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"
43 /// Enum used to categorize the alignment types stored by LayoutAlignElem
45 INVALID_ALIGN = 0, ///< An invalid alignment
46 INTEGER_ALIGN = 'i', ///< Integer type alignment
47 VECTOR_ALIGN = 'v', ///< Vector type alignment
48 FLOAT_ALIGN = 'f', ///< Floating point type alignment
49 AGGREGATE_ALIGN = 'a' ///< Aggregate alignment
52 /// Layout alignment element.
54 /// Stores the alignment data associated with a given alignment type (integer,
55 /// vector, float) and type bit width.
57 /// @note The unusual order of elements in the structure attempts to reduce
58 /// padding and make the structure slightly more cache friendly.
59 struct LayoutAlignElem {
60 unsigned AlignType : 8; ///< Alignment type (AlignTypeEnum)
61 unsigned TypeBitWidth : 24; ///< Type bit width
62 unsigned ABIAlign : 16; ///< ABI alignment for this type/bitw
63 unsigned PrefAlign : 16; ///< Pref. alignment for this type/bitw
66 static LayoutAlignElem get(AlignTypeEnum align_type, unsigned abi_align,
67 unsigned pref_align, uint32_t bit_width);
68 /// Equality predicate
69 bool operator==(const LayoutAlignElem &rhs) const;
72 /// Layout pointer alignment element.
74 /// Stores the alignment data associated with a given pointer and address space.
76 /// @note The unusual order of elements in the structure attempts to reduce
77 /// padding and make the structure slightly more cache friendly.
78 struct PointerAlignElem {
79 unsigned ABIAlign; ///< ABI alignment for this type/bitw
80 unsigned PrefAlign; ///< Pref. alignment for this type/bitw
81 uint32_t TypeByteWidth; ///< Type byte width
82 uint32_t AddressSpace; ///< Address space for the pointer type
85 static PointerAlignElem get(uint32_t AddressSpace, unsigned ABIAlign,
86 unsigned PrefAlign, uint32_t TypeByteWidth);
87 /// Equality predicate
88 bool operator==(const PointerAlignElem &rhs) const;
91 /// This class holds a parsed version of the target data layout string in a
92 /// module and provides methods for querying it. The target data layout string
93 /// is specified *by the target* - a frontend generating LLVM IR is required to
94 /// generate the right target data for the target being codegen'd to.
97 bool LittleEndian; ///< Defaults to false
98 unsigned StackNaturalAlign; ///< Stack natural alignment
107 ManglingModeT ManglingMode;
109 SmallVector<unsigned char, 8> LegalIntWidths; ///< Legal Integers.
111 /// Alignments - Where the primitive type alignment data is stored.
114 /// @note Could support multiple size pointer alignments, e.g., 32-bit
115 /// pointers vs. 64-bit pointers by extending LayoutAlignment, but for now,
117 SmallVector<LayoutAlignElem, 16> Alignments;
118 DenseMap<unsigned, PointerAlignElem> Pointers;
120 /// InvalidAlignmentElem - This member is a signal that a requested alignment
121 /// type and bit width were not found in the SmallVector.
122 static const LayoutAlignElem InvalidAlignmentElem;
124 /// InvalidPointerElem - This member is a signal that a requested pointer
125 /// type and bit width were not found in the DenseSet.
126 static const PointerAlignElem InvalidPointerElem;
128 // The StructType -> StructLayout map.
129 mutable void *LayoutMap;
131 //! Set/initialize target alignments
132 void setAlignment(AlignTypeEnum align_type, unsigned abi_align,
133 unsigned pref_align, uint32_t bit_width);
134 unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width,
135 bool ABIAlign, Type *Ty) const;
137 //! Set/initialize pointer alignments
138 void setPointerAlignment(uint32_t AddrSpace, unsigned ABIAlign,
139 unsigned PrefAlign, uint32_t TypeByteWidth);
141 //! Internal helper method that returns requested alignment for type.
142 unsigned getAlignment(Type *Ty, bool abi_or_pref) const;
144 /// Valid alignment predicate.
146 /// Predicate that tests a LayoutAlignElem reference returned by get() against
147 /// InvalidAlignmentElem.
148 bool validAlignment(const LayoutAlignElem &align) const {
149 return &align != &InvalidAlignmentElem;
152 /// Valid pointer predicate.
154 /// Predicate that tests a PointerAlignElem reference returned by get() against
155 /// InvalidPointerElem.
156 bool validPointer(const PointerAlignElem &align) const {
157 return &align != &InvalidPointerElem;
160 /// Parses a target data specification string. Assert if the string is
162 void parseSpecifier(StringRef LayoutDescription);
164 // Free all internal data structures.
168 /// Constructs a DataLayout from a specification string. See reset().
169 explicit DataLayout(StringRef LayoutDescription) : LayoutMap(0) {
170 reset(LayoutDescription);
173 /// Initialize target data from properties stored in the module.
174 explicit DataLayout(const Module *M);
176 DataLayout(const DataLayout &DL) : LayoutMap(0) { *this = DL; }
178 DataLayout &operator=(const DataLayout &DL) {
180 LittleEndian = DL.isLittleEndian();
181 StackNaturalAlign = DL.StackNaturalAlign;
182 ManglingMode = DL.ManglingMode;
183 LegalIntWidths = DL.LegalIntWidths;
184 Alignments = DL.Alignments;
185 Pointers = DL.Pointers;
189 ~DataLayout(); // Not virtual, do not subclass this class
191 /// Parse a data layout string (with fallback to default values).
192 void reset(StringRef LayoutDescription);
194 /// Layout endianness...
195 bool isLittleEndian() const { return LittleEndian; }
196 bool isBigEndian() const { return !LittleEndian; }
198 /// getStringRepresentation - Return the string representation of the
199 /// DataLayout. This representation is in the same format accepted by the
200 /// string constructor above.
201 std::string getStringRepresentation() const;
203 /// isLegalInteger - This function returns true if the specified type is
204 /// known to be a native integer type supported by the CPU. For example,
205 /// i64 is not native on most 32-bit CPUs and i37 is not native on any known
206 /// one. This returns false if the integer width is not legal.
208 /// The width is specified in bits.
210 bool isLegalInteger(unsigned Width) const {
211 for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i)
212 if (LegalIntWidths[i] == Width)
217 bool isIllegalInteger(unsigned Width) const {
218 return !isLegalInteger(Width);
221 /// Returns true if the given alignment exceeds the natural stack alignment.
222 bool exceedsNaturalStackAlignment(unsigned Align) const {
223 return (StackNaturalAlign != 0) && (Align > StackNaturalAlign);
226 bool hasMicrosoftFastStdCallMangling() const {
227 return ManglingMode == MM_WINCOFF;
230 bool hasLinkerPrivateGlobalPrefix() const {
231 return ManglingMode == MM_MachO;
234 const char *getLinkerPrivateGlobalPrefix() const {
235 if (ManglingMode == MM_MachO)
237 return getPrivateGlobalPrefix();
240 char getGlobalPrefix() const {
241 switch (ManglingMode) {
250 llvm_unreachable("invalid mangling mode");
253 const char *getPrivateGlobalPrefix() const {
254 switch (ManglingMode) {
265 llvm_unreachable("invalid mangling mode");
268 static const char *getManglingComponent(const Triple &T);
270 /// fitsInLegalInteger - This function returns true if the specified type fits
271 /// in a native integer type supported by the CPU. For example, if the CPU
272 /// only supports i32 as a native integer type, then i27 fits in a legal
273 // integer type but i45 does not.
274 bool fitsInLegalInteger(unsigned Width) const {
275 for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i)
276 if (Width <= LegalIntWidths[i])
281 /// Layout pointer alignment
282 /// FIXME: The defaults need to be removed once all of
283 /// the backends/clients are updated.
284 unsigned getPointerABIAlignment(unsigned AS = 0) const {
285 DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS);
286 if (val == Pointers.end()) {
287 val = Pointers.find(0);
289 return val->second.ABIAlign;
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 {
296 DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS);
297 if (val == Pointers.end()) {
298 val = Pointers.find(0);
300 return val->second.PrefAlign;
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 {
306 DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS);
307 if (val == Pointers.end()) {
308 val = Pointers.find(0);
310 return val->second.TypeByteWidth;
312 /// Layout pointer size, in bits
313 /// FIXME: The defaults need to be removed once all of
314 /// the backends/clients are updated.
315 unsigned getPointerSizeInBits(unsigned AS = 0) const {
316 return getPointerSize(AS) * 8;
319 /// Layout pointer size, in bits, based on the type. If this function is
320 /// called with a pointer type, then the type size of the pointer is returned.
321 /// If this function is called with a vector of pointers, then the type size
322 /// of the pointer is returned. This should only be called with a pointer or
323 /// vector of pointers.
324 unsigned getPointerTypeSizeInBits(Type *) const;
326 unsigned getPointerTypeSize(Type *Ty) const {
327 return getPointerTypeSizeInBits(Ty) / 8;
332 /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*]
333 /// ---- ---------- --------------- ---------------
342 /// X86_FP80 80 80 96
344 /// [*] The alloc size depends on the alignment, and thus on the target.
345 /// These values are for x86-32 linux.
347 /// getTypeSizeInBits - Return the number of bits necessary to hold the
348 /// specified type. For example, returns 36 for i36 and 80 for x86_fp80.
349 /// The type passed must have a size (Type::isSized() must return true).
350 uint64_t getTypeSizeInBits(Type *Ty) const;
352 /// getTypeStoreSize - Return the maximum number of bytes that may be
353 /// overwritten by storing the specified type. For example, returns 5
354 /// for i36 and 10 for x86_fp80.
355 uint64_t getTypeStoreSize(Type *Ty) const {
356 return (getTypeSizeInBits(Ty)+7)/8;
359 /// getTypeStoreSizeInBits - Return the maximum number of bits that may be
360 /// overwritten by storing the specified type; always a multiple of 8. For
361 /// example, returns 40 for i36 and 80 for x86_fp80.
362 uint64_t getTypeStoreSizeInBits(Type *Ty) const {
363 return 8*getTypeStoreSize(Ty);
366 /// getTypeAllocSize - Return the offset in bytes between successive objects
367 /// of the specified type, including alignment padding. This is the amount
368 /// that alloca reserves for this type. For example, returns 12 or 16 for
369 /// x86_fp80, depending on alignment.
370 uint64_t getTypeAllocSize(Type *Ty) const {
371 // Round up to the next alignment boundary.
372 return RoundUpAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty));
375 /// getTypeAllocSizeInBits - Return the offset in bits between successive
376 /// objects of the specified type, including alignment padding; always a
377 /// multiple of 8. This is the amount that alloca reserves for this type.
378 /// For example, returns 96 or 128 for x86_fp80, depending on alignment.
379 uint64_t getTypeAllocSizeInBits(Type *Ty) const {
380 return 8*getTypeAllocSize(Ty);
383 /// getABITypeAlignment - Return the minimum ABI-required alignment for the
385 unsigned getABITypeAlignment(Type *Ty) const;
387 /// getABIIntegerTypeAlignment - Return the minimum ABI-required alignment for
388 /// an integer type of the specified bitwidth.
389 unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const;
391 /// getPrefTypeAlignment - Return the preferred stack/global alignment for
392 /// the specified type. This is always at least as good as the ABI alignment.
393 unsigned getPrefTypeAlignment(Type *Ty) const;
395 /// getPreferredTypeAlignmentShift - Return the preferred alignment for the
396 /// specified type, returned as log2 of the value (a shift amount).
397 unsigned getPreferredTypeAlignmentShift(Type *Ty) const;
399 /// getIntPtrType - Return an integer type with size at least as big as that
400 /// of a pointer in the given address space.
401 IntegerType *getIntPtrType(LLVMContext &C, unsigned AddressSpace = 0) const;
403 /// getIntPtrType - Return an integer (vector of integer) type with size at
404 /// least as big as that of a pointer of the given pointer (vector of pointer)
406 Type *getIntPtrType(Type *) const;
408 /// getSmallestLegalIntType - Return the smallest integer type with size at
409 /// least as big as Width bits.
410 Type *getSmallestLegalIntType(LLVMContext &C, unsigned Width = 0) const;
412 /// getLargestLegalIntType - Return the largest legal integer type, or null if
414 Type *getLargestLegalIntType(LLVMContext &C) const {
415 unsigned LargestSize = getLargestLegalIntTypeSize();
416 return (LargestSize == 0) ? 0 : Type::getIntNTy(C, LargestSize);
419 /// getLargestLegalIntType - Return the size of largest legal integer type
420 /// size, or 0 if none are set.
421 unsigned getLargestLegalIntTypeSize() const;
423 /// getIndexedOffset - return the offset from the beginning of the type for
424 /// the specified indices. This is used to implement getelementptr.
425 uint64_t getIndexedOffset(Type *Ty, ArrayRef<Value *> Indices) const;
427 /// getStructLayout - Return a StructLayout object, indicating the alignment
428 /// of the struct, its size, and the offsets of its fields. Note that this
429 /// information is lazily cached.
430 const StructLayout *getStructLayout(StructType *Ty) const;
432 /// getPreferredAlignment - Return the preferred alignment of the specified
433 /// global. This includes an explicitly requested alignment (if the global
435 unsigned getPreferredAlignment(const GlobalVariable *GV) const;
437 /// getPreferredAlignmentLog - Return the preferred alignment of the
438 /// specified global, returned in log form. This includes an explicitly
439 /// requested alignment (if the global has one).
440 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const;
442 /// RoundUpAlignment - Round the specified value up to the next alignment
443 /// boundary specified by Alignment. For example, 7 rounded up to an
444 /// alignment boundary of 4 is 8. 8 rounded up to the alignment boundary of 4
445 /// is 8 because it is already aligned.
446 template <typename UIntTy>
447 static UIntTy RoundUpAlignment(UIntTy Val, unsigned Alignment) {
448 assert((Alignment & (Alignment-1)) == 0 && "Alignment must be power of 2!");
449 return (Val + (Alignment-1)) & ~UIntTy(Alignment-1);
453 class DataLayoutPass : public ImmutablePass {
457 /// This has to exist, because this is a pass, but it should never be used.
461 const DataLayout &getDataLayout() const { return DL; }
463 // For use with the C API. C++ code should always use the constructor that
465 explicit DataLayoutPass(const DataLayout &DL);
467 explicit DataLayoutPass(const Module *M);
469 static char ID; // Pass identification, replacement for typeid
472 /// StructLayout - used to lazily calculate structure layout information for a
473 /// target machine, based on the DataLayout structure.
477 unsigned StructAlignment;
478 unsigned NumElements;
479 uint64_t MemberOffsets[1]; // variable sized array!
482 uint64_t getSizeInBytes() const {
486 uint64_t getSizeInBits() const {
490 unsigned getAlignment() const {
491 return StructAlignment;
494 /// getElementContainingOffset - Given a valid byte offset into the structure,
495 /// return the structure index that contains it.
497 unsigned getElementContainingOffset(uint64_t Offset) const;
499 uint64_t getElementOffset(unsigned Idx) const {
500 assert(Idx < NumElements && "Invalid element idx!");
501 return MemberOffsets[Idx];
504 uint64_t getElementOffsetInBits(unsigned Idx) const {
505 return getElementOffset(Idx)*8;
509 friend class DataLayout; // Only DataLayout can create this class
510 StructLayout(StructType *ST, const DataLayout &DL);
514 // The implementation of this method is provided inline as it is particularly
515 // well suited to constant folding when called on a specific Type subclass.
516 inline uint64_t DataLayout::getTypeSizeInBits(Type *Ty) const {
517 assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!");
518 switch (Ty->getTypeID()) {
519 case Type::LabelTyID:
520 return getPointerSizeInBits(0);
521 case Type::PointerTyID:
522 return getPointerSizeInBits(Ty->getPointerAddressSpace());
523 case Type::ArrayTyID: {
524 ArrayType *ATy = cast<ArrayType>(Ty);
525 return ATy->getNumElements() *
526 getTypeAllocSizeInBits(ATy->getElementType());
528 case Type::StructTyID:
529 // Get the layout annotation... which is lazily created on demand.
530 return getStructLayout(cast<StructType>(Ty))->getSizeInBits();
531 case Type::IntegerTyID:
532 return Ty->getIntegerBitWidth();
535 case Type::FloatTyID:
537 case Type::DoubleTyID:
538 case Type::X86_MMXTyID:
540 case Type::PPC_FP128TyID:
541 case Type::FP128TyID:
543 // In memory objects this is always aligned to a higher boundary, but
544 // only 80 bits contain information.
545 case Type::X86_FP80TyID:
547 case Type::VectorTyID: {
548 VectorType *VTy = cast<VectorType>(Ty);
549 return VTy->getNumElements() * getTypeSizeInBits(VTy->getElementType());
552 llvm_unreachable("DataLayout::getTypeSizeInBits(): Unsupported type");
556 } // End llvm namespace