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/Support/ErrorHandling.h"
26 #include "llvm/ADT/SmallVector.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 char ABIAlign; //< ABI alignment for this type/bitw
57 unsigned char PrefAlign; //< Pref. alignment for this type/bitw
58 uint32_t TypeBitWidth; //< Type bit width
61 static TargetAlignElem get(AlignTypeEnum align_type, unsigned char abi_align,
62 unsigned char pref_align, uint32_t bit_width);
63 /// Equality predicate
64 bool operator==(const TargetAlignElem &rhs) const;
65 /// output stream operator
66 std::ostream &dump(std::ostream &os) const;
69 class TargetData : public ImmutablePass {
71 bool LittleEndian; ///< Defaults to false
72 unsigned char PointerMemSize; ///< Pointer size in bytes
73 unsigned char PointerABIAlign; ///< Pointer ABI alignment
74 unsigned char PointerPrefAlign; ///< Pointer preferred alignment
76 //! Where the primitive type alignment data is stored.
79 @note Could support multiple size pointer alignments, e.g., 32-bit pointers
80 vs. 64-bit pointers by extending TargetAlignment, but for now, we don't.
82 SmallVector<TargetAlignElem, 16> Alignments;
83 //! Alignment iterator shorthand
84 typedef SmallVector<TargetAlignElem, 16>::iterator align_iterator;
85 //! Constant alignment iterator shorthand
86 typedef SmallVector<TargetAlignElem, 16>::const_iterator align_const_iterator;
87 //! Invalid alignment.
89 This member is a signal that a requested alignment type and bit width were
90 not found in the SmallVector.
92 static const TargetAlignElem InvalidAlignmentElem;
94 //! Set/initialize target alignments
95 void setAlignment(AlignTypeEnum align_type, unsigned char abi_align,
96 unsigned char pref_align, uint32_t bit_width);
97 unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width,
98 bool ABIAlign, const Type *Ty) const;
99 //! Internal helper method that returns requested alignment for type.
100 unsigned char getAlignment(const Type *Ty, bool abi_or_pref) const;
102 /// Valid alignment predicate.
104 /// Predicate that tests a TargetAlignElem reference returned by get() against
105 /// InvalidAlignmentElem.
106 inline bool validAlignment(const TargetAlignElem &align) const {
107 return (&align != &InvalidAlignmentElem);
113 /// @note This has to exist, because this is a pass, but it should never be
115 TargetData() : ImmutablePass(&ID) {
116 llvm_report_error("Bad TargetData ctor used. "
117 "Tool did not specify a TargetData to use?");
120 /// Constructs a TargetData from a specification string. See init().
121 explicit TargetData(const std::string &TargetDescription)
122 : ImmutablePass(&ID) {
123 init(TargetDescription);
126 /// Initialize target data from properties stored in the module.
127 explicit TargetData(const Module *M);
129 TargetData(const TargetData &TD) :
131 LittleEndian(TD.isLittleEndian()),
132 PointerMemSize(TD.PointerMemSize),
133 PointerABIAlign(TD.PointerABIAlign),
134 PointerPrefAlign(TD.PointerPrefAlign),
135 Alignments(TD.Alignments)
138 ~TargetData(); // Not virtual, do not subclass this class
140 //! Parse a target data layout string and initialize TargetData alignments.
141 void init(const std::string &TargetDescription);
143 /// Target endianness...
144 bool isLittleEndian() const { return LittleEndian; }
145 bool isBigEndian() const { return !LittleEndian; }
147 /// getStringRepresentation - Return the string representation of the
148 /// TargetData. This representation is in the same format accepted by the
149 /// string constructor above.
150 std::string getStringRepresentation() const;
151 /// Target pointer alignment
152 unsigned char getPointerABIAlignment() const { return PointerABIAlign; }
153 /// Return target's alignment for stack-based pointers
154 unsigned char getPointerPrefAlignment() const { return PointerPrefAlign; }
155 /// Target pointer size
156 unsigned char getPointerSize() const { return PointerMemSize; }
157 /// Target pointer size, in bits
158 unsigned char getPointerSizeInBits() const { return 8*PointerMemSize; }
162 /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*]
163 /// ---- ---------- --------------- ---------------
172 /// X86_FP80 80 80 96
174 /// [*] The alloc size depends on the alignment, and thus on the target.
175 /// These values are for x86-32 linux.
177 /// getTypeSizeInBits - Return the number of bits necessary to hold the
178 /// specified type. For example, returns 36 for i36 and 80 for x86_fp80.
179 uint64_t getTypeSizeInBits(const Type* Ty) const;
181 /// getTypeStoreSize - Return the maximum number of bytes that may be
182 /// overwritten by storing the specified type. For example, returns 5
183 /// for i36 and 10 for x86_fp80.
184 uint64_t getTypeStoreSize(const Type *Ty) const {
185 return (getTypeSizeInBits(Ty)+7)/8;
188 /// getTypeStoreSizeInBits - Return the maximum number of bits that may be
189 /// overwritten by storing the specified type; always a multiple of 8. For
190 /// example, returns 40 for i36 and 80 for x86_fp80.
191 uint64_t getTypeStoreSizeInBits(const Type *Ty) const {
192 return 8*getTypeStoreSize(Ty);
195 /// getTypeAllocSize - Return the offset in bytes between successive objects
196 /// of the specified type, including alignment padding. This is the amount
197 /// that alloca reserves for this type. For example, returns 12 or 16 for
198 /// x86_fp80, depending on alignment.
199 uint64_t getTypeAllocSize(const Type* Ty) const {
200 // Round up to the next alignment boundary.
201 return RoundUpAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty));
204 /// getTypeAllocSizeInBits - Return the offset in bits between successive
205 /// objects of the specified type, including alignment padding; always a
206 /// multiple of 8. This is the amount that alloca reserves for this type.
207 /// For example, returns 96 or 128 for x86_fp80, depending on alignment.
208 uint64_t getTypeAllocSizeInBits(const Type* Ty) const {
209 return 8*getTypeAllocSize(Ty);
212 /// getABITypeAlignment - Return the minimum ABI-required alignment for the
214 unsigned char getABITypeAlignment(const Type *Ty) const;
216 /// getCallFrameTypeAlignment - Return the minimum ABI-required alignment
217 /// for the specified type when it is part of a call frame.
218 unsigned char getCallFrameTypeAlignment(const Type *Ty) const;
221 /// getPrefTypeAlignment - Return the preferred stack/global alignment for
222 /// the specified type. This is always at least as good as the ABI alignment.
223 unsigned char getPrefTypeAlignment(const Type *Ty) const;
225 /// getPreferredTypeAlignmentShift - Return the preferred alignment for the
226 /// specified type, returned as log2 of the value (a shift amount).
228 unsigned char getPreferredTypeAlignmentShift(const Type *Ty) const;
230 /// getIntPtrType - Return an unsigned integer type that is the same size or
231 /// greater to the host pointer size.
233 const IntegerType *getIntPtrType(LLVMContext &C) const;
235 /// getIndexedOffset - return the offset from the beginning of the type for
236 /// the specified indices. This is used to implement getelementptr.
238 uint64_t getIndexedOffset(const Type *Ty,
239 Value* const* Indices, unsigned NumIndices) const;
241 /// getStructLayout - Return a StructLayout object, indicating the alignment
242 /// of the struct, its size, and the offsets of its fields. Note that this
243 /// information is lazily cached.
244 const StructLayout *getStructLayout(const StructType *Ty) const;
246 /// InvalidateStructLayoutInfo - TargetData speculatively caches StructLayout
247 /// objects. If a TargetData object is alive when types are being refined and
248 /// removed, this method must be called whenever a StructType is removed to
249 /// avoid a dangling pointer in this cache.
250 void InvalidateStructLayoutInfo(const StructType *Ty) const;
252 /// getPreferredAlignment - Return the preferred alignment of the specified
253 /// global. This includes an explicitly requested alignment (if the global
255 unsigned getPreferredAlignment(const GlobalVariable *GV) const;
257 /// getPreferredAlignmentLog - Return the preferred alignment of the
258 /// specified global, returned in log form. This includes an explicitly
259 /// requested alignment (if the global has one).
260 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const;
262 /// RoundUpAlignment - Round the specified value up to the next alignment
263 /// boundary specified by Alignment. For example, 7 rounded up to an
264 /// alignment boundary of 4 is 8. 8 rounded up to the alignment boundary of 4
265 /// is 8 because it is already aligned.
266 template <typename UIntTy>
267 static UIntTy RoundUpAlignment(UIntTy Val, unsigned Alignment) {
268 assert((Alignment & (Alignment-1)) == 0 && "Alignment must be power of 2!");
269 return (Val + (Alignment-1)) & ~UIntTy(Alignment-1);
272 static char ID; // Pass identification, replacement for typeid
275 /// StructLayout - used to lazily calculate structure layout information for a
276 /// target machine, based on the TargetData structure.
280 unsigned StructAlignment;
281 unsigned NumElements;
282 uint64_t MemberOffsets[1]; // variable sized array!
285 uint64_t getSizeInBytes() const {
289 uint64_t getSizeInBits() const {
293 unsigned getAlignment() const {
294 return StructAlignment;
297 /// getElementContainingOffset - Given a valid byte offset into the structure,
298 /// return the structure index that contains it.
300 unsigned getElementContainingOffset(uint64_t Offset) const;
302 uint64_t getElementOffset(unsigned Idx) const {
303 assert(Idx < NumElements && "Invalid element idx!");
304 return MemberOffsets[Idx];
307 uint64_t getElementOffsetInBits(unsigned Idx) const {
308 return getElementOffset(Idx)*8;
312 friend class TargetData; // Only TargetData can create this class
313 StructLayout(const StructType *ST, const TargetData &TD);
316 } // End llvm namespace