Anders Carlsson | 45372a6 | 2009-07-23 03:17:50 +0000 | [diff] [blame] | 1 | //===--- CGRecordLayoutBuilder.cpp - Record builder helper ------*- C++ -*-===// |
| 2 | // |
| 3 | // The LLVM Compiler Infrastructure |
| 4 | // |
| 5 | // This file is distributed under the University of Illinois Open Source |
| 6 | // License. See LICENSE.TXT for details. |
| 7 | // |
| 8 | //===----------------------------------------------------------------------===// |
| 9 | // |
| 10 | // This is a helper class used to build CGRecordLayout objects and LLVM types. |
| 11 | // |
| 12 | //===----------------------------------------------------------------------===// |
| 13 | |
| 14 | #include "CGRecordLayoutBuilder.h" |
| 15 | |
| 16 | #include "clang/AST/ASTContext.h" |
| 17 | #include "clang/AST/Attr.h" |
| 18 | #include "clang/AST/DeclCXX.h" |
| 19 | #include "clang/AST/Expr.h" |
| 20 | #include "clang/AST/RecordLayout.h" |
| 21 | #include "CodeGenTypes.h" |
| 22 | #include "llvm/DerivedTypes.h" |
| 23 | #include "llvm/Target/TargetData.h" |
| 24 | |
| 25 | |
| 26 | using namespace clang; |
| 27 | using namespace CodeGen; |
| 28 | |
| 29 | void CGRecordLayoutBuilder::Layout(const RecordDecl *D) { |
Anders Carlsson | 5a6e398 | 2009-07-23 03:43:54 +0000 | [diff] [blame] | 30 | if (D->isUnion()) { |
| 31 | LayoutUnion(D); |
| 32 | return; |
| 33 | } |
| 34 | |
Anders Carlsson | 45372a6 | 2009-07-23 03:17:50 +0000 | [diff] [blame] | 35 | if (const PackedAttr* PA = D->getAttr<PackedAttr>()) |
| 36 | StructPacking = PA->getAlignment(); |
| 37 | |
| 38 | if (LayoutFields(D)) |
| 39 | return; |
| 40 | |
| 41 | assert(!StructPacking && |
| 42 | "FIXME: Were not able to lay out a struct with #pragma pack!"); |
| 43 | |
| 44 | // We weren't able to layout the struct. Try again with a packed struct |
| 45 | StructPacking = 1; |
| 46 | AlignmentAsLLVMStruct = 1; |
| 47 | FieldTypes.clear(); |
| 48 | FieldInfos.clear(); |
| 49 | LLVMFields.clear(); |
| 50 | LLVMBitFields.clear(); |
| 51 | |
| 52 | LayoutFields(D); |
| 53 | } |
| 54 | |
| 55 | void CGRecordLayoutBuilder::LayoutBitField(const FieldDecl *D, |
| 56 | uint64_t FieldOffset) { |
| 57 | uint64_t FieldSize = |
| 58 | D->getBitWidth()->EvaluateAsInt(Types.getContext()).getZExtValue(); |
| 59 | |
| 60 | if (FieldSize == 0) |
| 61 | return; |
| 62 | |
| 63 | uint64_t NextFieldOffset = getNextFieldOffsetInBytes() * 8; |
| 64 | unsigned NumBytesToAppend; |
| 65 | |
| 66 | if (FieldOffset < NextFieldOffset) { |
| 67 | assert(BitsAvailableInLastField && "Bitfield size mismatch!"); |
| 68 | assert(!FieldInfos.empty() && "Field infos can't be empty!"); |
| 69 | |
| 70 | // The bitfield begins in the previous bit-field. |
| 71 | NumBytesToAppend = |
| 72 | llvm::RoundUpToAlignment(FieldSize - BitsAvailableInLastField, 8) / 8; |
| 73 | } else { |
| 74 | assert(FieldOffset % 8 == 0 && "Field offset not aligned correctly"); |
| 75 | |
| 76 | // Append padding if necessary. |
| 77 | AppendBytes((FieldOffset - NextFieldOffset) / 8); |
| 78 | |
| 79 | NumBytesToAppend = |
| 80 | llvm::RoundUpToAlignment(FieldSize, 8) / 8; |
| 81 | |
| 82 | assert(NumBytesToAppend && "No bytes to append!"); |
| 83 | } |
| 84 | |
| 85 | const llvm::Type *Ty = Types.ConvertTypeForMemRecursive(D->getType()); |
| 86 | uint64_t TypeSizeInBits = getTypeSizeInBytes(Ty) * 8; |
| 87 | |
| 88 | LLVMFields.push_back(LLVMFieldInfo(D, FieldOffset / TypeSizeInBits)); |
| 89 | LLVMBitFields.push_back(LLVMBitFieldInfo(D, FieldOffset % TypeSizeInBits, |
| 90 | FieldSize)); |
| 91 | |
| 92 | AppendBytes(NumBytesToAppend); |
| 93 | |
| 94 | if (!NumBytesToAppend) |
| 95 | BitsAvailableInLastField -= FieldSize; |
| 96 | else |
| 97 | BitsAvailableInLastField = NumBytesToAppend * 8 - FieldSize; |
| 98 | } |
| 99 | |
| 100 | bool CGRecordLayoutBuilder::LayoutField(const FieldDecl *D, |
| 101 | uint64_t FieldOffset) { |
| 102 | unsigned FieldPacking = StructPacking; |
| 103 | |
| 104 | // FIXME: Should this override struct packing? Probably we want to |
| 105 | // take the minimum? |
| 106 | if (const PackedAttr *PA = D->getAttr<PackedAttr>()) |
| 107 | FieldPacking = PA->getAlignment(); |
| 108 | |
| 109 | // If the field is packed, then we need a packed struct. |
| 110 | if (!StructPacking && FieldPacking) |
| 111 | return false; |
| 112 | |
| 113 | if (D->isBitField()) { |
| 114 | // We must use packed structs for unnamed bit fields since they |
| 115 | // don't affect the struct alignment. |
| 116 | if (!StructPacking && !D->getDeclName()) |
| 117 | return false; |
| 118 | |
| 119 | LayoutBitField(D, FieldOffset); |
| 120 | return true; |
| 121 | } |
| 122 | |
| 123 | const llvm::Type *Ty = Types.ConvertTypeForMemRecursive(D->getType()); |
| 124 | |
| 125 | // Check if the field is aligned. |
| 126 | if (const AlignedAttr *PA = D->getAttr<AlignedAttr>()) { |
| 127 | unsigned FieldAlign = PA->getAlignment(); |
| 128 | |
| 129 | if (!StructPacking && getTypeAlignment(Ty) > FieldAlign) |
| 130 | return false; |
| 131 | } |
| 132 | |
| 133 | assert(FieldOffset % 8 == 0 && "FieldOffset is not on a byte boundary!"); |
| 134 | |
| 135 | uint64_t FieldOffsetInBytes = FieldOffset / 8; |
| 136 | |
| 137 | // Append padding if necessary. |
| 138 | AppendPadding(FieldOffsetInBytes, Ty); |
| 139 | |
| 140 | uint64_t FieldSizeInBytes = getTypeSizeInBytes(Ty); |
| 141 | |
| 142 | // Now append the field. |
| 143 | LLVMFields.push_back(LLVMFieldInfo(D, FieldTypes.size())); |
| 144 | AppendField(FieldOffsetInBytes, FieldSizeInBytes, Ty); |
| 145 | |
| 146 | return true; |
| 147 | } |
| 148 | |
Anders Carlsson | 5a6e398 | 2009-07-23 03:43:54 +0000 | [diff] [blame] | 149 | void CGRecordLayoutBuilder::LayoutUnion(const RecordDecl *D) { |
| 150 | assert(D->isUnion() && "Can't call LayoutUnion on a non-union record!"); |
| 151 | |
| 152 | const ASTRecordLayout &Layout = Types.getContext().getASTRecordLayout(D); |
| 153 | |
Anders Carlsson | cfc6758 | 2009-07-23 04:59:05 +0000 | [diff] [blame^] | 154 | const FieldDecl *FD = 0; |
Anders Carlsson | 5a6e398 | 2009-07-23 03:43:54 +0000 | [diff] [blame] | 155 | const llvm::Type *Ty = 0; |
| 156 | uint64_t Size = 0; |
| 157 | unsigned Align = 0; |
| 158 | |
| 159 | unsigned FieldNo = 0; |
| 160 | for (RecordDecl::field_iterator Field = D->field_begin(), |
| 161 | FieldEnd = D->field_end(); Field != FieldEnd; ++Field, ++FieldNo) { |
| 162 | assert(Layout.getFieldOffset(FieldNo) == 0 && |
| 163 | "Union field offset did not start at the beginning of record!"); |
Anders Carlsson | 2cc8f17 | 2009-07-23 04:00:39 +0000 | [diff] [blame] | 164 | |
| 165 | if (Field->isBitField()) { |
| 166 | uint64_t FieldSize = |
| 167 | Field->getBitWidth()->EvaluateAsInt(Types.getContext()).getZExtValue(); |
| 168 | |
| 169 | // Ignore zero sized bit fields. |
| 170 | if (FieldSize == 0) |
| 171 | continue; |
| 172 | } |
Anders Carlsson | 5a6e398 | 2009-07-23 03:43:54 +0000 | [diff] [blame] | 173 | |
| 174 | const llvm::Type *FieldTy = |
| 175 | Types.ConvertTypeForMemRecursive(Field->getType()); |
| 176 | unsigned FieldAlign = Types.getTargetData().getTypeAllocSize(FieldTy); |
| 177 | uint64_t FieldSize = Types.getTargetData().getABITypeAlignment(FieldTy); |
| 178 | |
| 179 | if (FieldAlign < Align) |
| 180 | continue; |
| 181 | |
| 182 | if (FieldAlign > Align || FieldSize > Size) { |
| 183 | Ty = FieldTy; |
| 184 | Align = FieldAlign; |
| 185 | Size = FieldSize; |
Anders Carlsson | cfc6758 | 2009-07-23 04:59:05 +0000 | [diff] [blame^] | 186 | FD = *Field; |
Anders Carlsson | 5a6e398 | 2009-07-23 03:43:54 +0000 | [diff] [blame] | 187 | } |
| 188 | } |
| 189 | |
| 190 | // Now add our field. |
Anders Carlsson | cfc6758 | 2009-07-23 04:59:05 +0000 | [diff] [blame^] | 191 | if (FD) { |
Anders Carlsson | 5a6e398 | 2009-07-23 03:43:54 +0000 | [diff] [blame] | 192 | AppendField(0, Size, Ty); |
Anders Carlsson | cfc6758 | 2009-07-23 04:59:05 +0000 | [diff] [blame^] | 193 | Types.addFieldInfo(FD, 0); |
| 194 | |
| 195 | if (FD->isBitField()) { |
| 196 | uint64_t FieldSize = |
| 197 | FD->getBitWidth()->EvaluateAsInt(Types.getContext()).getZExtValue(); |
| 198 | Types.addBitFieldInfo(FD, 0, FieldSize); |
| 199 | } |
| 200 | } |
Anders Carlsson | 5a6e398 | 2009-07-23 03:43:54 +0000 | [diff] [blame] | 201 | |
| 202 | // Append tail padding. |
| 203 | if (Layout.getSize() / 8 > Size) |
| 204 | AppendPadding(Layout.getSize() / 8, Align); |
| 205 | } |
| 206 | |
Anders Carlsson | 45372a6 | 2009-07-23 03:17:50 +0000 | [diff] [blame] | 207 | bool CGRecordLayoutBuilder::LayoutFields(const RecordDecl *D) { |
| 208 | assert(!D->isUnion() && "Can't call LayoutFields on a union!"); |
| 209 | |
Anders Carlsson | 5a6e398 | 2009-07-23 03:43:54 +0000 | [diff] [blame] | 210 | const ASTRecordLayout &Layout = Types.getContext().getASTRecordLayout(D); |
Anders Carlsson | 45372a6 | 2009-07-23 03:17:50 +0000 | [diff] [blame] | 211 | |
| 212 | unsigned FieldNo = 0; |
| 213 | for (RecordDecl::field_iterator Field = D->field_begin(), |
| 214 | FieldEnd = D->field_end(); Field != FieldEnd; ++Field, ++FieldNo) { |
| 215 | if (!LayoutField(*Field, Layout.getFieldOffset(FieldNo))) { |
| 216 | assert(!StructPacking && |
| 217 | "Could not layout fields even with a packed LLVM struct!"); |
| 218 | return false; |
| 219 | } |
| 220 | } |
| 221 | |
| 222 | // Append tail padding if necessary. |
| 223 | if (Layout.getSize() / 8 > getNextFieldOffsetInBytes()) |
| 224 | AppendPadding(Layout.getSize() / 8, AlignmentAsLLVMStruct); |
| 225 | |
| 226 | return true; |
| 227 | } |
| 228 | |
| 229 | void CGRecordLayoutBuilder::AppendField(uint64_t FieldOffsetInBytes, |
| 230 | uint64_t FieldSizeInBytes, |
| 231 | const llvm::Type *FieldTy) { |
| 232 | AlignmentAsLLVMStruct = std::max(AlignmentAsLLVMStruct, |
| 233 | getTypeAlignment(FieldTy)); |
| 234 | |
| 235 | FieldTypes.push_back(FieldTy); |
| 236 | FieldInfos.push_back(FieldInfo(FieldOffsetInBytes, FieldSizeInBytes)); |
| 237 | |
| 238 | BitsAvailableInLastField = 0; |
| 239 | } |
| 240 | |
| 241 | void |
| 242 | CGRecordLayoutBuilder::AppendPadding(uint64_t FieldOffsetInBytes, |
| 243 | const llvm::Type *FieldTy) { |
| 244 | AppendPadding(FieldOffsetInBytes, getTypeAlignment(FieldTy)); |
| 245 | } |
| 246 | |
| 247 | void CGRecordLayoutBuilder::AppendPadding(uint64_t FieldOffsetInBytes, |
| 248 | unsigned FieldAlignment) { |
| 249 | uint64_t NextFieldOffsetInBytes = getNextFieldOffsetInBytes(); |
| 250 | assert(NextFieldOffsetInBytes <= FieldOffsetInBytes && |
| 251 | "Incorrect field layout!"); |
| 252 | |
| 253 | // Round up the field offset to the alignment of the field type. |
| 254 | uint64_t AlignedNextFieldOffsetInBytes = |
| 255 | llvm::RoundUpToAlignment(NextFieldOffsetInBytes, FieldAlignment); |
| 256 | |
| 257 | if (AlignedNextFieldOffsetInBytes < FieldOffsetInBytes) { |
| 258 | // Even with alignment, the field offset is not at the right place, |
| 259 | // insert padding. |
| 260 | uint64_t PaddingInBytes = FieldOffsetInBytes - NextFieldOffsetInBytes; |
| 261 | |
| 262 | AppendBytes(PaddingInBytes); |
| 263 | } |
| 264 | } |
| 265 | |
| 266 | void CGRecordLayoutBuilder::AppendBytes(uint64_t NumBytes) { |
| 267 | if (NumBytes == 0) |
| 268 | return; |
| 269 | |
| 270 | const llvm::Type *Ty = llvm::Type::Int8Ty; |
| 271 | if (NumBytes > 1) { |
| 272 | // FIXME: Use a VMContext. |
| 273 | Ty = llvm::ArrayType::get(Ty, NumBytes); |
| 274 | } |
| 275 | |
| 276 | // Append the padding field |
| 277 | AppendField(getNextFieldOffsetInBytes(), NumBytes, Ty); |
| 278 | } |
| 279 | |
| 280 | uint64_t CGRecordLayoutBuilder::getNextFieldOffsetInBytes() const { |
| 281 | if (FieldInfos.empty()) |
| 282 | return 0; |
| 283 | |
| 284 | const FieldInfo &LastInfo = FieldInfos.back(); |
| 285 | return LastInfo.OffsetInBytes + LastInfo.SizeInBytes; |
| 286 | } |
| 287 | |
| 288 | unsigned CGRecordLayoutBuilder::getTypeAlignment(const llvm::Type *Ty) const { |
| 289 | if (StructPacking) { |
| 290 | assert(StructPacking == 1 && "FIXME: What if StructPacking is not 1 here"); |
| 291 | return 1; |
| 292 | } |
| 293 | |
| 294 | return Types.getTargetData().getABITypeAlignment(Ty); |
| 295 | } |
| 296 | |
| 297 | uint64_t CGRecordLayoutBuilder::getTypeSizeInBytes(const llvm::Type *Ty) const { |
| 298 | return Types.getTargetData().getTypeAllocSize(Ty); |
| 299 | } |
| 300 | |
| 301 | CGRecordLayout * |
| 302 | CGRecordLayoutBuilder::ComputeLayout(CodeGenTypes &Types, |
| 303 | const RecordDecl *D) { |
| 304 | CGRecordLayoutBuilder Builder(Types); |
| 305 | |
Anders Carlsson | 45372a6 | 2009-07-23 03:17:50 +0000 | [diff] [blame] | 306 | Builder.Layout(D); |
| 307 | |
| 308 | // FIXME: Once this works well enough, enable it. |
| 309 | return 0; |
| 310 | |
| 311 | // FIXME: Use a VMContext. |
| 312 | const llvm::Type *Ty = llvm::StructType::get(Builder.FieldTypes, |
| 313 | Builder.StructPacking); |
| 314 | |
| 315 | // Add all the field numbers. |
| 316 | for (unsigned i = 0, e = Builder.LLVMFields.size(); i != e; ++i) { |
| 317 | const FieldDecl *FD = Builder.LLVMFields[i].first; |
| 318 | unsigned FieldNo = Builder.LLVMFields[i].second; |
| 319 | |
| 320 | Types.addFieldInfo(FD, FieldNo); |
| 321 | } |
| 322 | |
| 323 | // Add bitfield info. |
| 324 | for (unsigned i = 0, e = Builder.LLVMBitFields.size(); i != e; ++i) { |
| 325 | const LLVMBitFieldInfo &Info = Builder.LLVMBitFields[i]; |
| 326 | |
| 327 | Types.addBitFieldInfo(Info.FD, Info.Start, Info.Size); |
| 328 | } |
| 329 | |
| 330 | return new CGRecordLayout(Ty, llvm::SmallSet<unsigned, 8>()); |
| 331 | } |