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 typedef SmallVector<PointerAlignElem, 8> PointersTy;
122 PointersTy::const_iterator
123 findPointerLowerBound(uint32_t AddressSpace) const {
124 return const_cast<DataLayout *>(this)->findPointerLowerBound(AddressSpace);
127 PointersTy::iterator findPointerLowerBound(uint32_t AddressSpace);
129 /// This member is a signal that a requested alignment type and bit width were
130 /// not found in the SmallVector.
131 static const LayoutAlignElem InvalidAlignmentElem;
133 /// This member is a signal that a requested pointer type and bit width were
134 /// not found in the DenseSet.
135 static const PointerAlignElem InvalidPointerElem;
137 // The StructType -> StructLayout map.
138 mutable void *LayoutMap;
140 void setAlignment(AlignTypeEnum align_type, unsigned abi_align,
141 unsigned pref_align, uint32_t bit_width);
142 unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width,
143 bool ABIAlign, Type *Ty) const;
144 void setPointerAlignment(uint32_t AddrSpace, unsigned ABIAlign,
145 unsigned PrefAlign, uint32_t TypeByteWidth);
147 /// Internal helper method that returns requested alignment for type.
148 unsigned getAlignment(Type *Ty, bool abi_or_pref) const;
150 /// \brief Valid alignment predicate.
152 /// Predicate that tests a LayoutAlignElem reference returned by get() against
153 /// InvalidAlignmentElem.
154 bool validAlignment(const LayoutAlignElem &align) const {
155 return &align != &InvalidAlignmentElem;
158 /// \brief Valid pointer predicate.
160 /// Predicate that tests a PointerAlignElem reference returned by get()
161 /// against \c InvalidPointerElem.
162 bool validPointer(const PointerAlignElem &align) const {
163 return &align != &InvalidPointerElem;
166 /// Parses a target data specification string. Assert if the string is
168 void parseSpecifier(StringRef LayoutDescription);
170 // Free all internal data structures.
174 /// Constructs a DataLayout from a specification string. See reset().
175 explicit DataLayout(StringRef LayoutDescription) : LayoutMap(nullptr) {
176 reset(LayoutDescription);
179 /// Initialize target data from properties stored in the module.
180 explicit DataLayout(const Module *M);
182 void init(const Module *M);
184 DataLayout(const DataLayout &DL) : LayoutMap(nullptr) { *this = DL; }
186 DataLayout &operator=(const DataLayout &DL) {
188 BigEndian = DL.isBigEndian();
189 StackNaturalAlign = DL.StackNaturalAlign;
190 ManglingMode = DL.ManglingMode;
191 LegalIntWidths = DL.LegalIntWidths;
192 Alignments = DL.Alignments;
193 Pointers = DL.Pointers;
197 bool operator==(const DataLayout &Other) const;
198 bool operator!=(const DataLayout &Other) const { return !(*this == Other); }
200 ~DataLayout(); // Not virtual, do not subclass this class
202 /// Parse a data layout string (with fallback to default values).
203 void reset(StringRef LayoutDescription);
205 /// Layout endianness...
206 bool isLittleEndian() const { return !BigEndian; }
207 bool isBigEndian() const { return BigEndian; }
209 /// \brief Returns the string representation of the DataLayout.
211 /// This representation is in the same format accepted by the string
212 /// constructor above.
213 std::string getStringRepresentation() const;
215 /// \brief Returns true if the specified type is known to be a native integer
216 /// type supported by the CPU.
218 /// For example, i64 is not native on most 32-bit CPUs and i37 is not native
219 /// on any known one. This returns false if the integer width is not legal.
221 /// The width is specified in bits.
222 bool isLegalInteger(unsigned Width) const {
223 for (unsigned LegalIntWidth : LegalIntWidths)
224 if (LegalIntWidth == Width)
229 bool isIllegalInteger(unsigned Width) const { return !isLegalInteger(Width); }
231 /// Returns true if the given alignment exceeds the natural stack alignment.
232 bool exceedsNaturalStackAlignment(unsigned Align) const {
233 return (StackNaturalAlign != 0) && (Align > StackNaturalAlign);
236 unsigned getStackAlignment() const { return StackNaturalAlign; }
238 bool hasMicrosoftFastStdCallMangling() const {
239 return ManglingMode == MM_WINCOFF;
242 bool hasLinkerPrivateGlobalPrefix() const { return ManglingMode == MM_MachO; }
244 const char *getLinkerPrivateGlobalPrefix() const {
245 if (ManglingMode == MM_MachO)
247 return getPrivateGlobalPrefix();
250 char getGlobalPrefix() const {
251 switch (ManglingMode) {
260 llvm_unreachable("invalid mangling mode");
263 const char *getPrivateGlobalPrefix() const {
264 switch (ManglingMode) {
275 llvm_unreachable("invalid mangling mode");
278 static const char *getManglingComponent(const Triple &T);
280 /// \brief Returns true if the specified type fits in a native integer type
281 /// supported by the CPU.
283 /// For example, if the CPU only supports i32 as a native integer type, then
284 /// i27 fits in a legal integer type but i45 does not.
285 bool fitsInLegalInteger(unsigned Width) const {
286 for (unsigned LegalIntWidth : LegalIntWidths)
287 if (Width <= LegalIntWidth)
292 /// Layout pointer alignment
293 /// FIXME: The defaults need to be removed once all of
294 /// the backends/clients are updated.
295 unsigned getPointerABIAlignment(unsigned AS = 0) const;
297 /// Return target's alignment for stack-based pointers
298 /// FIXME: The defaults need to be removed once all of
299 /// the backends/clients are updated.
300 unsigned getPointerPrefAlignment(unsigned AS = 0) const;
302 /// Layout pointer size
303 /// FIXME: The defaults need to be removed once all of
304 /// the backends/clients are updated.
305 unsigned getPointerSize(unsigned AS = 0) const;
307 /// Layout pointer size, in bits
308 /// FIXME: The defaults need to be removed once all of
309 /// the backends/clients are updated.
310 unsigned getPointerSizeInBits(unsigned AS = 0) const {
311 return getPointerSize(AS) * 8;
314 /// Layout pointer size, in bits, based on the type. If this function is
315 /// called with a pointer type, then the type size of the pointer is returned.
316 /// If this function is called with a vector of pointers, then the type size
317 /// of the pointer is returned. This should only be called with a pointer or
318 /// vector of pointers.
319 unsigned getPointerTypeSizeInBits(Type *) const;
321 unsigned getPointerTypeSize(Type *Ty) const {
322 return getPointerTypeSizeInBits(Ty) / 8;
327 /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*]
328 /// ---- ---------- --------------- ---------------
337 /// X86_FP80 80 80 96
339 /// [*] The alloc size depends on the alignment, and thus on the target.
340 /// These values are for x86-32 linux.
342 /// \brief Returns the number of bits necessary to hold the specified type.
344 /// For example, returns 36 for i36 and 80 for x86_fp80. The type passed must
345 /// have a size (Type::isSized() must return true).
346 uint64_t getTypeSizeInBits(Type *Ty) const;
348 /// \brief Returns the maximum number of bytes that may be overwritten by
349 /// storing the specified type.
351 /// For example, returns 5 for i36 and 10 for x86_fp80.
352 uint64_t getTypeStoreSize(Type *Ty) const {
353 return (getTypeSizeInBits(Ty) + 7) / 8;
356 /// \brief Returns the maximum number of bits that may be overwritten by
357 /// storing the specified type; always a multiple of 8.
359 /// For example, returns 40 for i36 and 80 for x86_fp80.
360 uint64_t getTypeStoreSizeInBits(Type *Ty) const {
361 return 8 * getTypeStoreSize(Ty);
364 /// \brief Returns the offset in bytes between successive objects of the
365 /// specified type, including alignment padding.
367 /// This is the amount that alloca reserves for this type. For example,
368 /// returns 12 or 16 for x86_fp80, depending on alignment.
369 uint64_t getTypeAllocSize(Type *Ty) const {
370 // Round up to the next alignment boundary.
371 return RoundUpToAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty));
374 /// \brief Returns the offset in bits between successive objects of the
375 /// specified type, including alignment padding; always a multiple of 8.
377 /// This is the amount that alloca reserves for this type. For example,
378 /// returns 96 or 128 for x86_fp80, depending on alignment.
379 uint64_t getTypeAllocSizeInBits(Type *Ty) const {
380 return 8 * getTypeAllocSize(Ty);
383 /// \brief Returns the minimum ABI-required alignment for the specified type.
384 unsigned getABITypeAlignment(Type *Ty) const;
386 /// \brief Returns the minimum ABI-required alignment for an integer type of
387 /// the specified bitwidth.
388 unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const;
390 /// \brief Returns the preferred stack/global alignment for the specified
393 /// This is always at least as good as the ABI alignment.
394 unsigned getPrefTypeAlignment(Type *Ty) const;
396 /// \brief Returns the preferred alignment for the specified type, returned as
397 /// log2 of the value (a shift amount).
398 unsigned getPreferredTypeAlignmentShift(Type *Ty) const;
400 /// \brief Returns an integer type with size at least as big as that of a
401 /// pointer in the given address space.
402 IntegerType *getIntPtrType(LLVMContext &C, unsigned AddressSpace = 0) const;
404 /// \brief Returns an integer (vector of integer) type with size at least as
405 /// big as that of a pointer of the given pointer (vector of pointer) type.
406 Type *getIntPtrType(Type *) const;
408 /// \brief Returns the smallest integer type with size at least as big as
410 Type *getSmallestLegalIntType(LLVMContext &C, unsigned Width = 0) const;
412 /// \brief Returns the largest legal integer type, or null if none are set.
413 Type *getLargestLegalIntType(LLVMContext &C) const {
414 unsigned LargestSize = getLargestLegalIntTypeSize();
415 return (LargestSize == 0) ? nullptr : Type::getIntNTy(C, LargestSize);
418 /// \brief Returns the size of largest legal integer type size, or 0 if none
420 unsigned getLargestLegalIntTypeSize() const;
422 /// \brief Returns the offset from the beginning of the type for the specified
425 /// This is used to implement getelementptr.
426 uint64_t getIndexedOffset(Type *Ty, ArrayRef<Value *> Indices) const;
428 /// \brief Returns a StructLayout object, indicating the alignment of the
429 /// struct, its size, and the offsets of its fields.
431 /// Note that this information is lazily cached.
432 const StructLayout *getStructLayout(StructType *Ty) const;
434 /// \brief Returns the preferred alignment of the specified global.
436 /// This includes an explicitly requested alignment (if the global has one).
437 unsigned getPreferredAlignment(const GlobalVariable *GV) const;
439 /// \brief Returns the preferred alignment of the specified global, returned
442 /// This includes an explicitly requested alignment (if the global has one).
443 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const;
446 inline DataLayout *unwrap(LLVMTargetDataRef P) {
447 return reinterpret_cast<DataLayout *>(P);
450 inline LLVMTargetDataRef wrap(const DataLayout *P) {
451 return reinterpret_cast<LLVMTargetDataRef>(const_cast<DataLayout *>(P));
454 class DataLayoutPass : public ImmutablePass {
458 /// This has to exist, because this is a pass, but it should never be used.
462 const DataLayout &getDataLayout() const { return DL; }
464 static char ID; // Pass identification, replacement for typeid
466 bool doFinalization(Module &M) override;
467 bool doInitialization(Module &M) override;
470 /// Used to lazily calculate structure layout information for a target machine,
471 /// based on the DataLayout structure.
474 unsigned StructAlignment;
475 unsigned NumElements;
476 uint64_t MemberOffsets[1]; // variable sized array!
478 uint64_t getSizeInBytes() const { return StructSize; }
480 uint64_t getSizeInBits() const { return 8 * StructSize; }
482 unsigned getAlignment() const { return StructAlignment; }
484 /// \brief Given a valid byte offset into the structure, returns the structure
485 /// index that contains it.
486 unsigned getElementContainingOffset(uint64_t Offset) const;
488 uint64_t getElementOffset(unsigned Idx) const {
489 assert(Idx < NumElements && "Invalid element idx!");
490 return MemberOffsets[Idx];
493 uint64_t getElementOffsetInBits(unsigned Idx) const {
494 return getElementOffset(Idx) * 8;
498 friend class DataLayout; // Only DataLayout can create this class
499 StructLayout(StructType *ST, const DataLayout &DL);
502 // The implementation of this method is provided inline as it is particularly
503 // well suited to constant folding when called on a specific Type subclass.
504 inline uint64_t DataLayout::getTypeSizeInBits(Type *Ty) const {
505 assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!");
506 switch (Ty->getTypeID()) {
507 case Type::LabelTyID:
508 return getPointerSizeInBits(0);
509 case Type::PointerTyID:
510 return getPointerSizeInBits(Ty->getPointerAddressSpace());
511 case Type::ArrayTyID: {
512 ArrayType *ATy = cast<ArrayType>(Ty);
513 return ATy->getNumElements() *
514 getTypeAllocSizeInBits(ATy->getElementType());
516 case Type::StructTyID:
517 // Get the layout annotation... which is lazily created on demand.
518 return getStructLayout(cast<StructType>(Ty))->getSizeInBits();
519 case Type::IntegerTyID:
520 return Ty->getIntegerBitWidth();
523 case Type::FloatTyID:
525 case Type::DoubleTyID:
526 case Type::X86_MMXTyID:
528 case Type::PPC_FP128TyID:
529 case Type::FP128TyID:
531 // In memory objects this is always aligned to a higher boundary, but
532 // only 80 bits contain information.
533 case Type::X86_FP80TyID:
535 case Type::VectorTyID: {
536 VectorType *VTy = cast<VectorType>(Ty);
537 return VTy->getNumElements() * getTypeSizeInBits(VTy->getElementType());
540 llvm_unreachable("DataLayout::getTypeSizeInBits(): Unsupported type");
544 } // End llvm namespace