CGExprConstant.cpp revision 210299
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 "CodeGenModule.h" 16#include "CGObjCRuntime.h" 17#include "CGRecordLayout.h" 18#include "clang/AST/APValue.h" 19#include "clang/AST/ASTContext.h" 20#include "clang/AST/RecordLayout.h" 21#include "clang/AST/StmtVisitor.h" 22#include "clang/Basic/Builtins.h" 23#include "llvm/Constants.h" 24#include "llvm/Function.h" 25#include "llvm/GlobalVariable.h" 26#include "llvm/Target/TargetData.h" 27using namespace clang; 28using namespace CodeGen; 29 30//===----------------------------------------------------------------------===// 31// ConstStructBuilder 32//===----------------------------------------------------------------------===// 33 34namespace { 35class ConstStructBuilder { 36 CodeGenModule &CGM; 37 CodeGenFunction *CGF; 38 39 bool Packed; 40 unsigned NextFieldOffsetInBytes; 41 unsigned LLVMStructAlignment; 42 std::vector<llvm::Constant *> Elements; 43public: 44 static llvm::Constant *BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF, 45 InitListExpr *ILE); 46 47private: 48 ConstStructBuilder(CodeGenModule &CGM, CodeGenFunction *CGF) 49 : CGM(CGM), CGF(CGF), Packed(false), NextFieldOffsetInBytes(0), 50 LLVMStructAlignment(1) { } 51 52 bool AppendField(const FieldDecl *Field, uint64_t FieldOffset, 53 llvm::Constant *InitExpr); 54 55 void AppendBitField(const FieldDecl *Field, uint64_t FieldOffset, 56 llvm::ConstantInt *InitExpr); 57 58 void AppendPadding(uint64_t NumBytes); 59 60 void AppendTailPadding(uint64_t RecordSize); 61 62 void ConvertStructToPacked(); 63 64 bool Build(InitListExpr *ILE); 65 66 unsigned getAlignment(const llvm::Constant *C) const { 67 if (Packed) return 1; 68 return CGM.getTargetData().getABITypeAlignment(C->getType()); 69 } 70 71 uint64_t getSizeInBytes(const llvm::Constant *C) const { 72 return CGM.getTargetData().getTypeAllocSize(C->getType()); 73 } 74}; 75 76bool ConstStructBuilder:: 77AppendField(const FieldDecl *Field, uint64_t FieldOffset, 78 llvm::Constant *InitCst) { 79 uint64_t FieldOffsetInBytes = FieldOffset / 8; 80 81 assert(NextFieldOffsetInBytes <= FieldOffsetInBytes 82 && "Field offset mismatch!"); 83 84 // Emit the field. 85 if (!InitCst) 86 return false; 87 88 unsigned FieldAlignment = getAlignment(InitCst); 89 90 // Round up the field offset to the alignment of the field type. 91 uint64_t AlignedNextFieldOffsetInBytes = 92 llvm::RoundUpToAlignment(NextFieldOffsetInBytes, FieldAlignment); 93 94 if (AlignedNextFieldOffsetInBytes > FieldOffsetInBytes) { 95 assert(!Packed && "Alignment is wrong even with a packed struct!"); 96 97 // Convert the struct to a packed struct. 98 ConvertStructToPacked(); 99 100 AlignedNextFieldOffsetInBytes = NextFieldOffsetInBytes; 101 } 102 103 if (AlignedNextFieldOffsetInBytes < FieldOffsetInBytes) { 104 // We need to append padding. 105 AppendPadding(FieldOffsetInBytes - NextFieldOffsetInBytes); 106 107 assert(NextFieldOffsetInBytes == FieldOffsetInBytes && 108 "Did not add enough padding!"); 109 110 AlignedNextFieldOffsetInBytes = NextFieldOffsetInBytes; 111 } 112 113 // Add the field. 114 Elements.push_back(InitCst); 115 NextFieldOffsetInBytes = AlignedNextFieldOffsetInBytes + 116 getSizeInBytes(InitCst); 117 118 if (Packed) 119 assert(LLVMStructAlignment == 1 && "Packed struct not byte-aligned!"); 120 else 121 LLVMStructAlignment = std::max(LLVMStructAlignment, FieldAlignment); 122 123 return true; 124} 125 126void ConstStructBuilder::AppendBitField(const FieldDecl *Field, 127 uint64_t FieldOffset, 128 llvm::ConstantInt *CI) { 129 if (FieldOffset > NextFieldOffsetInBytes * 8) { 130 // We need to add padding. 131 uint64_t NumBytes = 132 llvm::RoundUpToAlignment(FieldOffset - 133 NextFieldOffsetInBytes * 8, 8) / 8; 134 135 AppendPadding(NumBytes); 136 } 137 138 uint64_t FieldSize = 139 Field->getBitWidth()->EvaluateAsInt(CGM.getContext()).getZExtValue(); 140 141 llvm::APInt FieldValue = CI->getValue(); 142 143 // Promote the size of FieldValue if necessary 144 // FIXME: This should never occur, but currently it can because initializer 145 // constants are cast to bool, and because clang is not enforcing bitfield 146 // width limits. 147 if (FieldSize > FieldValue.getBitWidth()) 148 FieldValue.zext(FieldSize); 149 150 // Truncate the size of FieldValue to the bit field size. 151 if (FieldSize < FieldValue.getBitWidth()) 152 FieldValue.trunc(FieldSize); 153 154 if (FieldOffset < NextFieldOffsetInBytes * 8) { 155 // Either part of the field or the entire field can go into the previous 156 // byte. 157 assert(!Elements.empty() && "Elements can't be empty!"); 158 159 unsigned BitsInPreviousByte = 160 NextFieldOffsetInBytes * 8 - FieldOffset; 161 162 bool FitsCompletelyInPreviousByte = 163 BitsInPreviousByte >= FieldValue.getBitWidth(); 164 165 llvm::APInt Tmp = FieldValue; 166 167 if (!FitsCompletelyInPreviousByte) { 168 unsigned NewFieldWidth = FieldSize - BitsInPreviousByte; 169 170 if (CGM.getTargetData().isBigEndian()) { 171 Tmp = Tmp.lshr(NewFieldWidth); 172 Tmp.trunc(BitsInPreviousByte); 173 174 // We want the remaining high bits. 175 FieldValue.trunc(NewFieldWidth); 176 } else { 177 Tmp.trunc(BitsInPreviousByte); 178 179 // We want the remaining low bits. 180 FieldValue = FieldValue.lshr(BitsInPreviousByte); 181 FieldValue.trunc(NewFieldWidth); 182 } 183 } 184 185 Tmp.zext(8); 186 if (CGM.getTargetData().isBigEndian()) { 187 if (FitsCompletelyInPreviousByte) 188 Tmp = Tmp.shl(BitsInPreviousByte - FieldValue.getBitWidth()); 189 } else { 190 Tmp = Tmp.shl(8 - BitsInPreviousByte); 191 } 192 193 // 'or' in the bits that go into the previous byte. 194 llvm::Value *LastElt = Elements.back(); 195 if (llvm::ConstantInt *Val = dyn_cast<llvm::ConstantInt>(LastElt)) 196 Tmp |= Val->getValue(); 197 else { 198 assert(isa<llvm::UndefValue>(LastElt)); 199 // If there is an undef field that we're adding to, it can either be a 200 // scalar undef (in which case, we just replace it with our field) or it 201 // is an array. If it is an array, we have to pull one byte off the 202 // array so that the other undef bytes stay around. 203 if (!isa<llvm::IntegerType>(LastElt->getType())) { 204 // The undef padding will be a multibyte array, create a new smaller 205 // padding and then an hole for our i8 to get plopped into. 206 assert(isa<llvm::ArrayType>(LastElt->getType()) && 207 "Expected array padding of undefs"); 208 const llvm::ArrayType *AT = cast<llvm::ArrayType>(LastElt->getType()); 209 assert(AT->getElementType()->isIntegerTy(8) && 210 AT->getNumElements() != 0 && 211 "Expected non-empty array padding of undefs"); 212 213 // Remove the padding array. 214 NextFieldOffsetInBytes -= AT->getNumElements(); 215 Elements.pop_back(); 216 217 // Add the padding back in two chunks. 218 AppendPadding(AT->getNumElements()-1); 219 AppendPadding(1); 220 assert(isa<llvm::UndefValue>(Elements.back()) && 221 Elements.back()->getType()->isIntegerTy(8) && 222 "Padding addition didn't work right"); 223 } 224 } 225 226 Elements.back() = llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp); 227 228 if (FitsCompletelyInPreviousByte) 229 return; 230 } 231 232 while (FieldValue.getBitWidth() > 8) { 233 llvm::APInt Tmp; 234 235 if (CGM.getTargetData().isBigEndian()) { 236 // We want the high bits. 237 Tmp = FieldValue; 238 Tmp = Tmp.lshr(Tmp.getBitWidth() - 8); 239 Tmp.trunc(8); 240 } else { 241 // We want the low bits. 242 Tmp = FieldValue; 243 Tmp.trunc(8); 244 245 FieldValue = FieldValue.lshr(8); 246 } 247 248 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp)); 249 NextFieldOffsetInBytes++; 250 251 FieldValue.trunc(FieldValue.getBitWidth() - 8); 252 } 253 254 assert(FieldValue.getBitWidth() > 0 && 255 "Should have at least one bit left!"); 256 assert(FieldValue.getBitWidth() <= 8 && 257 "Should not have more than a byte left!"); 258 259 if (FieldValue.getBitWidth() < 8) { 260 if (CGM.getTargetData().isBigEndian()) { 261 unsigned BitWidth = FieldValue.getBitWidth(); 262 263 FieldValue.zext(8); 264 FieldValue = FieldValue << (8 - BitWidth); 265 } else 266 FieldValue.zext(8); 267 } 268 269 // Append the last element. 270 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), 271 FieldValue)); 272 NextFieldOffsetInBytes++; 273} 274 275void ConstStructBuilder::AppendPadding(uint64_t NumBytes) { 276 if (!NumBytes) 277 return; 278 279 const llvm::Type *Ty = llvm::Type::getInt8Ty(CGM.getLLVMContext()); 280 if (NumBytes > 1) 281 Ty = llvm::ArrayType::get(Ty, NumBytes); 282 283 llvm::Constant *C = llvm::UndefValue::get(Ty); 284 Elements.push_back(C); 285 assert(getAlignment(C) == 1 && "Padding must have 1 byte alignment!"); 286 287 NextFieldOffsetInBytes += getSizeInBytes(C); 288} 289 290void ConstStructBuilder::AppendTailPadding(uint64_t RecordSize) { 291 assert(RecordSize % 8 == 0 && "Invalid record size!"); 292 293 uint64_t RecordSizeInBytes = RecordSize / 8; 294 assert(NextFieldOffsetInBytes <= RecordSizeInBytes && "Size mismatch!"); 295 296 unsigned NumPadBytes = RecordSizeInBytes - NextFieldOffsetInBytes; 297 AppendPadding(NumPadBytes); 298} 299 300void ConstStructBuilder::ConvertStructToPacked() { 301 std::vector<llvm::Constant *> PackedElements; 302 uint64_t ElementOffsetInBytes = 0; 303 304 for (unsigned i = 0, e = Elements.size(); i != e; ++i) { 305 llvm::Constant *C = Elements[i]; 306 307 unsigned ElementAlign = 308 CGM.getTargetData().getABITypeAlignment(C->getType()); 309 uint64_t AlignedElementOffsetInBytes = 310 llvm::RoundUpToAlignment(ElementOffsetInBytes, ElementAlign); 311 312 if (AlignedElementOffsetInBytes > ElementOffsetInBytes) { 313 // We need some padding. 314 uint64_t NumBytes = 315 AlignedElementOffsetInBytes - ElementOffsetInBytes; 316 317 const llvm::Type *Ty = llvm::Type::getInt8Ty(CGM.getLLVMContext()); 318 if (NumBytes > 1) 319 Ty = llvm::ArrayType::get(Ty, NumBytes); 320 321 llvm::Constant *Padding = llvm::UndefValue::get(Ty); 322 PackedElements.push_back(Padding); 323 ElementOffsetInBytes += getSizeInBytes(Padding); 324 } 325 326 PackedElements.push_back(C); 327 ElementOffsetInBytes += getSizeInBytes(C); 328 } 329 330 assert(ElementOffsetInBytes == NextFieldOffsetInBytes && 331 "Packing the struct changed its size!"); 332 333 Elements = PackedElements; 334 LLVMStructAlignment = 1; 335 Packed = true; 336} 337 338bool ConstStructBuilder::Build(InitListExpr *ILE) { 339 RecordDecl *RD = ILE->getType()->getAs<RecordType>()->getDecl(); 340 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); 341 342 unsigned FieldNo = 0; 343 unsigned ElementNo = 0; 344 for (RecordDecl::field_iterator Field = RD->field_begin(), 345 FieldEnd = RD->field_end(); Field != FieldEnd; ++Field, ++FieldNo) { 346 347 // If this is a union, skip all the fields that aren't being initialized. 348 if (RD->isUnion() && ILE->getInitializedFieldInUnion() != *Field) 349 continue; 350 351 // Don't emit anonymous bitfields, they just affect layout. 352 if (Field->isBitField() && !Field->getIdentifier()) 353 continue; 354 355 // Get the initializer. A struct can include fields without initializers, 356 // we just use explicit null values for them. 357 llvm::Constant *EltInit; 358 if (ElementNo < ILE->getNumInits()) 359 EltInit = CGM.EmitConstantExpr(ILE->getInit(ElementNo++), 360 Field->getType(), CGF); 361 else 362 EltInit = CGM.EmitNullConstant(Field->getType()); 363 364 if (!Field->isBitField()) { 365 // Handle non-bitfield members. 366 if (!AppendField(*Field, Layout.getFieldOffset(FieldNo), EltInit)) 367 return false; 368 } else { 369 // Otherwise we have a bitfield. 370 AppendBitField(*Field, Layout.getFieldOffset(FieldNo), 371 cast<llvm::ConstantInt>(EltInit)); 372 } 373 } 374 375 uint64_t LayoutSizeInBytes = Layout.getSize() / 8; 376 377 if (NextFieldOffsetInBytes > LayoutSizeInBytes) { 378 // If the struct is bigger than the size of the record type, 379 // we must have a flexible array member at the end. 380 assert(RD->hasFlexibleArrayMember() && 381 "Must have flexible array member if struct is bigger than type!"); 382 383 // No tail padding is necessary. 384 return true; 385 } 386 387 uint64_t LLVMSizeInBytes = llvm::RoundUpToAlignment(NextFieldOffsetInBytes, 388 LLVMStructAlignment); 389 390 // Check if we need to convert the struct to a packed struct. 391 if (NextFieldOffsetInBytes <= LayoutSizeInBytes && 392 LLVMSizeInBytes > LayoutSizeInBytes) { 393 assert(!Packed && "Size mismatch!"); 394 395 ConvertStructToPacked(); 396 assert(NextFieldOffsetInBytes <= LayoutSizeInBytes && 397 "Converting to packed did not help!"); 398 } 399 400 // Append tail padding if necessary. 401 AppendTailPadding(Layout.getSize()); 402 403 assert(Layout.getSize() / 8 == NextFieldOffsetInBytes && 404 "Tail padding mismatch!"); 405 406 return true; 407} 408 409llvm::Constant *ConstStructBuilder:: 410 BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF, InitListExpr *ILE) { 411 ConstStructBuilder Builder(CGM, CGF); 412 413 if (!Builder.Build(ILE)) 414 return 0; 415 416 llvm::Constant *Result = 417 llvm::ConstantStruct::get(CGM.getLLVMContext(), 418 Builder.Elements, Builder.Packed); 419 420 assert(llvm::RoundUpToAlignment(Builder.NextFieldOffsetInBytes, 421 Builder.getAlignment(Result)) == 422 Builder.getSizeInBytes(Result) && "Size mismatch!"); 423 424 return Result; 425} 426 427 428//===----------------------------------------------------------------------===// 429// ConstExprEmitter 430//===----------------------------------------------------------------------===// 431 432class ConstExprEmitter : 433 public StmtVisitor<ConstExprEmitter, llvm::Constant*> { 434 CodeGenModule &CGM; 435 CodeGenFunction *CGF; 436 llvm::LLVMContext &VMContext; 437public: 438 ConstExprEmitter(CodeGenModule &cgm, CodeGenFunction *cgf) 439 : CGM(cgm), CGF(cgf), VMContext(cgm.getLLVMContext()) { 440 } 441 442 //===--------------------------------------------------------------------===// 443 // Visitor Methods 444 //===--------------------------------------------------------------------===// 445 446 llvm::Constant *VisitStmt(Stmt *S) { 447 return 0; 448 } 449 450 llvm::Constant *VisitParenExpr(ParenExpr *PE) { 451 return Visit(PE->getSubExpr()); 452 } 453 454 llvm::Constant *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) { 455 return Visit(E->getInitializer()); 456 } 457 458 llvm::Constant *EmitMemberFunctionPointer(CXXMethodDecl *MD) { 459 assert(MD->isInstance() && "Member function must not be static!"); 460 461 MD = MD->getCanonicalDecl(); 462 463 const llvm::Type *PtrDiffTy = 464 CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType()); 465 466 llvm::Constant *Values[2]; 467 468 Values[0] = CGM.GetCXXMemberFunctionPointerValue(MD); 469 470 // The adjustment will always be 0. 471 Values[1] = llvm::ConstantInt::get(PtrDiffTy, 0); 472 473 return llvm::ConstantStruct::get(CGM.getLLVMContext(), 474 Values, 2, /*Packed=*/false); 475 } 476 477 llvm::Constant *VisitUnaryAddrOf(UnaryOperator *E) { 478 if (const MemberPointerType *MPT = 479 E->getType()->getAs<MemberPointerType>()) { 480 QualType T = MPT->getPointeeType(); 481 DeclRefExpr *DRE = cast<DeclRefExpr>(E->getSubExpr()); 482 483 NamedDecl *ND = DRE->getDecl(); 484 if (T->isFunctionProtoType()) 485 return EmitMemberFunctionPointer(cast<CXXMethodDecl>(ND)); 486 487 // We have a pointer to data member. 488 return CGM.EmitPointerToDataMember(cast<FieldDecl>(ND)); 489 } 490 491 return 0; 492 } 493 494 llvm::Constant *VisitBinSub(BinaryOperator *E) { 495 // This must be a pointer/pointer subtraction. This only happens for 496 // address of label. 497 if (!isa<AddrLabelExpr>(E->getLHS()->IgnoreParenNoopCasts(CGM.getContext())) || 498 !isa<AddrLabelExpr>(E->getRHS()->IgnoreParenNoopCasts(CGM.getContext()))) 499 return 0; 500 501 llvm::Constant *LHS = CGM.EmitConstantExpr(E->getLHS(), 502 E->getLHS()->getType(), CGF); 503 llvm::Constant *RHS = CGM.EmitConstantExpr(E->getRHS(), 504 E->getRHS()->getType(), CGF); 505 506 const llvm::Type *ResultType = ConvertType(E->getType()); 507 LHS = llvm::ConstantExpr::getPtrToInt(LHS, ResultType); 508 RHS = llvm::ConstantExpr::getPtrToInt(RHS, ResultType); 509 510 // No need to divide by element size, since addr of label is always void*, 511 // which has size 1 in GNUish. 512 return llvm::ConstantExpr::getSub(LHS, RHS); 513 } 514 515 llvm::Constant *VisitCastExpr(CastExpr* E) { 516 switch (E->getCastKind()) { 517 case CastExpr::CK_ToUnion: { 518 // GCC cast to union extension 519 assert(E->getType()->isUnionType() && 520 "Destination type is not union type!"); 521 const llvm::Type *Ty = ConvertType(E->getType()); 522 Expr *SubExpr = E->getSubExpr(); 523 524 llvm::Constant *C = 525 CGM.EmitConstantExpr(SubExpr, SubExpr->getType(), CGF); 526 if (!C) 527 return 0; 528 529 // Build a struct with the union sub-element as the first member, 530 // and padded to the appropriate size 531 std::vector<llvm::Constant*> Elts; 532 std::vector<const llvm::Type*> Types; 533 Elts.push_back(C); 534 Types.push_back(C->getType()); 535 unsigned CurSize = CGM.getTargetData().getTypeAllocSize(C->getType()); 536 unsigned TotalSize = CGM.getTargetData().getTypeAllocSize(Ty); 537 538 assert(CurSize <= TotalSize && "Union size mismatch!"); 539 if (unsigned NumPadBytes = TotalSize - CurSize) { 540 const llvm::Type *Ty = llvm::Type::getInt8Ty(VMContext); 541 if (NumPadBytes > 1) 542 Ty = llvm::ArrayType::get(Ty, NumPadBytes); 543 544 Elts.push_back(llvm::UndefValue::get(Ty)); 545 Types.push_back(Ty); 546 } 547 548 llvm::StructType* STy = 549 llvm::StructType::get(C->getType()->getContext(), Types, false); 550 return llvm::ConstantStruct::get(STy, Elts); 551 } 552 case CastExpr::CK_NullToMemberPointer: 553 return CGM.EmitNullConstant(E->getType()); 554 555 case CastExpr::CK_BaseToDerivedMemberPointer: { 556 Expr *SubExpr = E->getSubExpr(); 557 558 const MemberPointerType *SrcTy = 559 SubExpr->getType()->getAs<MemberPointerType>(); 560 const MemberPointerType *DestTy = 561 E->getType()->getAs<MemberPointerType>(); 562 563 const CXXRecordDecl *DerivedClass = 564 cast<CXXRecordDecl>(cast<RecordType>(DestTy->getClass())->getDecl()); 565 566 if (SrcTy->getPointeeType()->isFunctionProtoType()) { 567 llvm::Constant *C = 568 CGM.EmitConstantExpr(SubExpr, SubExpr->getType(), CGF); 569 if (!C) 570 return 0; 571 572 llvm::ConstantStruct *CS = cast<llvm::ConstantStruct>(C); 573 574 // Check if we need to update the adjustment. 575 if (llvm::Constant *Offset = 576 CGM.GetNonVirtualBaseClassOffset(DerivedClass, E->getBasePath())) { 577 llvm::Constant *Values[2]; 578 579 Values[0] = CS->getOperand(0); 580 Values[1] = llvm::ConstantExpr::getAdd(CS->getOperand(1), Offset); 581 return llvm::ConstantStruct::get(CGM.getLLVMContext(), Values, 2, 582 /*Packed=*/false); 583 } 584 585 return CS; 586 } 587 } 588 589 case CastExpr::CK_BitCast: 590 // This must be a member function pointer cast. 591 return Visit(E->getSubExpr()); 592 593 default: { 594 // FIXME: This should be handled by the CK_NoOp cast kind. 595 // Explicit and implicit no-op casts 596 QualType Ty = E->getType(), SubTy = E->getSubExpr()->getType(); 597 if (CGM.getContext().hasSameUnqualifiedType(Ty, SubTy)) 598 return Visit(E->getSubExpr()); 599 600 // Handle integer->integer casts for address-of-label differences. 601 if (Ty->isIntegerType() && SubTy->isIntegerType() && 602 CGF) { 603 llvm::Value *Src = Visit(E->getSubExpr()); 604 if (Src == 0) return 0; 605 606 // Use EmitScalarConversion to perform the conversion. 607 return cast<llvm::Constant>(CGF->EmitScalarConversion(Src, SubTy, Ty)); 608 } 609 610 return 0; 611 } 612 } 613 } 614 615 llvm::Constant *VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) { 616 return Visit(DAE->getExpr()); 617 } 618 619 llvm::Constant *EmitArrayInitialization(InitListExpr *ILE) { 620 unsigned NumInitElements = ILE->getNumInits(); 621 if (NumInitElements == 1 && 622 (isa<StringLiteral>(ILE->getInit(0)) || 623 isa<ObjCEncodeExpr>(ILE->getInit(0)))) 624 return Visit(ILE->getInit(0)); 625 626 std::vector<llvm::Constant*> Elts; 627 const llvm::ArrayType *AType = 628 cast<llvm::ArrayType>(ConvertType(ILE->getType())); 629 const llvm::Type *ElemTy = AType->getElementType(); 630 unsigned NumElements = AType->getNumElements(); 631 632 // Initialising an array requires us to automatically 633 // initialise any elements that have not been initialised explicitly 634 unsigned NumInitableElts = std::min(NumInitElements, NumElements); 635 636 // Copy initializer elements. 637 unsigned i = 0; 638 bool RewriteType = false; 639 for (; i < NumInitableElts; ++i) { 640 Expr *Init = ILE->getInit(i); 641 llvm::Constant *C = CGM.EmitConstantExpr(Init, Init->getType(), CGF); 642 if (!C) 643 return 0; 644 RewriteType |= (C->getType() != ElemTy); 645 Elts.push_back(C); 646 } 647 648 // Initialize remaining array elements. 649 // FIXME: This doesn't handle member pointers correctly! 650 for (; i < NumElements; ++i) 651 Elts.push_back(llvm::Constant::getNullValue(ElemTy)); 652 653 if (RewriteType) { 654 // FIXME: Try to avoid packing the array 655 std::vector<const llvm::Type*> Types; 656 for (unsigned i = 0; i < Elts.size(); ++i) 657 Types.push_back(Elts[i]->getType()); 658 const llvm::StructType *SType = llvm::StructType::get(AType->getContext(), 659 Types, true); 660 return llvm::ConstantStruct::get(SType, Elts); 661 } 662 663 return llvm::ConstantArray::get(AType, Elts); 664 } 665 666 llvm::Constant *EmitStructInitialization(InitListExpr *ILE) { 667 return ConstStructBuilder::BuildStruct(CGM, CGF, ILE); 668 } 669 670 llvm::Constant *EmitUnionInitialization(InitListExpr *ILE) { 671 return ConstStructBuilder::BuildStruct(CGM, CGF, ILE); 672 } 673 674 llvm::Constant *VisitImplicitValueInitExpr(ImplicitValueInitExpr* E) { 675 return CGM.EmitNullConstant(E->getType()); 676 } 677 678 llvm::Constant *VisitInitListExpr(InitListExpr *ILE) { 679 if (ILE->getType()->isScalarType()) { 680 // We have a scalar in braces. Just use the first element. 681 if (ILE->getNumInits() > 0) { 682 Expr *Init = ILE->getInit(0); 683 return CGM.EmitConstantExpr(Init, Init->getType(), CGF); 684 } 685 return CGM.EmitNullConstant(ILE->getType()); 686 } 687 688 if (ILE->getType()->isArrayType()) 689 return EmitArrayInitialization(ILE); 690 691 if (ILE->getType()->isRecordType()) 692 return EmitStructInitialization(ILE); 693 694 if (ILE->getType()->isUnionType()) 695 return EmitUnionInitialization(ILE); 696 697 // If ILE was a constant vector, we would have handled it already. 698 if (ILE->getType()->isVectorType()) 699 return 0; 700 701 assert(0 && "Unable to handle InitListExpr"); 702 // Get rid of control reaches end of void function warning. 703 // Not reached. 704 return 0; 705 } 706 707 llvm::Constant *VisitCXXConstructExpr(CXXConstructExpr *E) { 708 if (!E->getConstructor()->isTrivial()) 709 return 0; 710 711 QualType Ty = E->getType(); 712 713 // FIXME: We should not have to call getBaseElementType here. 714 const RecordType *RT = 715 CGM.getContext().getBaseElementType(Ty)->getAs<RecordType>(); 716 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); 717 718 // If the class doesn't have a trivial destructor, we can't emit it as a 719 // constant expr. 720 if (!RD->hasTrivialDestructor()) 721 return 0; 722 723 // Only copy and default constructors can be trivial. 724 725 726 if (E->getNumArgs()) { 727 assert(E->getNumArgs() == 1 && "trivial ctor with > 1 argument"); 728 assert(E->getConstructor()->isCopyConstructor() && 729 "trivial ctor has argument but isn't a copy ctor"); 730 731 Expr *Arg = E->getArg(0); 732 assert(CGM.getContext().hasSameUnqualifiedType(Ty, Arg->getType()) && 733 "argument to copy ctor is of wrong type"); 734 735 return Visit(Arg); 736 } 737 738 return CGM.EmitNullConstant(Ty); 739 } 740 741 llvm::Constant *VisitStringLiteral(StringLiteral *E) { 742 assert(!E->getType()->isPointerType() && "Strings are always arrays"); 743 744 // This must be a string initializing an array in a static initializer. 745 // Don't emit it as the address of the string, emit the string data itself 746 // as an inline array. 747 return llvm::ConstantArray::get(VMContext, 748 CGM.GetStringForStringLiteral(E), false); 749 } 750 751 llvm::Constant *VisitObjCEncodeExpr(ObjCEncodeExpr *E) { 752 // This must be an @encode initializing an array in a static initializer. 753 // Don't emit it as the address of the string, emit the string data itself 754 // as an inline array. 755 std::string Str; 756 CGM.getContext().getObjCEncodingForType(E->getEncodedType(), Str); 757 const ConstantArrayType *CAT = cast<ConstantArrayType>(E->getType()); 758 759 // Resize the string to the right size, adding zeros at the end, or 760 // truncating as needed. 761 Str.resize(CAT->getSize().getZExtValue(), '\0'); 762 return llvm::ConstantArray::get(VMContext, Str, false); 763 } 764 765 llvm::Constant *VisitUnaryExtension(const UnaryOperator *E) { 766 return Visit(E->getSubExpr()); 767 } 768 769 // Utility methods 770 const llvm::Type *ConvertType(QualType T) { 771 return CGM.getTypes().ConvertType(T); 772 } 773 774public: 775 llvm::Constant *EmitLValue(Expr *E) { 776 switch (E->getStmtClass()) { 777 default: break; 778 case Expr::CompoundLiteralExprClass: { 779 // Note that due to the nature of compound literals, this is guaranteed 780 // to be the only use of the variable, so we just generate it here. 781 CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E); 782 llvm::Constant* C = Visit(CLE->getInitializer()); 783 // FIXME: "Leaked" on failure. 784 if (C) 785 C = new llvm::GlobalVariable(CGM.getModule(), C->getType(), 786 E->getType().isConstant(CGM.getContext()), 787 llvm::GlobalValue::InternalLinkage, 788 C, ".compoundliteral", 0, false, 789 E->getType().getAddressSpace()); 790 return C; 791 } 792 case Expr::DeclRefExprClass: { 793 ValueDecl *Decl = cast<DeclRefExpr>(E)->getDecl(); 794 if (Decl->hasAttr<WeakRefAttr>()) 795 return CGM.GetWeakRefReference(Decl); 796 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Decl)) 797 return CGM.GetAddrOfFunction(FD); 798 if (const VarDecl* VD = dyn_cast<VarDecl>(Decl)) { 799 // We can never refer to a variable with local storage. 800 if (!VD->hasLocalStorage()) { 801 if (VD->isFileVarDecl() || VD->hasExternalStorage()) 802 return CGM.GetAddrOfGlobalVar(VD); 803 else if (VD->isBlockVarDecl()) { 804 assert(CGF && "Can't access static local vars without CGF"); 805 return CGF->GetAddrOfStaticLocalVar(VD); 806 } 807 } 808 } 809 break; 810 } 811 case Expr::StringLiteralClass: 812 return CGM.GetAddrOfConstantStringFromLiteral(cast<StringLiteral>(E)); 813 case Expr::ObjCEncodeExprClass: 814 return CGM.GetAddrOfConstantStringFromObjCEncode(cast<ObjCEncodeExpr>(E)); 815 case Expr::ObjCStringLiteralClass: { 816 ObjCStringLiteral* SL = cast<ObjCStringLiteral>(E); 817 llvm::Constant *C = 818 CGM.getObjCRuntime().GenerateConstantString(SL->getString()); 819 return llvm::ConstantExpr::getBitCast(C, ConvertType(E->getType())); 820 } 821 case Expr::PredefinedExprClass: { 822 unsigned Type = cast<PredefinedExpr>(E)->getIdentType(); 823 if (CGF) { 824 LValue Res = CGF->EmitPredefinedFunctionName(Type); 825 return cast<llvm::Constant>(Res.getAddress()); 826 } else if (Type == PredefinedExpr::PrettyFunction) { 827 return CGM.GetAddrOfConstantCString("top level", ".tmp"); 828 } 829 830 return CGM.GetAddrOfConstantCString("", ".tmp"); 831 } 832 case Expr::AddrLabelExprClass: { 833 assert(CGF && "Invalid address of label expression outside function."); 834 llvm::Constant *Ptr = 835 CGF->GetAddrOfLabel(cast<AddrLabelExpr>(E)->getLabel()); 836 return llvm::ConstantExpr::getBitCast(Ptr, ConvertType(E->getType())); 837 } 838 case Expr::CallExprClass: { 839 CallExpr* CE = cast<CallExpr>(E); 840 unsigned builtin = CE->isBuiltinCall(CGM.getContext()); 841 if (builtin != 842 Builtin::BI__builtin___CFStringMakeConstantString && 843 builtin != 844 Builtin::BI__builtin___NSStringMakeConstantString) 845 break; 846 const Expr *Arg = CE->getArg(0)->IgnoreParenCasts(); 847 const StringLiteral *Literal = cast<StringLiteral>(Arg); 848 if (builtin == 849 Builtin::BI__builtin___NSStringMakeConstantString) { 850 return CGM.getObjCRuntime().GenerateConstantString(Literal); 851 } 852 // FIXME: need to deal with UCN conversion issues. 853 return CGM.GetAddrOfConstantCFString(Literal); 854 } 855 case Expr::BlockExprClass: { 856 std::string FunctionName; 857 if (CGF) 858 FunctionName = CGF->CurFn->getName(); 859 else 860 FunctionName = "global"; 861 862 return CGM.GetAddrOfGlobalBlock(cast<BlockExpr>(E), FunctionName.c_str()); 863 } 864 } 865 866 return 0; 867 } 868}; 869 870} // end anonymous namespace. 871 872llvm::Constant *CodeGenModule::EmitConstantExpr(const Expr *E, 873 QualType DestType, 874 CodeGenFunction *CGF) { 875 Expr::EvalResult Result; 876 877 bool Success = false; 878 879 if (DestType->isReferenceType()) 880 Success = E->EvaluateAsLValue(Result, Context); 881 else 882 Success = E->Evaluate(Result, Context); 883 884 if (Success && !Result.HasSideEffects) { 885 switch (Result.Val.getKind()) { 886 case APValue::Uninitialized: 887 assert(0 && "Constant expressions should be initialized."); 888 return 0; 889 case APValue::LValue: { 890 const llvm::Type *DestTy = getTypes().ConvertTypeForMem(DestType); 891 llvm::Constant *Offset = 892 llvm::ConstantInt::get(llvm::Type::getInt64Ty(VMContext), 893 Result.Val.getLValueOffset().getQuantity()); 894 895 llvm::Constant *C; 896 if (const Expr *LVBase = Result.Val.getLValueBase()) { 897 C = ConstExprEmitter(*this, CGF).EmitLValue(const_cast<Expr*>(LVBase)); 898 899 // Apply offset if necessary. 900 if (!Offset->isNullValue()) { 901 const llvm::Type *Type = llvm::Type::getInt8PtrTy(VMContext); 902 llvm::Constant *Casted = llvm::ConstantExpr::getBitCast(C, Type); 903 Casted = llvm::ConstantExpr::getGetElementPtr(Casted, &Offset, 1); 904 C = llvm::ConstantExpr::getBitCast(Casted, C->getType()); 905 } 906 907 // Convert to the appropriate type; this could be an lvalue for 908 // an integer. 909 if (isa<llvm::PointerType>(DestTy)) 910 return llvm::ConstantExpr::getBitCast(C, DestTy); 911 912 return llvm::ConstantExpr::getPtrToInt(C, DestTy); 913 } else { 914 C = Offset; 915 916 // Convert to the appropriate type; this could be an lvalue for 917 // an integer. 918 if (isa<llvm::PointerType>(DestTy)) 919 return llvm::ConstantExpr::getIntToPtr(C, DestTy); 920 921 // If the types don't match this should only be a truncate. 922 if (C->getType() != DestTy) 923 return llvm::ConstantExpr::getTrunc(C, DestTy); 924 925 return C; 926 } 927 } 928 case APValue::Int: { 929 llvm::Constant *C = llvm::ConstantInt::get(VMContext, 930 Result.Val.getInt()); 931 932 if (C->getType()->isIntegerTy(1)) { 933 const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType()); 934 C = llvm::ConstantExpr::getZExt(C, BoolTy); 935 } 936 return C; 937 } 938 case APValue::ComplexInt: { 939 llvm::Constant *Complex[2]; 940 941 Complex[0] = llvm::ConstantInt::get(VMContext, 942 Result.Val.getComplexIntReal()); 943 Complex[1] = llvm::ConstantInt::get(VMContext, 944 Result.Val.getComplexIntImag()); 945 946 // FIXME: the target may want to specify that this is packed. 947 return llvm::ConstantStruct::get(VMContext, Complex, 2, false); 948 } 949 case APValue::Float: 950 return llvm::ConstantFP::get(VMContext, Result.Val.getFloat()); 951 case APValue::ComplexFloat: { 952 llvm::Constant *Complex[2]; 953 954 Complex[0] = llvm::ConstantFP::get(VMContext, 955 Result.Val.getComplexFloatReal()); 956 Complex[1] = llvm::ConstantFP::get(VMContext, 957 Result.Val.getComplexFloatImag()); 958 959 // FIXME: the target may want to specify that this is packed. 960 return llvm::ConstantStruct::get(VMContext, Complex, 2, false); 961 } 962 case APValue::Vector: { 963 llvm::SmallVector<llvm::Constant *, 4> Inits; 964 unsigned NumElts = Result.Val.getVectorLength(); 965 966 for (unsigned i = 0; i != NumElts; ++i) { 967 APValue &Elt = Result.Val.getVectorElt(i); 968 if (Elt.isInt()) 969 Inits.push_back(llvm::ConstantInt::get(VMContext, Elt.getInt())); 970 else 971 Inits.push_back(llvm::ConstantFP::get(VMContext, Elt.getFloat())); 972 } 973 return llvm::ConstantVector::get(&Inits[0], Inits.size()); 974 } 975 } 976 } 977 978 llvm::Constant* C = ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E)); 979 if (C && C->getType()->isIntegerTy(1)) { 980 const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType()); 981 C = llvm::ConstantExpr::getZExt(C, BoolTy); 982 } 983 return C; 984} 985 986static void 987FillInNullDataMemberPointers(CodeGenModule &CGM, QualType T, 988 std::vector<llvm::Constant *> &Elements, 989 uint64_t StartOffset) { 990 assert(StartOffset % 8 == 0 && "StartOffset not byte aligned!"); 991 992 if (!CGM.getTypes().ContainsPointerToDataMember(T)) 993 return; 994 995 if (const ConstantArrayType *CAT = 996 CGM.getContext().getAsConstantArrayType(T)) { 997 QualType ElementTy = CAT->getElementType(); 998 uint64_t ElementSize = CGM.getContext().getTypeSize(ElementTy); 999 1000 for (uint64_t I = 0, E = CAT->getSize().getZExtValue(); I != E; ++I) { 1001 FillInNullDataMemberPointers(CGM, ElementTy, Elements, 1002 StartOffset + I * ElementSize); 1003 } 1004 } else if (const RecordType *RT = T->getAs<RecordType>()) { 1005 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); 1006 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); 1007 1008 // Go through all bases and fill in any null pointer to data members. 1009 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 1010 E = RD->bases_end(); I != E; ++I) { 1011 if (I->isVirtual()) { 1012 // FIXME: We should initialize null pointer to data members in virtual 1013 // bases here. 1014 continue; 1015 } 1016 1017 const CXXRecordDecl *BaseDecl = 1018 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); 1019 1020 // Ignore empty bases. 1021 if (BaseDecl->isEmpty()) 1022 continue; 1023 1024 // Ignore bases that don't have any pointer to data members. 1025 if (!CGM.getTypes().ContainsPointerToDataMember(BaseDecl)) 1026 continue; 1027 1028 uint64_t BaseOffset = Layout.getBaseClassOffset(BaseDecl); 1029 FillInNullDataMemberPointers(CGM, I->getType(), 1030 Elements, StartOffset + BaseOffset); 1031 } 1032 1033 // Visit all fields. 1034 unsigned FieldNo = 0; 1035 for (RecordDecl::field_iterator I = RD->field_begin(), 1036 E = RD->field_end(); I != E; ++I, ++FieldNo) { 1037 QualType FieldType = I->getType(); 1038 1039 if (!CGM.getTypes().ContainsPointerToDataMember(FieldType)) 1040 continue; 1041 1042 uint64_t FieldOffset = StartOffset + Layout.getFieldOffset(FieldNo); 1043 FillInNullDataMemberPointers(CGM, FieldType, Elements, FieldOffset); 1044 } 1045 } else { 1046 assert(T->isMemberPointerType() && "Should only see member pointers here!"); 1047 assert(!T->getAs<MemberPointerType>()->getPointeeType()->isFunctionType() && 1048 "Should only see pointers to data members here!"); 1049 1050 uint64_t StartIndex = StartOffset / 8; 1051 uint64_t EndIndex = StartIndex + CGM.getContext().getTypeSize(T) / 8; 1052 1053 llvm::Constant *NegativeOne = 1054 llvm::ConstantInt::get(llvm::Type::getInt8Ty(CGM.getLLVMContext()), 1055 -1ULL, /*isSigned=*/true); 1056 1057 // Fill in the null data member pointer. 1058 for (uint64_t I = StartIndex; I != EndIndex; ++I) 1059 Elements[I] = NegativeOne; 1060 } 1061} 1062 1063llvm::Constant *CodeGenModule::EmitNullConstant(QualType T) { 1064 if (!getTypes().ContainsPointerToDataMember(T)) 1065 return llvm::Constant::getNullValue(getTypes().ConvertTypeForMem(T)); 1066 1067 if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(T)) { 1068 1069 QualType ElementTy = CAT->getElementType(); 1070 1071 llvm::Constant *Element = EmitNullConstant(ElementTy); 1072 unsigned NumElements = CAT->getSize().getZExtValue(); 1073 std::vector<llvm::Constant *> Array(NumElements); 1074 for (unsigned i = 0; i != NumElements; ++i) 1075 Array[i] = Element; 1076 1077 const llvm::ArrayType *ATy = 1078 cast<llvm::ArrayType>(getTypes().ConvertTypeForMem(T)); 1079 return llvm::ConstantArray::get(ATy, Array); 1080 } 1081 1082 if (const RecordType *RT = T->getAs<RecordType>()) { 1083 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); 1084 const llvm::StructType *STy = 1085 cast<llvm::StructType>(getTypes().ConvertTypeForMem(T)); 1086 unsigned NumElements = STy->getNumElements(); 1087 std::vector<llvm::Constant *> Elements(NumElements); 1088 1089 const CGRecordLayout &Layout = getTypes().getCGRecordLayout(RD); 1090 1091 // Go through all bases and fill in any null pointer to data members. 1092 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 1093 E = RD->bases_end(); I != E; ++I) { 1094 if (I->isVirtual()) { 1095 // FIXME: We should initialize null pointer to data members in virtual 1096 // bases here. 1097 continue; 1098 } 1099 1100 const CXXRecordDecl *BaseDecl = 1101 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); 1102 1103 // Ignore empty bases. 1104 if (BaseDecl->isEmpty()) 1105 continue; 1106 1107 // Ignore bases that don't have any pointer to data members. 1108 if (!getTypes().ContainsPointerToDataMember(BaseDecl)) 1109 continue; 1110 1111 // Currently, all bases are arrays of i8. Figure out how many elements 1112 // this base array has. 1113 unsigned BaseFieldNo = Layout.getNonVirtualBaseLLVMFieldNo(BaseDecl); 1114 const llvm::ArrayType *BaseArrayTy = 1115 cast<llvm::ArrayType>(STy->getElementType(BaseFieldNo)); 1116 1117 unsigned NumBaseElements = BaseArrayTy->getNumElements(); 1118 std::vector<llvm::Constant *> BaseElements(NumBaseElements); 1119 1120 // Now fill in null data member pointers. 1121 FillInNullDataMemberPointers(*this, I->getType(), BaseElements, 0); 1122 1123 // Now go through all other elements and zero them out. 1124 if (NumBaseElements) { 1125 llvm::Constant *Zero = 1126 llvm::ConstantInt::get(llvm::Type::getInt8Ty(getLLVMContext()), 0); 1127 1128 for (unsigned I = 0; I != NumBaseElements; ++I) { 1129 if (!BaseElements[I]) 1130 BaseElements[I] = Zero; 1131 } 1132 } 1133 1134 Elements[BaseFieldNo] = llvm::ConstantArray::get(BaseArrayTy, 1135 BaseElements); 1136 } 1137 1138 for (RecordDecl::field_iterator I = RD->field_begin(), 1139 E = RD->field_end(); I != E; ++I) { 1140 const FieldDecl *FD = *I; 1141 1142 // Ignore bit fields. 1143 if (FD->isBitField()) 1144 continue; 1145 1146 unsigned FieldNo = Layout.getLLVMFieldNo(FD); 1147 Elements[FieldNo] = EmitNullConstant(FD->getType()); 1148 } 1149 1150 // Now go through all other fields and zero them out. 1151 for (unsigned i = 0; i != NumElements; ++i) { 1152 if (!Elements[i]) 1153 Elements[i] = llvm::Constant::getNullValue(STy->getElementType(i)); 1154 } 1155 1156 return llvm::ConstantStruct::get(STy, Elements); 1157 } 1158 1159 assert(T->isMemberPointerType() && "Should only see member pointers here!"); 1160 assert(!T->getAs<MemberPointerType>()->getPointeeType()->isFunctionType() && 1161 "Should only see pointers to data members here!"); 1162 1163 // Itanium C++ ABI 2.3: 1164 // A NULL pointer is represented as -1. 1165 return llvm::ConstantInt::get(getTypes().ConvertTypeForMem(T), -1ULL, 1166 /*isSigned=*/true); 1167} 1168 1169llvm::Constant * 1170CodeGenModule::EmitPointerToDataMember(const FieldDecl *FD) { 1171 1172 // Itanium C++ ABI 2.3: 1173 // A pointer to data member is an offset from the base address of the class 1174 // object containing it, represented as a ptrdiff_t 1175 1176 const CXXRecordDecl *ClassDecl = cast<CXXRecordDecl>(FD->getParent()); 1177 QualType ClassType = 1178 getContext().getTypeDeclType(const_cast<CXXRecordDecl *>(ClassDecl)); 1179 1180 const llvm::StructType *ClassLTy = 1181 cast<llvm::StructType>(getTypes().ConvertType(ClassType)); 1182 1183 const CGRecordLayout &RL = 1184 getTypes().getCGRecordLayout(FD->getParent()); 1185 unsigned FieldNo = RL.getLLVMFieldNo(FD); 1186 uint64_t Offset = 1187 getTargetData().getStructLayout(ClassLTy)->getElementOffset(FieldNo); 1188 1189 const llvm::Type *PtrDiffTy = 1190 getTypes().ConvertType(getContext().getPointerDiffType()); 1191 1192 return llvm::ConstantInt::get(PtrDiffTy, Offset); 1193} 1194