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"
42 /// Enum used to categorize the alignment types stored by LayoutAlignElem
44 INVALID_ALIGN = 0, ///< An invalid alignment
45 INTEGER_ALIGN = 'i', ///< Integer type alignment
46 VECTOR_ALIGN = 'v', ///< Vector type alignment
47 FLOAT_ALIGN = 'f', ///< Floating point type alignment
48 AGGREGATE_ALIGN = 'a', ///< Aggregate alignment
49 STACK_ALIGN = 's' ///< Stack objects 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 TypeBitWidth; ///< Type bit width
82 uint32_t AddressSpace; ///< Address space for the pointer type
85 static PointerAlignElem get(uint32_t addr_space, unsigned abi_align,
86 unsigned pref_align, uint32_t bit_width);
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
103 SmallVector<unsigned char, 8> LegalIntWidths; ///< Legal Integers.
105 /// Alignments - Where the primitive type alignment data is stored.
108 /// @note Could support multiple size pointer alignments, e.g., 32-bit
109 /// pointers vs. 64-bit pointers by extending LayoutAlignment, but for now,
111 SmallVector<LayoutAlignElem, 16> Alignments;
112 DenseMap<unsigned, PointerAlignElem> Pointers;
114 /// InvalidAlignmentElem - This member is a signal that a requested alignment
115 /// type and bit width were not found in the SmallVector.
116 static const LayoutAlignElem InvalidAlignmentElem;
118 /// InvalidPointerElem - This member is a signal that a requested pointer
119 /// type and bit width were not found in the DenseSet.
120 static const PointerAlignElem InvalidPointerElem;
122 // The StructType -> StructLayout map.
123 mutable void *LayoutMap;
125 //! Set/initialize target alignments
126 void setAlignment(AlignTypeEnum align_type, unsigned abi_align,
127 unsigned pref_align, uint32_t bit_width);
128 unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width,
129 bool ABIAlign, Type *Ty) const;
131 //! Set/initialize pointer alignments
132 void setPointerAlignment(uint32_t addr_space, unsigned abi_align,
133 unsigned pref_align, uint32_t bit_width);
135 //! Internal helper method that returns requested alignment for type.
136 unsigned getAlignment(Type *Ty, bool abi_or_pref) const;
138 /// Valid alignment predicate.
140 /// Predicate that tests a LayoutAlignElem reference returned by get() against
141 /// InvalidAlignmentElem.
142 bool validAlignment(const LayoutAlignElem &align) const {
143 return &align != &InvalidAlignmentElem;
146 /// Valid pointer predicate.
148 /// Predicate that tests a PointerAlignElem reference returned by get() against
149 /// InvalidPointerElem.
150 bool validPointer(const PointerAlignElem &align) const {
151 return &align != &InvalidPointerElem;
154 /// Parses a target data specification string. Assert if the string is
156 void parseSpecifier(StringRef LayoutDescription);
161 /// @note This has to exist, because this is a pass, but it should never be
165 /// Constructs a DataLayout from a specification string. See init().
166 explicit DataLayout(StringRef LayoutDescription)
167 : ImmutablePass(ID) {
168 init(LayoutDescription);
171 /// Initialize target data from properties stored in the module.
172 explicit DataLayout(const Module *M);
174 DataLayout(const DataLayout &DL) :
176 LittleEndian(DL.isLittleEndian()),
177 StackNaturalAlign(DL.StackNaturalAlign),
178 LegalIntWidths(DL.LegalIntWidths),
179 Alignments(DL.Alignments),
180 Pointers(DL.Pointers),
184 ~DataLayout(); // Not virtual, do not subclass this class
186 /// DataLayout is an immutable pass, but holds state. This allows the pass
187 /// manager to clear its mutable state.
188 bool doFinalization(Module &M);
190 /// Parse a data layout string (with fallback to default values). Ensure that
191 /// the data layout pass is registered.
192 void init(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 /// fitsInLegalInteger - This function returns true if the specified type fits
227 /// in a native integer type supported by the CPU. For example, if the CPU
228 /// only supports i32 as a native integer type, then i27 fits in a legal
229 // integer type but i45 does not.
230 bool fitsInLegalInteger(unsigned Width) const {
231 for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i)
232 if (Width <= LegalIntWidths[i])
237 /// Layout pointer alignment
238 /// FIXME: The defaults need to be removed once all of
239 /// the backends/clients are updated.
240 unsigned getPointerABIAlignment(unsigned AS = 0) const {
241 DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS);
242 if (val == Pointers.end()) {
243 val = Pointers.find(0);
245 return val->second.ABIAlign;
248 /// Return target's alignment for stack-based pointers
249 /// FIXME: The defaults need to be removed once all of
250 /// the backends/clients are updated.
251 unsigned getPointerPrefAlignment(unsigned AS = 0) const {
252 DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS);
253 if (val == Pointers.end()) {
254 val = Pointers.find(0);
256 return val->second.PrefAlign;
258 /// Layout pointer size
259 /// FIXME: The defaults need to be removed once all of
260 /// the backends/clients are updated.
261 unsigned getPointerSize(unsigned AS = 0) const {
262 DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS);
263 if (val == Pointers.end()) {
264 val = Pointers.find(0);
266 return val->second.TypeBitWidth;
268 /// Layout pointer size, in bits
269 /// FIXME: The defaults need to be removed once all of
270 /// the backends/clients are updated.
271 unsigned getPointerSizeInBits(unsigned AS = 0) const {
272 return getPointerSize(AS) * 8;
275 /// Layout pointer size, in bits, based on the type. If this function is
276 /// called with a pointer type, then the type size of the pointer is returned.
277 /// If this function is called with a vector of pointers, then the type size
278 /// of the pointer is returned. This should only be called with a pointer or
279 /// vector of pointers.
280 unsigned getPointerTypeSizeInBits(Type *) const;
282 unsigned getPointerTypeSize(Type *Ty) const {
283 return getPointerTypeSizeInBits(Ty) / 8;
288 /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*]
289 /// ---- ---------- --------------- ---------------
298 /// X86_FP80 80 80 96
300 /// [*] The alloc size depends on the alignment, and thus on the target.
301 /// These values are for x86-32 linux.
303 /// getTypeSizeInBits - Return the number of bits necessary to hold the
304 /// specified type. For example, returns 36 for i36 and 80 for x86_fp80.
305 /// The type passed must have a size (Type::isSized() must return true).
306 uint64_t getTypeSizeInBits(Type *Ty) const;
308 /// getTypeStoreSize - Return the maximum number of bytes that may be
309 /// overwritten by storing the specified type. For example, returns 5
310 /// for i36 and 10 for x86_fp80.
311 uint64_t getTypeStoreSize(Type *Ty) const {
312 return (getTypeSizeInBits(Ty)+7)/8;
315 /// getTypeStoreSizeInBits - Return the maximum number of bits that may be
316 /// overwritten by storing the specified type; always a multiple of 8. For
317 /// example, returns 40 for i36 and 80 for x86_fp80.
318 uint64_t getTypeStoreSizeInBits(Type *Ty) const {
319 return 8*getTypeStoreSize(Ty);
322 /// getTypeAllocSize - Return the offset in bytes between successive objects
323 /// of the specified type, including alignment padding. This is the amount
324 /// that alloca reserves for this type. For example, returns 12 or 16 for
325 /// x86_fp80, depending on alignment.
326 uint64_t getTypeAllocSize(Type *Ty) const {
327 // Round up to the next alignment boundary.
328 return RoundUpAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty));
331 /// getTypeAllocSizeInBits - Return the offset in bits between successive
332 /// objects of the specified type, including alignment padding; always a
333 /// multiple of 8. This is the amount that alloca reserves for this type.
334 /// For example, returns 96 or 128 for x86_fp80, depending on alignment.
335 uint64_t getTypeAllocSizeInBits(Type *Ty) const {
336 return 8*getTypeAllocSize(Ty);
339 /// getABITypeAlignment - Return the minimum ABI-required alignment for the
341 unsigned getABITypeAlignment(Type *Ty) const;
343 /// getABIIntegerTypeAlignment - Return the minimum ABI-required alignment for
344 /// an integer type of the specified bitwidth.
345 unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const;
347 /// getCallFrameTypeAlignment - Return the minimum ABI-required alignment
348 /// for the specified type when it is part of a call frame.
349 unsigned getCallFrameTypeAlignment(Type *Ty) const;
351 /// getPrefTypeAlignment - Return the preferred stack/global alignment for
352 /// the specified type. This is always at least as good as the ABI alignment.
353 unsigned getPrefTypeAlignment(Type *Ty) const;
355 /// getPreferredTypeAlignmentShift - Return the preferred alignment for the
356 /// specified type, returned as log2 of the value (a shift amount).
357 unsigned getPreferredTypeAlignmentShift(Type *Ty) const;
359 /// getIntPtrType - Return an integer type with size at least as big as that
360 /// of a pointer in the given address space.
361 IntegerType *getIntPtrType(LLVMContext &C, unsigned AddressSpace = 0) const;
363 /// getIntPtrType - Return an integer (vector of integer) type with size at
364 /// least as big as that of a pointer of the given pointer (vector of pointer)
366 Type *getIntPtrType(Type *) const;
368 /// getSmallestLegalIntType - Return the smallest integer type with size at
369 /// least as big as Width bits.
370 Type *getSmallestLegalIntType(LLVMContext &C, unsigned Width = 0) const;
372 /// getLargestLegalIntType - Return the largest legal integer type, or null if
374 Type *getLargestLegalIntType(LLVMContext &C) const {
375 unsigned LargestSize = getLargestLegalIntTypeSize();
376 return (LargestSize == 0) ? 0 : Type::getIntNTy(C, LargestSize);
379 /// getLargestLegalIntType - Return the size of largest legal integer type
380 /// size, or 0 if none are set.
381 unsigned getLargestLegalIntTypeSize() const;
383 /// getIndexedOffset - return the offset from the beginning of the type for
384 /// the specified indices. This is used to implement getelementptr.
385 uint64_t getIndexedOffset(Type *Ty, ArrayRef<Value *> Indices) const;
387 /// getStructLayout - Return a StructLayout object, indicating the alignment
388 /// of the struct, its size, and the offsets of its fields. Note that this
389 /// information is lazily cached.
390 const StructLayout *getStructLayout(StructType *Ty) const;
392 /// getPreferredAlignment - Return the preferred alignment of the specified
393 /// global. This includes an explicitly requested alignment (if the global
395 unsigned getPreferredAlignment(const GlobalVariable *GV) const;
397 /// getPreferredAlignmentLog - Return the preferred alignment of the
398 /// specified global, returned in log form. This includes an explicitly
399 /// requested alignment (if the global has one).
400 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const;
402 /// RoundUpAlignment - Round the specified value up to the next alignment
403 /// boundary specified by Alignment. For example, 7 rounded up to an
404 /// alignment boundary of 4 is 8. 8 rounded up to the alignment boundary of 4
405 /// is 8 because it is already aligned.
406 template <typename UIntTy>
407 static UIntTy RoundUpAlignment(UIntTy Val, unsigned Alignment) {
408 assert((Alignment & (Alignment-1)) == 0 && "Alignment must be power of 2!");
409 return (Val + (Alignment-1)) & ~UIntTy(Alignment-1);
412 static char ID; // Pass identification, replacement for typeid
415 /// StructLayout - used to lazily calculate structure layout information for a
416 /// target machine, based on the DataLayout structure.
420 unsigned StructAlignment;
421 unsigned NumElements;
422 uint64_t MemberOffsets[1]; // variable sized array!
425 uint64_t getSizeInBytes() const {
429 uint64_t getSizeInBits() const {
433 unsigned getAlignment() const {
434 return StructAlignment;
437 /// getElementContainingOffset - Given a valid byte offset into the structure,
438 /// return the structure index that contains it.
440 unsigned getElementContainingOffset(uint64_t Offset) const;
442 uint64_t getElementOffset(unsigned Idx) const {
443 assert(Idx < NumElements && "Invalid element idx!");
444 return MemberOffsets[Idx];
447 uint64_t getElementOffsetInBits(unsigned Idx) const {
448 return getElementOffset(Idx)*8;
452 friend class DataLayout; // Only DataLayout can create this class
453 StructLayout(StructType *ST, const DataLayout &DL);
457 // The implementation of this method is provided inline as it is particularly
458 // well suited to constant folding when called on a specific Type subclass.
459 inline uint64_t DataLayout::getTypeSizeInBits(Type *Ty) const {
460 assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!");
461 switch (Ty->getTypeID()) {
462 case Type::LabelTyID:
463 return getPointerSizeInBits(0);
464 case Type::PointerTyID:
465 return getPointerSizeInBits(Ty->getPointerAddressSpace());
466 case Type::ArrayTyID: {
467 ArrayType *ATy = cast<ArrayType>(Ty);
468 return ATy->getNumElements() *
469 getTypeAllocSizeInBits(ATy->getElementType());
471 case Type::StructTyID:
472 // Get the layout annotation... which is lazily created on demand.
473 return getStructLayout(cast<StructType>(Ty))->getSizeInBits();
474 case Type::IntegerTyID:
475 return Ty->getIntegerBitWidth();
478 case Type::FloatTyID:
480 case Type::DoubleTyID:
481 case Type::X86_MMXTyID:
483 case Type::PPC_FP128TyID:
484 case Type::FP128TyID:
486 // In memory objects this is always aligned to a higher boundary, but
487 // only 80 bits contain information.
488 case Type::X86_FP80TyID:
490 case Type::VectorTyID: {
491 VectorType *VTy = cast<VectorType>(Ty);
492 return VTy->getNumElements() * getTypeSizeInBits(VTy->getElementType());
495 llvm_unreachable("DataLayout::getTypeSizeInBits(): Unsupported type");
499 } // End llvm namespace