1 //===-- llvm/Target/TargetData.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 target 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_TARGET_TARGETDATA_H
21 #define LLVM_TARGET_TARGETDATA_H
23 #include "llvm/Pass.h"
24 #include "llvm/ADT/SmallVector.h"
25 #include "llvm/Support/DataTypes.h"
39 /// Enum used to categorize the alignment types stored by TargetAlignElem
41 INTEGER_ALIGN = 'i', ///< Integer type alignment
42 VECTOR_ALIGN = 'v', ///< Vector type alignment
43 FLOAT_ALIGN = 'f', ///< Floating point type alignment
44 AGGREGATE_ALIGN = 'a', ///< Aggregate alignment
45 STACK_ALIGN = 's' ///< Stack objects alignment
47 /// Target alignment element.
49 /// Stores the alignment data associated with a given alignment type (pointer,
50 /// integer, vector, float) and type bit width.
52 /// @note The unusual order of elements in the structure attempts to reduce
53 /// padding and make the structure slightly more cache friendly.
54 struct TargetAlignElem {
55 AlignTypeEnum AlignType : 8; //< Alignment type (AlignTypeEnum)
56 unsigned ABIAlign; //< ABI alignment for this type/bitw
57 unsigned PrefAlign; //< Pref. alignment for this type/bitw
58 uint32_t TypeBitWidth; //< Type bit width
61 static TargetAlignElem get(AlignTypeEnum align_type, unsigned abi_align,
62 unsigned pref_align, uint32_t bit_width);
63 /// Equality predicate
64 bool operator==(const TargetAlignElem &rhs) const;
67 class TargetData : public ImmutablePass {
69 bool LittleEndian; ///< Defaults to false
70 unsigned PointerMemSize; ///< Pointer size in bytes
71 unsigned PointerABIAlign; ///< Pointer ABI alignment
72 unsigned PointerPrefAlign; ///< Pointer preferred alignment
73 unsigned StackNaturalAlign; ///< Stack natural alignment
75 SmallVector<unsigned char, 8> LegalIntWidths; ///< Legal Integers.
77 /// Alignments- Where the primitive type alignment data is stored.
80 /// @note Could support multiple size pointer alignments, e.g., 32-bit
81 /// pointers vs. 64-bit pointers by extending TargetAlignment, but for now,
83 SmallVector<TargetAlignElem, 16> Alignments;
85 /// InvalidAlignmentElem - This member is a signal that a requested alignment
86 /// type and bit width were not found in the SmallVector.
87 static const TargetAlignElem InvalidAlignmentElem;
89 // The StructType -> StructLayout map.
90 mutable void *LayoutMap;
92 //! Set/initialize target alignments
93 void setAlignment(AlignTypeEnum align_type, unsigned abi_align,
94 unsigned pref_align, uint32_t bit_width);
95 unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width,
96 bool ABIAlign, Type *Ty) const;
97 //! Internal helper method that returns requested alignment for type.
98 unsigned getAlignment(Type *Ty, bool abi_or_pref) const;
100 /// Valid alignment predicate.
102 /// Predicate that tests a TargetAlignElem reference returned by get() against
103 /// InvalidAlignmentElem.
104 bool validAlignment(const TargetAlignElem &align) const {
105 return &align != &InvalidAlignmentElem;
111 /// @note This has to exist, because this is a pass, but it should never be
115 /// Constructs a TargetData from a specification string. See init().
116 explicit TargetData(StringRef TargetDescription)
117 : ImmutablePass(ID) {
118 init(TargetDescription);
121 /// Initialize target data from properties stored in the module.
122 explicit TargetData(const Module *M);
124 TargetData(const TargetData &TD) :
126 LittleEndian(TD.isLittleEndian()),
127 PointerMemSize(TD.PointerMemSize),
128 PointerABIAlign(TD.PointerABIAlign),
129 PointerPrefAlign(TD.PointerPrefAlign),
130 LegalIntWidths(TD.LegalIntWidths),
131 Alignments(TD.Alignments),
135 ~TargetData(); // Not virtual, do not subclass this class
137 //! Parse a target data layout string and initialize TargetData alignments.
138 void init(StringRef TargetDescription);
140 /// Target endianness...
141 bool isLittleEndian() const { return LittleEndian; }
142 bool isBigEndian() const { return !LittleEndian; }
144 /// getStringRepresentation - Return the string representation of the
145 /// TargetData. This representation is in the same format accepted by the
146 /// string constructor above.
147 std::string getStringRepresentation() const;
149 /// isLegalInteger - This function returns true if the specified type is
150 /// known to be a native integer type supported by the CPU. For example,
151 /// i64 is not native on most 32-bit CPUs and i37 is not native on any known
152 /// one. This returns false if the integer width is not legal.
154 /// The width is specified in bits.
156 bool isLegalInteger(unsigned Width) const {
157 for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i)
158 if (LegalIntWidths[i] == Width)
163 bool isIllegalInteger(unsigned Width) const {
164 return !isLegalInteger(Width);
167 /// Returns true if the given alignment exceeds the natural stack alignment.
168 bool exceedsNaturalStackAlignment(unsigned Align) const {
169 return (StackNaturalAlign != 0) && (Align > StackNaturalAlign);
172 /// fitsInLegalInteger - This function returns true if the specified type fits
173 /// in a native integer type supported by the CPU. For example, if the CPU
174 /// only supports i32 as a native integer type, then i27 fits in a legal
175 // integer type but i45 does not.
176 bool fitsInLegalInteger(unsigned Width) const {
177 for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i)
178 if (Width <= LegalIntWidths[i])
183 /// Target pointer alignment
184 unsigned getPointerABIAlignment() const { return PointerABIAlign; }
185 /// Return target's alignment for stack-based pointers
186 unsigned getPointerPrefAlignment() const { return PointerPrefAlign; }
187 /// Target pointer size
188 unsigned getPointerSize() const { return PointerMemSize; }
189 /// Target pointer size, in bits
190 unsigned getPointerSizeInBits() const { return 8*PointerMemSize; }
194 /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*]
195 /// ---- ---------- --------------- ---------------
204 /// X86_FP80 80 80 96
206 /// [*] The alloc size depends on the alignment, and thus on the target.
207 /// These values are for x86-32 linux.
209 /// getTypeSizeInBits - Return the number of bits necessary to hold the
210 /// specified type. For example, returns 36 for i36 and 80 for x86_fp80.
211 uint64_t getTypeSizeInBits(Type* Ty) const;
213 /// getTypeStoreSize - Return the maximum number of bytes that may be
214 /// overwritten by storing the specified type. For example, returns 5
215 /// for i36 and 10 for x86_fp80.
216 uint64_t getTypeStoreSize(Type *Ty) const {
217 return (getTypeSizeInBits(Ty)+7)/8;
220 /// getTypeStoreSizeInBits - Return the maximum number of bits that may be
221 /// overwritten by storing the specified type; always a multiple of 8. For
222 /// example, returns 40 for i36 and 80 for x86_fp80.
223 uint64_t getTypeStoreSizeInBits(Type *Ty) const {
224 return 8*getTypeStoreSize(Ty);
227 /// getTypeAllocSize - Return the offset in bytes between successive objects
228 /// of the specified type, including alignment padding. This is the amount
229 /// that alloca reserves for this type. For example, returns 12 or 16 for
230 /// x86_fp80, depending on alignment.
231 uint64_t getTypeAllocSize(Type* Ty) const {
232 // Round up to the next alignment boundary.
233 return RoundUpAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty));
236 /// getTypeAllocSizeInBits - Return the offset in bits between successive
237 /// objects of the specified type, including alignment padding; always a
238 /// multiple of 8. This is the amount that alloca reserves for this type.
239 /// For example, returns 96 or 128 for x86_fp80, depending on alignment.
240 uint64_t getTypeAllocSizeInBits(Type* Ty) const {
241 return 8*getTypeAllocSize(Ty);
244 /// getABITypeAlignment - Return the minimum ABI-required alignment for the
246 unsigned getABITypeAlignment(Type *Ty) const;
248 /// getABIIntegerTypeAlignment - Return the minimum ABI-required alignment for
249 /// an integer type of the specified bitwidth.
250 unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const;
253 /// getCallFrameTypeAlignment - Return the minimum ABI-required alignment
254 /// for the specified type when it is part of a call frame.
255 unsigned getCallFrameTypeAlignment(Type *Ty) const;
258 /// getPrefTypeAlignment - Return the preferred stack/global alignment for
259 /// the specified type. This is always at least as good as the ABI alignment.
260 unsigned getPrefTypeAlignment(Type *Ty) const;
262 /// getPreferredTypeAlignmentShift - Return the preferred alignment for the
263 /// specified type, returned as log2 of the value (a shift amount).
265 unsigned getPreferredTypeAlignmentShift(Type *Ty) const;
267 /// getIntPtrType - Return an unsigned integer type that is the same size or
268 /// greater to the host pointer size.
270 IntegerType *getIntPtrType(LLVMContext &C) const;
272 /// getIndexedOffset - return the offset from the beginning of the type for
273 /// the specified indices. This is used to implement getelementptr.
275 uint64_t getIndexedOffset(Type *Ty, ArrayRef<Value *> Indices) const;
277 /// getStructLayout - Return a StructLayout object, indicating the alignment
278 /// of the struct, its size, and the offsets of its fields. Note that this
279 /// information is lazily cached.
280 const StructLayout *getStructLayout(StructType *Ty) const;
282 /// getPreferredAlignment - Return the preferred alignment of the specified
283 /// global. This includes an explicitly requested alignment (if the global
285 unsigned getPreferredAlignment(const GlobalVariable *GV) const;
287 /// getPreferredAlignmentLog - Return the preferred alignment of the
288 /// specified global, returned in log form. This includes an explicitly
289 /// requested alignment (if the global has one).
290 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const;
292 /// RoundUpAlignment - Round the specified value up to the next alignment
293 /// boundary specified by Alignment. For example, 7 rounded up to an
294 /// alignment boundary of 4 is 8. 8 rounded up to the alignment boundary of 4
295 /// is 8 because it is already aligned.
296 template <typename UIntTy>
297 static UIntTy RoundUpAlignment(UIntTy Val, unsigned Alignment) {
298 assert((Alignment & (Alignment-1)) == 0 && "Alignment must be power of 2!");
299 return (Val + (Alignment-1)) & ~UIntTy(Alignment-1);
302 static char ID; // Pass identification, replacement for typeid
305 /// StructLayout - used to lazily calculate structure layout information for a
306 /// target machine, based on the TargetData structure.
310 unsigned StructAlignment;
311 unsigned NumElements;
312 uint64_t MemberOffsets[1]; // variable sized array!
315 uint64_t getSizeInBytes() const {
319 uint64_t getSizeInBits() const {
323 unsigned getAlignment() const {
324 return StructAlignment;
327 /// getElementContainingOffset - Given a valid byte offset into the structure,
328 /// return the structure index that contains it.
330 unsigned getElementContainingOffset(uint64_t Offset) const;
332 uint64_t getElementOffset(unsigned Idx) const {
333 assert(Idx < NumElements && "Invalid element idx!");
334 return MemberOffsets[Idx];
337 uint64_t getElementOffsetInBits(unsigned Idx) const {
338 return getElementOffset(Idx)*8;
342 friend class TargetData; // Only TargetData can create this class
343 StructLayout(StructType *ST, const TargetData &TD);
346 } // End llvm namespace