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/SmallVector.h"
24 #include "llvm/ADT/STLExtras.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;
45 /// Enum used to categorize the alignment types stored by LayoutAlignElem
54 // FIXME: Currently the DataLayout string carries a "preferred alignment"
55 // for types. As the DataLayout is module/global, this should likely be
56 // sunk down to an FTTI element that is queried rather than a global
59 /// \brief Layout alignment element.
61 /// Stores the alignment data associated with a given alignment type (integer,
62 /// vector, float) and type bit width.
64 /// \note The unusual order of elements in the structure attempts to reduce
65 /// padding and make the structure slightly more cache friendly.
66 struct LayoutAlignElem {
67 /// \brief Alignment type from \c AlignTypeEnum
68 unsigned AlignType : 8;
69 unsigned TypeBitWidth : 24;
70 unsigned ABIAlign : 16;
71 unsigned PrefAlign : 16;
73 static LayoutAlignElem get(AlignTypeEnum align_type, unsigned abi_align,
74 unsigned pref_align, uint32_t bit_width);
75 bool operator==(const LayoutAlignElem &rhs) const;
78 /// \brief Layout pointer alignment element.
80 /// Stores the alignment data associated with a given pointer and address space.
82 /// \note The unusual order of elements in the structure attempts to reduce
83 /// padding and make the structure slightly more cache friendly.
84 struct PointerAlignElem {
87 uint32_t TypeByteWidth;
88 uint32_t AddressSpace;
91 static PointerAlignElem get(uint32_t AddressSpace, unsigned ABIAlign,
92 unsigned PrefAlign, uint32_t TypeByteWidth);
93 bool operator==(const PointerAlignElem &rhs) const;
96 /// \brief A parsed version of the target data layout string in and methods for
99 /// The target data layout string is specified *by the target* - a frontend
100 /// generating LLVM IR is required to generate the right target data for the
101 /// target being codegen'd to.
104 /// Defaults to false.
107 unsigned StackNaturalAlign;
117 ManglingModeT ManglingMode;
119 SmallVector<unsigned char, 8> LegalIntWidths;
121 /// \brief Primitive type alignment data.
122 SmallVector<LayoutAlignElem, 16> Alignments;
124 /// \brief The string representation used to create this DataLayout
125 std::string StringRepresentation;
127 typedef SmallVector<PointerAlignElem, 8> PointersTy;
130 PointersTy::const_iterator
131 findPointerLowerBound(uint32_t AddressSpace) const {
132 return const_cast<DataLayout *>(this)->findPointerLowerBound(AddressSpace);
135 PointersTy::iterator findPointerLowerBound(uint32_t AddressSpace);
137 /// This member is a signal that a requested alignment type and bit width were
138 /// not found in the SmallVector.
139 static const LayoutAlignElem InvalidAlignmentElem;
141 /// This member is a signal that a requested pointer type and bit width were
142 /// not found in the DenseSet.
143 static const PointerAlignElem InvalidPointerElem;
145 // The StructType -> StructLayout map.
146 mutable void *LayoutMap;
148 /// Pointers in these address spaces are non-integral, and don't have a
149 /// well-defined bitwise representation.
150 SmallVector<unsigned, 8> NonIntegralAddressSpaces;
152 void setAlignment(AlignTypeEnum align_type, unsigned abi_align,
153 unsigned pref_align, uint32_t bit_width);
154 unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width,
155 bool ABIAlign, Type *Ty) const;
156 void setPointerAlignment(uint32_t AddrSpace, unsigned ABIAlign,
157 unsigned PrefAlign, uint32_t TypeByteWidth);
159 /// Internal helper method that returns requested alignment for type.
160 unsigned getAlignment(Type *Ty, bool abi_or_pref) const;
162 /// \brief Valid alignment predicate.
164 /// Predicate that tests a LayoutAlignElem reference returned by get() against
165 /// InvalidAlignmentElem.
166 bool validAlignment(const LayoutAlignElem &align) const {
167 return &align != &InvalidAlignmentElem;
170 /// \brief Valid pointer predicate.
172 /// Predicate that tests a PointerAlignElem reference returned by get()
173 /// against \c InvalidPointerElem.
174 bool validPointer(const PointerAlignElem &align) const {
175 return &align != &InvalidPointerElem;
178 /// Parses a target data specification string. Assert if the string is
180 void parseSpecifier(StringRef LayoutDescription);
182 // Free all internal data structures.
186 /// Constructs a DataLayout from a specification string. See reset().
187 explicit DataLayout(StringRef LayoutDescription) : LayoutMap(nullptr) {
188 reset(LayoutDescription);
191 /// Initialize target data from properties stored in the module.
192 explicit DataLayout(const Module *M);
194 void init(const Module *M);
196 DataLayout(const DataLayout &DL) : LayoutMap(nullptr) { *this = DL; }
198 DataLayout &operator=(const DataLayout &DL) {
200 StringRepresentation = DL.StringRepresentation;
201 BigEndian = DL.isBigEndian();
202 StackNaturalAlign = DL.StackNaturalAlign;
203 ManglingMode = DL.ManglingMode;
204 LegalIntWidths = DL.LegalIntWidths;
205 Alignments = DL.Alignments;
206 Pointers = DL.Pointers;
207 NonIntegralAddressSpaces = DL.NonIntegralAddressSpaces;
211 bool operator==(const DataLayout &Other) const;
212 bool operator!=(const DataLayout &Other) const { return !(*this == Other); }
214 ~DataLayout(); // Not virtual, do not subclass this class
216 /// Parse a data layout string (with fallback to default values).
217 void reset(StringRef LayoutDescription);
219 /// Layout endianness...
220 bool isLittleEndian() const { return !BigEndian; }
221 bool isBigEndian() const { return BigEndian; }
223 /// \brief Returns the string representation of the DataLayout.
225 /// This representation is in the same format accepted by the string
226 /// constructor above. This should not be used to compare two DataLayout as
227 /// different string can represent the same layout.
228 const std::string &getStringRepresentation() const {
229 return StringRepresentation;
232 /// \brief Test if the DataLayout was constructed from an empty string.
233 bool isDefault() const { return StringRepresentation.empty(); }
235 /// \brief Returns true if the specified type is known to be a native integer
236 /// type supported by the CPU.
238 /// For example, i64 is not native on most 32-bit CPUs and i37 is not native
239 /// on any known one. This returns false if the integer width is not legal.
241 /// The width is specified in bits.
242 bool isLegalInteger(uint64_t Width) const {
243 for (unsigned LegalIntWidth : LegalIntWidths)
244 if (LegalIntWidth == Width)
249 bool isIllegalInteger(uint64_t Width) const { return !isLegalInteger(Width); }
251 /// Returns true if the given alignment exceeds the natural stack alignment.
252 bool exceedsNaturalStackAlignment(unsigned Align) const {
253 return (StackNaturalAlign != 0) && (Align > StackNaturalAlign);
256 unsigned getStackAlignment() const { return StackNaturalAlign; }
258 bool hasMicrosoftFastStdCallMangling() const {
259 return ManglingMode == MM_WinCOFFX86;
262 bool hasLinkerPrivateGlobalPrefix() const { return ManglingMode == MM_MachO; }
264 StringRef getLinkerPrivateGlobalPrefix() const {
265 if (ManglingMode == MM_MachO)
270 char getGlobalPrefix() const {
271 switch (ManglingMode) {
281 llvm_unreachable("invalid mangling mode");
284 StringRef getPrivateGlobalPrefix() const {
285 switch (ManglingMode) {
297 llvm_unreachable("invalid mangling mode");
300 static const char *getManglingComponent(const Triple &T);
302 /// \brief Returns true if the specified type fits in a native integer type
303 /// supported by the CPU.
305 /// For example, if the CPU only supports i32 as a native integer type, then
306 /// i27 fits in a legal integer type but i45 does not.
307 bool fitsInLegalInteger(unsigned Width) const {
308 for (unsigned LegalIntWidth : LegalIntWidths)
309 if (Width <= LegalIntWidth)
314 /// Layout pointer alignment
315 /// FIXME: The defaults need to be removed once all of
316 /// the backends/clients are updated.
317 unsigned getPointerABIAlignment(unsigned AS = 0) const;
319 /// Return target's alignment for stack-based pointers
320 /// FIXME: The defaults need to be removed once all of
321 /// the backends/clients are updated.
322 unsigned getPointerPrefAlignment(unsigned AS = 0) const;
324 /// Layout pointer size
325 /// FIXME: The defaults need to be removed once all of
326 /// the backends/clients are updated.
327 unsigned getPointerSize(unsigned AS = 0) const;
329 /// Return the address spaces containing non-integral pointers. Pointers in
330 /// this address space don't have a well-defined bitwise representation.
331 ArrayRef<unsigned> getNonIntegralAddressSpaces() const {
332 return NonIntegralAddressSpaces;
335 bool isNonIntegralPointerType(PointerType *PT) const {
336 ArrayRef<unsigned> NonIntegralSpaces = getNonIntegralAddressSpaces();
337 return find(NonIntegralSpaces, PT->getAddressSpace()) !=
338 NonIntegralSpaces.end();
341 bool isNonIntegralPointerType(Type *Ty) const {
342 auto *PTy = dyn_cast<PointerType>(Ty);
343 return PTy && isNonIntegralPointerType(PTy);
346 /// Layout pointer size, in bits
347 /// FIXME: The defaults need to be removed once all of
348 /// the backends/clients are updated.
349 unsigned getPointerSizeInBits(unsigned AS = 0) const {
350 return getPointerSize(AS) * 8;
353 /// Layout pointer size, in bits, based on the type. If this function is
354 /// called with a pointer type, then the type size of the pointer is returned.
355 /// If this function is called with a vector of pointers, then the type size
356 /// of the pointer is returned. This should only be called with a pointer or
357 /// vector of pointers.
358 unsigned getPointerTypeSizeInBits(Type *) const;
360 unsigned getPointerTypeSize(Type *Ty) const {
361 return getPointerTypeSizeInBits(Ty) / 8;
366 /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*]
367 /// ---- ---------- --------------- ---------------
376 /// X86_FP80 80 80 96
378 /// [*] The alloc size depends on the alignment, and thus on the target.
379 /// These values are for x86-32 linux.
381 /// \brief Returns the number of bits necessary to hold the specified type.
383 /// For example, returns 36 for i36 and 80 for x86_fp80. The type passed must
384 /// have a size (Type::isSized() must return true).
385 uint64_t getTypeSizeInBits(Type *Ty) const;
387 /// \brief Returns the maximum number of bytes that may be overwritten by
388 /// storing the specified type.
390 /// For example, returns 5 for i36 and 10 for x86_fp80.
391 uint64_t getTypeStoreSize(Type *Ty) const {
392 return (getTypeSizeInBits(Ty) + 7) / 8;
395 /// \brief Returns the maximum number of bits that may be overwritten by
396 /// storing the specified type; always a multiple of 8.
398 /// For example, returns 40 for i36 and 80 for x86_fp80.
399 uint64_t getTypeStoreSizeInBits(Type *Ty) const {
400 return 8 * getTypeStoreSize(Ty);
403 /// \brief Returns the offset in bytes between successive objects of the
404 /// specified type, including alignment padding.
406 /// This is the amount that alloca reserves for this type. For example,
407 /// returns 12 or 16 for x86_fp80, depending on alignment.
408 uint64_t getTypeAllocSize(Type *Ty) const {
409 // Round up to the next alignment boundary.
410 return alignTo(getTypeStoreSize(Ty), getABITypeAlignment(Ty));
413 /// \brief Returns the offset in bits between successive objects of the
414 /// specified type, including alignment padding; always a multiple of 8.
416 /// This is the amount that alloca reserves for this type. For example,
417 /// returns 96 or 128 for x86_fp80, depending on alignment.
418 uint64_t getTypeAllocSizeInBits(Type *Ty) const {
419 return 8 * getTypeAllocSize(Ty);
422 /// \brief Returns the minimum ABI-required alignment for the specified type.
423 unsigned getABITypeAlignment(Type *Ty) const;
425 /// \brief Returns the minimum ABI-required alignment for an integer type of
426 /// the specified bitwidth.
427 unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const;
429 /// \brief Returns the preferred stack/global alignment for the specified
432 /// This is always at least as good as the ABI alignment.
433 unsigned getPrefTypeAlignment(Type *Ty) const;
435 /// \brief Returns the preferred alignment for the specified type, returned as
436 /// log2 of the value (a shift amount).
437 unsigned getPreferredTypeAlignmentShift(Type *Ty) const;
439 /// \brief Returns an integer type with size at least as big as that of a
440 /// pointer in the given address space.
441 IntegerType *getIntPtrType(LLVMContext &C, unsigned AddressSpace = 0) const;
443 /// \brief Returns an integer (vector of integer) type with size at least as
444 /// big as that of a pointer of the given pointer (vector of pointer) type.
445 Type *getIntPtrType(Type *) const;
447 /// \brief Returns the smallest integer type with size at least as big as
449 Type *getSmallestLegalIntType(LLVMContext &C, unsigned Width = 0) const;
451 /// \brief Returns the largest legal integer type, or null if none are set.
452 Type *getLargestLegalIntType(LLVMContext &C) const {
453 unsigned LargestSize = getLargestLegalIntTypeSizeInBits();
454 return (LargestSize == 0) ? nullptr : Type::getIntNTy(C, LargestSize);
457 /// \brief Returns the size of largest legal integer type size, or 0 if none
459 unsigned getLargestLegalIntTypeSizeInBits() const;
461 /// \brief Returns the offset from the beginning of the type for the specified
464 /// Note that this takes the element type, not the pointer type.
465 /// This is used to implement getelementptr.
466 int64_t getIndexedOffsetInType(Type *ElemTy, ArrayRef<Value *> Indices) const;
468 /// \brief Returns a StructLayout object, indicating the alignment of the
469 /// struct, its size, and the offsets of its fields.
471 /// Note that this information is lazily cached.
472 const StructLayout *getStructLayout(StructType *Ty) const;
474 /// \brief Returns the preferred alignment of the specified global.
476 /// This includes an explicitly requested alignment (if the global has one).
477 unsigned getPreferredAlignment(const GlobalVariable *GV) const;
479 /// \brief Returns the preferred alignment of the specified global, returned
482 /// This includes an explicitly requested alignment (if the global has one).
483 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const;
486 inline DataLayout *unwrap(LLVMTargetDataRef P) {
487 return reinterpret_cast<DataLayout *>(P);
490 inline LLVMTargetDataRef wrap(const DataLayout *P) {
491 return reinterpret_cast<LLVMTargetDataRef>(const_cast<DataLayout *>(P));
494 /// Used to lazily calculate structure layout information for a target machine,
495 /// based on the DataLayout structure.
498 unsigned StructAlignment;
499 unsigned IsPadded : 1;
500 unsigned NumElements : 31;
501 uint64_t MemberOffsets[1]; // variable sized array!
503 uint64_t getSizeInBytes() const { return StructSize; }
505 uint64_t getSizeInBits() const { return 8 * StructSize; }
507 unsigned getAlignment() const { return StructAlignment; }
509 /// Returns whether the struct has padding or not between its fields.
510 /// NB: Padding in nested element is not taken into account.
511 bool hasPadding() const { return IsPadded; }
513 /// \brief Given a valid byte offset into the structure, returns the structure
514 /// index that contains it.
515 unsigned getElementContainingOffset(uint64_t Offset) const;
517 uint64_t getElementOffset(unsigned Idx) const {
518 assert(Idx < NumElements && "Invalid element idx!");
519 return MemberOffsets[Idx];
522 uint64_t getElementOffsetInBits(unsigned Idx) const {
523 return getElementOffset(Idx) * 8;
527 friend class DataLayout; // Only DataLayout can create this class
528 StructLayout(StructType *ST, const DataLayout &DL);
531 // The implementation of this method is provided inline as it is particularly
532 // well suited to constant folding when called on a specific Type subclass.
533 inline uint64_t DataLayout::getTypeSizeInBits(Type *Ty) const {
534 assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!");
535 switch (Ty->getTypeID()) {
536 case Type::LabelTyID:
537 return getPointerSizeInBits(0);
538 case Type::PointerTyID:
539 return getPointerSizeInBits(Ty->getPointerAddressSpace());
540 case Type::ArrayTyID: {
541 ArrayType *ATy = cast<ArrayType>(Ty);
542 return ATy->getNumElements() *
543 getTypeAllocSizeInBits(ATy->getElementType());
545 case Type::StructTyID:
546 // Get the layout annotation... which is lazily created on demand.
547 return getStructLayout(cast<StructType>(Ty))->getSizeInBits();
548 case Type::IntegerTyID:
549 return Ty->getIntegerBitWidth();
552 case Type::FloatTyID:
554 case Type::DoubleTyID:
555 case Type::X86_MMXTyID:
557 case Type::PPC_FP128TyID:
558 case Type::FP128TyID:
560 // In memory objects this is always aligned to a higher boundary, but
561 // only 80 bits contain information.
562 case Type::X86_FP80TyID:
564 case Type::VectorTyID: {
565 VectorType *VTy = cast<VectorType>(Ty);
566 return VTy->getNumElements() * getTypeSizeInBits(VTy->getElementType());
569 llvm_unreachable("DataLayout::getTypeSizeInBits(): Unsupported type");
573 } // End llvm namespace