TargetData.cpp revision f59ce9276349598ed46bbd1bdc0011b7e2b211b4 
1//===-- TargetData.cpp - Data size & alignment routines --------------------==//
2//
3// This file defines target properties related to datatype size/offset/alignment
4// information.  It uses lazy annotations to cache information about how
5// structure types are laid out and used.
6//
7// This structure should be created once, filled in if the defaults are not
8// correct and then passed around by const&.  None of the members functions
9// require modification to the object.
10//
11//===----------------------------------------------------------------------===//
12
13#include "llvm/Target/TargetData.h"
14#include "llvm/DerivedTypes.h"
15#include "llvm/ConstantVals.h"
16
17static inline void getTypeInfo(const Type *Ty, const TargetData *TD,
18			       unsigned &Size, unsigned char &Alignment);
19
20//===----------------------------------------------------------------------===//
21// Support for StructLayout Annotation
22//===----------------------------------------------------------------------===//
23
24StructLayout::StructLayout(const StructType *ST, const TargetData &TD)
25  : Annotation(TD.getStructLayoutAID()) {
26  StructAlignment = 0;
27  StructSize = 0;
28
29  // Loop over each of the elements, placing them in memory...
30  for (StructType::ElementTypes::const_iterator
31	 TI = ST->getElementTypes().begin(),
32	 TE = ST->getElementTypes().end(); TI != TE; ++TI) {
33    const Type *Ty = *TI;
34    unsigned char A;
35    unsigned TySize, TyAlign;
36    getTypeInfo(Ty, &TD, TySize, A);  TyAlign = A;
37
38    // Add padding if neccesary to make the data element aligned properly...
39    if (StructSize % TyAlign != 0)
40      StructSize = (StructSize/TyAlign + 1) * TyAlign;   // Add padding...
41
42    // Keep track of maximum alignment constraint
43    StructAlignment = max(TyAlign, StructAlignment);
44
45    MemberOffsets.push_back(StructSize);
46    StructSize += TySize;                 // Consume space for this data item...
47  }
48
49  // Add padding to the end of the struct so that it could be put in an array
50  // and all array elements would be aligned correctly.
51  if (StructSize % StructAlignment != 0)
52    StructSize = (StructSize/StructAlignment + 1) * StructAlignment;
53
54  if (StructSize == 0) {
55    StructSize = 1;           // Empty struct is 1 byte
56    StructAlignment = 1;
57  }
58}
59
60Annotation *TargetData::TypeAnFactory(AnnotationID AID, const Annotable *T,
61				      void *D) {
62  const TargetData &TD = *(const TargetData*)D;
63  assert(AID == TD.AID && "Target data annotation ID mismatch!");
64  const Type *Ty = cast<const Type>((const Value *)T);
65  assert(Ty->isStructType() &&
66	 "Can only create StructLayout annotation on structs!");
67  return new StructLayout((const StructType *)Ty, TD);
68}
69
70//===----------------------------------------------------------------------===//
71//                       TargetData Class Implementation
72//===----------------------------------------------------------------------===//
73
74TargetData::TargetData(const string &TargetName, unsigned char PtrSize = 8,
75	     unsigned char PtrAl = 8, unsigned char DoubleAl = 8,
76	     unsigned char FloatAl = 4, unsigned char LongAl = 8,
77	     unsigned char IntAl = 4, unsigned char ShortAl = 2,
78	     unsigned char ByteAl = 1)
79  : AID(AnnotationManager::getID("TargetData::" + TargetName)) {
80  AnnotationManager::registerAnnotationFactory(AID, TypeAnFactory, this);
81
82  PointerSize      = PtrSize;
83  PointerAlignment = PtrAl;
84  DoubleAlignment  = DoubleAl;
85  FloatAlignment   = FloatAl;
86  LongAlignment    = LongAl;
87  IntAlignment     = IntAl;
88  ShortAlignment   = ShortAl;
89  ByteAlignment    = ByteAl;
90}
91
92TargetData::~TargetData() {
93  AnnotationManager::registerAnnotationFactory(AID, 0);   // Deregister factory
94}
95
96static inline void getTypeInfo(const Type *Ty, const TargetData *TD,
97			       unsigned &Size, unsigned char &Alignment) {
98  assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!");
99  switch (Ty->getPrimitiveID()) {
100  case Type::VoidTyID:
101  case Type::BoolTyID:
102  case Type::UByteTyID:
103  case Type::SByteTyID:  Size = 1; Alignment = TD->getByteAlignment(); return;
104  case Type::UShortTyID:
105  case Type::ShortTyID:  Size = 2; Alignment = TD->getShortAlignment(); return;
106  case Type::UIntTyID:
107  case Type::IntTyID:    Size = 4; Alignment = TD->getIntAlignment(); return;
108  case Type::ULongTyID:
109  case Type::LongTyID:   Size = 8; Alignment = TD->getLongAlignment(); return;
110  case Type::FloatTyID:  Size = 4; Alignment = TD->getFloatAlignment(); return;
111  case Type::DoubleTyID: Size = 8; Alignment = TD->getDoubleAlignment(); return;
112  case Type::LabelTyID:
113  case Type::PointerTyID:
114    Size = TD->getPointerSize(); Alignment = TD->getPointerAlignment();
115    return;
116  case Type::ArrayTyID: {
117    const ArrayType *ATy = (const ArrayType *)Ty;
118    getTypeInfo(ATy->getElementType(), TD, Size, Alignment);
119    Size *= ATy->getNumElements();
120    return;
121  }
122  case Type::StructTyID: {
123    // Get the layout annotation... which is lazily created on demand.
124    const StructLayout *Layout = TD->getStructLayout((const StructType*)Ty);
125    Size = Layout->StructSize; Alignment = Layout->StructAlignment;
126    return;
127  }
128
129  case Type::TypeTyID:
130  default:
131    assert(0 && "Bad type for getTypeInfo!!!");
132    return;
133  }
134}
135
136unsigned TargetData::getTypeSize(const Type *Ty) const {
137  unsigned Size; unsigned char Align;
138  getTypeInfo(Ty, this, Size, Align);
139  return Size;
140}
141
142unsigned char TargetData::getTypeAlignment(const Type *Ty) const {
143  unsigned Size; unsigned char Align;
144  getTypeInfo(Ty, this, Size, Align);
145  return Align;
146}
147
148unsigned TargetData::getIndexedOffset(const Type *ptrTy,
149				      const vector<Constant*> &Idx) const {
150  const PointerType *PtrTy = cast<const PointerType>(ptrTy);
151  unsigned Result = 0;
152
153  // Get the type pointed to...
154  const Type *Ty = PtrTy->getElementType();
155
156  for (unsigned CurIDX = 0; CurIDX < Idx.size(); ++CurIDX) {
157    if (const StructType *STy = dyn_cast<const StructType>(Ty)) {
158      assert(Idx[CurIDX]->getType() == Type::UByteTy && "Illegal struct idx");
159      unsigned FieldNo = cast<ConstantUInt>(Idx[CurIDX])->getValue();
160
161      // Get structure layout information...
162      const StructLayout *Layout = getStructLayout(STy);
163
164      // Add in the offset, as calculated by the structure layout info...
165      assert(FieldNo < Layout->MemberOffsets.size() && "FieldNo out of range!");
166      Result += Layout->MemberOffsets[FieldNo];
167
168      // Update Ty to refer to current element
169      Ty = STy->getElementTypes()[FieldNo];
170
171    } else if (const ArrayType *ATy = dyn_cast<const ArrayType>(Ty)) {
172      assert(0 && "Loading from arrays not implemented yet!");
173    } else {
174      assert(0 && "Indexing type that is not struct or array?");
175      return 0;                         // Load directly through ptr
176    }
177  }
178
179  return Result;
180}
181