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 VECTOR_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 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,
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
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 TargetData(const std::string &TargetDescription) {
119 init(TargetDescription);
122 /// Initialize target data from properties stored in the module.
123 TargetData(const Module *M);
125 TargetData(const TargetData &TD) :
127 LittleEndian(TD.isLittleEndian()),
128 PointerMemSize(TD.PointerMemSize),
129 PointerABIAlign(TD.PointerABIAlign),
130 PointerPrefAlign(TD.PointerPrefAlign),
131 Alignments(TD.Alignments)
134 ~TargetData(); // Not virtual, do not subclass this class
136 //! Parse a target data layout string and initialize TargetData alignments.
137 void init(const std::string &TargetDescription);
139 /// Target endianness...
140 bool isLittleEndian() const { return LittleEndian; }
141 bool isBigEndian() const { return !LittleEndian; }
143 /// getStringRepresentation - Return the string representation of the
144 /// TargetData. This representation is in the same format accepted by the
145 /// string constructor above.
146 std::string getStringRepresentation() const;
147 /// Target pointer alignment
148 unsigned char getPointerABIAlignment() const { return PointerABIAlign; }
149 /// Return target's alignment for stack-based pointers
150 unsigned char getPointerPrefAlignment() const { return PointerPrefAlign; }
151 /// Target pointer size
152 unsigned char getPointerSize() const { return PointerMemSize; }
153 /// Target pointer size, in bits
154 unsigned char getPointerSizeInBits() const { return 8*PointerMemSize; }
156 /// getTypeSize - Return the number of bytes necessary to hold the specified
158 uint64_t getTypeSize(const Type *Ty) const;
160 /// getTypeSizeInBits - Return the number of bits necessary to hold the
162 uint64_t getTypeSizeInBits(const Type* Ty) const;
164 /// getABITypeAlignment - Return the minimum ABI-required alignment for the
166 unsigned char getABITypeAlignment(const Type *Ty) const;
168 /// getPrefTypeAlignment - Return the preferred stack/global alignment for
169 /// the specified type.
170 unsigned char getPrefTypeAlignment(const Type *Ty) const;
172 /// getPreferredTypeAlignmentShift - Return the preferred alignment for the
173 /// specified type, returned as log2 of the value (a shift amount).
175 unsigned char getPreferredTypeAlignmentShift(const Type *Ty) const;
177 /// getIntPtrType - Return an unsigned integer type that is the same size or
178 /// greater to the host pointer size.
180 const Type *getIntPtrType() const;
182 /// getIndexOffset - return the offset from the beginning of the type for the
183 /// specified indices. This is used to implement getelementptr.
185 uint64_t getIndexedOffset(const Type *Ty,
186 Value* const* Indices, unsigned NumIndices) const;
188 /// getStructLayout - Return a StructLayout object, indicating the alignment
189 /// of the struct, its size, and the offsets of its fields. Note that this
190 /// information is lazily cached.
191 const StructLayout *getStructLayout(const StructType *Ty) const;
193 /// InvalidateStructLayoutInfo - TargetData speculatively caches StructLayout
194 /// objects. If a TargetData object is alive when types are being refined and
195 /// removed, this method must be called whenever a StructType is removed to
196 /// avoid a dangling pointer in this cache.
197 void InvalidateStructLayoutInfo(const StructType *Ty) const;
199 /// getPreferredAlignmentLog - Return the preferred alignment of the
200 /// specified global, returned in log form. This includes an explicitly
201 /// requested alignment (if the global has one).
202 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const;
205 /// StructLayout - used to lazily calculate structure layout information for a
206 /// target machine, based on the TargetData structure.
210 unsigned StructAlignment;
211 unsigned NumElements;
212 uint64_t MemberOffsets[1]; // variable sized array!
215 uint64_t getSizeInBytes() const {
219 unsigned getAlignment() const {
220 return StructAlignment;
223 /// getElementContainingOffset - Given a valid offset into the structure,
224 /// return the structure index that contains it.
226 unsigned getElementContainingOffset(uint64_t Offset) const;
228 uint64_t getElementOffset(unsigned Idx) const {
229 assert(Idx < NumElements && "Invalid element idx!");
230 return MemberOffsets[Idx];
234 friend class TargetData; // Only TargetData can create this class
235 StructLayout(const StructType *ST, const TargetData &TD);
238 } // End llvm namespace