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"
36 /// Enum used to categorize the alignment types stored by TargetAlignElem
38 INTEGER_ALIGN = 'i', ///< Integer type alignment
39 VECTOR_ALIGN = 'v', ///< Vector type alignment
40 FLOAT_ALIGN = 'f', ///< Floating point type alignment
41 AGGREGATE_ALIGN = 'a', ///< Aggregate alignment
42 STACK_ALIGN = 's' ///< Stack objects alignment
44 /// Target alignment element.
46 /// Stores the alignment data associated with a given alignment type (pointer,
47 /// integer, vector, float) and type bit width.
49 /// @note The unusual order of elements in the structure attempts to reduce
50 /// padding and make the structure slightly more cache friendly.
51 struct TargetAlignElem {
52 AlignTypeEnum AlignType : 8; //< Alignment type (AlignTypeEnum)
53 unsigned ABIAlign; //< ABI alignment for this type/bitw
54 unsigned PrefAlign; //< Pref. alignment for this type/bitw
55 uint32_t TypeBitWidth; //< Type bit width
58 static TargetAlignElem get(AlignTypeEnum align_type, unsigned abi_align,
59 unsigned pref_align, uint32_t bit_width);
60 /// Equality predicate
61 bool operator==(const TargetAlignElem &rhs) const;
64 class TargetData : public ImmutablePass {
66 bool LittleEndian; ///< Defaults to false
67 unsigned PointerMemSize; ///< Pointer size in bytes
68 unsigned PointerABIAlign; ///< Pointer ABI alignment
69 unsigned PointerPrefAlign; ///< Pointer preferred alignment
71 SmallVector<unsigned char, 8> LegalIntWidths; ///< Legal Integers.
73 /// Alignments- Where the primitive type alignment data is stored.
76 /// @note Could support multiple size pointer alignments, e.g., 32-bit
77 /// pointers vs. 64-bit pointers by extending TargetAlignment, but for now,
79 SmallVector<TargetAlignElem, 16> Alignments;
81 /// InvalidAlignmentElem - This member is a signal that a requested alignment
82 /// type and bit width were not found in the SmallVector.
83 static const TargetAlignElem InvalidAlignmentElem;
85 // The StructType -> StructLayout map.
86 mutable void *LayoutMap;
88 //! Set/initialize target alignments
89 void setAlignment(AlignTypeEnum align_type, unsigned abi_align,
90 unsigned pref_align, uint32_t bit_width);
91 unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width,
92 bool ABIAlign, const Type *Ty) const;
93 //! Internal helper method that returns requested alignment for type.
94 unsigned getAlignment(const Type *Ty, bool abi_or_pref) const;
96 /// Valid alignment predicate.
98 /// Predicate that tests a TargetAlignElem reference returned by get() against
99 /// InvalidAlignmentElem.
100 bool validAlignment(const TargetAlignElem &align) const {
101 return &align != &InvalidAlignmentElem;
107 /// @note This has to exist, because this is a pass, but it should never be
111 /// Constructs a TargetData from a specification string. See init().
112 explicit TargetData(StringRef TargetDescription)
113 : ImmutablePass(ID) {
114 init(TargetDescription);
117 /// Initialize target data from properties stored in the module.
118 explicit TargetData(const Module *M);
120 TargetData(const TargetData &TD) :
122 LittleEndian(TD.isLittleEndian()),
123 PointerMemSize(TD.PointerMemSize),
124 PointerABIAlign(TD.PointerABIAlign),
125 PointerPrefAlign(TD.PointerPrefAlign),
126 LegalIntWidths(TD.LegalIntWidths),
127 Alignments(TD.Alignments),
131 ~TargetData(); // Not virtual, do not subclass this class
133 //! Parse a target data layout string and initialize TargetData alignments.
134 void init(StringRef TargetDescription);
136 /// Target endianness...
137 bool isLittleEndian() const { return LittleEndian; }
138 bool isBigEndian() const { return !LittleEndian; }
140 /// getStringRepresentation - Return the string representation of the
141 /// TargetData. This representation is in the same format accepted by the
142 /// string constructor above.
143 std::string getStringRepresentation() const;
145 /// isLegalInteger - This function returns true if the specified type is
146 /// known tobe a native integer type supported by the CPU. For example,
147 /// i64 is not native on most 32-bit CPUs and i37 is not native on any known
148 /// one. This returns false if the integer width is not legal.
150 /// The width is specified in bits.
152 bool isLegalInteger(unsigned Width) const {
153 for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i)
154 if (LegalIntWidths[i] == Width)
159 bool isIllegalInteger(unsigned Width) const {
160 return !isLegalInteger(Width);
163 /// Target pointer alignment
164 unsigned getPointerABIAlignment() const { return PointerABIAlign; }
165 /// Return target's alignment for stack-based pointers
166 unsigned getPointerPrefAlignment() const { return PointerPrefAlign; }
167 /// Target pointer size
168 unsigned getPointerSize() const { return PointerMemSize; }
169 /// Target pointer size, in bits
170 unsigned getPointerSizeInBits() const { return 8*PointerMemSize; }
174 /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*]
175 /// ---- ---------- --------------- ---------------
184 /// X86_FP80 80 80 96
186 /// [*] The alloc size depends on the alignment, and thus on the target.
187 /// These values are for x86-32 linux.
189 /// getTypeSizeInBits - Return the number of bits necessary to hold the
190 /// specified type. For example, returns 36 for i36 and 80 for x86_fp80.
191 uint64_t getTypeSizeInBits(const Type* Ty) const;
193 /// getTypeStoreSize - Return the maximum number of bytes that may be
194 /// overwritten by storing the specified type. For example, returns 5
195 /// for i36 and 10 for x86_fp80.
196 uint64_t getTypeStoreSize(const Type *Ty) const {
197 return (getTypeSizeInBits(Ty)+7)/8;
200 /// getTypeStoreSizeInBits - Return the maximum number of bits that may be
201 /// overwritten by storing the specified type; always a multiple of 8. For
202 /// example, returns 40 for i36 and 80 for x86_fp80.
203 uint64_t getTypeStoreSizeInBits(const Type *Ty) const {
204 return 8*getTypeStoreSize(Ty);
207 /// getTypeAllocSize - Return the offset in bytes between successive objects
208 /// of the specified type, including alignment padding. This is the amount
209 /// that alloca reserves for this type. For example, returns 12 or 16 for
210 /// x86_fp80, depending on alignment.
211 uint64_t getTypeAllocSize(const Type* Ty) const {
212 // Round up to the next alignment boundary.
213 return RoundUpAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty));
216 /// getTypeAllocSizeInBits - Return the offset in bits between successive
217 /// objects of the specified type, including alignment padding; always a
218 /// multiple of 8. This is the amount that alloca reserves for this type.
219 /// For example, returns 96 or 128 for x86_fp80, depending on alignment.
220 uint64_t getTypeAllocSizeInBits(const Type* Ty) const {
221 return 8*getTypeAllocSize(Ty);
224 /// getABITypeAlignment - Return the minimum ABI-required alignment for the
226 unsigned getABITypeAlignment(const Type *Ty) const;
228 /// getABIIntegerTypeAlignment - Return the minimum ABI-required alignment for
229 /// an integer type of the specified bitwidth.
230 unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const;
233 /// getCallFrameTypeAlignment - Return the minimum ABI-required alignment
234 /// for the specified type when it is part of a call frame.
235 unsigned getCallFrameTypeAlignment(const Type *Ty) const;
238 /// getPrefTypeAlignment - Return the preferred stack/global alignment for
239 /// the specified type. This is always at least as good as the ABI alignment.
240 unsigned getPrefTypeAlignment(const Type *Ty) const;
242 /// getPreferredTypeAlignmentShift - Return the preferred alignment for the
243 /// specified type, returned as log2 of the value (a shift amount).
245 unsigned getPreferredTypeAlignmentShift(const Type *Ty) const;
247 /// getIntPtrType - Return an unsigned integer type that is the same size or
248 /// greater to the host pointer size.
250 const IntegerType *getIntPtrType(LLVMContext &C) const;
252 /// getIndexedOffset - return the offset from the beginning of the type for
253 /// the specified indices. This is used to implement getelementptr.
255 uint64_t getIndexedOffset(const Type *Ty,
256 Value* const* Indices, unsigned NumIndices) const;
258 /// getStructLayout - Return a StructLayout object, indicating the alignment
259 /// of the struct, its size, and the offsets of its fields. Note that this
260 /// information is lazily cached.
261 const StructLayout *getStructLayout(const StructType *Ty) const;
263 /// InvalidateStructLayoutInfo - TargetData speculatively caches StructLayout
264 /// objects. If a TargetData object is alive when types are being refined and
265 /// removed, this method must be called whenever a StructType is removed to
266 /// avoid a dangling pointer in this cache.
267 void InvalidateStructLayoutInfo(const StructType *Ty) const;
269 /// getPreferredAlignment - Return the preferred alignment of the specified
270 /// global. This includes an explicitly requested alignment (if the global
272 unsigned getPreferredAlignment(const GlobalVariable *GV) const;
274 /// getPreferredAlignmentLog - Return the preferred alignment of the
275 /// specified global, returned in log form. This includes an explicitly
276 /// requested alignment (if the global has one).
277 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const;
279 /// RoundUpAlignment - Round the specified value up to the next alignment
280 /// boundary specified by Alignment. For example, 7 rounded up to an
281 /// alignment boundary of 4 is 8. 8 rounded up to the alignment boundary of 4
282 /// is 8 because it is already aligned.
283 template <typename UIntTy>
284 static UIntTy RoundUpAlignment(UIntTy Val, unsigned Alignment) {
285 assert((Alignment & (Alignment-1)) == 0 && "Alignment must be power of 2!");
286 return (Val + (Alignment-1)) & ~UIntTy(Alignment-1);
289 static char ID; // Pass identification, replacement for typeid
292 /// StructLayout - used to lazily calculate structure layout information for a
293 /// target machine, based on the TargetData structure.
297 unsigned StructAlignment;
298 unsigned NumElements;
299 uint64_t MemberOffsets[1]; // variable sized array!
302 uint64_t getSizeInBytes() const {
306 uint64_t getSizeInBits() const {
310 unsigned getAlignment() const {
311 return StructAlignment;
314 /// getElementContainingOffset - Given a valid byte offset into the structure,
315 /// return the structure index that contains it.
317 unsigned getElementContainingOffset(uint64_t Offset) const;
319 uint64_t getElementOffset(unsigned Idx) const {
320 assert(Idx < NumElements && "Invalid element idx!");
321 return MemberOffsets[Idx];
324 uint64_t getElementOffsetInBits(unsigned Idx) const {
325 return getElementOffset(Idx)*8;
329 friend class TargetData; // Only TargetData can create this class
330 StructLayout(const StructType *ST, const TargetData &TD);
333 } // End llvm namespace