1 //===--------- llvm/DataLayout.h - Data size & alignment info ---*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines layout properties related to datatype size/offset/alignment
11 // information. It uses lazy annotations to cache information about how
12 // structure types are laid out and used.
14 // This structure should be created once, filled in if the defaults are not
15 // correct and then passed around by const&. None of the members functions
16 // require modification to the object.
18 //===----------------------------------------------------------------------===//
20 #ifndef LLVM_IR_DATALAYOUT_H
21 #define LLVM_IR_DATALAYOUT_H
23 #include "llvm/ADT/DenseMap.h"
24 #include "llvm/ADT/SmallVector.h"
25 #include "llvm/IR/DerivedTypes.h"
26 #include "llvm/IR/Type.h"
27 #include "llvm/Pass.h"
28 #include "llvm/Support/DataTypes.h"
30 // This needs to be outside of the namespace, to avoid conflict with llvm-c
32 typedef struct LLVMOpaqueTargetData *LLVMTargetDataRef;
47 /// Enum used to categorize the alignment types stored by LayoutAlignElem
56 // FIXME: Currently the DataLayout string carries a "preferred alignment"
57 // for types. As the DataLayout is module/global, this should likely be
58 // sunk down to an FTTI element that is queried rather than a global
61 /// \brief Layout alignment element.
63 /// Stores the alignment data associated with a given alignment type (integer,
64 /// vector, float) and type bit width.
66 /// \note The unusual order of elements in the structure attempts to reduce
67 /// padding and make the structure slightly more cache friendly.
68 struct LayoutAlignElem {
69 /// \brief Alignment type from \c AlignTypeEnum
70 unsigned AlignType : 8;
71 unsigned TypeBitWidth : 24;
72 unsigned ABIAlign : 16;
73 unsigned PrefAlign : 16;
75 static LayoutAlignElem get(AlignTypeEnum align_type, unsigned abi_align,
76 unsigned pref_align, uint32_t bit_width);
77 bool operator==(const LayoutAlignElem &rhs) const;
80 /// \brief Layout pointer alignment element.
82 /// Stores the alignment data associated with a given pointer and address space.
84 /// \note The unusual order of elements in the structure attempts to reduce
85 /// padding and make the structure slightly more cache friendly.
86 struct PointerAlignElem {
89 uint32_t TypeByteWidth;
90 uint32_t AddressSpace;
93 static PointerAlignElem get(uint32_t AddressSpace, unsigned ABIAlign,
94 unsigned PrefAlign, uint32_t TypeByteWidth);
95 bool operator==(const PointerAlignElem &rhs) const;
98 /// \brief A parsed version of the target data layout string in and methods for
101 /// The target data layout string is specified *by the target* - a frontend
102 /// generating LLVM IR is required to generate the right target data for the
103 /// target being codegen'd to.
106 /// Defaults to false.
109 unsigned StackNaturalAlign;
119 ManglingModeT ManglingMode;
121 SmallVector<unsigned char, 8> LegalIntWidths;
123 /// \brief Primitive type alignment data.
124 SmallVector<LayoutAlignElem, 16> Alignments;
126 /// \brief The string representation used to create this DataLayout
127 std::string StringRepresentation;
129 typedef SmallVector<PointerAlignElem, 8> PointersTy;
132 PointersTy::const_iterator
133 findPointerLowerBound(uint32_t AddressSpace) const {
134 return const_cast<DataLayout *>(this)->findPointerLowerBound(AddressSpace);
137 PointersTy::iterator findPointerLowerBound(uint32_t AddressSpace);
139 /// This member is a signal that a requested alignment type and bit width were
140 /// not found in the SmallVector.
141 static const LayoutAlignElem InvalidAlignmentElem;
143 /// This member is a signal that a requested pointer type and bit width were
144 /// not found in the DenseSet.
145 static const PointerAlignElem InvalidPointerElem;
147 // The StructType -> StructLayout map.
148 mutable void *LayoutMap;
150 void setAlignment(AlignTypeEnum align_type, unsigned abi_align,
151 unsigned pref_align, uint32_t bit_width);
152 unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width,
153 bool ABIAlign, const Type *Ty) const;
154 void setPointerAlignment(uint32_t AddrSpace, unsigned ABIAlign,
155 unsigned PrefAlign, uint32_t TypeByteWidth);
157 /// Internal helper method that returns requested alignment for type.
158 unsigned getAlignment(const Type *Ty, bool abi_or_pref) const;
160 /// \brief Valid alignment predicate.
162 /// Predicate that tests a LayoutAlignElem reference returned by get() against
163 /// InvalidAlignmentElem.
164 bool validAlignment(const LayoutAlignElem &align) const {
165 return &align != &InvalidAlignmentElem;
168 /// \brief Valid pointer predicate.
170 /// Predicate that tests a PointerAlignElem reference returned by get()
171 /// against \c InvalidPointerElem.
172 bool validPointer(const PointerAlignElem &align) const {
173 return &align != &InvalidPointerElem;
176 /// Parses a target data specification string. Assert if the string is
178 void parseSpecifier(StringRef LayoutDescription);
180 // Free all internal data structures.
184 /// Constructs a DataLayout from a specification string. See reset().
185 explicit DataLayout(StringRef LayoutDescription) : LayoutMap(nullptr) {
186 reset(LayoutDescription);
189 /// Initialize target data from properties stored in the module.
190 explicit DataLayout(const Module *M);
192 void init(const Module *M);
194 DataLayout(const DataLayout &DL) : LayoutMap(nullptr) { *this = DL; }
196 DataLayout &operator=(const DataLayout &DL) {
198 StringRepresentation = DL.StringRepresentation;
199 BigEndian = DL.isBigEndian();
200 StackNaturalAlign = DL.StackNaturalAlign;
201 ManglingMode = DL.ManglingMode;
202 LegalIntWidths = DL.LegalIntWidths;
203 Alignments = DL.Alignments;
204 Pointers = DL.Pointers;
208 bool operator==(const DataLayout &Other) const;
209 bool operator!=(const DataLayout &Other) const { return !(*this == Other); }
211 ~DataLayout(); // Not virtual, do not subclass this class
213 /// Parse a data layout string (with fallback to default values).
214 void reset(StringRef LayoutDescription);
216 /// Layout endianness...
217 bool isLittleEndian() const { return !BigEndian; }
218 bool isBigEndian() const { return BigEndian; }
220 /// \brief Returns the string representation of the DataLayout.
222 /// This representation is in the same format accepted by the string
223 /// constructor above. This should not be used to compare two DataLayout as
224 /// different string can represent the same layout.
225 const std::string &getStringRepresentation() const {
226 return StringRepresentation;
229 /// \brief Test if the DataLayout was constructed from an empty string.
230 bool isDefault() const { return StringRepresentation.empty(); }
232 /// \brief Returns true if the specified type is known to be a native integer
233 /// type supported by the CPU.
235 /// For example, i64 is not native on most 32-bit CPUs and i37 is not native
236 /// on any known one. This returns false if the integer width is not legal.
238 /// The width is specified in bits.
239 bool isLegalInteger(unsigned Width) const {
240 for (unsigned LegalIntWidth : LegalIntWidths)
241 if (LegalIntWidth == Width)
246 bool isIllegalInteger(unsigned Width) const { return !isLegalInteger(Width); }
248 /// Returns true if the given alignment exceeds the natural stack alignment.
249 bool exceedsNaturalStackAlignment(unsigned Align) const {
250 return (StackNaturalAlign != 0) && (Align > StackNaturalAlign);
253 unsigned getStackAlignment() const { return StackNaturalAlign; }
255 bool hasMicrosoftFastStdCallMangling() const {
256 return ManglingMode == MM_WinCOFFX86;
259 bool hasLinkerPrivateGlobalPrefix() const { return ManglingMode == MM_MachO; }
261 const char *getLinkerPrivateGlobalPrefix() const {
262 if (ManglingMode == MM_MachO)
267 char getGlobalPrefix() const {
268 switch (ManglingMode) {
278 llvm_unreachable("invalid mangling mode");
281 const char *getPrivateGlobalPrefix() const {
282 switch (ManglingMode) {
294 llvm_unreachable("invalid mangling mode");
297 static const char *getManglingComponent(const Triple &T);
299 /// \brief Returns true if the specified type fits in a native integer type
300 /// supported by the CPU.
302 /// For example, if the CPU only supports i32 as a native integer type, then
303 /// i27 fits in a legal integer type but i45 does not.
304 bool fitsInLegalInteger(unsigned Width) const {
305 for (unsigned LegalIntWidth : LegalIntWidths)
306 if (Width <= LegalIntWidth)
311 /// Layout pointer alignment
312 /// FIXME: The defaults need to be removed once all of
313 /// the backends/clients are updated.
314 unsigned getPointerABIAlignment(unsigned AS = 0) const;
316 /// Return target's alignment for stack-based pointers
317 /// FIXME: The defaults need to be removed once all of
318 /// the backends/clients are updated.
319 unsigned getPointerPrefAlignment(unsigned AS = 0) const;
321 /// Layout pointer size
322 /// FIXME: The defaults need to be removed once all of
323 /// the backends/clients are updated.
324 unsigned getPointerSize(unsigned AS = 0) const;
326 /// Layout pointer size, in bits
327 /// FIXME: The defaults need to be removed once all of
328 /// the backends/clients are updated.
329 unsigned getPointerSizeInBits(unsigned AS = 0) const {
330 return getPointerSize(AS) * 8;
333 /// Layout pointer size, in bits, based on the type. If this function is
334 /// called with a pointer type, then the type size of the pointer is returned.
335 /// If this function is called with a vector of pointers, then the type size
336 /// of the pointer is returned. This should only be called with a pointer or
337 /// vector of pointers.
338 unsigned getPointerTypeSizeInBits(const Type *) const;
340 unsigned getPointerTypeSize(const Type *Ty) const {
341 return getPointerTypeSizeInBits(Ty) / 8;
346 /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*]
347 /// ---- ---------- --------------- ---------------
356 /// X86_FP80 80 80 96
358 /// [*] The alloc size depends on the alignment, and thus on the target.
359 /// These values are for x86-32 linux.
361 /// \brief Returns the number of bits necessary to hold the specified type.
363 /// For example, returns 36 for i36 and 80 for x86_fp80. The type passed must
364 /// have a size (Type::isSized() must return true).
365 uint64_t getTypeSizeInBits(const Type *Ty) const;
367 /// \brief Returns the maximum number of bytes that may be overwritten by
368 /// storing the specified type.
370 /// For example, returns 5 for i36 and 10 for x86_fp80.
371 uint64_t getTypeStoreSize(const Type *Ty) const {
372 return (getTypeSizeInBits(Ty) + 7) / 8;
375 /// \brief Returns the maximum number of bits that may be overwritten by
376 /// storing the specified type; always a multiple of 8.
378 /// For example, returns 40 for i36 and 80 for x86_fp80.
379 uint64_t getTypeStoreSizeInBits(const Type *Ty) const {
380 return 8 * getTypeStoreSize(Ty);
383 /// \brief Returns the offset in bytes between successive objects of the
384 /// specified type, including alignment padding.
386 /// This is the amount that alloca reserves for this type. For example,
387 /// returns 12 or 16 for x86_fp80, depending on alignment.
388 uint64_t getTypeAllocSize(const Type *Ty) const {
389 // Round up to the next alignment boundary.
390 return RoundUpToAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty));
393 /// \brief Returns the offset in bits between successive objects of the
394 /// specified type, including alignment padding; always a multiple of 8.
396 /// This is the amount that alloca reserves for this type. For example,
397 /// returns 96 or 128 for x86_fp80, depending on alignment.
398 uint64_t getTypeAllocSizeInBits(const Type *Ty) const {
399 return 8 * getTypeAllocSize(Ty);
402 /// \brief Returns the minimum ABI-required alignment for the specified type.
403 unsigned getABITypeAlignment(const Type *Ty) const;
405 /// \brief Returns the minimum ABI-required alignment for an integer type of
406 /// the specified bitwidth.
407 unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const;
409 /// \brief Returns the preferred stack/global alignment for the specified
412 /// This is always at least as good as the ABI alignment.
413 unsigned getPrefTypeAlignment(const Type *Ty) const;
415 /// \brief Returns the preferred alignment for the specified type, returned as
416 /// log2 of the value (a shift amount).
417 unsigned getPreferredTypeAlignmentShift(const Type *Ty) const;
419 /// \brief Returns an integer type with size at least as big as that of a
420 /// pointer in the given address space.
421 IntegerType *getIntPtrType(LLVMContext &C, unsigned AddressSpace = 0) const;
423 /// \brief Returns an integer (vector of integer) type with size at least as
424 /// big as that of a pointer of the given pointer (vector of pointer) type.
425 Type *getIntPtrType(const Type *) const;
427 /// \brief Returns the smallest integer type with size at least as big as
429 Type *getSmallestLegalIntType(LLVMContext &C, unsigned Width = 0) const;
431 /// \brief Returns the largest legal integer type, or null if none are set.
432 Type *getLargestLegalIntType(LLVMContext &C) const {
433 unsigned LargestSize = getLargestLegalIntTypeSize();
434 return (LargestSize == 0) ? nullptr : Type::getIntNTy(C, LargestSize);
437 /// \brief Returns the size of largest legal integer type size, or 0 if none
439 unsigned getLargestLegalIntTypeSize() const;
441 /// \brief Returns the offset from the beginning of the type for the specified
444 /// This is used to implement getelementptr.
445 uint64_t getIndexedOffset(Type *Ty, ArrayRef<Value *> Indices) const;
447 /// \brief Returns a StructLayout object, indicating the alignment of the
448 /// struct, its size, and the offsets of its fields.
450 /// Note that this information is lazily cached.
451 const StructLayout *getStructLayout(const StructType *Ty) const;
453 /// \brief Returns the preferred alignment of the specified global.
455 /// This includes an explicitly requested alignment (if the global has one).
456 unsigned getPreferredAlignment(const GlobalVariable *GV) const;
458 /// \brief Returns the preferred alignment of the specified global, returned
461 /// This includes an explicitly requested alignment (if the global has one).
462 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const;
465 inline DataLayout *unwrap(LLVMTargetDataRef P) {
466 return reinterpret_cast<DataLayout *>(P);
469 inline LLVMTargetDataRef wrap(const DataLayout *P) {
470 return reinterpret_cast<LLVMTargetDataRef>(const_cast<DataLayout *>(P));
473 /// Used to lazily calculate structure layout information for a target machine,
474 /// based on the DataLayout structure.
477 unsigned StructAlignment;
478 unsigned NumElements;
479 uint64_t MemberOffsets[1]; // variable sized array!
481 uint64_t getSizeInBytes() const { return StructSize; }
483 uint64_t getSizeInBits() const { return 8 * StructSize; }
485 unsigned getAlignment() const { return StructAlignment; }
487 /// \brief Given a valid byte offset into the structure, returns the structure
488 /// index that contains it.
489 unsigned getElementContainingOffset(uint64_t Offset) const;
491 uint64_t getElementOffset(unsigned Idx) const {
492 assert(Idx < NumElements && "Invalid element idx!");
493 return MemberOffsets[Idx];
496 uint64_t getElementOffsetInBits(unsigned Idx) const {
497 return getElementOffset(Idx) * 8;
501 friend class DataLayout; // Only DataLayout can create this class
502 StructLayout(const StructType *ST, const DataLayout &DL);
505 // The implementation of this method is provided inline as it is particularly
506 // well suited to constant folding when called on a specific Type subclass.
507 inline uint64_t DataLayout::getTypeSizeInBits(const Type *Ty) const {
508 assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!");
509 switch (Ty->getTypeID()) {
510 case Type::LabelTyID:
511 return getPointerSizeInBits(0);
512 case Type::PointerTyID:
513 return getPointerSizeInBits(Ty->getPointerAddressSpace());
514 case Type::ArrayTyID: {
515 const ArrayType *ATy = cast<ArrayType>(Ty);
516 return ATy->getNumElements() *
517 getTypeAllocSizeInBits(ATy->getElementType());
519 case Type::StructTyID:
520 // Get the layout annotation... which is lazily created on demand.
521 return getStructLayout(cast<StructType>(Ty))->getSizeInBits();
522 case Type::IntegerTyID:
523 return Ty->getIntegerBitWidth();
526 case Type::FloatTyID:
528 case Type::DoubleTyID:
529 case Type::X86_MMXTyID:
531 case Type::PPC_FP128TyID:
532 case Type::FP128TyID:
534 // In memory objects this is always aligned to a higher boundary, but
535 // only 80 bits contain information.
536 case Type::X86_FP80TyID:
538 case Type::VectorTyID: {
539 const VectorType *VTy = cast<VectorType>(Ty);
540 return VTy->getNumElements() * getTypeSizeInBits(VTy->getElementType());
543 llvm_unreachable("DataLayout::getTypeSizeInBits(): Unsupported type");
547 } // End llvm namespace