1 //===-- llvm/Target/TargetData.h - Data size & alignment info ---*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source 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 PACKED_ALIGN = 'v', ///< Vector type alignment
40 FLOAT_ALIGN = 'f', ///< Floating point type alignment
41 AGGREGATE_ALIGN = 'a' ///< Aggregate alignment
43 /// Target alignment element.
45 /// Stores the alignment data associated with a given alignment type (pointer,
46 /// integer, packed/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 short TypeBitWidth; //< Type bit width
57 static TargetAlignElem get(AlignTypeEnum align_type, unsigned char abi_align,
58 unsigned char pref_align, short bit_width);
59 /// Less-than predicate
60 bool operator<(const TargetAlignElem &rhs) const;
61 /// Equality predicate
62 bool operator==(const TargetAlignElem &rhs) const;
63 /// output stream operator
64 std::ostream &dump(std::ostream &os) const;
67 class TargetData : public ImmutablePass {
69 bool LittleEndian; ///< Defaults to false
70 unsigned char PointerMemSize; ///< Pointer size in bytes
71 unsigned char PointerABIAlign; ///< Pointer ABI alignment
72 unsigned char PointerPrefAlign; ///< Pointer preferred alignment
74 //! Where the primitive type alignment data is stored.
77 @note Could support multiple size pointer alignments, e.g., 32-bit pointers
78 vs. 64-bit pointers by extending TargetAlignment, but for now, we don't.
80 SmallVector<TargetAlignElem, 16> Alignments;
81 //! Alignment iterator shorthand
82 typedef SmallVector<TargetAlignElem, 16>::iterator align_iterator;
83 //! Constant alignment iterator shorthand
84 typedef SmallVector<TargetAlignElem, 16>::const_iterator align_const_iterator;
85 //! Invalid alignment.
87 This member is a signal that a requested alignment type and bit width were
88 not found in the SmallVector.
90 static const TargetAlignElem InvalidAlignmentElem;
92 //! Set/initialize target alignments
93 void setAlignment(AlignTypeEnum align_type, unsigned char abi_align,
94 unsigned char pref_align, short bit_width);
95 //! Get TargetAlignElem from alignment type and bit width
96 const TargetAlignElem &getAlignment(AlignTypeEnum align_type,
97 short bit_width) const;
98 //! Internal helper method that returns requested alignment for type.
99 unsigned char getAlignment(const Type *Ty, bool abi_or_pref) const;
101 /// Valid alignment predicate.
103 /// Predicate that tests a TargetAlignElem reference returned by get() against
104 /// InvalidAlignmentElem.
105 inline bool validAlignment(const TargetAlignElem &align) const {
106 return (&align != &InvalidAlignmentElem);
112 /// @note This has to exist, because this is a pass, but it should never be
115 assert(0 && "ERROR: Bad TargetData ctor used. "
116 "Tool did not specify a TargetData to use?");
120 /// Constructs a TargetData from a specification string. See init().
121 TargetData(const std::string &TargetDescription) {
122 init(TargetDescription);
125 /// Initialize target data from properties stored in the module.
126 TargetData(const Module *M);
128 TargetData(const TargetData &TD) :
130 LittleEndian(TD.isLittleEndian()),
131 PointerMemSize(TD.PointerMemSize),
132 PointerABIAlign(TD.PointerABIAlign),
133 PointerPrefAlign(TD.PointerPrefAlign),
134 Alignments(TD.Alignments)
137 ~TargetData(); // Not virtual, do not subclass this class
139 //! Parse a target data layout string and initialize TargetData alignments.
140 void init(const std::string &TargetDescription);
142 /// Target endianness...
143 bool isLittleEndian() const { return LittleEndian; }
144 bool isBigEndian() const { return !LittleEndian; }
146 /// getStringRepresentation - Return the string representation of the
147 /// TargetData. This representation is in the same format accepted by the
148 /// string constructor above.
149 std::string getStringRepresentation() const;
150 /// Target pointer alignment
151 unsigned char getPointerABIAlignment() const { return PointerABIAlign; }
152 /// Return target's alignment for stack-based pointers
153 unsigned char getPointerPrefAlignment() const { return PointerPrefAlign; }
154 /// Target pointer size
155 unsigned char getPointerSize() const { return PointerMemSize; }
156 /// Target pointer size, in bits
157 unsigned char getPointerSizeInBits() const { return 8*PointerMemSize; }
159 /// getTypeSize - Return the number of bytes necessary to hold the specified
161 uint64_t getTypeSize(const Type *Ty) const;
163 /// getTypeSizeInBits - Return the number of bytes necessary to hold the
165 uint64_t getTypeSizeInBits(const Type* Ty) const;
167 /// getTypeAlignmentABI - Return the minimum ABI-required alignment for the
169 unsigned char getABITypeAlignment(const Type *Ty) const;
171 /// getTypeAlignmentPref - Return the preferred stack/global alignment for
172 /// the specified type.
173 unsigned char getPrefTypeAlignment(const Type *Ty) const;
175 /// getPreferredTypeAlignmentShift - Return the preferred alignment for the
176 /// specified type, returned as log2 of the value (a shift amount).
178 unsigned char getPreferredTypeAlignmentShift(const Type *Ty) const;
180 /// getIntPtrType - Return an unsigned integer type that is the same size or
181 /// greater to the host pointer size.
183 const Type *getIntPtrType() const;
185 /// getIndexOffset - return the offset from the beginning of the type for the
186 /// specified indices. This is used to implement getelementptr.
188 uint64_t getIndexedOffset(const Type *Ty,
189 Value* const* Indices, unsigned NumIndices) const;
191 /// getStructLayout - Return a StructLayout object, indicating the alignment
192 /// of the struct, its size, and the offsets of its fields. Note that this
193 /// information is lazily cached.
194 const StructLayout *getStructLayout(const StructType *Ty) const;
196 /// InvalidateStructLayoutInfo - TargetData speculatively caches StructLayout
197 /// objects. If a TargetData object is alive when types are being refined and
198 /// removed, this method must be called whenever a StructType is removed to
199 /// avoid a dangling pointer in this cache.
200 void InvalidateStructLayoutInfo(const StructType *Ty) const;
202 /// getPreferredAlignmentLog - Return the preferred alignment of the
203 /// specified global, returned in log form. This includes an explicitly
204 /// requested alignment (if the global has one).
205 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const;
208 /// StructLayout - used to lazily calculate structure layout information for a
209 /// target machine, based on the TargetData structure.
213 unsigned StructAlignment;
214 unsigned NumElements;
215 uint64_t MemberOffsets[1]; // variable sized array!
218 uint64_t getSizeInBytes() const {
222 unsigned getAlignment() const {
223 return StructAlignment;
226 /// getElementContainingOffset - Given a valid offset into the structure,
227 /// return the structure index that contains it.
229 unsigned getElementContainingOffset(uint64_t Offset) const;
231 uint64_t getElementOffset(unsigned Idx) const {
232 assert(Idx < NumElements && "Invalid element idx!");
233 return MemberOffsets[Idx];
237 friend class TargetData; // Only TargetData can create this class
238 StructLayout(const StructType *ST, const TargetData &TD);
241 } // End llvm namespace