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;
111 enum ManglingModeT { MM_None, MM_ELF, MM_MachO, MM_WINCOFF, MM_Mips };
112 ManglingModeT ManglingMode;
114 SmallVector<unsigned char, 8> LegalIntWidths;
116 /// \brief Primitive type alignment data.
117 SmallVector<LayoutAlignElem, 16> Alignments;
119 /// \brief The string representation used to create this DataLayout
120 std::string StringRepresentation;
122 typedef SmallVector<PointerAlignElem, 8> PointersTy;
125 PointersTy::const_iterator
126 findPointerLowerBound(uint32_t AddressSpace) const {
127 return const_cast<DataLayout *>(this)->findPointerLowerBound(AddressSpace);
130 PointersTy::iterator findPointerLowerBound(uint32_t AddressSpace);
132 /// This member is a signal that a requested alignment type and bit width were
133 /// not found in the SmallVector.
134 static const LayoutAlignElem InvalidAlignmentElem;
136 /// This member is a signal that a requested pointer type and bit width were
137 /// not found in the DenseSet.
138 static const PointerAlignElem InvalidPointerElem;
140 // The StructType -> StructLayout map.
141 mutable void *LayoutMap;
143 void setAlignment(AlignTypeEnum align_type, unsigned abi_align,
144 unsigned pref_align, uint32_t bit_width);
145 unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width,
146 bool ABIAlign, Type *Ty) const;
147 void setPointerAlignment(uint32_t AddrSpace, unsigned ABIAlign,
148 unsigned PrefAlign, uint32_t TypeByteWidth);
150 /// Internal helper method that returns requested alignment for type.
151 unsigned getAlignment(Type *Ty, bool abi_or_pref) const;
153 /// \brief Valid alignment predicate.
155 /// Predicate that tests a LayoutAlignElem reference returned by get() against
156 /// InvalidAlignmentElem.
157 bool validAlignment(const LayoutAlignElem &align) const {
158 return &align != &InvalidAlignmentElem;
161 /// \brief Valid pointer predicate.
163 /// Predicate that tests a PointerAlignElem reference returned by get()
164 /// against \c InvalidPointerElem.
165 bool validPointer(const PointerAlignElem &align) const {
166 return &align != &InvalidPointerElem;
169 /// Parses a target data specification string. Assert if the string is
171 void parseSpecifier(StringRef LayoutDescription);
173 // Free all internal data structures.
177 /// Constructs a DataLayout from a specification string. See reset().
178 explicit DataLayout(StringRef LayoutDescription) : LayoutMap(nullptr) {
179 reset(LayoutDescription);
182 /// Initialize target data from properties stored in the module.
183 explicit DataLayout(const Module *M);
185 void init(const Module *M);
187 DataLayout(const DataLayout &DL) : LayoutMap(nullptr) { *this = DL; }
189 DataLayout &operator=(const DataLayout &DL) {
191 StringRepresentation = DL.StringRepresentation;
192 BigEndian = DL.isBigEndian();
193 StackNaturalAlign = DL.StackNaturalAlign;
194 ManglingMode = DL.ManglingMode;
195 LegalIntWidths = DL.LegalIntWidths;
196 Alignments = DL.Alignments;
197 Pointers = DL.Pointers;
201 bool operator==(const DataLayout &Other) const;
202 bool operator!=(const DataLayout &Other) const { return !(*this == Other); }
204 ~DataLayout(); // Not virtual, do not subclass this class
206 /// Parse a data layout string (with fallback to default values).
207 void reset(StringRef LayoutDescription);
209 /// Layout endianness...
210 bool isLittleEndian() const { return !BigEndian; }
211 bool isBigEndian() const { return BigEndian; }
213 /// \brief Returns the string representation of the DataLayout.
215 /// This representation is in the same format accepted by the string
216 /// constructor above. This should not be used to compare two DataLayout as
217 /// different string can represent the same layout.
218 std::string getStringRepresentation() const { return StringRepresentation; }
220 /// \brief Test if the DataLayout was constructed from an empty string.
221 bool isDefault() const { return StringRepresentation.empty(); }
223 /// \brief Returns true if the specified type is known to be a native integer
224 /// type supported by the CPU.
226 /// For example, i64 is not native on most 32-bit CPUs and i37 is not native
227 /// on any known one. This returns false if the integer width is not legal.
229 /// The width is specified in bits.
230 bool isLegalInteger(unsigned Width) const {
231 for (unsigned LegalIntWidth : LegalIntWidths)
232 if (LegalIntWidth == Width)
237 bool isIllegalInteger(unsigned Width) const { return !isLegalInteger(Width); }
239 /// Returns true if the given alignment exceeds the natural stack alignment.
240 bool exceedsNaturalStackAlignment(unsigned Align) const {
241 return (StackNaturalAlign != 0) && (Align > StackNaturalAlign);
244 unsigned getStackAlignment() const { return StackNaturalAlign; }
246 bool hasMicrosoftFastStdCallMangling() const {
247 return ManglingMode == MM_WINCOFF;
250 bool hasLinkerPrivateGlobalPrefix() const { return ManglingMode == MM_MachO; }
252 const char *getLinkerPrivateGlobalPrefix() const {
253 if (ManglingMode == MM_MachO)
255 return getPrivateGlobalPrefix();
258 char getGlobalPrefix() const {
259 switch (ManglingMode) {
268 llvm_unreachable("invalid mangling mode");
271 const char *getPrivateGlobalPrefix() const {
272 switch (ManglingMode) {
283 llvm_unreachable("invalid mangling mode");
286 static const char *getManglingComponent(const Triple &T);
288 /// \brief Returns true if the specified type fits in a native integer type
289 /// supported by the CPU.
291 /// For example, if the CPU only supports i32 as a native integer type, then
292 /// i27 fits in a legal integer type but i45 does not.
293 bool fitsInLegalInteger(unsigned Width) const {
294 for (unsigned LegalIntWidth : LegalIntWidths)
295 if (Width <= LegalIntWidth)
300 /// Layout pointer alignment
301 /// FIXME: The defaults need to be removed once all of
302 /// the backends/clients are updated.
303 unsigned getPointerABIAlignment(unsigned AS = 0) const;
305 /// Return target's alignment for stack-based pointers
306 /// FIXME: The defaults need to be removed once all of
307 /// the backends/clients are updated.
308 unsigned getPointerPrefAlignment(unsigned AS = 0) const;
310 /// Layout pointer size
311 /// FIXME: The defaults need to be removed once all of
312 /// the backends/clients are updated.
313 unsigned getPointerSize(unsigned AS = 0) const;
315 /// Layout pointer size, in bits
316 /// FIXME: The defaults need to be removed once all of
317 /// the backends/clients are updated.
318 unsigned getPointerSizeInBits(unsigned AS = 0) const {
319 return getPointerSize(AS) * 8;
322 /// Layout pointer size, in bits, based on the type. If this function is
323 /// called with a pointer type, then the type size of the pointer is returned.
324 /// If this function is called with a vector of pointers, then the type size
325 /// of the pointer is returned. This should only be called with a pointer or
326 /// vector of pointers.
327 unsigned getPointerTypeSizeInBits(Type *) const;
329 unsigned getPointerTypeSize(Type *Ty) const {
330 return getPointerTypeSizeInBits(Ty) / 8;
335 /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*]
336 /// ---- ---------- --------------- ---------------
345 /// X86_FP80 80 80 96
347 /// [*] The alloc size depends on the alignment, and thus on the target.
348 /// These values are for x86-32 linux.
350 /// \brief Returns the number of bits necessary to hold the specified type.
352 /// For example, returns 36 for i36 and 80 for x86_fp80. The type passed must
353 /// have a size (Type::isSized() must return true).
354 uint64_t getTypeSizeInBits(Type *Ty) const;
356 /// \brief Returns the maximum number of bytes that may be overwritten by
357 /// storing the specified type.
359 /// For example, returns 5 for i36 and 10 for x86_fp80.
360 uint64_t getTypeStoreSize(Type *Ty) const {
361 return (getTypeSizeInBits(Ty) + 7) / 8;
364 /// \brief Returns the maximum number of bits that may be overwritten by
365 /// storing the specified type; always a multiple of 8.
367 /// For example, returns 40 for i36 and 80 for x86_fp80.
368 uint64_t getTypeStoreSizeInBits(Type *Ty) const {
369 return 8 * getTypeStoreSize(Ty);
372 /// \brief Returns the offset in bytes between successive objects of the
373 /// specified type, including alignment padding.
375 /// This is the amount that alloca reserves for this type. For example,
376 /// returns 12 or 16 for x86_fp80, depending on alignment.
377 uint64_t getTypeAllocSize(Type *Ty) const {
378 // Round up to the next alignment boundary.
379 return RoundUpToAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty));
382 /// \brief Returns the offset in bits between successive objects of the
383 /// specified type, including alignment padding; always a multiple of 8.
385 /// This is the amount that alloca reserves for this type. For example,
386 /// returns 96 or 128 for x86_fp80, depending on alignment.
387 uint64_t getTypeAllocSizeInBits(Type *Ty) const {
388 return 8 * getTypeAllocSize(Ty);
391 /// \brief Returns the minimum ABI-required alignment for the specified type.
392 unsigned getABITypeAlignment(Type *Ty) const;
394 /// \brief Returns the minimum ABI-required alignment for an integer type of
395 /// the specified bitwidth.
396 unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const;
398 /// \brief Returns the preferred stack/global alignment for the specified
401 /// This is always at least as good as the ABI alignment.
402 unsigned getPrefTypeAlignment(Type *Ty) const;
404 /// \brief Returns the preferred alignment for the specified type, returned as
405 /// log2 of the value (a shift amount).
406 unsigned getPreferredTypeAlignmentShift(Type *Ty) const;
408 /// \brief Returns an integer type with size at least as big as that of a
409 /// pointer in the given address space.
410 IntegerType *getIntPtrType(LLVMContext &C, unsigned AddressSpace = 0) const;
412 /// \brief Returns an integer (vector of integer) type with size at least as
413 /// big as that of a pointer of the given pointer (vector of pointer) type.
414 Type *getIntPtrType(Type *) const;
416 /// \brief Returns the smallest integer type with size at least as big as
418 Type *getSmallestLegalIntType(LLVMContext &C, unsigned Width = 0) const;
420 /// \brief Returns the largest legal integer type, or null if none are set.
421 Type *getLargestLegalIntType(LLVMContext &C) const {
422 unsigned LargestSize = getLargestLegalIntTypeSize();
423 return (LargestSize == 0) ? nullptr : Type::getIntNTy(C, LargestSize);
426 /// \brief Returns the size of largest legal integer type size, or 0 if none
428 unsigned getLargestLegalIntTypeSize() const;
430 /// \brief Returns the offset from the beginning of the type for the specified
433 /// This is used to implement getelementptr.
434 uint64_t getIndexedOffset(Type *Ty, ArrayRef<Value *> Indices) const;
436 /// \brief Returns a StructLayout object, indicating the alignment of the
437 /// struct, its size, and the offsets of its fields.
439 /// Note that this information is lazily cached.
440 const StructLayout *getStructLayout(StructType *Ty) const;
442 /// \brief Returns the preferred alignment of the specified global.
444 /// This includes an explicitly requested alignment (if the global has one).
445 unsigned getPreferredAlignment(const GlobalVariable *GV) const;
447 /// \brief Returns the preferred alignment of the specified global, returned
450 /// This includes an explicitly requested alignment (if the global has one).
451 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const;
454 inline DataLayout *unwrap(LLVMTargetDataRef P) {
455 return reinterpret_cast<DataLayout *>(P);
458 inline LLVMTargetDataRef wrap(const DataLayout *P) {
459 return reinterpret_cast<LLVMTargetDataRef>(const_cast<DataLayout *>(P));
462 /// Used to lazily calculate structure layout information for a target machine,
463 /// based on the DataLayout structure.
466 unsigned StructAlignment;
467 unsigned NumElements;
468 uint64_t MemberOffsets[1]; // variable sized array!
470 uint64_t getSizeInBytes() const { return StructSize; }
472 uint64_t getSizeInBits() const { return 8 * StructSize; }
474 unsigned getAlignment() const { return StructAlignment; }
476 /// \brief Given a valid byte offset into the structure, returns the structure
477 /// index that contains it.
478 unsigned getElementContainingOffset(uint64_t Offset) const;
480 uint64_t getElementOffset(unsigned Idx) const {
481 assert(Idx < NumElements && "Invalid element idx!");
482 return MemberOffsets[Idx];
485 uint64_t getElementOffsetInBits(unsigned Idx) const {
486 return getElementOffset(Idx) * 8;
490 friend class DataLayout; // Only DataLayout can create this class
491 StructLayout(StructType *ST, const DataLayout &DL);
494 // The implementation of this method is provided inline as it is particularly
495 // well suited to constant folding when called on a specific Type subclass.
496 inline uint64_t DataLayout::getTypeSizeInBits(Type *Ty) const {
497 assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!");
498 switch (Ty->getTypeID()) {
499 case Type::LabelTyID:
500 return getPointerSizeInBits(0);
501 case Type::PointerTyID:
502 return getPointerSizeInBits(Ty->getPointerAddressSpace());
503 case Type::ArrayTyID: {
504 ArrayType *ATy = cast<ArrayType>(Ty);
505 return ATy->getNumElements() *
506 getTypeAllocSizeInBits(ATy->getElementType());
508 case Type::StructTyID:
509 // Get the layout annotation... which is lazily created on demand.
510 return getStructLayout(cast<StructType>(Ty))->getSizeInBits();
511 case Type::IntegerTyID:
512 return Ty->getIntegerBitWidth();
515 case Type::FloatTyID:
517 case Type::DoubleTyID:
518 case Type::X86_MMXTyID:
520 case Type::PPC_FP128TyID:
521 case Type::FP128TyID:
523 // In memory objects this is always aligned to a higher boundary, but
524 // only 80 bits contain information.
525 case Type::X86_FP80TyID:
527 case Type::VectorTyID: {
528 VectorType *VTy = cast<VectorType>(Ty);
529 return VTy->getNumElements() * getTypeSizeInBits(VTy->getElementType());
532 llvm_unreachable("DataLayout::getTypeSizeInBits(): Unsupported type");
536 } // End llvm namespace