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"
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 char ABIAlign; //< ABI alignment for this type/bitw
54 unsigned char PrefAlign; //< Pref. alignment for this type/bitw
55 uint32_t TypeBitWidth; //< Type bit width
58 static TargetAlignElem get(AlignTypeEnum align_type, unsigned char abi_align,
59 unsigned char pref_align, uint32_t bit_width);
60 /// Equality predicate
61 bool operator==(const TargetAlignElem &rhs) const;
62 /// output stream operator
63 std::ostream &dump(std::ostream &os) const;
66 class TargetData : public ImmutablePass {
68 bool LittleEndian; ///< Defaults to false
69 unsigned char PointerMemSize; ///< Pointer size in bytes
70 unsigned char PointerABIAlign; ///< Pointer ABI alignment
71 unsigned char PointerPrefAlign; ///< Pointer preferred alignment
73 //! Where the primitive type alignment data is stored.
76 @note Could support multiple size pointer alignments, e.g., 32-bit pointers
77 vs. 64-bit pointers by extending TargetAlignment, but for now, we don't.
79 SmallVector<TargetAlignElem, 16> Alignments;
80 //! Alignment iterator shorthand
81 typedef SmallVector<TargetAlignElem, 16>::iterator align_iterator;
82 //! Constant alignment iterator shorthand
83 typedef SmallVector<TargetAlignElem, 16>::const_iterator align_const_iterator;
84 //! Invalid alignment.
86 This member is a signal that a requested alignment type and bit width were
87 not found in the SmallVector.
89 static const TargetAlignElem InvalidAlignmentElem;
91 //! Set/initialize target alignments
92 void setAlignment(AlignTypeEnum align_type, unsigned char abi_align,
93 unsigned char pref_align, uint32_t bit_width);
94 unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width,
95 bool ABIAlign, const Type *Ty) const;
96 //! Internal helper method that returns requested alignment for type.
97 unsigned char getAlignment(const Type *Ty, bool abi_or_pref) const;
99 /// Valid alignment predicate.
101 /// Predicate that tests a TargetAlignElem reference returned by get() against
102 /// InvalidAlignmentElem.
103 inline bool validAlignment(const TargetAlignElem &align) const {
104 return (&align != &InvalidAlignmentElem);
110 /// @note This has to exist, because this is a pass, but it should never be
112 TargetData() : ImmutablePass(intptr_t(&ID)) {
113 assert(0 && "ERROR: Bad TargetData ctor used. "
114 "Tool did not specify a TargetData to use?");
118 /// Constructs a TargetData from a specification string. See init().
119 explicit TargetData(const std::string &TargetDescription)
120 : ImmutablePass(intptr_t(&ID)) {
121 init(TargetDescription);
124 /// Initialize target data from properties stored in the module.
125 explicit TargetData(const Module *M);
127 TargetData(const TargetData &TD) :
128 ImmutablePass(intptr_t(&ID)),
129 LittleEndian(TD.isLittleEndian()),
130 PointerMemSize(TD.PointerMemSize),
131 PointerABIAlign(TD.PointerABIAlign),
132 PointerPrefAlign(TD.PointerPrefAlign),
133 Alignments(TD.Alignments)
136 ~TargetData(); // Not virtual, do not subclass this class
138 //! Parse a target data layout string and initialize TargetData alignments.
139 void init(const std::string &TargetDescription);
141 /// Target endianness...
142 bool isLittleEndian() const { return LittleEndian; }
143 bool isBigEndian() const { return !LittleEndian; }
145 /// getStringRepresentation - Return the string representation of the
146 /// TargetData. This representation is in the same format accepted by the
147 /// string constructor above.
148 std::string getStringRepresentation() const;
149 /// Target pointer alignment
150 unsigned char getPointerABIAlignment() const { return PointerABIAlign; }
151 /// Return target's alignment for stack-based pointers
152 unsigned char getPointerPrefAlignment() const { return PointerPrefAlign; }
153 /// Target pointer size
154 unsigned char getPointerSize() const { return PointerMemSize; }
155 /// Target pointer size, in bits
156 unsigned char getPointerSizeInBits() const { return 8*PointerMemSize; }
158 /// getTypeSizeInBits - Return the number of bits necessary to hold the
159 /// specified type. For example, returns 36 for i36 and 80 for x86_fp80.
160 uint64_t getTypeSizeInBits(const Type* Ty) const;
162 /// getTypeStoreSize - Return the maximum number of bytes that may be
163 /// overwritten by storing the specified type. For example, returns 5
164 /// for i36 and 10 for x86_fp80.
165 uint64_t getTypeStoreSize(const Type *Ty) const {
166 return (getTypeSizeInBits(Ty)+7)/8;
169 /// getTypeStoreSizeInBits - Return the maximum number of bits that may be
170 /// overwritten by storing the specified type; always a multiple of 8. For
171 /// example, returns 40 for i36 and 80 for x86_fp80.
172 uint64_t getTypeStoreSizeInBits(const Type *Ty) const {
173 return 8*getTypeStoreSize(Ty);
176 /// getABITypeSize - Return the offset in bytes between successive objects
177 /// of the specified type, including alignment padding. This is the amount
178 /// that alloca reserves for this type. For example, returns 12 or 16 for
179 /// x86_fp80, depending on alignment.
180 uint64_t getABITypeSize(const Type* Ty) const {
181 unsigned char Align = getABITypeAlignment(Ty);
182 return (getTypeStoreSize(Ty) + Align - 1)/Align*Align;
185 /// getABITypeSizeInBits - Return the offset in bits between successive
186 /// objects of the specified type, including alignment padding; always a
187 /// multiple of 8. This is the amount that alloca reserves for this type.
188 /// For example, returns 96 or 128 for x86_fp80, depending on alignment.
189 uint64_t getABITypeSizeInBits(const Type* Ty) const {
190 return 8*getABITypeSize(Ty);
193 /// getABITypeAlignment - Return the minimum ABI-required alignment for the
195 unsigned char getABITypeAlignment(const Type *Ty) const;
197 /// getCallFrameTypeAlignment - Return the minimum ABI-required alignment
198 /// for the specified type when it is part of a call frame.
199 unsigned char getCallFrameTypeAlignment(const Type *Ty) const;
202 /// getPrefTypeAlignment - Return the preferred stack/global alignment for
203 /// the specified type. This is always at least as good as the ABI alignment.
204 unsigned char getPrefTypeAlignment(const Type *Ty) const;
206 /// getPreferredTypeAlignmentShift - Return the preferred alignment for the
207 /// specified type, returned as log2 of the value (a shift amount).
209 unsigned char getPreferredTypeAlignmentShift(const Type *Ty) const;
211 /// getIntPtrType - Return an unsigned integer type that is the same size or
212 /// greater to the host pointer size.
214 const Type *getIntPtrType() const;
216 /// getIndexedOffset - return the offset from the beginning of the type for the
217 /// specified indices. This is used to implement getelementptr.
219 uint64_t getIndexedOffset(const Type *Ty,
220 Value* const* Indices, unsigned NumIndices) const;
222 /// getStructLayout - Return a StructLayout object, indicating the alignment
223 /// of the struct, its size, and the offsets of its fields. Note that this
224 /// information is lazily cached.
225 const StructLayout *getStructLayout(const StructType *Ty) const;
227 /// InvalidateStructLayoutInfo - TargetData speculatively caches StructLayout
228 /// objects. If a TargetData object is alive when types are being refined and
229 /// removed, this method must be called whenever a StructType is removed to
230 /// avoid a dangling pointer in this cache.
231 void InvalidateStructLayoutInfo(const StructType *Ty) const;
233 /// getPreferredAlignment - Return the preferred alignment of the specified
234 /// global. This includes an explicitly requested alignment (if the global
236 unsigned getPreferredAlignment(const GlobalVariable *GV) const;
238 /// getPreferredAlignmentLog - Return the preferred alignment of the
239 /// specified global, returned in log form. This includes an explicitly
240 /// requested alignment (if the global has one).
241 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const;
243 static char ID; // Pass identification, replacement for typeid
246 /// StructLayout - used to lazily calculate structure layout information for a
247 /// target machine, based on the TargetData structure.
251 unsigned StructAlignment;
252 unsigned NumElements;
253 uint64_t MemberOffsets[1]; // variable sized array!
256 uint64_t getSizeInBytes() const {
260 uint64_t getSizeInBits() const {
264 unsigned getAlignment() const {
265 return StructAlignment;
268 /// getElementContainingOffset - Given a valid offset into the structure,
269 /// return the structure index that contains it.
271 unsigned getElementContainingOffset(uint64_t Offset) const;
273 uint64_t getElementOffset(unsigned Idx) const {
274 assert(Idx < NumElements && "Invalid element idx!");
275 return MemberOffsets[Idx];
278 uint64_t getElementOffsetInBits(unsigned Idx) const {
279 return getElementOffset(Idx)*8;
283 friend class TargetData; // Only TargetData can create this class
284 StructLayout(const StructType *ST, const TargetData &TD);
287 } // End llvm namespace