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 /// \brief Layout alignment element.
58 /// Stores the alignment data associated with a given alignment type (integer,
59 /// vector, float) and type bit width.
61 /// \note The unusual order of elements in the structure attempts to reduce
62 /// padding and make the structure slightly more cache friendly.
63 struct LayoutAlignElem {
64 /// \brief Alignment type from \c AlignTypeEnum
65 unsigned AlignType : 8;
66 unsigned TypeBitWidth : 24;
67 unsigned ABIAlign : 16;
68 unsigned PrefAlign : 16;
70 static LayoutAlignElem get(AlignTypeEnum align_type, unsigned abi_align,
71 unsigned pref_align, uint32_t bit_width);
72 bool operator==(const LayoutAlignElem &rhs) const;
75 /// \brief Layout pointer alignment element.
77 /// Stores the alignment data associated with a given pointer and address space.
79 /// \note The unusual order of elements in the structure attempts to reduce
80 /// padding and make the structure slightly more cache friendly.
81 struct PointerAlignElem {
84 uint32_t TypeByteWidth;
85 uint32_t AddressSpace;
88 static PointerAlignElem get(uint32_t AddressSpace, unsigned ABIAlign,
89 unsigned PrefAlign, uint32_t TypeByteWidth);
90 bool operator==(const PointerAlignElem &rhs) const;
93 /// \brief A parsed version of the target data layout string in and methods for
96 /// The target data layout string is specified *by the target* - a frontend
97 /// generating LLVM IR is required to generate the right target data for the
98 /// target being codegen'd to.
101 /// Defaults to false.
104 unsigned StackNaturalAlign;
106 enum ManglingModeT { MM_None, MM_ELF, MM_MachO, MM_WINCOFF, MM_Mips };
107 ManglingModeT ManglingMode;
109 SmallVector<unsigned char, 8> LegalIntWidths;
111 /// \brief Primitive type alignment data.
112 SmallVector<LayoutAlignElem, 16> Alignments;
114 typedef SmallVector<PointerAlignElem, 8> PointersTy;
117 PointersTy::const_iterator
118 findPointerLowerBound(uint32_t AddressSpace) const {
119 return const_cast<DataLayout *>(this)->findPointerLowerBound(AddressSpace);
122 PointersTy::iterator findPointerLowerBound(uint32_t AddressSpace);
124 /// This member is a signal that a requested alignment type and bit width were
125 /// not found in the SmallVector.
126 static const LayoutAlignElem InvalidAlignmentElem;
128 /// This member is a signal that a requested pointer type and bit width were
129 /// not found in the DenseSet.
130 static const PointerAlignElem InvalidPointerElem;
132 // The StructType -> StructLayout map.
133 mutable void *LayoutMap;
135 void setAlignment(AlignTypeEnum align_type, unsigned abi_align,
136 unsigned pref_align, uint32_t bit_width);
137 unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width,
138 bool ABIAlign, Type *Ty) const;
139 void setPointerAlignment(uint32_t AddrSpace, unsigned ABIAlign,
140 unsigned PrefAlign, uint32_t TypeByteWidth);
142 /// Internal helper method that returns requested alignment for type.
143 unsigned getAlignment(Type *Ty, bool abi_or_pref) const;
145 /// \brief Valid alignment predicate.
147 /// Predicate that tests a LayoutAlignElem reference returned by get() against
148 /// InvalidAlignmentElem.
149 bool validAlignment(const LayoutAlignElem &align) const {
150 return &align != &InvalidAlignmentElem;
153 /// \brief Valid pointer predicate.
155 /// Predicate that tests a PointerAlignElem reference returned by get()
156 /// against \c InvalidPointerElem.
157 bool validPointer(const PointerAlignElem &align) const {
158 return &align != &InvalidPointerElem;
161 /// Parses a target data specification string. Assert if the string is
163 void parseSpecifier(StringRef LayoutDescription);
165 // Free all internal data structures.
169 /// Constructs a DataLayout from a specification string. See reset().
170 explicit DataLayout(StringRef LayoutDescription) : LayoutMap(nullptr) {
171 reset(LayoutDescription);
174 /// Initialize target data from properties stored in the module.
175 explicit DataLayout(const Module *M);
177 void init(const Module *M);
179 DataLayout(const DataLayout &DL) : LayoutMap(nullptr) { *this = DL; }
181 DataLayout &operator=(const DataLayout &DL) {
183 BigEndian = DL.isBigEndian();
184 StackNaturalAlign = DL.StackNaturalAlign;
185 ManglingMode = DL.ManglingMode;
186 LegalIntWidths = DL.LegalIntWidths;
187 Alignments = DL.Alignments;
188 Pointers = DL.Pointers;
192 bool operator==(const DataLayout &Other) const;
193 bool operator!=(const DataLayout &Other) const { return !(*this == Other); }
195 ~DataLayout(); // Not virtual, do not subclass this class
197 /// Parse a data layout string (with fallback to default values).
198 void reset(StringRef LayoutDescription);
200 /// Layout endianness...
201 bool isLittleEndian() const { return !BigEndian; }
202 bool isBigEndian() const { return BigEndian; }
204 /// \brief Returns the string representation of the DataLayout.
206 /// This representation is in the same format accepted by the string
207 /// constructor above.
208 std::string getStringRepresentation() const;
210 /// \brief Returns true if the specified type is known to be a native integer
211 /// type supported by the CPU.
213 /// For example, i64 is not native on most 32-bit CPUs and i37 is not native
214 /// on any known one. This returns false if the integer width is not legal.
216 /// The width is specified in bits.
217 bool isLegalInteger(unsigned Width) const {
218 for (unsigned LegalIntWidth : LegalIntWidths)
219 if (LegalIntWidth == Width)
224 bool isIllegalInteger(unsigned Width) const { return !isLegalInteger(Width); }
226 /// Returns true if the given alignment exceeds the natural stack alignment.
227 bool exceedsNaturalStackAlignment(unsigned Align) const {
228 return (StackNaturalAlign != 0) && (Align > StackNaturalAlign);
231 unsigned getStackAlignment() const { return StackNaturalAlign; }
233 bool hasMicrosoftFastStdCallMangling() const {
234 return ManglingMode == MM_WINCOFF;
237 bool hasLinkerPrivateGlobalPrefix() const { return ManglingMode == MM_MachO; }
239 const char *getLinkerPrivateGlobalPrefix() const {
240 if (ManglingMode == MM_MachO)
242 return getPrivateGlobalPrefix();
245 char getGlobalPrefix() const {
246 switch (ManglingMode) {
255 llvm_unreachable("invalid mangling mode");
258 const char *getPrivateGlobalPrefix() const {
259 switch (ManglingMode) {
270 llvm_unreachable("invalid mangling mode");
273 static const char *getManglingComponent(const Triple &T);
275 /// \brief Returns true if the specified type fits in a native integer type
276 /// supported by the CPU.
278 /// For example, if the CPU only supports i32 as a native integer type, then
279 /// i27 fits in a legal integer type but i45 does not.
280 bool fitsInLegalInteger(unsigned Width) const {
281 for (unsigned LegalIntWidth : LegalIntWidths)
282 if (Width <= LegalIntWidth)
287 /// Layout pointer alignment
288 /// FIXME: The defaults need to be removed once all of
289 /// the backends/clients are updated.
290 unsigned getPointerABIAlignment(unsigned AS = 0) const;
292 /// Return target's alignment for stack-based pointers
293 /// FIXME: The defaults need to be removed once all of
294 /// the backends/clients are updated.
295 unsigned getPointerPrefAlignment(unsigned AS = 0) const;
297 /// Layout pointer size
298 /// FIXME: The defaults need to be removed once all of
299 /// the backends/clients are updated.
300 unsigned getPointerSize(unsigned AS = 0) const;
302 /// Layout pointer size, in bits
303 /// FIXME: The defaults need to be removed once all of
304 /// the backends/clients are updated.
305 unsigned getPointerSizeInBits(unsigned AS = 0) const {
306 return getPointerSize(AS) * 8;
309 /// Layout pointer size, in bits, based on the type. If this function is
310 /// called with a pointer type, then the type size of the pointer is returned.
311 /// If this function is called with a vector of pointers, then the type size
312 /// of the pointer is returned. This should only be called with a pointer or
313 /// vector of pointers.
314 unsigned getPointerTypeSizeInBits(Type *) const;
316 unsigned getPointerTypeSize(Type *Ty) const {
317 return getPointerTypeSizeInBits(Ty) / 8;
322 /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*]
323 /// ---- ---------- --------------- ---------------
332 /// X86_FP80 80 80 96
334 /// [*] The alloc size depends on the alignment, and thus on the target.
335 /// These values are for x86-32 linux.
337 /// \brief Returns the number of bits necessary to hold the specified type.
339 /// For example, returns 36 for i36 and 80 for x86_fp80. The type passed must
340 /// have a size (Type::isSized() must return true).
341 uint64_t getTypeSizeInBits(Type *Ty) const;
343 /// \brief Returns the maximum number of bytes that may be overwritten by
344 /// storing the specified type.
346 /// For example, returns 5 for i36 and 10 for x86_fp80.
347 uint64_t getTypeStoreSize(Type *Ty) const {
348 return (getTypeSizeInBits(Ty) + 7) / 8;
351 /// \brief Returns the maximum number of bits that may be overwritten by
352 /// storing the specified type; always a multiple of 8.
354 /// For example, returns 40 for i36 and 80 for x86_fp80.
355 uint64_t getTypeStoreSizeInBits(Type *Ty) const {
356 return 8 * getTypeStoreSize(Ty);
359 /// \brief Returns the offset in bytes between successive objects of the
360 /// specified type, including alignment padding.
362 /// This is the amount that alloca reserves for this type. For example,
363 /// returns 12 or 16 for x86_fp80, depending on alignment.
364 uint64_t getTypeAllocSize(Type *Ty) const {
365 // Round up to the next alignment boundary.
366 return RoundUpToAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty));
369 /// \brief Returns the offset in bits between successive objects of the
370 /// specified type, including alignment padding; always a multiple of 8.
372 /// This is the amount that alloca reserves for this type. For example,
373 /// returns 96 or 128 for x86_fp80, depending on alignment.
374 uint64_t getTypeAllocSizeInBits(Type *Ty) const {
375 return 8 * getTypeAllocSize(Ty);
378 /// \brief Returns the minimum ABI-required alignment for the specified type.
379 unsigned getABITypeAlignment(Type *Ty) const;
381 /// \brief Returns the minimum ABI-required alignment for an integer type of
382 /// the specified bitwidth.
383 unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const;
385 /// \brief Returns the preferred stack/global alignment for the specified
388 /// This is always at least as good as the ABI alignment.
389 unsigned getPrefTypeAlignment(Type *Ty) const;
391 /// \brief Returns the preferred alignment for the specified type, returned as
392 /// log2 of the value (a shift amount).
393 unsigned getPreferredTypeAlignmentShift(Type *Ty) const;
395 /// \brief Returns an integer type with size at least as big as that of a
396 /// pointer in the given address space.
397 IntegerType *getIntPtrType(LLVMContext &C, unsigned AddressSpace = 0) const;
399 /// \brief Returns an integer (vector of integer) type with size at least as
400 /// big as that of a pointer of the given pointer (vector of pointer) type.
401 Type *getIntPtrType(Type *) const;
403 /// \brief Returns the smallest integer type with size at least as big as
405 Type *getSmallestLegalIntType(LLVMContext &C, unsigned Width = 0) const;
407 /// \brief Returns the largest legal integer type, or null if none are set.
408 Type *getLargestLegalIntType(LLVMContext &C) const {
409 unsigned LargestSize = getLargestLegalIntTypeSize();
410 return (LargestSize == 0) ? nullptr : Type::getIntNTy(C, LargestSize);
413 /// \brief Returns the size of largest legal integer type size, or 0 if none
415 unsigned getLargestLegalIntTypeSize() const;
417 /// \brief Returns the offset from the beginning of the type for the specified
420 /// This is used to implement getelementptr.
421 uint64_t getIndexedOffset(Type *Ty, ArrayRef<Value *> Indices) const;
423 /// \brief Returns a StructLayout object, indicating the alignment of the
424 /// struct, its size, and the offsets of its fields.
426 /// Note that this information is lazily cached.
427 const StructLayout *getStructLayout(StructType *Ty) const;
429 /// \brief Returns the preferred alignment of the specified global.
431 /// This includes an explicitly requested alignment (if the global has one).
432 unsigned getPreferredAlignment(const GlobalVariable *GV) const;
434 /// \brief Returns the preferred alignment of the specified global, returned
437 /// This includes an explicitly requested alignment (if the global has one).
438 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const;
441 inline DataLayout *unwrap(LLVMTargetDataRef P) {
442 return reinterpret_cast<DataLayout *>(P);
445 inline LLVMTargetDataRef wrap(const DataLayout *P) {
446 return reinterpret_cast<LLVMTargetDataRef>(const_cast<DataLayout *>(P));
449 class DataLayoutPass : public ImmutablePass {
453 /// This has to exist, because this is a pass, but it should never be used.
457 const DataLayout &getDataLayout() const { return DL; }
459 static char ID; // Pass identification, replacement for typeid
461 bool doFinalization(Module &M) override;
462 bool doInitialization(Module &M) override;
465 /// Used to lazily calculate structure layout information for a target machine,
466 /// based on the DataLayout structure.
469 unsigned StructAlignment;
470 unsigned NumElements;
471 uint64_t MemberOffsets[1]; // variable sized array!
473 uint64_t getSizeInBytes() const { return StructSize; }
475 uint64_t getSizeInBits() const { return 8 * StructSize; }
477 unsigned getAlignment() const { return StructAlignment; }
479 /// \brief Given a valid byte offset into the structure, returns the structure
480 /// index that contains it.
481 unsigned getElementContainingOffset(uint64_t Offset) const;
483 uint64_t getElementOffset(unsigned Idx) const {
484 assert(Idx < NumElements && "Invalid element idx!");
485 return MemberOffsets[Idx];
488 uint64_t getElementOffsetInBits(unsigned Idx) const {
489 return getElementOffset(Idx) * 8;
493 friend class DataLayout; // Only DataLayout can create this class
494 StructLayout(StructType *ST, const DataLayout &DL);
497 // The implementation of this method is provided inline as it is particularly
498 // well suited to constant folding when called on a specific Type subclass.
499 inline uint64_t DataLayout::getTypeSizeInBits(Type *Ty) const {
500 assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!");
501 switch (Ty->getTypeID()) {
502 case Type::LabelTyID:
503 return getPointerSizeInBits(0);
504 case Type::PointerTyID:
505 return getPointerSizeInBits(Ty->getPointerAddressSpace());
506 case Type::ArrayTyID: {
507 ArrayType *ATy = cast<ArrayType>(Ty);
508 return ATy->getNumElements() *
509 getTypeAllocSizeInBits(ATy->getElementType());
511 case Type::StructTyID:
512 // Get the layout annotation... which is lazily created on demand.
513 return getStructLayout(cast<StructType>(Ty))->getSizeInBits();
514 case Type::IntegerTyID:
515 return Ty->getIntegerBitWidth();
518 case Type::FloatTyID:
520 case Type::DoubleTyID:
521 case Type::X86_MMXTyID:
523 case Type::PPC_FP128TyID:
524 case Type::FP128TyID:
526 // In memory objects this is always aligned to a higher boundary, but
527 // only 80 bits contain information.
528 case Type::X86_FP80TyID:
530 case Type::VectorTyID: {
531 VectorType *VTy = cast<VectorType>(Ty);
532 return VTy->getNumElements() * getTypeSizeInBits(VTy->getElementType());
535 llvm_unreachable("DataLayout::getTypeSizeInBits(): Unsupported type");
539 } // End llvm namespace