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/Support/DataTypes.h"
25 #include "llvm/ADT/SmallVector.h"
26 #include "llvm/DerivedTypes.h"
35 /// Enum used to categorize the alignment types stored by TargetAlignElem
37 INTEGER_ALIGN = 'i', ///< Integer type alignment
38 VECTOR_ALIGN = 'v', ///< Vector type alignment
39 FLOAT_ALIGN = 'f', ///< Floating point type alignment
40 AGGREGATE_ALIGN = 'a', ///< Aggregate alignment
41 STACK_ALIGN = 's' ///< Stack objects alignment
43 /// Target alignment element.
45 /// Stores the alignment data associated with a given alignment type (pointer,
46 /// integer, vector, float) and type bit width.
48 /// @note The unusual order of elements in the structure attempts to reduce
49 /// padding and make the structure slightly more cache friendly.
50 struct TargetAlignElem {
51 AlignTypeEnum AlignType : 8; //< Alignment type (AlignTypeEnum)
52 unsigned char ABIAlign; //< ABI alignment for this type/bitw
53 unsigned char PrefAlign; //< Pref. alignment for this type/bitw
54 uint32_t TypeBitWidth; //< Type bit width
57 static TargetAlignElem get(AlignTypeEnum align_type, unsigned char abi_align,
58 unsigned char pref_align, uint32_t bit_width);
59 /// Equality predicate
60 bool operator==(const TargetAlignElem &rhs) const;
61 /// output stream operator
62 std::ostream &dump(std::ostream &os) const;
65 class TargetData : public ImmutablePass {
67 bool LittleEndian; ///< Defaults to false
68 unsigned char PointerMemSize; ///< Pointer size in bytes
69 unsigned char PointerABIAlign; ///< Pointer ABI alignment
70 unsigned char PointerPrefAlign; ///< Pointer preferred alignment
72 //! Where the primitive type alignment data is stored.
75 @note Could support multiple size pointer alignments, e.g., 32-bit pointers
76 vs. 64-bit pointers by extending TargetAlignment, but for now, we don't.
78 SmallVector<TargetAlignElem, 16> Alignments;
79 //! Alignment iterator shorthand
80 typedef SmallVector<TargetAlignElem, 16>::iterator align_iterator;
81 //! Constant alignment iterator shorthand
82 typedef SmallVector<TargetAlignElem, 16>::const_iterator align_const_iterator;
83 //! Invalid alignment.
85 This member is a signal that a requested alignment type and bit width were
86 not found in the SmallVector.
88 static const TargetAlignElem InvalidAlignmentElem;
90 //! Set/initialize target alignments
91 void setAlignment(AlignTypeEnum align_type, unsigned char abi_align,
92 unsigned char pref_align, uint32_t bit_width);
93 unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width,
94 bool ABIAlign, const Type *Ty) const;
95 //! Internal helper method that returns requested alignment for type.
96 unsigned char getAlignment(const Type *Ty, bool abi_or_pref) const;
98 /// Valid alignment predicate.
100 /// Predicate that tests a TargetAlignElem reference returned by get() against
101 /// InvalidAlignmentElem.
102 inline bool validAlignment(const TargetAlignElem &align) const {
103 return (&align != &InvalidAlignmentElem);
109 /// @note This has to exist, because this is a pass, but it should never be
111 TargetData() : ImmutablePass(&ID) {
112 assert(0 && "ERROR: Bad TargetData ctor used. "
113 "Tool did not specify a TargetData to use?");
117 /// Constructs a TargetData from a specification string. See init().
118 explicit TargetData(const std::string &TargetDescription)
119 : ImmutablePass(&ID) {
120 init(TargetDescription);
123 /// Initialize target data from properties stored in the module.
124 explicit TargetData(const Module *M);
126 TargetData(const TargetData &TD) :
128 LittleEndian(TD.isLittleEndian()),
129 PointerMemSize(TD.PointerMemSize),
130 PointerABIAlign(TD.PointerABIAlign),
131 PointerPrefAlign(TD.PointerPrefAlign),
132 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(const std::string &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;
148 /// Target pointer alignment
149 unsigned char getPointerABIAlignment() const { return PointerABIAlign; }
150 /// Return target's alignment for stack-based pointers
151 unsigned char getPointerPrefAlignment() const { return PointerPrefAlign; }
152 /// Target pointer size
153 unsigned char getPointerSize() const { return PointerMemSize; }
154 /// Target pointer size, in bits
155 unsigned char getPointerSizeInBits() const { return 8*PointerMemSize; }
159 /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*]
160 /// ---- ---------- --------------- ---------------
169 /// X86_FP80 80 80 96
171 /// [*] The alloc size depends on the alignment, and thus on the target.
172 /// These values are for x86-32 linux.
174 /// getTypeSizeInBits - Return the number of bits necessary to hold the
175 /// specified type. For example, returns 36 for i36 and 80 for x86_fp80.
176 uint64_t getTypeSizeInBits(const Type* Ty) const;
178 /// getTypeStoreSize - Return the maximum number of bytes that may be
179 /// overwritten by storing the specified type. For example, returns 5
180 /// for i36 and 10 for x86_fp80.
181 uint64_t getTypeStoreSize(const Type *Ty) const {
182 return (getTypeSizeInBits(Ty)+7)/8;
185 /// getTypeStoreSizeInBits - Return the maximum number of bits that may be
186 /// overwritten by storing the specified type; always a multiple of 8. For
187 /// example, returns 40 for i36 and 80 for x86_fp80.
188 uint64_t getTypeStoreSizeInBits(const Type *Ty) const {
189 return 8*getTypeStoreSize(Ty);
192 /// getTypeAllocSize - Return the offset in bytes between successive objects
193 /// of the specified type, including alignment padding. This is the amount
194 /// that alloca reserves for this type. For example, returns 12 or 16 for
195 /// x86_fp80, depending on alignment.
196 uint64_t getTypeAllocSize(const Type* Ty) const {
197 // Round up to the next alignment boundary.
198 return RoundUpAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty));
201 /// getTypeAllocSizeInBits - Return the offset in bits between successive
202 /// objects of the specified type, including alignment padding; always a
203 /// multiple of 8. This is the amount that alloca reserves for this type.
204 /// For example, returns 96 or 128 for x86_fp80, depending on alignment.
205 uint64_t getTypeAllocSizeInBits(const Type* Ty) const {
206 return 8*getTypeAllocSize(Ty);
209 /// getABITypeAlignment - Return the minimum ABI-required alignment for the
211 unsigned char getABITypeAlignment(const Type *Ty) const;
213 /// getCallFrameTypeAlignment - Return the minimum ABI-required alignment
214 /// for the specified type when it is part of a call frame.
215 unsigned char getCallFrameTypeAlignment(const Type *Ty) const;
218 /// getPrefTypeAlignment - Return the preferred stack/global alignment for
219 /// the specified type. This is always at least as good as the ABI alignment.
220 unsigned char getPrefTypeAlignment(const Type *Ty) const;
222 /// getPreferredTypeAlignmentShift - Return the preferred alignment for the
223 /// specified type, returned as log2 of the value (a shift amount).
225 unsigned char getPreferredTypeAlignmentShift(const Type *Ty) const;
227 /// getIntPtrType - Return an unsigned integer type that is the same size or
228 /// greater to the host pointer size.
230 const IntegerType *getIntPtrType() const;
232 /// getIndexedOffset - return the offset from the beginning of the type for
233 /// the specified indices. This is used to implement getelementptr.
235 uint64_t getIndexedOffset(const Type *Ty,
236 Value* const* Indices, unsigned NumIndices) const;
238 /// getStructLayout - Return a StructLayout object, indicating the alignment
239 /// of the struct, its size, and the offsets of its fields. Note that this
240 /// information is lazily cached.
241 const StructLayout *getStructLayout(const StructType *Ty) const;
243 /// InvalidateStructLayoutInfo - TargetData speculatively caches StructLayout
244 /// objects. If a TargetData object is alive when types are being refined and
245 /// removed, this method must be called whenever a StructType is removed to
246 /// avoid a dangling pointer in this cache.
247 void InvalidateStructLayoutInfo(const StructType *Ty) const;
249 /// getPreferredAlignment - Return the preferred alignment of the specified
250 /// global. This includes an explicitly requested alignment (if the global
252 unsigned getPreferredAlignment(const GlobalVariable *GV) const;
254 /// getPreferredAlignmentLog - Return the preferred alignment of the
255 /// specified global, returned in log form. This includes an explicitly
256 /// requested alignment (if the global has one).
257 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const;
259 /// RoundUpAlignment - Round the specified value up to the next alignment
260 /// boundary specified by Alignment. For example, 7 rounded up to an
261 /// alignment boundary of 4 is 8. 8 rounded up to the alignment boundary of 4
262 /// is 8 because it is already aligned.
263 template <typename UIntTy>
264 static UIntTy RoundUpAlignment(UIntTy Val, unsigned Alignment) {
265 assert((Alignment & (Alignment-1)) == 0 && "Alignment must be power of 2!");
266 return (Val + (Alignment-1)) & ~UIntTy(Alignment-1);
269 static char ID; // Pass identification, replacement for typeid
272 /// StructLayout - used to lazily calculate structure layout information for a
273 /// target machine, based on the TargetData structure.
277 unsigned StructAlignment;
278 unsigned NumElements;
279 uint64_t MemberOffsets[1]; // variable sized array!
282 uint64_t getSizeInBytes() const {
286 uint64_t getSizeInBits() const {
290 unsigned getAlignment() const {
291 return StructAlignment;
294 /// getElementContainingOffset - Given a valid offset into the structure,
295 /// return the structure index that contains it.
297 unsigned getElementContainingOffset(uint64_t Offset) const;
299 uint64_t getElementOffset(unsigned Idx) const {
300 assert(Idx < NumElements && "Invalid element idx!");
301 return MemberOffsets[Idx];
304 uint64_t getElementOffsetInBits(unsigned Idx) const {
305 return getElementOffset(Idx)*8;
309 friend class TargetData; // Only TargetData can create this class
310 StructLayout(const StructType *ST, const TargetData &TD);
313 } // End llvm namespace