CGExprConstant.cpp revision 208600
15897Sjmz//===--- CGExprConstant.cpp - Emit LLVM Code from Constant Expressions ----===// 25897Sjmz// 35897Sjmz// The LLVM Compiler Infrastructure 45897Sjmz// 55897Sjmz// This file is distributed under the University of Illinois Open Source 65897Sjmz// License. See LICENSE.TXT for details. 75897Sjmz// 85897Sjmz//===----------------------------------------------------------------------===// 95897Sjmz// 105897Sjmz// This contains code to emit Constant Expr nodes as LLVM code. 115897Sjmz// 125897Sjmz//===----------------------------------------------------------------------===// 135897Sjmz 145897Sjmz#include "CodeGenFunction.h" 155897Sjmz#include "CodeGenModule.h" 165897Sjmz#include "CGObjCRuntime.h" 175897Sjmz#include "CGRecordLayout.h" 185897Sjmz#include "clang/AST/APValue.h" 195897Sjmz#include "clang/AST/ASTContext.h" 205897Sjmz#include "clang/AST/RecordLayout.h" 215897Sjmz#include "clang/AST/StmtVisitor.h" 225897Sjmz#include "clang/Basic/Builtins.h" 235897Sjmz#include "llvm/Constants.h" 245897Sjmz#include "llvm/Function.h" 255897Sjmz#include "llvm/GlobalVariable.h" 265897Sjmz#include "llvm/Target/TargetData.h" 275897Sjmzusing namespace clang; 285897Sjmzusing namespace CodeGen; 295897Sjmz 305897Sjmz//===----------------------------------------------------------------------===// 315897Sjmz// ConstStructBuilder 325897Sjmz//===----------------------------------------------------------------------===// 3332726Seivind 3432726Seivindnamespace { 357430Sbdeclass ConstStructBuilder { 367430Sbde CodeGenModule &CGM; 3712675Sjulian CodeGenFunction *CGF; 3812675Sjulian 3912675Sjulian bool Packed; 4012675Sjulian unsigned NextFieldOffsetInBytes; 4112675Sjulian unsigned LLVMStructAlignment; 4234924Sbde std::vector<llvm::Constant *> Elements; 436734Sbdepublic: 4412854Sbde static llvm::Constant *BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF, 456734Sbde InitListExpr *ILE); 466734Sbde 475897Sjmzprivate: 486734Sbde ConstStructBuilder(CodeGenModule &CGM, CodeGenFunction *CGF) 495897Sjmz : CGM(CGM), CGF(CGF), Packed(false), NextFieldOffsetInBytes(0), 505897Sjmz LLVMStructAlignment(1) { } 518876Srgrimes 525897Sjmz bool AppendField(const FieldDecl *Field, uint64_t FieldOffset, 535897Sjmz llvm::Constant *InitExpr); 545897Sjmz 555897Sjmz bool AppendBitField(const FieldDecl *Field, uint64_t FieldOffset, 565897Sjmz llvm::Constant *InitExpr); 575897Sjmz 585897Sjmz void AppendPadding(uint64_t NumBytes); 595897Sjmz 605897Sjmz void AppendTailPadding(uint64_t RecordSize); 615897Sjmz 628876Srgrimes void ConvertStructToPacked(); 635993Sjmz 645998Sjmz bool Build(InitListExpr *ILE); 655998Sjmz 665897Sjmz unsigned getAlignment(const llvm::Constant *C) const { 675897Sjmz if (Packed) return 1; 6846570Speter return CGM.getTargetData().getABITypeAlignment(C->getType()); 6946570Speter } 705897Sjmz 715897Sjmz uint64_t getSizeInBytes(const llvm::Constant *C) const { 725897Sjmz return CGM.getTargetData().getTypeAllocSize(C->getType()); 735897Sjmz } 745897Sjmz}; 755897Sjmz 765897Sjmzbool ConstStructBuilder:: 775897SjmzAppendField(const FieldDecl *Field, uint64_t FieldOffset, 7812675Sjulian llvm::Constant *InitCst) { 7912675Sjulian uint64_t FieldOffsetInBytes = FieldOffset / 8; 8012675Sjulian 815897Sjmz assert(NextFieldOffsetInBytes <= FieldOffsetInBytes 825897Sjmz && "Field offset mismatch!"); 835897Sjmz 8412724Sphk // Emit the field. 8512724Sphk if (!InitCst) 865897Sjmz return false; 875897Sjmz 885897Sjmz unsigned FieldAlignment = getAlignment(InitCst); 8912675Sjulian 9012675Sjulian // Round up the field offset to the alignment of the field type. 9112675Sjulian uint64_t AlignedNextFieldOffsetInBytes = 9212675Sjulian llvm::RoundUpToAlignment(NextFieldOffsetInBytes, FieldAlignment); 9312675Sjulian 9412675Sjulian if (AlignedNextFieldOffsetInBytes > FieldOffsetInBytes) { 9512678Sphk assert(!Packed && "Alignment is wrong even with a packed struct!"); 9612675Sjulian 9712675Sjulian // Convert the struct to a packed struct. 9812675Sjulian ConvertStructToPacked(); 9912675Sjulian 10012854Sbde AlignedNextFieldOffsetInBytes = NextFieldOffsetInBytes; 1015897Sjmz } 1025897Sjmz 10312724Sphk if (AlignedNextFieldOffsetInBytes < FieldOffsetInBytes) { 1045897Sjmz // We need to append padding. 1055897Sjmz AppendPadding(FieldOffsetInBytes - NextFieldOffsetInBytes); 1065897Sjmz 1075897Sjmz assert(NextFieldOffsetInBytes == FieldOffsetInBytes && 1085897Sjmz "Did not add enough padding!"); 1095897Sjmz 1105897Sjmz AlignedNextFieldOffsetInBytes = NextFieldOffsetInBytes; 1115897Sjmz } 1125897Sjmz 1135897Sjmz // Add the field. 1145897Sjmz Elements.push_back(InitCst); 11512724Sphk NextFieldOffsetInBytes = AlignedNextFieldOffsetInBytes + 1165897Sjmz getSizeInBytes(InitCst); 1175897Sjmz 11812675Sjulian if (Packed) 1195897Sjmz assert(LLVMStructAlignment == 1 && "Packed struct not byte-aligned!"); 12012675Sjulian else 12112675Sjulian LLVMStructAlignment = std::max(LLVMStructAlignment, FieldAlignment); 12212675Sjulian 12312675Sjulian return true; 12414873Sscrappy} 12514873Sscrappy 12614873Sscrappybool ConstStructBuilder:: 12712675Sjulian AppendBitField(const FieldDecl *Field, uint64_t FieldOffset, 1285897Sjmz llvm::Constant *InitCst) { 1295897Sjmz llvm::ConstantInt *CI = cast_or_null<llvm::ConstantInt>(InitCst); 1305897Sjmz // FIXME: Can this ever happen? 13112675Sjulian if (!CI) 13210644Sbde return false; 1335897Sjmz 1345897Sjmz if (FieldOffset > NextFieldOffsetInBytes * 8) { 1355897Sjmz // We need to add padding. 1365897Sjmz uint64_t NumBytes = 1375897Sjmz llvm::RoundUpToAlignment(FieldOffset - 1385897Sjmz NextFieldOffsetInBytes * 8, 8) / 8; 1395897Sjmz 1405897Sjmz AppendPadding(NumBytes); 1415897Sjmz } 1425897Sjmz 14312675Sjulian uint64_t FieldSize = 14410644Sbde Field->getBitWidth()->EvaluateAsInt(CGM.getContext()).getZExtValue(); 1455897Sjmz 1465897Sjmz llvm::APInt FieldValue = CI->getValue(); 1475897Sjmz 1485897Sjmz // Promote the size of FieldValue if necessary 1495897Sjmz // FIXME: This should never occur, but currently it can because initializer 1505897Sjmz // constants are cast to bool, and because clang is not enforcing bitfield 1515897Sjmz // width limits. 1525897Sjmz if (FieldSize > FieldValue.getBitWidth()) 15312675Sjulian FieldValue.zext(FieldSize); 1545897Sjmz 1555897Sjmz // Truncate the size of FieldValue to the bit field size. 1565897Sjmz if (FieldSize < FieldValue.getBitWidth()) 1575897Sjmz FieldValue.trunc(FieldSize); 1585897Sjmz 1595897Sjmz if (FieldOffset < NextFieldOffsetInBytes * 8) { 1606644Sjmz // Either part of the field or the entire field can go into the previous 1618876Srgrimes // byte. 1625897Sjmz assert(!Elements.empty() && "Elements can't be empty!"); 1635897Sjmz 1645897Sjmz unsigned BitsInPreviousByte = 1655897Sjmz NextFieldOffsetInBytes * 8 - FieldOffset; 1665897Sjmz 1675897Sjmz bool FitsCompletelyInPreviousByte = 1685897Sjmz BitsInPreviousByte >= FieldValue.getBitWidth(); 1698876Srgrimes 1705897Sjmz llvm::APInt Tmp = FieldValue; 1715897Sjmz 1725897Sjmz if (!FitsCompletelyInPreviousByte) { 1735993Sjmz unsigned NewFieldWidth = FieldSize - BitsInPreviousByte; 1745897Sjmz 1755897Sjmz if (CGM.getTargetData().isBigEndian()) { 1765897Sjmz Tmp = Tmp.lshr(NewFieldWidth); 1775897Sjmz Tmp.trunc(BitsInPreviousByte); 1788876Srgrimes 1795897Sjmz // We want the remaining high bits. 1805897Sjmz FieldValue.trunc(NewFieldWidth); 1815897Sjmz } else { 1826644Sjmz Tmp.trunc(BitsInPreviousByte); 1836644Sjmz 1845897Sjmz // We want the remaining low bits. 1856644Sjmz FieldValue = FieldValue.lshr(BitsInPreviousByte); 1866644Sjmz FieldValue.trunc(NewFieldWidth); 1877430Sbde } 1885897Sjmz } 18912675Sjulian 19012675Sjulian Tmp.zext(8); 19136735Sdfr if (CGM.getTargetData().isBigEndian()) { 1925897Sjmz if (FitsCompletelyInPreviousByte) 1935897Sjmz Tmp = Tmp.shl(BitsInPreviousByte - FieldValue.getBitWidth()); 1945897Sjmz } else { 1955897Sjmz Tmp = Tmp.shl(8 - BitsInPreviousByte); 1965897Sjmz } 1975897Sjmz 1985897Sjmz // Or in the bits that go into the previous byte. 1995897Sjmz if (llvm::ConstantInt *Val = dyn_cast<llvm::ConstantInt>(Elements.back())) 2005897Sjmz Tmp |= Val->getValue(); 2015897Sjmz else 2025897Sjmz assert(isa<llvm::UndefValue>(Elements.back())); 2035897Sjmz 2045897Sjmz Elements.back() = llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp); 2055897Sjmz 2065897Sjmz if (FitsCompletelyInPreviousByte) 2075897Sjmz return true; 2085897Sjmz } 2095897Sjmz 2105897Sjmz while (FieldValue.getBitWidth() > 8) { 2115897Sjmz llvm::APInt Tmp; 2125897Sjmz 2135897Sjmz if (CGM.getTargetData().isBigEndian()) { 2145897Sjmz // We want the high bits. 2155897Sjmz Tmp = FieldValue; 2165897Sjmz Tmp = Tmp.lshr(Tmp.getBitWidth() - 8); 2175897Sjmz Tmp.trunc(8); 2185897Sjmz } else { 2195897Sjmz // We want the low bits. 2205897Sjmz Tmp = FieldValue; 2215897Sjmz Tmp.trunc(8); 2225897Sjmz 2235897Sjmz FieldValue = FieldValue.lshr(8); 22412675Sjulian } 2255897Sjmz 2265897Sjmz Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp)); 2275897Sjmz NextFieldOffsetInBytes++; 2285897Sjmz 2295897Sjmz FieldValue.trunc(FieldValue.getBitWidth() - 8); 2305897Sjmz } 2315897Sjmz 2325897Sjmz assert(FieldValue.getBitWidth() > 0 && 2335897Sjmz "Should have at least one bit left!"); 2345897Sjmz assert(FieldValue.getBitWidth() <= 8 && 2355897Sjmz "Should not have more than a byte left!"); 2365897Sjmz 23712502Sjulian if (FieldValue.getBitWidth() < 8) { 23846153Sdt if (CGM.getTargetData().isBigEndian()) { 23912502Sjulian unsigned BitWidth = FieldValue.getBitWidth(); 24012517Sjulian 24112502Sjulian FieldValue.zext(8); 24212517Sjulian FieldValue = FieldValue << (8 - BitWidth); 24312517Sjulian } else 24412502Sjulian FieldValue.zext(8); 24512517Sjulian } 24612517Sjulian 24712502Sjulian // Append the last element. 24812517Sjulian Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), 24912502Sjulian FieldValue)); 25012517Sjulian NextFieldOffsetInBytes++; 25112517Sjulian return true; 25212517Sjulian} 25314633Sjmz 25414633Sjmzvoid ConstStructBuilder::AppendPadding(uint64_t NumBytes) { 25514633Sjmz if (!NumBytes) 25614633Sjmz return; 25714633Sjmz 25814633Sjmz const llvm::Type *Ty = llvm::Type::getInt8Ty(CGM.getLLVMContext()); 25914633Sjmz if (NumBytes > 1) 26014633Sjmz Ty = llvm::ArrayType::get(Ty, NumBytes); 26114634Sjmz 26214633Sjmz llvm::Constant *C = llvm::UndefValue::get(Ty); 26324674Sdufault Elements.push_back(C); 26414633Sjmz assert(getAlignment(C) == 1 && "Padding must have 1 byte alignment!"); 26514633Sjmz 26614633Sjmz NextFieldOffsetInBytes += getSizeInBytes(C); 26714633Sjmz} 26814633Sjmz 26914633Sjmzvoid ConstStructBuilder::AppendTailPadding(uint64_t RecordSize) { 27014633Sjmz assert(RecordSize % 8 == 0 && "Invalid record size!"); 27114633Sjmz 27214633Sjmz uint64_t RecordSizeInBytes = RecordSize / 8; 27314633Sjmz assert(NextFieldOffsetInBytes <= RecordSizeInBytes && "Size mismatch!"); 27414633Sjmz 27514633Sjmz unsigned NumPadBytes = RecordSizeInBytes - NextFieldOffsetInBytes; 27614633Sjmz AppendPadding(NumPadBytes); 27724674Sdufault} 27814633Sjmz 27914633Sjmzvoid ConstStructBuilder::ConvertStructToPacked() { 28014633Sjmz std::vector<llvm::Constant *> PackedElements; 28114633Sjmz uint64_t ElementOffsetInBytes = 0; 28214633Sjmz 28324674Sdufault for (unsigned i = 0, e = Elements.size(); i != e; ++i) { 28424674Sdufault llvm::Constant *C = Elements[i]; 28514633Sjmz 28614633Sjmz unsigned ElementAlign = 28714633Sjmz CGM.getTargetData().getABITypeAlignment(C->getType()); 28814633Sjmz uint64_t AlignedElementOffsetInBytes = 28924674Sdufault llvm::RoundUpToAlignment(ElementOffsetInBytes, ElementAlign); 29014633Sjmz 29114633Sjmz if (AlignedElementOffsetInBytes > ElementOffsetInBytes) { 29214633Sjmz // We need some padding. 29324674Sdufault uint64_t NumBytes = 29424674Sdufault AlignedElementOffsetInBytes - ElementOffsetInBytes; 29514633Sjmz 29614633Sjmz const llvm::Type *Ty = llvm::Type::getInt8Ty(CGM.getLLVMContext()); 29714633Sjmz if (NumBytes > 1) 29814633Sjmz Ty = llvm::ArrayType::get(Ty, NumBytes); 29914633Sjmz 3005897Sjmz llvm::Constant *Padding = llvm::UndefValue::get(Ty); 301 PackedElements.push_back(Padding); 302 ElementOffsetInBytes += getSizeInBytes(Padding); 303 } 304 305 PackedElements.push_back(C); 306 ElementOffsetInBytes += getSizeInBytes(C); 307 } 308 309 assert(ElementOffsetInBytes == NextFieldOffsetInBytes && 310 "Packing the struct changed its size!"); 311 312 Elements = PackedElements; 313 LLVMStructAlignment = 1; 314 Packed = true; 315} 316 317bool ConstStructBuilder::Build(InitListExpr *ILE) { 318 RecordDecl *RD = ILE->getType()->getAs<RecordType>()->getDecl(); 319 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); 320 321 unsigned FieldNo = 0; 322 unsigned ElementNo = 0; 323 for (RecordDecl::field_iterator Field = RD->field_begin(), 324 FieldEnd = RD->field_end(); Field != FieldEnd; ++Field, ++FieldNo) { 325 326 // If this is a union, skip all the fields that aren't being initialized. 327 if (RD->isUnion() && ILE->getInitializedFieldInUnion() != *Field) 328 continue; 329 330 // Don't emit anonymous bitfields, they just affect layout. 331 if (Field->isBitField() && !Field->getIdentifier()) 332 continue; 333 334 // Get the initializer. A struct can include fields without initializers, 335 // we just use explicit null values for them. 336 llvm::Constant *EltInit; 337 if (ElementNo < ILE->getNumInits()) 338 EltInit = CGM.EmitConstantExpr(ILE->getInit(ElementNo++), 339 Field->getType(), CGF); 340 else 341 EltInit = CGM.EmitNullConstant(Field->getType()); 342 343 if (!Field->isBitField()) { 344 // Handle non-bitfield members. 345 if (!AppendField(*Field, Layout.getFieldOffset(FieldNo), EltInit)) 346 return false; 347 } else { 348 // Otherwise we have a bitfield. 349 if (!AppendBitField(*Field, Layout.getFieldOffset(FieldNo), EltInit)) 350 return false; 351 } 352 } 353 354 uint64_t LayoutSizeInBytes = Layout.getSize() / 8; 355 356 if (NextFieldOffsetInBytes > LayoutSizeInBytes) { 357 // If the struct is bigger than the size of the record type, 358 // we must have a flexible array member at the end. 359 assert(RD->hasFlexibleArrayMember() && 360 "Must have flexible array member if struct is bigger than type!"); 361 362 // No tail padding is necessary. 363 return true; 364 } 365 366 uint64_t LLVMSizeInBytes = llvm::RoundUpToAlignment(NextFieldOffsetInBytes, 367 LLVMStructAlignment); 368 369 // Check if we need to convert the struct to a packed struct. 370 if (NextFieldOffsetInBytes <= LayoutSizeInBytes && 371 LLVMSizeInBytes > LayoutSizeInBytes) { 372 assert(!Packed && "Size mismatch!"); 373 374 ConvertStructToPacked(); 375 assert(NextFieldOffsetInBytes <= LayoutSizeInBytes && 376 "Converting to packed did not help!"); 377 } 378 379 // Append tail padding if necessary. 380 AppendTailPadding(Layout.getSize()); 381 382 assert(Layout.getSize() / 8 == NextFieldOffsetInBytes && 383 "Tail padding mismatch!"); 384 385 return true; 386} 387 388llvm::Constant *ConstStructBuilder:: 389 BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF, InitListExpr *ILE) { 390 ConstStructBuilder Builder(CGM, CGF); 391 392 if (!Builder.Build(ILE)) 393 return 0; 394 395 llvm::Constant *Result = 396 llvm::ConstantStruct::get(CGM.getLLVMContext(), 397 Builder.Elements, Builder.Packed); 398 399 assert(llvm::RoundUpToAlignment(Builder.NextFieldOffsetInBytes, 400 Builder.getAlignment(Result)) == 401 Builder.getSizeInBytes(Result) && "Size mismatch!"); 402 403 return Result; 404} 405 406 407//===----------------------------------------------------------------------===// 408// ConstExprEmitter 409//===----------------------------------------------------------------------===// 410 411class ConstExprEmitter : 412 public StmtVisitor<ConstExprEmitter, llvm::Constant*> { 413 CodeGenModule &CGM; 414 CodeGenFunction *CGF; 415 llvm::LLVMContext &VMContext; 416public: 417 ConstExprEmitter(CodeGenModule &cgm, CodeGenFunction *cgf) 418 : CGM(cgm), CGF(cgf), VMContext(cgm.getLLVMContext()) { 419 } 420 421 //===--------------------------------------------------------------------===// 422 // Visitor Methods 423 //===--------------------------------------------------------------------===// 424 425 llvm::Constant *VisitStmt(Stmt *S) { 426 return 0; 427 } 428 429 llvm::Constant *VisitParenExpr(ParenExpr *PE) { 430 return Visit(PE->getSubExpr()); 431 } 432 433 llvm::Constant *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) { 434 return Visit(E->getInitializer()); 435 } 436 437 llvm::Constant *EmitMemberFunctionPointer(CXXMethodDecl *MD) { 438 assert(MD->isInstance() && "Member function must not be static!"); 439 440 MD = MD->getCanonicalDecl(); 441 442 const llvm::Type *PtrDiffTy = 443 CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType()); 444 445 llvm::Constant *Values[2]; 446 447 // Get the function pointer (or index if this is a virtual function). 448 if (MD->isVirtual()) { 449 uint64_t Index = CGM.getVTables().getMethodVTableIndex(MD); 450 451 // FIXME: We shouldn't use / 8 here. 452 uint64_t PointerWidthInBytes = 453 CGM.getContext().Target.getPointerWidth(0) / 8; 454 455 // Itanium C++ ABI 2.3: 456 // For a non-virtual function, this field is a simple function pointer. 457 // For a virtual function, it is 1 plus the virtual table offset 458 // (in bytes) of the function, represented as a ptrdiff_t. 459 Values[0] = llvm::ConstantInt::get(PtrDiffTy, 460 (Index * PointerWidthInBytes) + 1); 461 } else { 462 const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>(); 463 const llvm::Type *Ty = 464 CGM.getTypes().GetFunctionType(CGM.getTypes().getFunctionInfo(MD), 465 FPT->isVariadic()); 466 467 llvm::Constant *FuncPtr = CGM.GetAddrOfFunction(MD, Ty); 468 Values[0] = llvm::ConstantExpr::getPtrToInt(FuncPtr, PtrDiffTy); 469 } 470 471 // The adjustment will always be 0. 472 Values[1] = llvm::ConstantInt::get(PtrDiffTy, 0); 473 474 return llvm::ConstantStruct::get(CGM.getLLVMContext(), 475 Values, 2, /*Packed=*/false); 476 } 477 478 llvm::Constant *VisitUnaryAddrOf(UnaryOperator *E) { 479 if (const MemberPointerType *MPT = 480 E->getType()->getAs<MemberPointerType>()) { 481 QualType T = MPT->getPointeeType(); 482 DeclRefExpr *DRE = cast<DeclRefExpr>(E->getSubExpr()); 483 484 NamedDecl *ND = DRE->getDecl(); 485 if (T->isFunctionProtoType()) 486 return EmitMemberFunctionPointer(cast<CXXMethodDecl>(ND)); 487 488 // We have a pointer to data member. 489 return CGM.EmitPointerToDataMember(cast<FieldDecl>(ND)); 490 } 491 492 return 0; 493 } 494 495 llvm::Constant *VisitBinSub(BinaryOperator *E) { 496 // This must be a pointer/pointer subtraction. This only happens for 497 // address of label. 498 if (!isa<AddrLabelExpr>(E->getLHS()->IgnoreParenNoopCasts(CGM.getContext())) || 499 !isa<AddrLabelExpr>(E->getRHS()->IgnoreParenNoopCasts(CGM.getContext()))) 500 return 0; 501 502 llvm::Constant *LHS = CGM.EmitConstantExpr(E->getLHS(), 503 E->getLHS()->getType(), CGF); 504 llvm::Constant *RHS = CGM.EmitConstantExpr(E->getRHS(), 505 E->getRHS()->getType(), CGF); 506 507 const llvm::Type *ResultType = ConvertType(E->getType()); 508 LHS = llvm::ConstantExpr::getPtrToInt(LHS, ResultType); 509 RHS = llvm::ConstantExpr::getPtrToInt(RHS, ResultType); 510 511 // No need to divide by element size, since addr of label is always void*, 512 // which has size 1 in GNUish. 513 return llvm::ConstantExpr::getSub(LHS, RHS); 514 } 515 516 llvm::Constant *VisitCastExpr(CastExpr* E) { 517 switch (E->getCastKind()) { 518 case CastExpr::CK_ToUnion: { 519 // GCC cast to union extension 520 assert(E->getType()->isUnionType() && 521 "Destination type is not union type!"); 522 const llvm::Type *Ty = ConvertType(E->getType()); 523 Expr *SubExpr = E->getSubExpr(); 524 525 llvm::Constant *C = 526 CGM.EmitConstantExpr(SubExpr, SubExpr->getType(), CGF); 527 if (!C) 528 return 0; 529 530 // Build a struct with the union sub-element as the first member, 531 // and padded to the appropriate size 532 std::vector<llvm::Constant*> Elts; 533 std::vector<const llvm::Type*> Types; 534 Elts.push_back(C); 535 Types.push_back(C->getType()); 536 unsigned CurSize = CGM.getTargetData().getTypeAllocSize(C->getType()); 537 unsigned TotalSize = CGM.getTargetData().getTypeAllocSize(Ty); 538 539 assert(CurSize <= TotalSize && "Union size mismatch!"); 540 if (unsigned NumPadBytes = TotalSize - CurSize) { 541 const llvm::Type *Ty = llvm::Type::getInt8Ty(VMContext); 542 if (NumPadBytes > 1) 543 Ty = llvm::ArrayType::get(Ty, NumPadBytes); 544 545 Elts.push_back(llvm::UndefValue::get(Ty)); 546 Types.push_back(Ty); 547 } 548 549 llvm::StructType* STy = 550 llvm::StructType::get(C->getType()->getContext(), Types, false); 551 return llvm::ConstantStruct::get(STy, Elts); 552 } 553 case CastExpr::CK_NullToMemberPointer: 554 return CGM.EmitNullConstant(E->getType()); 555 556 case CastExpr::CK_BaseToDerivedMemberPointer: { 557 Expr *SubExpr = E->getSubExpr(); 558 559 const MemberPointerType *SrcTy = 560 SubExpr->getType()->getAs<MemberPointerType>(); 561 const MemberPointerType *DestTy = 562 E->getType()->getAs<MemberPointerType>(); 563 564 const CXXRecordDecl *DerivedClass = 565 cast<CXXRecordDecl>(cast<RecordType>(DestTy->getClass())->getDecl()); 566 567 if (SrcTy->getPointeeType()->isFunctionProtoType()) { 568 llvm::Constant *C = 569 CGM.EmitConstantExpr(SubExpr, SubExpr->getType(), CGF); 570 if (!C) 571 return 0; 572 573 llvm::ConstantStruct *CS = cast<llvm::ConstantStruct>(C); 574 575 // Check if we need to update the adjustment. 576 if (llvm::Constant *Offset = 577 CGM.GetNonVirtualBaseClassOffset(DerivedClass, E->getBasePath())) { 578 llvm::Constant *Values[2]; 579 580 Values[0] = CS->getOperand(0); 581 Values[1] = llvm::ConstantExpr::getAdd(CS->getOperand(1), Offset); 582 return llvm::ConstantStruct::get(CGM.getLLVMContext(), Values, 2, 583 /*Packed=*/false); 584 } 585 586 return CS; 587 } 588 } 589 590 case CastExpr::CK_BitCast: 591 // This must be a member function pointer cast. 592 return Visit(E->getSubExpr()); 593 594 default: { 595 // FIXME: This should be handled by the CK_NoOp cast kind. 596 // Explicit and implicit no-op casts 597 QualType Ty = E->getType(), SubTy = E->getSubExpr()->getType(); 598 if (CGM.getContext().hasSameUnqualifiedType(Ty, SubTy)) 599 return Visit(E->getSubExpr()); 600 601 // Handle integer->integer casts for address-of-label differences. 602 if (Ty->isIntegerType() && SubTy->isIntegerType() && 603 CGF) { 604 llvm::Value *Src = Visit(E->getSubExpr()); 605 if (Src == 0) return 0; 606 607 // Use EmitScalarConversion to perform the conversion. 608 return cast<llvm::Constant>(CGF->EmitScalarConversion(Src, SubTy, Ty)); 609 } 610 611 return 0; 612 } 613 } 614 } 615 616 llvm::Constant *VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) { 617 return Visit(DAE->getExpr()); 618 } 619 620 llvm::Constant *EmitArrayInitialization(InitListExpr *ILE) { 621 unsigned NumInitElements = ILE->getNumInits(); 622 if (NumInitElements == 1 && 623 (isa<StringLiteral>(ILE->getInit(0)) || 624 isa<ObjCEncodeExpr>(ILE->getInit(0)))) 625 return Visit(ILE->getInit(0)); 626 627 std::vector<llvm::Constant*> Elts; 628 const llvm::ArrayType *AType = 629 cast<llvm::ArrayType>(ConvertType(ILE->getType())); 630 const llvm::Type *ElemTy = AType->getElementType(); 631 unsigned NumElements = AType->getNumElements(); 632 633 // Initialising an array requires us to automatically 634 // initialise any elements that have not been initialised explicitly 635 unsigned NumInitableElts = std::min(NumInitElements, NumElements); 636 637 // Copy initializer elements. 638 unsigned i = 0; 639 bool RewriteType = false; 640 for (; i < NumInitableElts; ++i) { 641 Expr *Init = ILE->getInit(i); 642 llvm::Constant *C = CGM.EmitConstantExpr(Init, Init->getType(), CGF); 643 if (!C) 644 return 0; 645 RewriteType |= (C->getType() != ElemTy); 646 Elts.push_back(C); 647 } 648 649 // Initialize remaining array elements. 650 // FIXME: This doesn't handle member pointers correctly! 651 for (; i < NumElements; ++i) 652 Elts.push_back(llvm::Constant::getNullValue(ElemTy)); 653 654 if (RewriteType) { 655 // FIXME: Try to avoid packing the array 656 std::vector<const llvm::Type*> Types; 657 for (unsigned i = 0; i < Elts.size(); ++i) 658 Types.push_back(Elts[i]->getType()); 659 const llvm::StructType *SType = llvm::StructType::get(AType->getContext(), 660 Types, true); 661 return llvm::ConstantStruct::get(SType, Elts); 662 } 663 664 return llvm::ConstantArray::get(AType, Elts); 665 } 666 667 llvm::Constant *EmitStructInitialization(InitListExpr *ILE) { 668 return ConstStructBuilder::BuildStruct(CGM, CGF, ILE); 669 } 670 671 llvm::Constant *EmitUnionInitialization(InitListExpr *ILE) { 672 return ConstStructBuilder::BuildStruct(CGM, CGF, ILE); 673 } 674 675 llvm::Constant *VisitImplicitValueInitExpr(ImplicitValueInitExpr* E) { 676 return CGM.EmitNullConstant(E->getType()); 677 } 678 679 llvm::Constant *VisitInitListExpr(InitListExpr *ILE) { 680 if (ILE->getType()->isScalarType()) { 681 // We have a scalar in braces. Just use the first element. 682 if (ILE->getNumInits() > 0) { 683 Expr *Init = ILE->getInit(0); 684 return CGM.EmitConstantExpr(Init, Init->getType(), CGF); 685 } 686 return CGM.EmitNullConstant(ILE->getType()); 687 } 688 689 if (ILE->getType()->isArrayType()) 690 return EmitArrayInitialization(ILE); 691 692 if (ILE->getType()->isRecordType()) 693 return EmitStructInitialization(ILE); 694 695 if (ILE->getType()->isUnionType()) 696 return EmitUnionInitialization(ILE); 697 698 // If ILE was a constant vector, we would have handled it already. 699 if (ILE->getType()->isVectorType()) 700 return 0; 701 702 assert(0 && "Unable to handle InitListExpr"); 703 // Get rid of control reaches end of void function warning. 704 // Not reached. 705 return 0; 706 } 707 708 llvm::Constant *VisitCXXConstructExpr(CXXConstructExpr *E) { 709 if (!E->getConstructor()->isTrivial()) 710 return 0; 711 712 QualType Ty = E->getType(); 713 714 // FIXME: We should not have to call getBaseElementType here. 715 const RecordType *RT = 716 CGM.getContext().getBaseElementType(Ty)->getAs<RecordType>(); 717 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); 718 719 // If the class doesn't have a trivial destructor, we can't emit it as a 720 // constant expr. 721 if (!RD->hasTrivialDestructor()) 722 return 0; 723 724 // Only copy and default constructors can be trivial. 725 726 727 if (E->getNumArgs()) { 728 assert(E->getNumArgs() == 1 && "trivial ctor with > 1 argument"); 729 assert(E->getConstructor()->isCopyConstructor() && 730 "trivial ctor has argument but isn't a copy ctor"); 731 732 Expr *Arg = E->getArg(0); 733 assert(CGM.getContext().hasSameUnqualifiedType(Ty, Arg->getType()) && 734 "argument to copy ctor is of wrong type"); 735 736 return Visit(Arg); 737 } 738 739 return CGM.EmitNullConstant(Ty); 740 } 741 742 llvm::Constant *VisitStringLiteral(StringLiteral *E) { 743 assert(!E->getType()->isPointerType() && "Strings are always arrays"); 744 745 // This must be a string initializing an array in a static initializer. 746 // Don't emit it as the address of the string, emit the string data itself 747 // as an inline array. 748 return llvm::ConstantArray::get(VMContext, 749 CGM.GetStringForStringLiteral(E), false); 750 } 751 752 llvm::Constant *VisitObjCEncodeExpr(ObjCEncodeExpr *E) { 753 // This must be an @encode initializing an array in a static initializer. 754 // Don't emit it as the address of the string, emit the string data itself 755 // as an inline array. 756 std::string Str; 757 CGM.getContext().getObjCEncodingForType(E->getEncodedType(), Str); 758 const ConstantArrayType *CAT = cast<ConstantArrayType>(E->getType()); 759 760 // Resize the string to the right size, adding zeros at the end, or 761 // truncating as needed. 762 Str.resize(CAT->getSize().getZExtValue(), '\0'); 763 return llvm::ConstantArray::get(VMContext, Str, false); 764 } 765 766 llvm::Constant *VisitUnaryExtension(const UnaryOperator *E) { 767 return Visit(E->getSubExpr()); 768 } 769 770 // Utility methods 771 const llvm::Type *ConvertType(QualType T) { 772 return CGM.getTypes().ConvertType(T); 773 } 774 775public: 776 llvm::Constant *EmitLValue(Expr *E) { 777 switch (E->getStmtClass()) { 778 default: break; 779 case Expr::CompoundLiteralExprClass: { 780 // Note that due to the nature of compound literals, this is guaranteed 781 // to be the only use of the variable, so we just generate it here. 782 CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E); 783 llvm::Constant* C = Visit(CLE->getInitializer()); 784 // FIXME: "Leaked" on failure. 785 if (C) 786 C = new llvm::GlobalVariable(CGM.getModule(), C->getType(), 787 E->getType().isConstant(CGM.getContext()), 788 llvm::GlobalValue::InternalLinkage, 789 C, ".compoundliteral", 0, false, 790 E->getType().getAddressSpace()); 791 return C; 792 } 793 case Expr::DeclRefExprClass: { 794 ValueDecl *Decl = cast<DeclRefExpr>(E)->getDecl(); 795 if (Decl->hasAttr<WeakRefAttr>()) 796 return CGM.GetWeakRefReference(Decl); 797 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Decl)) 798 return CGM.GetAddrOfFunction(FD); 799 if (const VarDecl* VD = dyn_cast<VarDecl>(Decl)) { 800 // We can never refer to a variable with local storage. 801 if (!VD->hasLocalStorage()) { 802 if (VD->isFileVarDecl() || VD->hasExternalStorage()) 803 return CGM.GetAddrOfGlobalVar(VD); 804 else if (VD->isBlockVarDecl()) { 805 assert(CGF && "Can't access static local vars without CGF"); 806 return CGF->GetAddrOfStaticLocalVar(VD); 807 } 808 } 809 } 810 break; 811 } 812 case Expr::StringLiteralClass: 813 return CGM.GetAddrOfConstantStringFromLiteral(cast<StringLiteral>(E)); 814 case Expr::ObjCEncodeExprClass: 815 return CGM.GetAddrOfConstantStringFromObjCEncode(cast<ObjCEncodeExpr>(E)); 816 case Expr::ObjCStringLiteralClass: { 817 ObjCStringLiteral* SL = cast<ObjCStringLiteral>(E); 818 llvm::Constant *C = 819 CGM.getObjCRuntime().GenerateConstantString(SL->getString()); 820 return llvm::ConstantExpr::getBitCast(C, ConvertType(E->getType())); 821 } 822 case Expr::PredefinedExprClass: { 823 unsigned Type = cast<PredefinedExpr>(E)->getIdentType(); 824 if (CGF) { 825 LValue Res = CGF->EmitPredefinedFunctionName(Type); 826 return cast<llvm::Constant>(Res.getAddress()); 827 } else if (Type == PredefinedExpr::PrettyFunction) { 828 return CGM.GetAddrOfConstantCString("top level", ".tmp"); 829 } 830 831 return CGM.GetAddrOfConstantCString("", ".tmp"); 832 } 833 case Expr::AddrLabelExprClass: { 834 assert(CGF && "Invalid address of label expression outside function."); 835 llvm::Constant *Ptr = 836 CGF->GetAddrOfLabel(cast<AddrLabelExpr>(E)->getLabel()); 837 return llvm::ConstantExpr::getBitCast(Ptr, ConvertType(E->getType())); 838 } 839 case Expr::CallExprClass: { 840 CallExpr* CE = cast<CallExpr>(E); 841 unsigned builtin = CE->isBuiltinCall(CGM.getContext()); 842 if (builtin != 843 Builtin::BI__builtin___CFStringMakeConstantString && 844 builtin != 845 Builtin::BI__builtin___NSStringMakeConstantString) 846 break; 847 const Expr *Arg = CE->getArg(0)->IgnoreParenCasts(); 848 const StringLiteral *Literal = cast<StringLiteral>(Arg); 849 if (builtin == 850 Builtin::BI__builtin___NSStringMakeConstantString) { 851 return CGM.getObjCRuntime().GenerateConstantString(Literal); 852 } 853 // FIXME: need to deal with UCN conversion issues. 854 return CGM.GetAddrOfConstantCFString(Literal); 855 } 856 case Expr::BlockExprClass: { 857 std::string FunctionName; 858 if (CGF) 859 FunctionName = CGF->CurFn->getName(); 860 else 861 FunctionName = "global"; 862 863 return CGM.GetAddrOfGlobalBlock(cast<BlockExpr>(E), FunctionName.c_str()); 864 } 865 } 866 867 return 0; 868 } 869}; 870 871} // end anonymous namespace. 872 873llvm::Constant *CodeGenModule::EmitConstantExpr(const Expr *E, 874 QualType DestType, 875 CodeGenFunction *CGF) { 876 Expr::EvalResult Result; 877 878 bool Success = false; 879 880 if (DestType->isReferenceType()) 881 Success = E->EvaluateAsLValue(Result, Context); 882 else 883 Success = E->Evaluate(Result, Context); 884 885 if (Success && !Result.HasSideEffects) { 886 switch (Result.Val.getKind()) { 887 case APValue::Uninitialized: 888 assert(0 && "Constant expressions should be initialized."); 889 return 0; 890 case APValue::LValue: { 891 const llvm::Type *DestTy = getTypes().ConvertTypeForMem(DestType); 892 llvm::Constant *Offset = 893 llvm::ConstantInt::get(llvm::Type::getInt64Ty(VMContext), 894 Result.Val.getLValueOffset().getQuantity()); 895 896 llvm::Constant *C; 897 if (const Expr *LVBase = Result.Val.getLValueBase()) { 898 C = ConstExprEmitter(*this, CGF).EmitLValue(const_cast<Expr*>(LVBase)); 899 900 // Apply offset if necessary. 901 if (!Offset->isNullValue()) { 902 const llvm::Type *Type = llvm::Type::getInt8PtrTy(VMContext); 903 llvm::Constant *Casted = llvm::ConstantExpr::getBitCast(C, Type); 904 Casted = llvm::ConstantExpr::getGetElementPtr(Casted, &Offset, 1); 905 C = llvm::ConstantExpr::getBitCast(Casted, C->getType()); 906 } 907 908 // Convert to the appropriate type; this could be an lvalue for 909 // an integer. 910 if (isa<llvm::PointerType>(DestTy)) 911 return llvm::ConstantExpr::getBitCast(C, DestTy); 912 913 return llvm::ConstantExpr::getPtrToInt(C, DestTy); 914 } else { 915 C = Offset; 916 917 // Convert to the appropriate type; this could be an lvalue for 918 // an integer. 919 if (isa<llvm::PointerType>(DestTy)) 920 return llvm::ConstantExpr::getIntToPtr(C, DestTy); 921 922 // If the types don't match this should only be a truncate. 923 if (C->getType() != DestTy) 924 return llvm::ConstantExpr::getTrunc(C, DestTy); 925 926 return C; 927 } 928 } 929 case APValue::Int: { 930 llvm::Constant *C = llvm::ConstantInt::get(VMContext, 931 Result.Val.getInt()); 932 933 if (C->getType() == llvm::Type::getInt1Ty(VMContext)) { 934 const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType()); 935 C = llvm::ConstantExpr::getZExt(C, BoolTy); 936 } 937 return C; 938 } 939 case APValue::ComplexInt: { 940 llvm::Constant *Complex[2]; 941 942 Complex[0] = llvm::ConstantInt::get(VMContext, 943 Result.Val.getComplexIntReal()); 944 Complex[1] = llvm::ConstantInt::get(VMContext, 945 Result.Val.getComplexIntImag()); 946 947 // FIXME: the target may want to specify that this is packed. 948 return llvm::ConstantStruct::get(VMContext, Complex, 2, false); 949 } 950 case APValue::Float: 951 return llvm::ConstantFP::get(VMContext, Result.Val.getFloat()); 952 case APValue::ComplexFloat: { 953 llvm::Constant *Complex[2]; 954 955 Complex[0] = llvm::ConstantFP::get(VMContext, 956 Result.Val.getComplexFloatReal()); 957 Complex[1] = llvm::ConstantFP::get(VMContext, 958 Result.Val.getComplexFloatImag()); 959 960 // FIXME: the target may want to specify that this is packed. 961 return llvm::ConstantStruct::get(VMContext, Complex, 2, false); 962 } 963 case APValue::Vector: { 964 llvm::SmallVector<llvm::Constant *, 4> Inits; 965 unsigned NumElts = Result.Val.getVectorLength(); 966 967 for (unsigned i = 0; i != NumElts; ++i) { 968 APValue &Elt = Result.Val.getVectorElt(i); 969 if (Elt.isInt()) 970 Inits.push_back(llvm::ConstantInt::get(VMContext, Elt.getInt())); 971 else 972 Inits.push_back(llvm::ConstantFP::get(VMContext, Elt.getFloat())); 973 } 974 return llvm::ConstantVector::get(&Inits[0], Inits.size()); 975 } 976 } 977 } 978 979 llvm::Constant* C = ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E)); 980 if (C && C->getType() == llvm::Type::getInt1Ty(VMContext)) { 981 const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType()); 982 C = llvm::ConstantExpr::getZExt(C, BoolTy); 983 } 984 return C; 985} 986 987static void 988FillInNullDataMemberPointers(CodeGenModule &CGM, QualType T, 989 std::vector<llvm::Constant *> &Elements, 990 uint64_t StartOffset) { 991 assert(StartOffset % 8 == 0 && "StartOffset not byte aligned!"); 992 993 if (!CGM.getTypes().ContainsPointerToDataMember(T)) 994 return; 995 996 if (const ConstantArrayType *CAT = 997 CGM.getContext().getAsConstantArrayType(T)) { 998 QualType ElementTy = CAT->getElementType(); 999 uint64_t ElementSize = CGM.getContext().getTypeSize(ElementTy); 1000 1001 for (uint64_t I = 0, E = CAT->getSize().getZExtValue(); I != E; ++I) { 1002 FillInNullDataMemberPointers(CGM, ElementTy, Elements, 1003 StartOffset + I * ElementSize); 1004 } 1005 } else if (const RecordType *RT = T->getAs<RecordType>()) { 1006 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); 1007 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); 1008 1009 // Go through all bases and fill in any null pointer to data members. 1010 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 1011 E = RD->bases_end(); I != E; ++I) { 1012 assert(!I->isVirtual() && "Should not see virtual bases here!"); 1013 1014 const CXXRecordDecl *BaseDecl = 1015 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); 1016 1017 // Ignore empty bases. 1018 if (BaseDecl->isEmpty()) 1019 continue; 1020 1021 // Ignore bases that don't have any pointer to data members. 1022 if (!CGM.getTypes().ContainsPointerToDataMember(BaseDecl)) 1023 continue; 1024 1025 uint64_t BaseOffset = Layout.getBaseClassOffset(BaseDecl); 1026 FillInNullDataMemberPointers(CGM, I->getType(), 1027 Elements, StartOffset + BaseOffset); 1028 } 1029 1030 // Visit all fields. 1031 unsigned FieldNo = 0; 1032 for (RecordDecl::field_iterator I = RD->field_begin(), 1033 E = RD->field_end(); I != E; ++I, ++FieldNo) { 1034 QualType FieldType = I->getType(); 1035 1036 if (!CGM.getTypes().ContainsPointerToDataMember(FieldType)) 1037 continue; 1038 1039 uint64_t FieldOffset = StartOffset + Layout.getFieldOffset(FieldNo); 1040 FillInNullDataMemberPointers(CGM, FieldType, Elements, FieldOffset); 1041 } 1042 } else { 1043 assert(T->isMemberPointerType() && "Should only see member pointers here!"); 1044 assert(!T->getAs<MemberPointerType>()->getPointeeType()->isFunctionType() && 1045 "Should only see pointers to data members here!"); 1046 1047 uint64_t StartIndex = StartOffset / 8; 1048 uint64_t EndIndex = StartIndex + CGM.getContext().getTypeSize(T) / 8; 1049 1050 llvm::Constant *NegativeOne = 1051 llvm::ConstantInt::get(llvm::Type::getInt8Ty(CGM.getLLVMContext()), 1052 -1ULL, /*isSigned=*/true); 1053 1054 // Fill in the null data member pointer. 1055 for (uint64_t I = StartIndex; I != EndIndex; ++I) 1056 Elements[I] = NegativeOne; 1057 } 1058} 1059 1060llvm::Constant *CodeGenModule::EmitNullConstant(QualType T) { 1061 if (!getTypes().ContainsPointerToDataMember(T)) 1062 return llvm::Constant::getNullValue(getTypes().ConvertTypeForMem(T)); 1063 1064 if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(T)) { 1065 1066 QualType ElementTy = CAT->getElementType(); 1067 1068 llvm::Constant *Element = EmitNullConstant(ElementTy); 1069 unsigned NumElements = CAT->getSize().getZExtValue(); 1070 std::vector<llvm::Constant *> Array(NumElements); 1071 for (unsigned i = 0; i != NumElements; ++i) 1072 Array[i] = Element; 1073 1074 const llvm::ArrayType *ATy = 1075 cast<llvm::ArrayType>(getTypes().ConvertTypeForMem(T)); 1076 return llvm::ConstantArray::get(ATy, Array); 1077 } 1078 1079 if (const RecordType *RT = T->getAs<RecordType>()) { 1080 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); 1081 const llvm::StructType *STy = 1082 cast<llvm::StructType>(getTypes().ConvertTypeForMem(T)); 1083 unsigned NumElements = STy->getNumElements(); 1084 std::vector<llvm::Constant *> Elements(NumElements); 1085 1086 const CGRecordLayout &Layout = getTypes().getCGRecordLayout(RD); 1087 1088 // Go through all bases and fill in any null pointer to data members. 1089 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 1090 E = RD->bases_end(); I != E; ++I) { 1091 assert(!I->isVirtual() && "Should not see virtual bases here!"); 1092 1093 const CXXRecordDecl *BaseDecl = 1094 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); 1095 1096 // Ignore empty bases. 1097 if (BaseDecl->isEmpty()) 1098 continue; 1099 1100 // Ignore bases that don't have any pointer to data members. 1101 if (!getTypes().ContainsPointerToDataMember(BaseDecl)) 1102 continue; 1103 1104 // Currently, all bases are arrays of i8. Figure out how many elements 1105 // this base array has. 1106 unsigned BaseFieldNo = Layout.getNonVirtualBaseLLVMFieldNo(BaseDecl); 1107 const llvm::ArrayType *BaseArrayTy = 1108 cast<llvm::ArrayType>(STy->getElementType(BaseFieldNo)); 1109 1110 unsigned NumBaseElements = BaseArrayTy->getNumElements(); 1111 std::vector<llvm::Constant *> BaseElements(NumBaseElements); 1112 1113 // Now fill in null data member pointers. 1114 FillInNullDataMemberPointers(*this, I->getType(), BaseElements, 0); 1115 1116 // Now go through all other elements and zero them out. 1117 if (NumBaseElements) { 1118 llvm::Constant *Zero = 1119 llvm::ConstantInt::get(llvm::Type::getInt8Ty(getLLVMContext()), 0); 1120 1121 for (unsigned I = 0; I != NumBaseElements; ++I) { 1122 if (!BaseElements[I]) 1123 BaseElements[I] = Zero; 1124 } 1125 } 1126 1127 Elements[BaseFieldNo] = llvm::ConstantArray::get(BaseArrayTy, 1128 BaseElements); 1129 } 1130 1131 for (RecordDecl::field_iterator I = RD->field_begin(), 1132 E = RD->field_end(); I != E; ++I) { 1133 const FieldDecl *FD = *I; 1134 unsigned FieldNo = Layout.getLLVMFieldNo(FD); 1135 Elements[FieldNo] = EmitNullConstant(FD->getType()); 1136 } 1137 1138 // Now go through all other fields and zero them out. 1139 for (unsigned i = 0; i != NumElements; ++i) { 1140 if (!Elements[i]) 1141 Elements[i] = llvm::Constant::getNullValue(STy->getElementType(i)); 1142 } 1143 1144 return llvm::ConstantStruct::get(STy, Elements); 1145 } 1146 1147 assert(T->isMemberPointerType() && "Should only see member pointers here!"); 1148 assert(!T->getAs<MemberPointerType>()->getPointeeType()->isFunctionType() && 1149 "Should only see pointers to data members here!"); 1150 1151 // Itanium C++ ABI 2.3: 1152 // A NULL pointer is represented as -1. 1153 return llvm::ConstantInt::get(getTypes().ConvertTypeForMem(T), -1ULL, 1154 /*isSigned=*/true); 1155} 1156 1157llvm::Constant * 1158CodeGenModule::EmitPointerToDataMember(const FieldDecl *FD) { 1159 1160 // Itanium C++ ABI 2.3: 1161 // A pointer to data member is an offset from the base address of the class 1162 // object containing it, represented as a ptrdiff_t 1163 1164 const CXXRecordDecl *ClassDecl = cast<CXXRecordDecl>(FD->getParent()); 1165 QualType ClassType = 1166 getContext().getTypeDeclType(const_cast<CXXRecordDecl *>(ClassDecl)); 1167 1168 const llvm::StructType *ClassLTy = 1169 cast<llvm::StructType>(getTypes().ConvertType(ClassType)); 1170 1171 const CGRecordLayout &RL = 1172 getTypes().getCGRecordLayout(FD->getParent()); 1173 unsigned FieldNo = RL.getLLVMFieldNo(FD); 1174 uint64_t Offset = 1175 getTargetData().getStructLayout(ClassLTy)->getElementOffset(FieldNo); 1176 1177 const llvm::Type *PtrDiffTy = 1178 getTypes().ConvertType(getContext().getPointerDiffType()); 1179 1180 return llvm::ConstantInt::get(PtrDiffTy, Offset); 1181} 1182