1 //===--- CGExprConstant.cpp - Emit LLVM Code from Constant Expressions ----===// 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 contains code to emit Constant Expr nodes as LLVM code. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "CodeGenFunction.h" 15 #include "CGCXXABI.h" 16 #include "CGObjCRuntime.h" 17 #include "CGRecordLayout.h" 18 #include "CodeGenModule.h" 19 #include "clang/AST/APValue.h" 20 #include "clang/AST/ASTContext.h" 21 #include "clang/AST/RecordLayout.h" 22 #include "clang/AST/StmtVisitor.h" 23 #include "clang/Basic/Builtins.h" 24 #include "llvm/IR/Constants.h" 25 #include "llvm/IR/DataLayout.h" 26 #include "llvm/IR/Function.h" 27 #include "llvm/IR/GlobalVariable.h" 28 using namespace clang; 29 using namespace CodeGen; 30 31 //===----------------------------------------------------------------------===// 32 // ConstStructBuilder 33 //===----------------------------------------------------------------------===// 34 35 namespace { 36 class ConstStructBuilder { 37 CodeGenModule &CGM; 38 CodeGenFunction *CGF; 39 40 bool Packed; 41 CharUnits NextFieldOffsetInChars; 42 CharUnits LLVMStructAlignment; 43 SmallVector<llvm::Constant *, 32> Elements; 44 public: 45 static llvm::Constant *BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF, 46 InitListExpr *ILE); 47 static llvm::Constant *BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF, 48 const APValue &Value, QualType ValTy); 49 50 private: 51 ConstStructBuilder(CodeGenModule &CGM, CodeGenFunction *CGF) 52 : CGM(CGM), CGF(CGF), Packed(false), 53 NextFieldOffsetInChars(CharUnits::Zero()), 54 LLVMStructAlignment(CharUnits::One()) { } 55 56 void AppendField(const FieldDecl *Field, uint64_t FieldOffset, 57 llvm::Constant *InitExpr); 58 59 void AppendBytes(CharUnits FieldOffsetInChars, llvm::Constant *InitCst); 60 61 void AppendBitField(const FieldDecl *Field, uint64_t FieldOffset, 62 llvm::ConstantInt *InitExpr); 63 64 void AppendPadding(CharUnits PadSize); 65 66 void AppendTailPadding(CharUnits RecordSize); 67 68 void ConvertStructToPacked(); 69 70 bool Build(InitListExpr *ILE); 71 void Build(const APValue &Val, const RecordDecl *RD, bool IsPrimaryBase, 72 const CXXRecordDecl *VTableClass, CharUnits BaseOffset); 73 llvm::Constant *Finalize(QualType Ty); 74 75 CharUnits getAlignment(const llvm::Constant *C) const { 76 if (Packed) return CharUnits::One(); 77 return CharUnits::fromQuantity( 78 CGM.getDataLayout().getABITypeAlignment(C->getType())); 79 } 80 81 CharUnits getSizeInChars(const llvm::Constant *C) const { 82 return CharUnits::fromQuantity( 83 CGM.getDataLayout().getTypeAllocSize(C->getType())); 84 } 85 }; 86 87 void ConstStructBuilder:: 88 AppendField(const FieldDecl *Field, uint64_t FieldOffset, 89 llvm::Constant *InitCst) { 90 const ASTContext &Context = CGM.getContext(); 91 92 CharUnits FieldOffsetInChars = Context.toCharUnitsFromBits(FieldOffset); 93 94 AppendBytes(FieldOffsetInChars, InitCst); 95 } 96 97 void ConstStructBuilder:: 98 AppendBytes(CharUnits FieldOffsetInChars, llvm::Constant *InitCst) { 99 100 assert(NextFieldOffsetInChars <= FieldOffsetInChars 101 && "Field offset mismatch!"); 102 103 CharUnits FieldAlignment = getAlignment(InitCst); 104 105 // Round up the field offset to the alignment of the field type. 106 CharUnits AlignedNextFieldOffsetInChars = 107 NextFieldOffsetInChars.RoundUpToAlignment(FieldAlignment); 108 109 if (AlignedNextFieldOffsetInChars < FieldOffsetInChars) { 110 // We need to append padding. 111 AppendPadding(FieldOffsetInChars - NextFieldOffsetInChars); 112 113 assert(NextFieldOffsetInChars == FieldOffsetInChars && 114 "Did not add enough padding!"); 115 116 AlignedNextFieldOffsetInChars = 117 NextFieldOffsetInChars.RoundUpToAlignment(FieldAlignment); 118 } 119 120 if (AlignedNextFieldOffsetInChars > FieldOffsetInChars) { 121 assert(!Packed && "Alignment is wrong even with a packed struct!"); 122 123 // Convert the struct to a packed struct. 124 ConvertStructToPacked(); 125 126 // After we pack the struct, we may need to insert padding. 127 if (NextFieldOffsetInChars < FieldOffsetInChars) { 128 // We need to append padding. 129 AppendPadding(FieldOffsetInChars - NextFieldOffsetInChars); 130 131 assert(NextFieldOffsetInChars == FieldOffsetInChars && 132 "Did not add enough padding!"); 133 } 134 AlignedNextFieldOffsetInChars = NextFieldOffsetInChars; 135 } 136 137 // Add the field. 138 Elements.push_back(InitCst); 139 NextFieldOffsetInChars = AlignedNextFieldOffsetInChars + 140 getSizeInChars(InitCst); 141 142 if (Packed) 143 assert(LLVMStructAlignment == CharUnits::One() && 144 "Packed struct not byte-aligned!"); 145 else 146 LLVMStructAlignment = std::max(LLVMStructAlignment, FieldAlignment); 147 } 148 149 void ConstStructBuilder::AppendBitField(const FieldDecl *Field, 150 uint64_t FieldOffset, 151 llvm::ConstantInt *CI) { 152 const ASTContext &Context = CGM.getContext(); 153 const uint64_t CharWidth = Context.getCharWidth(); 154 uint64_t NextFieldOffsetInBits = Context.toBits(NextFieldOffsetInChars); 155 if (FieldOffset > NextFieldOffsetInBits) { 156 // We need to add padding. 157 CharUnits PadSize = Context.toCharUnitsFromBits( 158 llvm::RoundUpToAlignment(FieldOffset - NextFieldOffsetInBits, 159 Context.getTargetInfo().getCharAlign())); 160 161 AppendPadding(PadSize); 162 } 163 164 uint64_t FieldSize = Field->getBitWidthValue(Context); 165 166 llvm::APInt FieldValue = CI->getValue(); 167 168 // Promote the size of FieldValue if necessary 169 // FIXME: This should never occur, but currently it can because initializer 170 // constants are cast to bool, and because clang is not enforcing bitfield 171 // width limits. 172 if (FieldSize > FieldValue.getBitWidth()) 173 FieldValue = FieldValue.zext(FieldSize); 174 175 // Truncate the size of FieldValue to the bit field size. 176 if (FieldSize < FieldValue.getBitWidth()) 177 FieldValue = FieldValue.trunc(FieldSize); 178 179 NextFieldOffsetInBits = Context.toBits(NextFieldOffsetInChars); 180 if (FieldOffset < NextFieldOffsetInBits) { 181 // Either part of the field or the entire field can go into the previous 182 // byte. 183 assert(!Elements.empty() && "Elements can't be empty!"); 184 185 unsigned BitsInPreviousByte = NextFieldOffsetInBits - FieldOffset; 186 187 bool FitsCompletelyInPreviousByte = 188 BitsInPreviousByte >= FieldValue.getBitWidth(); 189 190 llvm::APInt Tmp = FieldValue; 191 192 if (!FitsCompletelyInPreviousByte) { 193 unsigned NewFieldWidth = FieldSize - BitsInPreviousByte; 194 195 if (CGM.getDataLayout().isBigEndian()) { 196 Tmp = Tmp.lshr(NewFieldWidth); 197 Tmp = Tmp.trunc(BitsInPreviousByte); 198 199 // We want the remaining high bits. 200 FieldValue = FieldValue.trunc(NewFieldWidth); 201 } else { 202 Tmp = Tmp.trunc(BitsInPreviousByte); 203 204 // We want the remaining low bits. 205 FieldValue = FieldValue.lshr(BitsInPreviousByte); 206 FieldValue = FieldValue.trunc(NewFieldWidth); 207 } 208 } 209 210 Tmp = Tmp.zext(CharWidth); 211 if (CGM.getDataLayout().isBigEndian()) { 212 if (FitsCompletelyInPreviousByte) 213 Tmp = Tmp.shl(BitsInPreviousByte - FieldValue.getBitWidth()); 214 } else { 215 Tmp = Tmp.shl(CharWidth - BitsInPreviousByte); 216 } 217 218 // 'or' in the bits that go into the previous byte. 219 llvm::Value *LastElt = Elements.back(); 220 if (llvm::ConstantInt *Val = dyn_cast<llvm::ConstantInt>(LastElt)) 221 Tmp |= Val->getValue(); 222 else { 223 assert(isa<llvm::UndefValue>(LastElt)); 224 // If there is an undef field that we're adding to, it can either be a 225 // scalar undef (in which case, we just replace it with our field) or it 226 // is an array. If it is an array, we have to pull one byte off the 227 // array so that the other undef bytes stay around. 228 if (!isa<llvm::IntegerType>(LastElt->getType())) { 229 // The undef padding will be a multibyte array, create a new smaller 230 // padding and then an hole for our i8 to get plopped into. 231 assert(isa<llvm::ArrayType>(LastElt->getType()) && 232 "Expected array padding of undefs"); 233 llvm::ArrayType *AT = cast<llvm::ArrayType>(LastElt->getType()); 234 assert(AT->getElementType()->isIntegerTy(CharWidth) && 235 AT->getNumElements() != 0 && 236 "Expected non-empty array padding of undefs"); 237 238 // Remove the padding array. 239 NextFieldOffsetInChars -= CharUnits::fromQuantity(AT->getNumElements()); 240 Elements.pop_back(); 241 242 // Add the padding back in two chunks. 243 AppendPadding(CharUnits::fromQuantity(AT->getNumElements()-1)); 244 AppendPadding(CharUnits::One()); 245 assert(isa<llvm::UndefValue>(Elements.back()) && 246 Elements.back()->getType()->isIntegerTy(CharWidth) && 247 "Padding addition didn't work right"); 248 } 249 } 250 251 Elements.back() = llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp); 252 253 if (FitsCompletelyInPreviousByte) 254 return; 255 } 256 257 while (FieldValue.getBitWidth() > CharWidth) { 258 llvm::APInt Tmp; 259 260 if (CGM.getDataLayout().isBigEndian()) { 261 // We want the high bits. 262 Tmp = 263 FieldValue.lshr(FieldValue.getBitWidth() - CharWidth).trunc(CharWidth); 264 } else { 265 // We want the low bits. 266 Tmp = FieldValue.trunc(CharWidth); 267 268 FieldValue = FieldValue.lshr(CharWidth); 269 } 270 271 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp)); 272 ++NextFieldOffsetInChars; 273 274 FieldValue = FieldValue.trunc(FieldValue.getBitWidth() - CharWidth); 275 } 276 277 assert(FieldValue.getBitWidth() > 0 && 278 "Should have at least one bit left!"); 279 assert(FieldValue.getBitWidth() <= CharWidth && 280 "Should not have more than a byte left!"); 281 282 if (FieldValue.getBitWidth() < CharWidth) { 283 if (CGM.getDataLayout().isBigEndian()) { 284 unsigned BitWidth = FieldValue.getBitWidth(); 285 286 FieldValue = FieldValue.zext(CharWidth) << (CharWidth - BitWidth); 287 } else 288 FieldValue = FieldValue.zext(CharWidth); 289 } 290 291 // Append the last element. 292 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), 293 FieldValue)); 294 ++NextFieldOffsetInChars; 295 } 296 297 void ConstStructBuilder::AppendPadding(CharUnits PadSize) { 298 if (PadSize.isZero()) 299 return; 300 301 llvm::Type *Ty = CGM.Int8Ty; 302 if (PadSize > CharUnits::One()) 303 Ty = llvm::ArrayType::get(Ty, PadSize.getQuantity()); 304 305 llvm::Constant *C = llvm::UndefValue::get(Ty); 306 Elements.push_back(C); 307 assert(getAlignment(C) == CharUnits::One() && 308 "Padding must have 1 byte alignment!"); 309 310 NextFieldOffsetInChars += getSizeInChars(C); 311 } 312 313 void ConstStructBuilder::AppendTailPadding(CharUnits RecordSize) { 314 assert(NextFieldOffsetInChars <= RecordSize && 315 "Size mismatch!"); 316 317 AppendPadding(RecordSize - NextFieldOffsetInChars); 318 } 319 320 void ConstStructBuilder::ConvertStructToPacked() { 321 SmallVector<llvm::Constant *, 16> PackedElements; 322 CharUnits ElementOffsetInChars = CharUnits::Zero(); 323 324 for (unsigned i = 0, e = Elements.size(); i != e; ++i) { 325 llvm::Constant *C = Elements[i]; 326 327 CharUnits ElementAlign = CharUnits::fromQuantity( 328 CGM.getDataLayout().getABITypeAlignment(C->getType())); 329 CharUnits AlignedElementOffsetInChars = 330 ElementOffsetInChars.RoundUpToAlignment(ElementAlign); 331 332 if (AlignedElementOffsetInChars > ElementOffsetInChars) { 333 // We need some padding. 334 CharUnits NumChars = 335 AlignedElementOffsetInChars - ElementOffsetInChars; 336 337 llvm::Type *Ty = CGM.Int8Ty; 338 if (NumChars > CharUnits::One()) 339 Ty = llvm::ArrayType::get(Ty, NumChars.getQuantity()); 340 341 llvm::Constant *Padding = llvm::UndefValue::get(Ty); 342 PackedElements.push_back(Padding); 343 ElementOffsetInChars += getSizeInChars(Padding); 344 } 345 346 PackedElements.push_back(C); 347 ElementOffsetInChars += getSizeInChars(C); 348 } 349 350 assert(ElementOffsetInChars == NextFieldOffsetInChars && 351 "Packing the struct changed its size!"); 352 353 Elements.swap(PackedElements); 354 LLVMStructAlignment = CharUnits::One(); 355 Packed = true; 356 } 357 358 bool ConstStructBuilder::Build(InitListExpr *ILE) { 359 RecordDecl *RD = ILE->getType()->getAs<RecordType>()->getDecl(); 360 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); 361 362 unsigned FieldNo = 0; 363 unsigned ElementNo = 0; 364 365 for (RecordDecl::field_iterator Field = RD->field_begin(), 366 FieldEnd = RD->field_end(); Field != FieldEnd; ++Field, ++FieldNo) { 367 // If this is a union, skip all the fields that aren't being initialized. 368 if (RD->isUnion() && ILE->getInitializedFieldInUnion() != *Field) 369 continue; 370 371 // Don't emit anonymous bitfields, they just affect layout. 372 if (Field->isUnnamedBitfield()) 373 continue; 374 375 // Get the initializer. A struct can include fields without initializers, 376 // we just use explicit null values for them. 377 llvm::Constant *EltInit; 378 if (ElementNo < ILE->getNumInits()) 379 EltInit = CGM.EmitConstantExpr(ILE->getInit(ElementNo++), 380 Field->getType(), CGF); 381 else 382 EltInit = CGM.EmitNullConstant(Field->getType()); 383 384 if (!EltInit) 385 return false; 386 387 if (!Field->isBitField()) { 388 // Handle non-bitfield members. 389 AppendField(*Field, Layout.getFieldOffset(FieldNo), EltInit); 390 } else { 391 // Otherwise we have a bitfield. 392 if (auto *CI = dyn_cast<llvm::ConstantInt>(EltInit)) { 393 AppendBitField(*Field, Layout.getFieldOffset(FieldNo), CI); 394 } else { 395 // We are trying to initialize a bitfield with a non-trivial constant, 396 // this must require run-time code. 397 return false; 398 } 399 } 400 } 401 402 return true; 403 } 404 405 namespace { 406 struct BaseInfo { 407 BaseInfo(const CXXRecordDecl *Decl, CharUnits Offset, unsigned Index) 408 : Decl(Decl), Offset(Offset), Index(Index) { 409 } 410 411 const CXXRecordDecl *Decl; 412 CharUnits Offset; 413 unsigned Index; 414 415 bool operator<(const BaseInfo &O) const { return Offset < O.Offset; } 416 }; 417 } 418 419 void ConstStructBuilder::Build(const APValue &Val, const RecordDecl *RD, 420 bool IsPrimaryBase, 421 const CXXRecordDecl *VTableClass, 422 CharUnits Offset) { 423 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); 424 425 if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) { 426 // Add a vtable pointer, if we need one and it hasn't already been added. 427 if (CD->isDynamicClass() && !IsPrimaryBase) { 428 llvm::Constant *VTableAddressPoint = 429 CGM.getCXXABI().getVTableAddressPointForConstExpr( 430 BaseSubobject(CD, Offset), VTableClass); 431 AppendBytes(Offset, VTableAddressPoint); 432 } 433 434 // Accumulate and sort bases, in order to visit them in address order, which 435 // may not be the same as declaration order. 436 SmallVector<BaseInfo, 8> Bases; 437 Bases.reserve(CD->getNumBases()); 438 unsigned BaseNo = 0; 439 for (CXXRecordDecl::base_class_const_iterator Base = CD->bases_begin(), 440 BaseEnd = CD->bases_end(); Base != BaseEnd; ++Base, ++BaseNo) { 441 assert(!Base->isVirtual() && "should not have virtual bases here"); 442 const CXXRecordDecl *BD = Base->getType()->getAsCXXRecordDecl(); 443 CharUnits BaseOffset = Layout.getBaseClassOffset(BD); 444 Bases.push_back(BaseInfo(BD, BaseOffset, BaseNo)); 445 } 446 std::stable_sort(Bases.begin(), Bases.end()); 447 448 for (unsigned I = 0, N = Bases.size(); I != N; ++I) { 449 BaseInfo &Base = Bases[I]; 450 451 bool IsPrimaryBase = Layout.getPrimaryBase() == Base.Decl; 452 Build(Val.getStructBase(Base.Index), Base.Decl, IsPrimaryBase, 453 VTableClass, Offset + Base.Offset); 454 } 455 } 456 457 unsigned FieldNo = 0; 458 uint64_t OffsetBits = CGM.getContext().toBits(Offset); 459 460 for (RecordDecl::field_iterator Field = RD->field_begin(), 461 FieldEnd = RD->field_end(); Field != FieldEnd; ++Field, ++FieldNo) { 462 // If this is a union, skip all the fields that aren't being initialized. 463 if (RD->isUnion() && Val.getUnionField() != *Field) 464 continue; 465 466 // Don't emit anonymous bitfields, they just affect layout. 467 if (Field->isUnnamedBitfield()) 468 continue; 469 470 // Emit the value of the initializer. 471 const APValue &FieldValue = 472 RD->isUnion() ? Val.getUnionValue() : Val.getStructField(FieldNo); 473 llvm::Constant *EltInit = 474 CGM.EmitConstantValueForMemory(FieldValue, Field->getType(), CGF); 475 assert(EltInit && "EmitConstantValue can't fail"); 476 477 if (!Field->isBitField()) { 478 // Handle non-bitfield members. 479 AppendField(*Field, Layout.getFieldOffset(FieldNo) + OffsetBits, EltInit); 480 } else { 481 // Otherwise we have a bitfield. 482 AppendBitField(*Field, Layout.getFieldOffset(FieldNo) + OffsetBits, 483 cast<llvm::ConstantInt>(EltInit)); 484 } 485 } 486 } 487 488 llvm::Constant *ConstStructBuilder::Finalize(QualType Ty) { 489 RecordDecl *RD = Ty->getAs<RecordType>()->getDecl(); 490 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); 491 492 CharUnits LayoutSizeInChars = Layout.getSize(); 493 494 if (NextFieldOffsetInChars > LayoutSizeInChars) { 495 // If the struct is bigger than the size of the record type, 496 // we must have a flexible array member at the end. 497 assert(RD->hasFlexibleArrayMember() && 498 "Must have flexible array member if struct is bigger than type!"); 499 500 // No tail padding is necessary. 501 } else { 502 // Append tail padding if necessary. 503 CharUnits LLVMSizeInChars = 504 NextFieldOffsetInChars.RoundUpToAlignment(LLVMStructAlignment); 505 506 if (LLVMSizeInChars != LayoutSizeInChars) 507 AppendTailPadding(LayoutSizeInChars); 508 509 LLVMSizeInChars = 510 NextFieldOffsetInChars.RoundUpToAlignment(LLVMStructAlignment); 511 512 // Check if we need to convert the struct to a packed struct. 513 if (NextFieldOffsetInChars <= LayoutSizeInChars && 514 LLVMSizeInChars > LayoutSizeInChars) { 515 assert(!Packed && "Size mismatch!"); 516 517 ConvertStructToPacked(); 518 assert(NextFieldOffsetInChars <= LayoutSizeInChars && 519 "Converting to packed did not help!"); 520 } 521 522 LLVMSizeInChars = 523 NextFieldOffsetInChars.RoundUpToAlignment(LLVMStructAlignment); 524 525 assert(LayoutSizeInChars == LLVMSizeInChars && 526 "Tail padding mismatch!"); 527 } 528 529 // Pick the type to use. If the type is layout identical to the ConvertType 530 // type then use it, otherwise use whatever the builder produced for us. 531 llvm::StructType *STy = 532 llvm::ConstantStruct::getTypeForElements(CGM.getLLVMContext(), 533 Elements, Packed); 534 llvm::Type *ValTy = CGM.getTypes().ConvertType(Ty); 535 if (llvm::StructType *ValSTy = dyn_cast<llvm::StructType>(ValTy)) { 536 if (ValSTy->isLayoutIdentical(STy)) 537 STy = ValSTy; 538 } 539 540 llvm::Constant *Result = llvm::ConstantStruct::get(STy, Elements); 541 542 assert(NextFieldOffsetInChars.RoundUpToAlignment(getAlignment(Result)) == 543 getSizeInChars(Result) && "Size mismatch!"); 544 545 return Result; 546 } 547 548 llvm::Constant *ConstStructBuilder::BuildStruct(CodeGenModule &CGM, 549 CodeGenFunction *CGF, 550 InitListExpr *ILE) { 551 ConstStructBuilder Builder(CGM, CGF); 552 553 if (!Builder.Build(ILE)) 554 return nullptr; 555 556 return Builder.Finalize(ILE->getType()); 557 } 558 559 llvm::Constant *ConstStructBuilder::BuildStruct(CodeGenModule &CGM, 560 CodeGenFunction *CGF, 561 const APValue &Val, 562 QualType ValTy) { 563 ConstStructBuilder Builder(CGM, CGF); 564 565 const RecordDecl *RD = ValTy->castAs<RecordType>()->getDecl(); 566 const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD); 567 Builder.Build(Val, RD, false, CD, CharUnits::Zero()); 568 569 return Builder.Finalize(ValTy); 570 } 571 572 573 //===----------------------------------------------------------------------===// 574 // ConstExprEmitter 575 //===----------------------------------------------------------------------===// 576 577 /// This class only needs to handle two cases: 578 /// 1) Literals (this is used by APValue emission to emit literals). 579 /// 2) Arrays, structs and unions (outside C++11 mode, we don't currently 580 /// constant fold these types). 581 class ConstExprEmitter : 582 public StmtVisitor<ConstExprEmitter, llvm::Constant*> { 583 CodeGenModule &CGM; 584 CodeGenFunction *CGF; 585 llvm::LLVMContext &VMContext; 586 public: 587 ConstExprEmitter(CodeGenModule &cgm, CodeGenFunction *cgf) 588 : CGM(cgm), CGF(cgf), VMContext(cgm.getLLVMContext()) { 589 } 590 591 //===--------------------------------------------------------------------===// 592 // Visitor Methods 593 //===--------------------------------------------------------------------===// 594 595 llvm::Constant *VisitStmt(Stmt *S) { 596 return nullptr; 597 } 598 599 llvm::Constant *VisitParenExpr(ParenExpr *PE) { 600 return Visit(PE->getSubExpr()); 601 } 602 603 llvm::Constant * 604 VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *PE) { 605 return Visit(PE->getReplacement()); 606 } 607 608 llvm::Constant *VisitGenericSelectionExpr(GenericSelectionExpr *GE) { 609 return Visit(GE->getResultExpr()); 610 } 611 612 llvm::Constant *VisitChooseExpr(ChooseExpr *CE) { 613 return Visit(CE->getChosenSubExpr()); 614 } 615 616 llvm::Constant *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) { 617 return Visit(E->getInitializer()); 618 } 619 620 llvm::Constant *VisitCastExpr(CastExpr* E) { 621 Expr *subExpr = E->getSubExpr(); 622 llvm::Constant *C = CGM.EmitConstantExpr(subExpr, subExpr->getType(), CGF); 623 if (!C) return nullptr; 624 625 llvm::Type *destType = ConvertType(E->getType()); 626 627 switch (E->getCastKind()) { 628 case CK_ToUnion: { 629 // GCC cast to union extension 630 assert(E->getType()->isUnionType() && 631 "Destination type is not union type!"); 632 633 // Build a struct with the union sub-element as the first member, 634 // and padded to the appropriate size 635 SmallVector<llvm::Constant*, 2> Elts; 636 SmallVector<llvm::Type*, 2> Types; 637 Elts.push_back(C); 638 Types.push_back(C->getType()); 639 unsigned CurSize = CGM.getDataLayout().getTypeAllocSize(C->getType()); 640 unsigned TotalSize = CGM.getDataLayout().getTypeAllocSize(destType); 641 642 assert(CurSize <= TotalSize && "Union size mismatch!"); 643 if (unsigned NumPadBytes = TotalSize - CurSize) { 644 llvm::Type *Ty = CGM.Int8Ty; 645 if (NumPadBytes > 1) 646 Ty = llvm::ArrayType::get(Ty, NumPadBytes); 647 648 Elts.push_back(llvm::UndefValue::get(Ty)); 649 Types.push_back(Ty); 650 } 651 652 llvm::StructType* STy = 653 llvm::StructType::get(C->getType()->getContext(), Types, false); 654 return llvm::ConstantStruct::get(STy, Elts); 655 } 656 657 case CK_AddressSpaceConversion: 658 return llvm::ConstantExpr::getAddrSpaceCast(C, destType); 659 660 case CK_LValueToRValue: 661 case CK_AtomicToNonAtomic: 662 case CK_NonAtomicToAtomic: 663 case CK_NoOp: 664 case CK_ConstructorConversion: 665 return C; 666 667 case CK_Dependent: llvm_unreachable("saw dependent cast!"); 668 669 case CK_BuiltinFnToFnPtr: 670 llvm_unreachable("builtin functions are handled elsewhere"); 671 672 case CK_ReinterpretMemberPointer: 673 case CK_DerivedToBaseMemberPointer: 674 case CK_BaseToDerivedMemberPointer: 675 return CGM.getCXXABI().EmitMemberPointerConversion(E, C); 676 677 // These will never be supported. 678 case CK_ObjCObjectLValueCast: 679 case CK_ARCProduceObject: 680 case CK_ARCConsumeObject: 681 case CK_ARCReclaimReturnedObject: 682 case CK_ARCExtendBlockObject: 683 case CK_CopyAndAutoreleaseBlockObject: 684 return nullptr; 685 686 // These don't need to be handled here because Evaluate knows how to 687 // evaluate them in the cases where they can be folded. 688 case CK_BitCast: 689 case CK_ToVoid: 690 case CK_Dynamic: 691 case CK_LValueBitCast: 692 case CK_NullToMemberPointer: 693 case CK_UserDefinedConversion: 694 case CK_CPointerToObjCPointerCast: 695 case CK_BlockPointerToObjCPointerCast: 696 case CK_AnyPointerToBlockPointerCast: 697 case CK_ArrayToPointerDecay: 698 case CK_FunctionToPointerDecay: 699 case CK_BaseToDerived: 700 case CK_DerivedToBase: 701 case CK_UncheckedDerivedToBase: 702 case CK_MemberPointerToBoolean: 703 case CK_VectorSplat: 704 case CK_FloatingRealToComplex: 705 case CK_FloatingComplexToReal: 706 case CK_FloatingComplexToBoolean: 707 case CK_FloatingComplexCast: 708 case CK_FloatingComplexToIntegralComplex: 709 case CK_IntegralRealToComplex: 710 case CK_IntegralComplexToReal: 711 case CK_IntegralComplexToBoolean: 712 case CK_IntegralComplexCast: 713 case CK_IntegralComplexToFloatingComplex: 714 case CK_PointerToIntegral: 715 case CK_PointerToBoolean: 716 case CK_NullToPointer: 717 case CK_IntegralCast: 718 case CK_IntegralToPointer: 719 case CK_IntegralToBoolean: 720 case CK_IntegralToFloating: 721 case CK_FloatingToIntegral: 722 case CK_FloatingToBoolean: 723 case CK_FloatingCast: 724 case CK_ZeroToOCLEvent: 725 return nullptr; 726 } 727 llvm_unreachable("Invalid CastKind"); 728 } 729 730 llvm::Constant *VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) { 731 return Visit(DAE->getExpr()); 732 } 733 734 llvm::Constant *VisitCXXDefaultInitExpr(CXXDefaultInitExpr *DIE) { 735 // No need for a DefaultInitExprScope: we don't handle 'this' in a 736 // constant expression. 737 return Visit(DIE->getExpr()); 738 } 739 740 llvm::Constant *VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E) { 741 return Visit(E->GetTemporaryExpr()); 742 } 743 744 llvm::Constant *EmitArrayInitialization(InitListExpr *ILE) { 745 if (ILE->isStringLiteralInit()) 746 return Visit(ILE->getInit(0)); 747 748 llvm::ArrayType *AType = 749 cast<llvm::ArrayType>(ConvertType(ILE->getType())); 750 llvm::Type *ElemTy = AType->getElementType(); 751 unsigned NumInitElements = ILE->getNumInits(); 752 unsigned NumElements = AType->getNumElements(); 753 754 // Initialising an array requires us to automatically 755 // initialise any elements that have not been initialised explicitly 756 unsigned NumInitableElts = std::min(NumInitElements, NumElements); 757 758 // Initialize remaining array elements. 759 // FIXME: This doesn't handle member pointers correctly! 760 llvm::Constant *fillC; 761 if (Expr *filler = ILE->getArrayFiller()) 762 fillC = CGM.EmitConstantExpr(filler, filler->getType(), CGF); 763 else 764 fillC = llvm::Constant::getNullValue(ElemTy); 765 if (!fillC) 766 return nullptr; 767 768 // Try to use a ConstantAggregateZero if we can. 769 if (fillC->isNullValue() && !NumInitableElts) 770 return llvm::ConstantAggregateZero::get(AType); 771 772 // Copy initializer elements. 773 std::vector<llvm::Constant*> Elts; 774 Elts.reserve(NumInitableElts + NumElements); 775 776 bool RewriteType = false; 777 for (unsigned i = 0; i < NumInitableElts; ++i) { 778 Expr *Init = ILE->getInit(i); 779 llvm::Constant *C = CGM.EmitConstantExpr(Init, Init->getType(), CGF); 780 if (!C) 781 return nullptr; 782 RewriteType |= (C->getType() != ElemTy); 783 Elts.push_back(C); 784 } 785 786 RewriteType |= (fillC->getType() != ElemTy); 787 Elts.resize(NumElements, fillC); 788 789 if (RewriteType) { 790 // FIXME: Try to avoid packing the array 791 std::vector<llvm::Type*> Types; 792 Types.reserve(NumInitableElts + NumElements); 793 for (unsigned i = 0, e = Elts.size(); i < e; ++i) 794 Types.push_back(Elts[i]->getType()); 795 llvm::StructType *SType = llvm::StructType::get(AType->getContext(), 796 Types, true); 797 return llvm::ConstantStruct::get(SType, Elts); 798 } 799 800 return llvm::ConstantArray::get(AType, Elts); 801 } 802 803 llvm::Constant *EmitRecordInitialization(InitListExpr *ILE) { 804 return ConstStructBuilder::BuildStruct(CGM, CGF, ILE); 805 } 806 807 llvm::Constant *VisitImplicitValueInitExpr(ImplicitValueInitExpr* E) { 808 return CGM.EmitNullConstant(E->getType()); 809 } 810 811 llvm::Constant *VisitInitListExpr(InitListExpr *ILE) { 812 if (ILE->getType()->isArrayType()) 813 return EmitArrayInitialization(ILE); 814 815 if (ILE->getType()->isRecordType()) 816 return EmitRecordInitialization(ILE); 817 818 return nullptr; 819 } 820 821 llvm::Constant *VisitCXXConstructExpr(CXXConstructExpr *E) { 822 if (!E->getConstructor()->isTrivial()) 823 return nullptr; 824 825 QualType Ty = E->getType(); 826 827 // FIXME: We should not have to call getBaseElementType here. 828 const RecordType *RT = 829 CGM.getContext().getBaseElementType(Ty)->getAs<RecordType>(); 830 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); 831 832 // If the class doesn't have a trivial destructor, we can't emit it as a 833 // constant expr. 834 if (!RD->hasTrivialDestructor()) 835 return nullptr; 836 837 // Only copy and default constructors can be trivial. 838 839 840 if (E->getNumArgs()) { 841 assert(E->getNumArgs() == 1 && "trivial ctor with > 1 argument"); 842 assert(E->getConstructor()->isCopyOrMoveConstructor() && 843 "trivial ctor has argument but isn't a copy/move ctor"); 844 845 Expr *Arg = E->getArg(0); 846 assert(CGM.getContext().hasSameUnqualifiedType(Ty, Arg->getType()) && 847 "argument to copy ctor is of wrong type"); 848 849 return Visit(Arg); 850 } 851 852 return CGM.EmitNullConstant(Ty); 853 } 854 855 llvm::Constant *VisitStringLiteral(StringLiteral *E) { 856 return CGM.GetConstantArrayFromStringLiteral(E); 857 } 858 859 llvm::Constant *VisitObjCEncodeExpr(ObjCEncodeExpr *E) { 860 // This must be an @encode initializing an array in a static initializer. 861 // Don't emit it as the address of the string, emit the string data itself 862 // as an inline array. 863 std::string Str; 864 CGM.getContext().getObjCEncodingForType(E->getEncodedType(), Str); 865 QualType T = E->getType(); 866 if (T->getTypeClass() == Type::TypeOfExpr) 867 T = cast<TypeOfExprType>(T)->getUnderlyingExpr()->getType(); 868 const ConstantArrayType *CAT = cast<ConstantArrayType>(T); 869 870 // Resize the string to the right size, adding zeros at the end, or 871 // truncating as needed. 872 Str.resize(CAT->getSize().getZExtValue(), '\0'); 873 return llvm::ConstantDataArray::getString(VMContext, Str, false); 874 } 875 876 llvm::Constant *VisitUnaryExtension(const UnaryOperator *E) { 877 return Visit(E->getSubExpr()); 878 } 879 880 // Utility methods 881 llvm::Type *ConvertType(QualType T) { 882 return CGM.getTypes().ConvertType(T); 883 } 884 885 public: 886 llvm::Constant *EmitLValue(APValue::LValueBase LVBase) { 887 if (const ValueDecl *Decl = LVBase.dyn_cast<const ValueDecl*>()) { 888 if (Decl->hasAttr<WeakRefAttr>()) 889 return CGM.GetWeakRefReference(Decl); 890 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Decl)) 891 return CGM.GetAddrOfFunction(FD); 892 if (const VarDecl* VD = dyn_cast<VarDecl>(Decl)) { 893 // We can never refer to a variable with local storage. 894 if (!VD->hasLocalStorage()) { 895 if (VD->isFileVarDecl() || VD->hasExternalStorage()) 896 return CGM.GetAddrOfGlobalVar(VD); 897 else if (VD->isLocalVarDecl()) 898 return CGM.getOrCreateStaticVarDecl( 899 *VD, CGM.getLLVMLinkageVarDefinition(VD, /*isConstant=*/false)); 900 } 901 } 902 return nullptr; 903 } 904 905 Expr *E = const_cast<Expr*>(LVBase.get<const Expr*>()); 906 switch (E->getStmtClass()) { 907 default: break; 908 case Expr::CompoundLiteralExprClass: { 909 // Note that due to the nature of compound literals, this is guaranteed 910 // to be the only use of the variable, so we just generate it here. 911 CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E); 912 llvm::Constant* C = CGM.EmitConstantExpr(CLE->getInitializer(), 913 CLE->getType(), CGF); 914 // FIXME: "Leaked" on failure. 915 if (C) 916 C = new llvm::GlobalVariable(CGM.getModule(), C->getType(), 917 E->getType().isConstant(CGM.getContext()), 918 llvm::GlobalValue::InternalLinkage, 919 C, ".compoundliteral", nullptr, 920 llvm::GlobalVariable::NotThreadLocal, 921 CGM.getContext().getTargetAddressSpace(E->getType())); 922 return C; 923 } 924 case Expr::StringLiteralClass: 925 return CGM.GetAddrOfConstantStringFromLiteral(cast<StringLiteral>(E)); 926 case Expr::ObjCEncodeExprClass: 927 return CGM.GetAddrOfConstantStringFromObjCEncode(cast<ObjCEncodeExpr>(E)); 928 case Expr::ObjCStringLiteralClass: { 929 ObjCStringLiteral* SL = cast<ObjCStringLiteral>(E); 930 llvm::Constant *C = 931 CGM.getObjCRuntime().GenerateConstantString(SL->getString()); 932 return llvm::ConstantExpr::getBitCast(C, ConvertType(E->getType())); 933 } 934 case Expr::PredefinedExprClass: { 935 unsigned Type = cast<PredefinedExpr>(E)->getIdentType(); 936 if (CGF) { 937 LValue Res = CGF->EmitPredefinedLValue(cast<PredefinedExpr>(E)); 938 return cast<llvm::Constant>(Res.getAddress()); 939 } else if (Type == PredefinedExpr::PrettyFunction) { 940 return CGM.GetAddrOfConstantCString("top level", ".tmp"); 941 } 942 943 return CGM.GetAddrOfConstantCString("", ".tmp"); 944 } 945 case Expr::AddrLabelExprClass: { 946 assert(CGF && "Invalid address of label expression outside function."); 947 llvm::Constant *Ptr = 948 CGF->GetAddrOfLabel(cast<AddrLabelExpr>(E)->getLabel()); 949 return llvm::ConstantExpr::getBitCast(Ptr, ConvertType(E->getType())); 950 } 951 case Expr::CallExprClass: { 952 CallExpr* CE = cast<CallExpr>(E); 953 unsigned builtin = CE->getBuiltinCallee(); 954 if (builtin != 955 Builtin::BI__builtin___CFStringMakeConstantString && 956 builtin != 957 Builtin::BI__builtin___NSStringMakeConstantString) 958 break; 959 const Expr *Arg = CE->getArg(0)->IgnoreParenCasts(); 960 const StringLiteral *Literal = cast<StringLiteral>(Arg); 961 if (builtin == 962 Builtin::BI__builtin___NSStringMakeConstantString) { 963 return CGM.getObjCRuntime().GenerateConstantString(Literal); 964 } 965 // FIXME: need to deal with UCN conversion issues. 966 return CGM.GetAddrOfConstantCFString(Literal); 967 } 968 case Expr::BlockExprClass: { 969 std::string FunctionName; 970 if (CGF) 971 FunctionName = CGF->CurFn->getName(); 972 else 973 FunctionName = "global"; 974 975 return CGM.GetAddrOfGlobalBlock(cast<BlockExpr>(E), FunctionName.c_str()); 976 } 977 case Expr::CXXTypeidExprClass: { 978 CXXTypeidExpr *Typeid = cast<CXXTypeidExpr>(E); 979 QualType T; 980 if (Typeid->isTypeOperand()) 981 T = Typeid->getTypeOperand(CGM.getContext()); 982 else 983 T = Typeid->getExprOperand()->getType(); 984 return CGM.GetAddrOfRTTIDescriptor(T); 985 } 986 case Expr::CXXUuidofExprClass: { 987 return CGM.GetAddrOfUuidDescriptor(cast<CXXUuidofExpr>(E)); 988 } 989 case Expr::MaterializeTemporaryExprClass: { 990 MaterializeTemporaryExpr *MTE = cast<MaterializeTemporaryExpr>(E); 991 assert(MTE->getStorageDuration() == SD_Static); 992 SmallVector<const Expr *, 2> CommaLHSs; 993 SmallVector<SubobjectAdjustment, 2> Adjustments; 994 const Expr *Inner = MTE->GetTemporaryExpr() 995 ->skipRValueSubobjectAdjustments(CommaLHSs, Adjustments); 996 return CGM.GetAddrOfGlobalTemporary(MTE, Inner); 997 } 998 } 999 1000 return nullptr; 1001 } 1002 }; 1003 1004 } // end anonymous namespace. 1005 1006 llvm::Constant *CodeGenModule::EmitConstantInit(const VarDecl &D, 1007 CodeGenFunction *CGF) { 1008 // Make a quick check if variable can be default NULL initialized 1009 // and avoid going through rest of code which may do, for c++11, 1010 // initialization of memory to all NULLs. 1011 if (!D.hasLocalStorage()) { 1012 QualType Ty = D.getType(); 1013 if (Ty->isArrayType()) 1014 Ty = Context.getBaseElementType(Ty); 1015 if (Ty->isRecordType()) 1016 if (const CXXConstructExpr *E = 1017 dyn_cast_or_null<CXXConstructExpr>(D.getInit())) { 1018 const CXXConstructorDecl *CD = E->getConstructor(); 1019 if (CD->isTrivial() && CD->isDefaultConstructor()) 1020 return EmitNullConstant(D.getType()); 1021 } 1022 } 1023 1024 if (const APValue *Value = D.evaluateValue()) 1025 return EmitConstantValueForMemory(*Value, D.getType(), CGF); 1026 1027 // FIXME: Implement C++11 [basic.start.init]p2: if the initializer of a 1028 // reference is a constant expression, and the reference binds to a temporary, 1029 // then constant initialization is performed. ConstExprEmitter will 1030 // incorrectly emit a prvalue constant in this case, and the calling code 1031 // interprets that as the (pointer) value of the reference, rather than the 1032 // desired value of the referee. 1033 if (D.getType()->isReferenceType()) 1034 return nullptr; 1035 1036 const Expr *E = D.getInit(); 1037 assert(E && "No initializer to emit"); 1038 1039 llvm::Constant* C = ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E)); 1040 if (C && C->getType()->isIntegerTy(1)) { 1041 llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType()); 1042 C = llvm::ConstantExpr::getZExt(C, BoolTy); 1043 } 1044 return C; 1045 } 1046 1047 llvm::Constant *CodeGenModule::EmitConstantExpr(const Expr *E, 1048 QualType DestType, 1049 CodeGenFunction *CGF) { 1050 Expr::EvalResult Result; 1051 1052 bool Success = false; 1053 1054 if (DestType->isReferenceType()) 1055 Success = E->EvaluateAsLValue(Result, Context); 1056 else 1057 Success = E->EvaluateAsRValue(Result, Context); 1058 1059 llvm::Constant *C = nullptr; 1060 if (Success && !Result.HasSideEffects) 1061 C = EmitConstantValue(Result.Val, DestType, CGF); 1062 else 1063 C = ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E)); 1064 1065 if (C && C->getType()->isIntegerTy(1)) { 1066 llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType()); 1067 C = llvm::ConstantExpr::getZExt(C, BoolTy); 1068 } 1069 return C; 1070 } 1071 1072 llvm::Constant *CodeGenModule::EmitConstantValue(const APValue &Value, 1073 QualType DestType, 1074 CodeGenFunction *CGF) { 1075 // For an _Atomic-qualified constant, we may need to add tail padding. 1076 if (auto *AT = DestType->getAs<AtomicType>()) { 1077 QualType InnerType = AT->getValueType(); 1078 auto *Inner = EmitConstantValue(Value, InnerType, CGF); 1079 1080 uint64_t InnerSize = Context.getTypeSize(InnerType); 1081 uint64_t OuterSize = Context.getTypeSize(DestType); 1082 if (InnerSize == OuterSize) 1083 return Inner; 1084 1085 assert(InnerSize < OuterSize && "emitted over-large constant for atomic"); 1086 llvm::Constant *Elts[] = { 1087 Inner, 1088 llvm::ConstantAggregateZero::get( 1089 llvm::ArrayType::get(Int8Ty, (OuterSize - InnerSize) / 8)) 1090 }; 1091 return llvm::ConstantStruct::getAnon(Elts); 1092 } 1093 1094 switch (Value.getKind()) { 1095 case APValue::Uninitialized: 1096 llvm_unreachable("Constant expressions should be initialized."); 1097 case APValue::LValue: { 1098 llvm::Type *DestTy = getTypes().ConvertTypeForMem(DestType); 1099 llvm::Constant *Offset = 1100 llvm::ConstantInt::get(Int64Ty, Value.getLValueOffset().getQuantity()); 1101 1102 llvm::Constant *C; 1103 if (APValue::LValueBase LVBase = Value.getLValueBase()) { 1104 // An array can be represented as an lvalue referring to the base. 1105 if (isa<llvm::ArrayType>(DestTy)) { 1106 assert(Offset->isNullValue() && "offset on array initializer"); 1107 return ConstExprEmitter(*this, CGF).Visit( 1108 const_cast<Expr*>(LVBase.get<const Expr*>())); 1109 } 1110 1111 C = ConstExprEmitter(*this, CGF).EmitLValue(LVBase); 1112 1113 // Apply offset if necessary. 1114 if (!Offset->isNullValue()) { 1115 unsigned AS = C->getType()->getPointerAddressSpace(); 1116 llvm::Type *CharPtrTy = Int8Ty->getPointerTo(AS); 1117 llvm::Constant *Casted = llvm::ConstantExpr::getBitCast(C, CharPtrTy); 1118 Casted = llvm::ConstantExpr::getGetElementPtr(Int8Ty, Casted, Offset); 1119 C = llvm::ConstantExpr::getPointerCast(Casted, C->getType()); 1120 } 1121 1122 // Convert to the appropriate type; this could be an lvalue for 1123 // an integer. 1124 if (isa<llvm::PointerType>(DestTy)) 1125 return llvm::ConstantExpr::getPointerCast(C, DestTy); 1126 1127 return llvm::ConstantExpr::getPtrToInt(C, DestTy); 1128 } else { 1129 C = Offset; 1130 1131 // Convert to the appropriate type; this could be an lvalue for 1132 // an integer. 1133 if (isa<llvm::PointerType>(DestTy)) 1134 return llvm::ConstantExpr::getIntToPtr(C, DestTy); 1135 1136 // If the types don't match this should only be a truncate. 1137 if (C->getType() != DestTy) 1138 return llvm::ConstantExpr::getTrunc(C, DestTy); 1139 1140 return C; 1141 } 1142 } 1143 case APValue::Int: 1144 return llvm::ConstantInt::get(VMContext, Value.getInt()); 1145 case APValue::ComplexInt: { 1146 llvm::Constant *Complex[2]; 1147 1148 Complex[0] = llvm::ConstantInt::get(VMContext, 1149 Value.getComplexIntReal()); 1150 Complex[1] = llvm::ConstantInt::get(VMContext, 1151 Value.getComplexIntImag()); 1152 1153 // FIXME: the target may want to specify that this is packed. 1154 llvm::StructType *STy = llvm::StructType::get(Complex[0]->getType(), 1155 Complex[1]->getType(), 1156 nullptr); 1157 return llvm::ConstantStruct::get(STy, Complex); 1158 } 1159 case APValue::Float: { 1160 const llvm::APFloat &Init = Value.getFloat(); 1161 if (&Init.getSemantics() == &llvm::APFloat::IEEEhalf && 1162 !Context.getLangOpts().NativeHalfType && 1163 !Context.getLangOpts().HalfArgsAndReturns) 1164 return llvm::ConstantInt::get(VMContext, Init.bitcastToAPInt()); 1165 else 1166 return llvm::ConstantFP::get(VMContext, Init); 1167 } 1168 case APValue::ComplexFloat: { 1169 llvm::Constant *Complex[2]; 1170 1171 Complex[0] = llvm::ConstantFP::get(VMContext, 1172 Value.getComplexFloatReal()); 1173 Complex[1] = llvm::ConstantFP::get(VMContext, 1174 Value.getComplexFloatImag()); 1175 1176 // FIXME: the target may want to specify that this is packed. 1177 llvm::StructType *STy = llvm::StructType::get(Complex[0]->getType(), 1178 Complex[1]->getType(), 1179 nullptr); 1180 return llvm::ConstantStruct::get(STy, Complex); 1181 } 1182 case APValue::Vector: { 1183 SmallVector<llvm::Constant *, 4> Inits; 1184 unsigned NumElts = Value.getVectorLength(); 1185 1186 for (unsigned i = 0; i != NumElts; ++i) { 1187 const APValue &Elt = Value.getVectorElt(i); 1188 if (Elt.isInt()) 1189 Inits.push_back(llvm::ConstantInt::get(VMContext, Elt.getInt())); 1190 else 1191 Inits.push_back(llvm::ConstantFP::get(VMContext, Elt.getFloat())); 1192 } 1193 return llvm::ConstantVector::get(Inits); 1194 } 1195 case APValue::AddrLabelDiff: { 1196 const AddrLabelExpr *LHSExpr = Value.getAddrLabelDiffLHS(); 1197 const AddrLabelExpr *RHSExpr = Value.getAddrLabelDiffRHS(); 1198 llvm::Constant *LHS = EmitConstantExpr(LHSExpr, LHSExpr->getType(), CGF); 1199 llvm::Constant *RHS = EmitConstantExpr(RHSExpr, RHSExpr->getType(), CGF); 1200 1201 // Compute difference 1202 llvm::Type *ResultType = getTypes().ConvertType(DestType); 1203 LHS = llvm::ConstantExpr::getPtrToInt(LHS, IntPtrTy); 1204 RHS = llvm::ConstantExpr::getPtrToInt(RHS, IntPtrTy); 1205 llvm::Constant *AddrLabelDiff = llvm::ConstantExpr::getSub(LHS, RHS); 1206 1207 // LLVM is a bit sensitive about the exact format of the 1208 // address-of-label difference; make sure to truncate after 1209 // the subtraction. 1210 return llvm::ConstantExpr::getTruncOrBitCast(AddrLabelDiff, ResultType); 1211 } 1212 case APValue::Struct: 1213 case APValue::Union: 1214 return ConstStructBuilder::BuildStruct(*this, CGF, Value, DestType); 1215 case APValue::Array: { 1216 const ArrayType *CAT = Context.getAsArrayType(DestType); 1217 unsigned NumElements = Value.getArraySize(); 1218 unsigned NumInitElts = Value.getArrayInitializedElts(); 1219 1220 // Emit array filler, if there is one. 1221 llvm::Constant *Filler = nullptr; 1222 if (Value.hasArrayFiller()) 1223 Filler = EmitConstantValueForMemory(Value.getArrayFiller(), 1224 CAT->getElementType(), CGF); 1225 1226 // Emit initializer elements. 1227 llvm::Type *CommonElementType = 1228 getTypes().ConvertType(CAT->getElementType()); 1229 1230 // Try to use a ConstantAggregateZero if we can. 1231 if (Filler && Filler->isNullValue() && !NumInitElts) { 1232 llvm::ArrayType *AType = 1233 llvm::ArrayType::get(CommonElementType, NumElements); 1234 return llvm::ConstantAggregateZero::get(AType); 1235 } 1236 1237 std::vector<llvm::Constant*> Elts; 1238 Elts.reserve(NumElements); 1239 for (unsigned I = 0; I < NumElements; ++I) { 1240 llvm::Constant *C = Filler; 1241 if (I < NumInitElts) 1242 C = EmitConstantValueForMemory(Value.getArrayInitializedElt(I), 1243 CAT->getElementType(), CGF); 1244 else 1245 assert(Filler && "Missing filler for implicit elements of initializer"); 1246 if (I == 0) 1247 CommonElementType = C->getType(); 1248 else if (C->getType() != CommonElementType) 1249 CommonElementType = nullptr; 1250 Elts.push_back(C); 1251 } 1252 1253 if (!CommonElementType) { 1254 // FIXME: Try to avoid packing the array 1255 std::vector<llvm::Type*> Types; 1256 Types.reserve(NumElements); 1257 for (unsigned i = 0, e = Elts.size(); i < e; ++i) 1258 Types.push_back(Elts[i]->getType()); 1259 llvm::StructType *SType = llvm::StructType::get(VMContext, Types, true); 1260 return llvm::ConstantStruct::get(SType, Elts); 1261 } 1262 1263 llvm::ArrayType *AType = 1264 llvm::ArrayType::get(CommonElementType, NumElements); 1265 return llvm::ConstantArray::get(AType, Elts); 1266 } 1267 case APValue::MemberPointer: 1268 return getCXXABI().EmitMemberPointer(Value, DestType); 1269 } 1270 llvm_unreachable("Unknown APValue kind"); 1271 } 1272 1273 llvm::Constant * 1274 CodeGenModule::EmitConstantValueForMemory(const APValue &Value, 1275 QualType DestType, 1276 CodeGenFunction *CGF) { 1277 llvm::Constant *C = EmitConstantValue(Value, DestType, CGF); 1278 if (C->getType()->isIntegerTy(1)) { 1279 llvm::Type *BoolTy = getTypes().ConvertTypeForMem(DestType); 1280 C = llvm::ConstantExpr::getZExt(C, BoolTy); 1281 } 1282 return C; 1283 } 1284 1285 llvm::Constant * 1286 CodeGenModule::GetAddrOfConstantCompoundLiteral(const CompoundLiteralExpr *E) { 1287 assert(E->isFileScope() && "not a file-scope compound literal expr"); 1288 return ConstExprEmitter(*this, nullptr).EmitLValue(E); 1289 } 1290 1291 llvm::Constant * 1292 CodeGenModule::getMemberPointerConstant(const UnaryOperator *uo) { 1293 // Member pointer constants always have a very particular form. 1294 const MemberPointerType *type = cast<MemberPointerType>(uo->getType()); 1295 const ValueDecl *decl = cast<DeclRefExpr>(uo->getSubExpr())->getDecl(); 1296 1297 // A member function pointer. 1298 if (const CXXMethodDecl *method = dyn_cast<CXXMethodDecl>(decl)) 1299 return getCXXABI().EmitMemberPointer(method); 1300 1301 // Otherwise, a member data pointer. 1302 uint64_t fieldOffset = getContext().getFieldOffset(decl); 1303 CharUnits chars = getContext().toCharUnitsFromBits((int64_t) fieldOffset); 1304 return getCXXABI().EmitMemberDataPointer(type, chars); 1305 } 1306 1307 static llvm::Constant *EmitNullConstantForBase(CodeGenModule &CGM, 1308 llvm::Type *baseType, 1309 const CXXRecordDecl *base); 1310 1311 static llvm::Constant *EmitNullConstant(CodeGenModule &CGM, 1312 const CXXRecordDecl *record, 1313 bool asCompleteObject) { 1314 const CGRecordLayout &layout = CGM.getTypes().getCGRecordLayout(record); 1315 llvm::StructType *structure = 1316 (asCompleteObject ? layout.getLLVMType() 1317 : layout.getBaseSubobjectLLVMType()); 1318 1319 unsigned numElements = structure->getNumElements(); 1320 std::vector<llvm::Constant *> elements(numElements); 1321 1322 // Fill in all the bases. 1323 for (const auto &I : record->bases()) { 1324 if (I.isVirtual()) { 1325 // Ignore virtual bases; if we're laying out for a complete 1326 // object, we'll lay these out later. 1327 continue; 1328 } 1329 1330 const CXXRecordDecl *base = 1331 cast<CXXRecordDecl>(I.getType()->castAs<RecordType>()->getDecl()); 1332 1333 // Ignore empty bases. 1334 if (base->isEmpty()) 1335 continue; 1336 1337 unsigned fieldIndex = layout.getNonVirtualBaseLLVMFieldNo(base); 1338 llvm::Type *baseType = structure->getElementType(fieldIndex); 1339 elements[fieldIndex] = EmitNullConstantForBase(CGM, baseType, base); 1340 } 1341 1342 // Fill in all the fields. 1343 for (const auto *Field : record->fields()) { 1344 // Fill in non-bitfields. (Bitfields always use a zero pattern, which we 1345 // will fill in later.) 1346 if (!Field->isBitField()) { 1347 unsigned fieldIndex = layout.getLLVMFieldNo(Field); 1348 elements[fieldIndex] = CGM.EmitNullConstant(Field->getType()); 1349 } 1350 1351 // For unions, stop after the first named field. 1352 if (record->isUnion() && Field->getDeclName()) 1353 break; 1354 } 1355 1356 // Fill in the virtual bases, if we're working with the complete object. 1357 if (asCompleteObject) { 1358 for (const auto &I : record->vbases()) { 1359 const CXXRecordDecl *base = 1360 cast<CXXRecordDecl>(I.getType()->castAs<RecordType>()->getDecl()); 1361 1362 // Ignore empty bases. 1363 if (base->isEmpty()) 1364 continue; 1365 1366 unsigned fieldIndex = layout.getVirtualBaseIndex(base); 1367 1368 // We might have already laid this field out. 1369 if (elements[fieldIndex]) continue; 1370 1371 llvm::Type *baseType = structure->getElementType(fieldIndex); 1372 elements[fieldIndex] = EmitNullConstantForBase(CGM, baseType, base); 1373 } 1374 } 1375 1376 // Now go through all other fields and zero them out. 1377 for (unsigned i = 0; i != numElements; ++i) { 1378 if (!elements[i]) 1379 elements[i] = llvm::Constant::getNullValue(structure->getElementType(i)); 1380 } 1381 1382 return llvm::ConstantStruct::get(structure, elements); 1383 } 1384 1385 /// Emit the null constant for a base subobject. 1386 static llvm::Constant *EmitNullConstantForBase(CodeGenModule &CGM, 1387 llvm::Type *baseType, 1388 const CXXRecordDecl *base) { 1389 const CGRecordLayout &baseLayout = CGM.getTypes().getCGRecordLayout(base); 1390 1391 // Just zero out bases that don't have any pointer to data members. 1392 if (baseLayout.isZeroInitializableAsBase()) 1393 return llvm::Constant::getNullValue(baseType); 1394 1395 // Otherwise, we can just use its null constant. 1396 return EmitNullConstant(CGM, base, /*asCompleteObject=*/false); 1397 } 1398 1399 llvm::Constant *CodeGenModule::EmitNullConstant(QualType T) { 1400 if (getTypes().isZeroInitializable(T)) 1401 return llvm::Constant::getNullValue(getTypes().ConvertTypeForMem(T)); 1402 1403 if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(T)) { 1404 llvm::ArrayType *ATy = 1405 cast<llvm::ArrayType>(getTypes().ConvertTypeForMem(T)); 1406 1407 QualType ElementTy = CAT->getElementType(); 1408 1409 llvm::Constant *Element = EmitNullConstant(ElementTy); 1410 unsigned NumElements = CAT->getSize().getZExtValue(); 1411 1412 if (Element->isNullValue()) 1413 return llvm::ConstantAggregateZero::get(ATy); 1414 1415 SmallVector<llvm::Constant *, 8> Array(NumElements, Element); 1416 return llvm::ConstantArray::get(ATy, Array); 1417 } 1418 1419 if (const RecordType *RT = T->getAs<RecordType>()) { 1420 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); 1421 return ::EmitNullConstant(*this, RD, /*complete object*/ true); 1422 } 1423 1424 assert(T->isMemberPointerType() && "Should only see member pointers here!"); 1425 assert(!T->getAs<MemberPointerType>()->getPointeeType()->isFunctionType() && 1426 "Should only see pointers to data members here!"); 1427 1428 return getCXXABI().EmitNullMemberPointer(T->castAs<MemberPointerType>()); 1429 } 1430 1431 llvm::Constant * 1432 CodeGenModule::EmitNullConstantForBase(const CXXRecordDecl *Record) { 1433 return ::EmitNullConstant(*this, Record, false); 1434 } 1435