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//===-- llvm/Target/TargetData.h - Data size & alignment info ---*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and 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/Support/DataTypes.h"
#include "llvm/ADT/SmallVector.h"
#include <string>
namespace llvm {
class Value;
class Type;
class StructType;
class StructLayout;
class GlobalVariable;
/// 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 char ABIAlign; //< ABI alignment for this type/bitw
unsigned char PrefAlign; //< Pref. alignment for this type/bitw
uint32_t TypeBitWidth; //< Type bit width
/// Initializer
static TargetAlignElem get(AlignTypeEnum align_type, unsigned char abi_align,
unsigned char pref_align, uint32_t bit_width);
/// Equality predicate
bool operator==(const TargetAlignElem &rhs) const;
/// output stream operator
std::ostream &dump(std::ostream &os) const;
};
class TargetData : public ImmutablePass {
private:
bool LittleEndian; ///< Defaults to false
unsigned char PointerMemSize; ///< Pointer size in bytes
unsigned char PointerABIAlign; ///< Pointer ABI alignment
unsigned char PointerPrefAlign; ///< Pointer preferred alignment
//! 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;
//! Alignment iterator shorthand
typedef SmallVector<TargetAlignElem, 16>::iterator align_iterator;
//! Constant alignment iterator shorthand
typedef SmallVector<TargetAlignElem, 16>::const_iterator align_const_iterator;
//! Invalid alignment.
/*!
This member is a signal that a requested alignment type and bit width were
not found in the SmallVector.
*/
static const TargetAlignElem InvalidAlignmentElem;
//! Set/initialize target alignments
void setAlignment(AlignTypeEnum align_type, unsigned char abi_align,
unsigned char pref_align, uint32_t bit_width);
unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width,
bool ABIAlign) const;
//! Internal helper method that returns requested alignment for type.
unsigned char getAlignment(const Type *Ty, bool abi_or_pref) const;
/// Valid alignment predicate.
///
/// Predicate that tests a TargetAlignElem reference returned by get() against
/// InvalidAlignmentElem.
inline 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() : ImmutablePass(intptr_t(&ID)) {
assert(0 && "ERROR: Bad TargetData ctor used. "
"Tool did not specify a TargetData to use?");
abort();
}
/// Constructs a TargetData from a specification string. See init().
explicit TargetData(const std::string &TargetDescription)
: ImmutablePass(intptr_t(&ID)) {
init(TargetDescription);
}
/// Initialize target data from properties stored in the module.
explicit TargetData(const Module *M);
TargetData(const TargetData &TD) :
ImmutablePass(intptr_t(&ID)),
LittleEndian(TD.isLittleEndian()),
PointerMemSize(TD.PointerMemSize),
PointerABIAlign(TD.PointerABIAlign),
PointerPrefAlign(TD.PointerPrefAlign),
Alignments(TD.Alignments)
{ }
~TargetData(); // Not virtual, do not subclass this class
//! Parse a target data layout string and initialize TargetData alignments.
void init(const std::string &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;
/// Target pointer alignment
unsigned char getPointerABIAlignment() const { return PointerABIAlign; }
/// Return target's alignment for stack-based pointers
unsigned char getPointerPrefAlignment() const { return PointerPrefAlign; }
/// Target pointer size
unsigned char getPointerSize() const { return PointerMemSize; }
/// Target pointer size, in bits
unsigned char getPointerSizeInBits() const { return 8*PointerMemSize; }
/// getTypeSize - Return the number of bytes necessary to hold the specified
/// type.
uint64_t getTypeSize(const Type *Ty) const;
/// getTypeSizeInBits - Return the number of bits necessary to hold the
/// specified type.
uint64_t getTypeSizeInBits(const Type* Ty) const;
/// getABITypeAlignment - Return the minimum ABI-required alignment for the
/// specified type.
unsigned char getABITypeAlignment(const Type *Ty) const;
/// getCallFrameTypeAlignment - Return the minimum ABI-required alignment
/// for the specified type when it is part of a call frame.
unsigned char getCallFrameTypeAlignment(const Type *Ty) const;
/// getPrefTypeAlignment - Return the preferred stack/global alignment for
/// the specified type.
unsigned char getPrefTypeAlignment(const Type *Ty) const;
/// getPreferredTypeAlignmentShift - Return the preferred alignment for the
/// specified type, returned as log2 of the value (a shift amount).
///
unsigned char getPreferredTypeAlignmentShift(const Type *Ty) const;
/// getIntPtrType - Return an unsigned integer type that is the same size or
/// greater to the host pointer size.
///
const Type *getIntPtrType() const;
/// getIndexedOffset - return the offset from the beginning of the type for the
/// specified indices. This is used to implement getelementptr.
///
uint64_t getIndexedOffset(const Type *Ty,
Value* const* Indices, unsigned NumIndices) 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(const StructType *Ty) const;
/// InvalidateStructLayoutInfo - TargetData speculatively caches StructLayout
/// objects. If a TargetData object is alive when types are being refined and
/// removed, this method must be called whenever a StructType is removed to
/// avoid a dangling pointer in this cache.
void InvalidateStructLayoutInfo(const StructType *Ty) 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;
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;
}
unsigned getAlignment() const {
return StructAlignment;
}
/// getElementContainingOffset - Given a valid 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];
}
private:
friend class TargetData; // Only TargetData can create this class
StructLayout(const StructType *ST, const TargetData &TD);
};
} // End llvm namespace
#endif
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