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;
92 /// DataLayout - This class holds a parsed version of the target data layout
93 /// string in a module and provides methods for querying it. The target data
94 /// layout string is specified *by the target* - a frontend generating LLVM IR
95 /// is required to generate the right target data for the target being codegen'd
96 /// to. If some measure of portability is desired, an empty string may be
97 /// specified in the module.
98 class DataLayout : public ImmutablePass {
100 bool LittleEndian; ///< Defaults to false
101 unsigned StackNaturalAlign; ///< Stack natural alignment
110 ManglingModeT ManglingMode;
112 SmallVector<unsigned char, 8> LegalIntWidths; ///< Legal Integers.
114 /// Alignments - Where the primitive type alignment data is stored.
117 /// @note Could support multiple size pointer alignments, e.g., 32-bit
118 /// pointers vs. 64-bit pointers by extending LayoutAlignment, but for now,
120 SmallVector<LayoutAlignElem, 16> Alignments;
121 DenseMap<unsigned, PointerAlignElem> Pointers;
123 /// InvalidAlignmentElem - This member is a signal that a requested alignment
124 /// type and bit width were not found in the SmallVector.
125 static const LayoutAlignElem InvalidAlignmentElem;
127 /// InvalidPointerElem - This member is a signal that a requested pointer
128 /// type and bit width were not found in the DenseSet.
129 static const PointerAlignElem InvalidPointerElem;
131 // The StructType -> StructLayout map.
132 mutable void *LayoutMap;
134 //! Set/initialize target alignments
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;
140 //! Set/initialize pointer alignments
141 void setPointerAlignment(uint32_t AddrSpace, unsigned ABIAlign,
142 unsigned PrefAlign, uint32_t TypeByteWidth);
144 //! Internal helper method that returns requested alignment for type.
145 unsigned getAlignment(Type *Ty, bool abi_or_pref) const;
147 /// Valid alignment predicate.
149 /// Predicate that tests a LayoutAlignElem reference returned by get() against
150 /// InvalidAlignmentElem.
151 bool validAlignment(const LayoutAlignElem &align) const {
152 return &align != &InvalidAlignmentElem;
155 /// Valid pointer predicate.
157 /// Predicate that tests a PointerAlignElem reference returned by get() against
158 /// InvalidPointerElem.
159 bool validPointer(const PointerAlignElem &align) const {
160 return &align != &InvalidPointerElem;
163 /// Parses a target data specification string. Assert if the string is
165 void parseSpecifier(StringRef LayoutDescription);
170 /// @note This has to exist, because this is a pass, but it should never be
174 /// Constructs a DataLayout from a specification string. See init().
175 explicit DataLayout(StringRef LayoutDescription)
176 : ImmutablePass(ID) {
177 init(LayoutDescription);
180 /// Initialize target data from properties stored in the module.
181 explicit DataLayout(const Module *M);
183 DataLayout(const DataLayout &DL) :
185 LittleEndian(DL.isLittleEndian()),
186 StackNaturalAlign(DL.StackNaturalAlign),
187 ManglingMode(DL.ManglingMode),
188 LegalIntWidths(DL.LegalIntWidths),
189 Alignments(DL.Alignments),
190 Pointers(DL.Pointers),
194 ~DataLayout(); // Not virtual, do not subclass this class
196 /// DataLayout is an immutable pass, but holds state. This allows the pass
197 /// manager to clear its mutable state.
198 bool doFinalization(Module &M);
200 /// Parse a data layout string (with fallback to default values). Ensure that
201 /// the data layout pass is registered.
202 void init(StringRef LayoutDescription);
204 /// Layout endianness...
205 bool isLittleEndian() const { return LittleEndian; }
206 bool isBigEndian() const { return !LittleEndian; }
208 /// getStringRepresentation - Return the string representation of the
209 /// DataLayout. This representation is in the same format accepted by the
210 /// string constructor above.
211 std::string getStringRepresentation() const;
213 /// isLegalInteger - This function returns true if the specified type is
214 /// known to be a native integer type supported by the CPU. For example,
215 /// i64 is not native on most 32-bit CPUs and i37 is not native on any known
216 /// one. This returns false if the integer width is not legal.
218 /// The width is specified in bits.
220 bool isLegalInteger(unsigned Width) const {
221 for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i)
222 if (LegalIntWidths[i] == Width)
227 bool isIllegalInteger(unsigned Width) const {
228 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 bool hasMicrosoftFastStdCallMangling() const {
237 return ManglingMode == MM_WINCOFF;
240 bool hasLinkerPrivateGlobalPrefix() const {
241 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 /// fitsInLegalInteger - This function returns true if the specified type fits
281 /// in a native integer type supported by the CPU. For example, if the CPU
282 /// only supports i32 as a native integer type, then i27 fits in a legal
283 // integer type but i45 does not.
284 bool fitsInLegalInteger(unsigned Width) const {
285 for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i)
286 if (Width <= LegalIntWidths[i])
291 /// Layout pointer alignment
292 /// FIXME: The defaults need to be removed once all of
293 /// the backends/clients are updated.
294 unsigned getPointerABIAlignment(unsigned AS = 0) const {
295 DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS);
296 if (val == Pointers.end()) {
297 val = Pointers.find(0);
299 return val->second.ABIAlign;
302 /// Return target's alignment for stack-based pointers
303 /// FIXME: The defaults need to be removed once all of
304 /// the backends/clients are updated.
305 unsigned getPointerPrefAlignment(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.PrefAlign;
312 /// Layout pointer size
313 /// FIXME: The defaults need to be removed once all of
314 /// the backends/clients are updated.
315 unsigned getPointerSize(unsigned AS = 0) const {
316 DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS);
317 if (val == Pointers.end()) {
318 val = Pointers.find(0);
320 return val->second.TypeByteWidth;
322 /// Layout pointer size, in bits
323 /// FIXME: The defaults need to be removed once all of
324 /// the backends/clients are updated.
325 unsigned getPointerSizeInBits(unsigned AS = 0) const {
326 return getPointerSize(AS) * 8;
329 /// Layout pointer size, in bits, based on the type. If this function is
330 /// called with a pointer type, then the type size of the pointer is returned.
331 /// If this function is called with a vector of pointers, then the type size
332 /// of the pointer is returned. This should only be called with a pointer or
333 /// vector of pointers.
334 unsigned getPointerTypeSizeInBits(Type *) const;
336 unsigned getPointerTypeSize(Type *Ty) const {
337 return getPointerTypeSizeInBits(Ty) / 8;
342 /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*]
343 /// ---- ---------- --------------- ---------------
352 /// X86_FP80 80 80 96
354 /// [*] The alloc size depends on the alignment, and thus on the target.
355 /// These values are for x86-32 linux.
357 /// getTypeSizeInBits - Return the number of bits necessary to hold the
358 /// specified type. For example, returns 36 for i36 and 80 for x86_fp80.
359 /// The type passed must have a size (Type::isSized() must return true).
360 uint64_t getTypeSizeInBits(Type *Ty) const;
362 /// getTypeStoreSize - Return the maximum number of bytes that may be
363 /// overwritten by storing the specified type. For example, returns 5
364 /// for i36 and 10 for x86_fp80.
365 uint64_t getTypeStoreSize(Type *Ty) const {
366 return (getTypeSizeInBits(Ty)+7)/8;
369 /// getTypeStoreSizeInBits - Return the maximum number of bits that may be
370 /// overwritten by storing the specified type; always a multiple of 8. For
371 /// example, returns 40 for i36 and 80 for x86_fp80.
372 uint64_t getTypeStoreSizeInBits(Type *Ty) const {
373 return 8*getTypeStoreSize(Ty);
376 /// getTypeAllocSize - Return the offset in bytes between successive objects
377 /// of the specified type, including alignment padding. This is the amount
378 /// that alloca reserves for this type. For example, returns 12 or 16 for
379 /// x86_fp80, depending on alignment.
380 uint64_t getTypeAllocSize(Type *Ty) const {
381 // Round up to the next alignment boundary.
382 return RoundUpAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty));
385 /// getTypeAllocSizeInBits - Return the offset in bits between successive
386 /// objects of the specified type, including alignment padding; always a
387 /// multiple of 8. This is the amount that alloca reserves for this type.
388 /// For example, returns 96 or 128 for x86_fp80, depending on alignment.
389 uint64_t getTypeAllocSizeInBits(Type *Ty) const {
390 return 8*getTypeAllocSize(Ty);
393 /// getABITypeAlignment - Return the minimum ABI-required alignment for the
395 unsigned getABITypeAlignment(Type *Ty) const;
397 /// getABIIntegerTypeAlignment - Return the minimum ABI-required alignment for
398 /// an integer type of the specified bitwidth.
399 unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const;
401 /// getPrefTypeAlignment - Return the preferred stack/global alignment for
402 /// the specified type. This is always at least as good as the ABI alignment.
403 unsigned getPrefTypeAlignment(Type *Ty) const;
405 /// getPreferredTypeAlignmentShift - Return the preferred alignment for the
406 /// specified type, returned as log2 of the value (a shift amount).
407 unsigned getPreferredTypeAlignmentShift(Type *Ty) const;
409 /// getIntPtrType - Return an integer type with size at least as big as that
410 /// of a pointer in the given address space.
411 IntegerType *getIntPtrType(LLVMContext &C, unsigned AddressSpace = 0) const;
413 /// getIntPtrType - Return an integer (vector of integer) type with size at
414 /// least as big as that of a pointer of the given pointer (vector of pointer)
416 Type *getIntPtrType(Type *) const;
418 /// getSmallestLegalIntType - Return the smallest integer type with size at
419 /// least as big as Width bits.
420 Type *getSmallestLegalIntType(LLVMContext &C, unsigned Width = 0) const;
422 /// getLargestLegalIntType - Return the largest legal integer type, or null if
424 Type *getLargestLegalIntType(LLVMContext &C) const {
425 unsigned LargestSize = getLargestLegalIntTypeSize();
426 return (LargestSize == 0) ? 0 : Type::getIntNTy(C, LargestSize);
429 /// getLargestLegalIntType - Return the size of largest legal integer type
430 /// size, or 0 if none are set.
431 unsigned getLargestLegalIntTypeSize() const;
433 /// getIndexedOffset - return the offset from the beginning of the type for
434 /// the specified indices. This is used to implement getelementptr.
435 uint64_t getIndexedOffset(Type *Ty, ArrayRef<Value *> Indices) const;
437 /// getStructLayout - Return a StructLayout object, indicating the alignment
438 /// of the struct, its size, and the offsets of its fields. Note that this
439 /// information is lazily cached.
440 const StructLayout *getStructLayout(StructType *Ty) const;
442 /// getPreferredAlignment - Return the preferred alignment of the specified
443 /// global. This includes an explicitly requested alignment (if the global
445 unsigned getPreferredAlignment(const GlobalVariable *GV) const;
447 /// getPreferredAlignmentLog - Return the preferred alignment of the
448 /// specified global, returned in log form. This includes an explicitly
449 /// requested alignment (if the global has one).
450 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const;
452 /// RoundUpAlignment - Round the specified value up to the next alignment
453 /// boundary specified by Alignment. For example, 7 rounded up to an
454 /// alignment boundary of 4 is 8. 8 rounded up to the alignment boundary of 4
455 /// is 8 because it is already aligned.
456 template <typename UIntTy>
457 static UIntTy RoundUpAlignment(UIntTy Val, unsigned Alignment) {
458 assert((Alignment & (Alignment-1)) == 0 && "Alignment must be power of 2!");
459 return (Val + (Alignment-1)) & ~UIntTy(Alignment-1);
462 static char ID; // Pass identification, replacement for typeid
465 /// StructLayout - used to lazily calculate structure layout information for a
466 /// target machine, based on the DataLayout structure.
470 unsigned StructAlignment;
471 unsigned NumElements;
472 uint64_t MemberOffsets[1]; // variable sized array!
475 uint64_t getSizeInBytes() const {
479 uint64_t getSizeInBits() const {
483 unsigned getAlignment() const {
484 return StructAlignment;
487 /// getElementContainingOffset - Given a valid byte offset into the structure,
488 /// return the structure index that contains it.
490 unsigned getElementContainingOffset(uint64_t Offset) const;
492 uint64_t getElementOffset(unsigned Idx) const {
493 assert(Idx < NumElements && "Invalid element idx!");
494 return MemberOffsets[Idx];
497 uint64_t getElementOffsetInBits(unsigned Idx) const {
498 return getElementOffset(Idx)*8;
502 friend class DataLayout; // Only DataLayout can create this class
503 StructLayout(StructType *ST, const DataLayout &DL);
507 // The implementation of this method is provided inline as it is particularly
508 // well suited to constant folding when called on a specific Type subclass.
509 inline uint64_t DataLayout::getTypeSizeInBits(Type *Ty) const {
510 assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!");
511 switch (Ty->getTypeID()) {
512 case Type::LabelTyID:
513 return getPointerSizeInBits(0);
514 case Type::PointerTyID:
515 return getPointerSizeInBits(Ty->getPointerAddressSpace());
516 case Type::ArrayTyID: {
517 ArrayType *ATy = cast<ArrayType>(Ty);
518 return ATy->getNumElements() *
519 getTypeAllocSizeInBits(ATy->getElementType());
521 case Type::StructTyID:
522 // Get the layout annotation... which is lazily created on demand.
523 return getStructLayout(cast<StructType>(Ty))->getSizeInBits();
524 case Type::IntegerTyID:
525 return Ty->getIntegerBitWidth();
528 case Type::FloatTyID:
530 case Type::DoubleTyID:
531 case Type::X86_MMXTyID:
533 case Type::PPC_FP128TyID:
534 case Type::FP128TyID:
536 // In memory objects this is always aligned to a higher boundary, but
537 // only 80 bits contain information.
538 case Type::X86_FP80TyID:
540 case Type::VectorTyID: {
541 VectorType *VTy = cast<VectorType>(Ty);
542 return VTy->getNumElements() * getTypeSizeInBits(VTy->getElementType());
545 llvm_unreachable("DataLayout::getTypeSizeInBits(): Unsupported type");
549 } // End llvm namespace