
/// This member is a signal that a requested alignment type and bit width were
/// not found in the SmallVector.
static const LayoutAlignElem InvalidAlignmentElem;
/// 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;
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;
void setPointerAlignment(uint32_t AddrSpace, unsigned ABIAlign,
unsigned PrefAlign, uint32_t TypeByteWidth);
/// Internal helper method that returns requested alignment for type.
unsigned getAlignment(Type *Ty, bool abi_or_pref) const;
/// \brief Valid alignment predicate.
///
/// Predicate that tests a LayoutAlignElem reference returned by get() against
/// InvalidAlignmentElem.
bool validAlignment(const LayoutAlignElem &align) const {
return &align != &InvalidAlignmentElem;
}
/// \brief Valid pointer predicate.
///
/// Predicate that tests a PointerAlignElem reference returned by get()
/// against \c 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);
// Free all internal data structures.
void clear();
public:
/// Constructs a DataLayout from a specification string. See reset().
explicit DataLayout(StringRef LayoutDescription) : LayoutMap(nullptr) {
reset(LayoutDescription);
}
/// Initialize target data from properties stored in the module.
explicit DataLayout(const Module *M);
void init(const Module *M);
DataLayout(const DataLayout &DL) : LayoutMap(nullptr) { *this = DL; }
DataLayout &operator=(const DataLayout &DL) {
clear();
StringRepresentation = DL.StringRepresentation;
BigEndian = DL.isBigEndian();
StackNaturalAlign = DL.StackNaturalAlign;
ManglingMode = DL.ManglingMode;
LegalIntWidths = DL.LegalIntWidths;
Alignments = DL.Alignments;
Pointers = DL.Pointers;
return *this;
}
bool operator==(const DataLayout &Other) const;
bool operator!=(const DataLayout &Other) const { return !(*this == Other); }
~DataLayout(); // Not virtual, do not subclass this class
/// Parse a data layout string (with fallback to default values).
void reset(StringRef LayoutDescription);
/// Layout endianness...
bool isLittleEndian() const { return !BigEndian; }
bool isBigEndian() const { return BigEndian; }
/// \brief Returns the string representation of the DataLayout.
///
/// This representation is in the same format accepted by the string
/// constructor above. This should not be used to compare two DataLayout as
/// different string can represent the same layout.
const std::string &getStringRepresentation() const {
return StringRepresentation;
}
/// \brief Test if the DataLayout was constructed from an empty string.
bool isDefault() const { return StringRepresentation.empty(); }
/// \brief 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(uint64_t Width) const {
for (unsigned LegalIntWidth : LegalIntWidths)
if (LegalIntWidth == Width)
return true;
return false;
}
bool isIllegalInteger(uint64_t 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);
}
unsigned getStackAlignment() const { return StackNaturalAlign; }
bool hasMicrosoftFastStdCallMangling() const {
return ManglingMode == MM_WinCOFFX86;
}
bool hasLinkerPrivateGlobalPrefix() const { return ManglingMode == MM_MachO; }
const char *getLinkerPrivateGlobalPrefix() const {
if (ManglingMode == MM_MachO)
return "l";
return "";
}
char getGlobalPrefix() const {
switch (ManglingMode) {
case MM_None:
case MM_ELF:
case MM_Mips:
case MM_WinCOFF:
return '\0';
case MM_MachO:
case MM_WinCOFFX86:
return '_';
}
llvm_unreachable("invalid mangling mode");
}
const char *getPrivateGlobalPrefix() const {
switch (ManglingMode) {
case MM_None:
return "";
case MM_ELF:
return ".L";
case MM_Mips:
return "$";
case MM_MachO:
case MM_WinCOFF:
case MM_WinCOFFX86:
return "L";
}
llvm_unreachable("invalid mangling mode");
}
static const char *getManglingComponent(const Triple &T);
/// \brief 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 LegalIntWidth : LegalIntWidths)
if (Width <= LegalIntWidth)
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;
/// 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;
/// Layout pointer size
/// FIXME: The defaults need to be removed once all of
/// the backends/clients are updated.
unsigned getPointerSize(unsigned AS = 0) const;
/// 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;
}
/// Layout pointer size, in bits, based on the type. If this function is
/// called with a pointer type, then the type size of the pointer is returned.
/// If this function is called with a vector of pointers, then the type size
/// of the pointer is returned. This should only be called with a pointer or
/// vector of pointers.
unsigned getPointerTypeSizeInBits(Type *) const;
unsigned getPointerTypeSize(Type *Ty) const {
return getPointerTypeSizeInBits(Ty) / 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.
/// \brief Returns 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;
/// \brief Returns 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;
}
/// \brief Returns 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);
}
/// \brief Returns 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 alignTo(getTypeStoreSize(Ty), getABITypeAlignment(Ty));
}
/// \brief Returns 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);
}
/// \brief Returns the minimum ABI-required alignment for the specified type.
unsigned getABITypeAlignment(Type *Ty) const;
/// \brief Returns the minimum ABI-required alignment for an integer type of
/// the specified bitwidth.
unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const;
/// \brief Returns 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;
/// \brief Returns the preferred alignment for the specified type, returned as
/// log2 of the value (a shift amount).
unsigned getPreferredTypeAlignmentShift(Type *Ty) const;
/// \brief Returns 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;
/// \brief Returns 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;
/// \brief Returns the smallest integer type with size at least as big as
/// Width bits.
Type *getSmallestLegalIntType(LLVMContext &C, unsigned Width = 0) const;
/// \brief Returns the largest legal integer type, or null if none are set.
Type *getLargestLegalIntType(LLVMContext &C) const {
unsigned LargestSize = getLargestLegalIntTypeSizeInBits();
return (LargestSize == 0) ? nullptr : Type::getIntNTy(C, LargestSize);
}
/// \brief Returns the size of largest legal integer type size, or 0 if none
/// are set.
unsigned getLargestLegalIntTypeSizeInBits() const;
/// \brief Returns the offset from the beginning of the type for the specified
/// indices.
///
/// Note that this takes the element type, not the pointer type.
/// This is used to implement getelementptr.
int64_t getIndexedOffsetInType(Type *ElemTy, ArrayRef<Value *> Indices) const;
/// \brief Returns 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;
/// \brief Returns the preferred alignment of the specified global.
///
/// This includes an explicitly requested alignment (if the global has one).
unsigned getPreferredAlignment(const GlobalVariable *GV) const;
/// \brief Returns 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;
};
inline DataLayout *unwrap(LLVMTargetDataRef P) {
return reinterpret_cast<DataLayout *>(P);
}
inline LLVMTargetDataRef wrap(const DataLayout *P) {
return reinterpret_cast<LLVMTargetDataRef>(const_cast<DataLayout *>(P));
}
/// Used to lazily calculate structure layout information for a target machine,
/// based on the DataLayout structure.
class StructLayout {
uint64_t StructSize;
unsigned StructAlignment;
unsigned IsPadded : 1;
unsigned NumElements : 31;
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; }
/// Returns whether the struct has padding or not between its fields.
/// NB: Padding in nested element is not taken into account.
bool hasPadding() const { return IsPadded; }
/// \brief Given a valid byte offset into the structure, returns 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 &DL);
};
// The implementation of this method is provided inline as it is particularly
// well suited to constant folding when called on a specific Type subclass.
inline uint64_t DataLayout::getTypeSizeInBits(Type *Ty) const {
assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!");
switch (Ty->getTypeID()) {
case Type::LabelTyID:
return getPointerSizeInBits(0);
case Type::PointerTyID:
return getPointerSizeInBits(Ty->getPointerAddressSpace());
case Type::ArrayTyID: {
ArrayType *ATy = cast<ArrayType>(Ty);
return ATy->getNumElements() *
getTypeAllocSizeInBits(ATy->getElementType());
}
case Type::StructTyID:
// Get the layout annotation... which is lazily created on demand.
return getStructLayout(cast<StructType>(Ty))->getSizeInBits();
case Type::IntegerTyID:
return Ty->getIntegerBitWidth();
case Type::HalfTyID:
return 16;
case Type::FloatTyID:
return 32;
case Type::DoubleTyID:
case Type::X86_MMXTyID:
return 64;
case Type::PPC_FP128TyID:
case Type::FP128TyID:
return 128;
// In memory objects this is always aligned to a higher boundary, but
// only 80 bits contain information.
case Type::X86_FP80TyID:
return 80;
case Type::VectorTyID: {
VectorType *VTy = cast<VectorType>(Ty);
return VTy->getNumElements() * getTypeSizeInBits(VTy->getElementType());
}
default:
llvm_unreachable("DataLayout::getTypeSizeInBits(): Unsupported type");
}
}
} // End llvm namespace
#endif
