//===-- llvm/Target/TargetData.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 target 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_TARGET_TARGETDATA_H
#define LLVM_TARGET_TARGETDATA_H
#include "llvm/Pass.h"
#include "llvm/ADT/SmallVector.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 TargetAlignElem
enum AlignTypeEnum {
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
};
/// Target alignment element.
///
/// Stores the alignment data associated with a given alignment type (pointer,
/// 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 TargetAlignElem {
AlignTypeEnum AlignType : 8; //< Alignment type (AlignTypeEnum)
unsigned ABIAlign; //< ABI alignment for this type/bitw
unsigned PrefAlign; //< Pref. alignment for this type/bitw
uint32_t TypeBitWidth; //< Type bit width
/// Initializer
static TargetAlignElem get(AlignTypeEnum align_type, unsigned abi_align,
unsigned pref_align, uint32_t bit_width);
/// Equality predicate
bool operator==(const TargetAlignElem &rhs) const;
};
/// TargetData - 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 TargetData : public ImmutablePass {
private:
bool LittleEndian; ///< Defaults to false
unsigned PointerMemSize; ///< Pointer size in bytes
unsigned PointerABIAlign; ///< Pointer ABI alignment
unsigned PointerPrefAlign; ///< Pointer preferred alignment
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 TargetAlignment, but for now,
/// we don't.
SmallVector<TargetAlignElem, 16> Alignments;
/// InvalidAlignmentElem - This member is a signal that a requested alignment
/// type and bit width were not found in the SmallVector.
static const TargetAlignElem InvalidAlignmentElem;
// 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;
//! 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 TargetAlignElem reference returned by get() against
/// InvalidAlignmentElem.
bool validAlignment(const TargetAlignElem &align) const {
return &align != &InvalidAlignmentElem;
}
public:
/// Default ctor.
///
/// @note This has to exist, because this is a pass, but it should never be
/// used.
TargetData();
/// Constructs a TargetData from a specification string. See init().
explicit TargetData(StringRef TargetDescription)
: ImmutablePass(ID) {
init(TargetDescription);
}
/// Initialize target data from properties stored in the module.
explicit TargetData(const Module *M);
TargetData(const TargetData &TD) :
ImmutablePass(ID),
LittleEndian(TD.isLittleEndian()),
PointerMemSize(TD.PointerMemSize),
PointerABIAlign(TD.PointerABIAlign),
PointerPrefAlign(TD.PointerPrefAlign),
LegalIntWidths(TD.LegalIntWidths),
Alignments(TD.Alignments),
LayoutMap(0)
{ }
~TargetData(); // Not virtual, do not subclass this class
//! Parse a target data layout string and initialize TargetData alignments.
void init(StringRef TargetDescription);
/// Target endianness...
bool isLittleEndian() const { return LittleEndian; }
bool isBigEndian() const { return !LittleEndian; }
/// getStringRepresentation - Return the string representation of the
/// TargetData. 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;
}
/// Target pointer alignment
unsigned getPointerABIAlignment() const { return PointerABIAlign; }
/// Return target's alignment for stack-based pointers
unsigned getPointerPrefAlignment() const { return PointerPrefAlign; }
/// Target pointer size
unsigned getPointerSize() const { return PointerMemSize; }
/// Target pointer size, in bits
unsigned getPointerSizeInBits() const { return 8*PointerMemSize; }
/// 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.
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 unsigned integer type that is the same size or
/// greater to the host pointer size.
///
IntegerType *getIntPtrType(LLVMContext &C) 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 TargetData 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 TargetData; // Only TargetData can create this class
StructLayout(StructType *ST, const TargetData &TD);
};
} // End llvm namespace
#endif