CGExprConstant.cpp revision a7e6845660f91ec611427e1db842780e1ec12bdb
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 unsigned FieldAlignment = getAlignment(InitCst); 85 86 // Round up the field offset to the alignment of the field type. 87 uint64_t AlignedNextFieldOffsetInBytes = 88 llvm::RoundUpToAlignment(NextFieldOffsetInBytes, FieldAlignment); 89 90 if (AlignedNextFieldOffsetInBytes > FieldOffsetInBytes) { 91 assert(!Packed && "Alignment is wrong even with a packed struct!"); 92 93 // Convert the struct to a packed struct. 94 ConvertStructToPacked(); 95 96 AlignedNextFieldOffsetInBytes = NextFieldOffsetInBytes; 97 } 98 99 if (AlignedNextFieldOffsetInBytes < FieldOffsetInBytes) { 100 // We need to append padding. 101 AppendPadding(FieldOffsetInBytes - NextFieldOffsetInBytes); 102 103 assert(NextFieldOffsetInBytes == FieldOffsetInBytes && 104 "Did not add enough padding!"); 105 106 AlignedNextFieldOffsetInBytes = NextFieldOffsetInBytes; 107 } 108 109 // Add the field. 110 Elements.push_back(InitCst); 111 NextFieldOffsetInBytes = AlignedNextFieldOffsetInBytes + 112 getSizeInBytes(InitCst); 113 114 if (Packed) 115 assert(LLVMStructAlignment == 1 && "Packed struct not byte-aligned!"); 116 else 117 LLVMStructAlignment = std::max(LLVMStructAlignment, FieldAlignment); 118 119 return true; 120} 121 122void ConstStructBuilder::AppendBitField(const FieldDecl *Field, 123 uint64_t FieldOffset, 124 llvm::ConstantInt *CI) { 125 if (FieldOffset > NextFieldOffsetInBytes * 8) { 126 // We need to add padding. 127 uint64_t NumBytes = 128 llvm::RoundUpToAlignment(FieldOffset - 129 NextFieldOffsetInBytes * 8, 8) / 8; 130 131 AppendPadding(NumBytes); 132 } 133 134 uint64_t FieldSize = 135 Field->getBitWidth()->EvaluateAsInt(CGM.getContext()).getZExtValue(); 136 137 llvm::APInt FieldValue = CI->getValue(); 138 139 // Promote the size of FieldValue if necessary 140 // FIXME: This should never occur, but currently it can because initializer 141 // constants are cast to bool, and because clang is not enforcing bitfield 142 // width limits. 143 if (FieldSize > FieldValue.getBitWidth()) 144 FieldValue.zext(FieldSize); 145 146 // Truncate the size of FieldValue to the bit field size. 147 if (FieldSize < FieldValue.getBitWidth()) 148 FieldValue.trunc(FieldSize); 149 150 if (FieldOffset < NextFieldOffsetInBytes * 8) { 151 // Either part of the field or the entire field can go into the previous 152 // byte. 153 assert(!Elements.empty() && "Elements can't be empty!"); 154 155 unsigned BitsInPreviousByte = 156 NextFieldOffsetInBytes * 8 - FieldOffset; 157 158 bool FitsCompletelyInPreviousByte = 159 BitsInPreviousByte >= FieldValue.getBitWidth(); 160 161 llvm::APInt Tmp = FieldValue; 162 163 if (!FitsCompletelyInPreviousByte) { 164 unsigned NewFieldWidth = FieldSize - BitsInPreviousByte; 165 166 if (CGM.getTargetData().isBigEndian()) { 167 Tmp = Tmp.lshr(NewFieldWidth); 168 Tmp.trunc(BitsInPreviousByte); 169 170 // We want the remaining high bits. 171 FieldValue.trunc(NewFieldWidth); 172 } else { 173 Tmp.trunc(BitsInPreviousByte); 174 175 // We want the remaining low bits. 176 FieldValue = FieldValue.lshr(BitsInPreviousByte); 177 FieldValue.trunc(NewFieldWidth); 178 } 179 } 180 181 Tmp.zext(8); 182 if (CGM.getTargetData().isBigEndian()) { 183 if (FitsCompletelyInPreviousByte) 184 Tmp = Tmp.shl(BitsInPreviousByte - FieldValue.getBitWidth()); 185 } else { 186 Tmp = Tmp.shl(8 - BitsInPreviousByte); 187 } 188 189 // 'or' in the bits that go into the previous byte. 190 llvm::Value *LastElt = Elements.back(); 191 if (llvm::ConstantInt *Val = dyn_cast<llvm::ConstantInt>(LastElt)) 192 Tmp |= Val->getValue(); 193 else { 194 assert(isa<llvm::UndefValue>(LastElt)); 195 // If there is an undef field that we're adding to, it can either be a 196 // scalar undef (in which case, we just replace it with our field) or it 197 // is an array. If it is an array, we have to pull one byte off the 198 // array so that the other undef bytes stay around. 199 if (!isa<llvm::IntegerType>(LastElt->getType())) { 200 // The undef padding will be a multibyte array, create a new smaller 201 // padding and then an hole for our i8 to get plopped into. 202 assert(isa<llvm::ArrayType>(LastElt->getType()) && 203 "Expected array padding of undefs"); 204 const llvm::ArrayType *AT = cast<llvm::ArrayType>(LastElt->getType()); 205 assert(AT->getElementType()->isIntegerTy(8) && 206 AT->getNumElements() != 0 && 207 "Expected non-empty array padding of undefs"); 208 209 // Remove the padding array. 210 NextFieldOffsetInBytes -= AT->getNumElements(); 211 Elements.pop_back(); 212 213 // Add the padding back in two chunks. 214 AppendPadding(AT->getNumElements()-1); 215 AppendPadding(1); 216 assert(isa<llvm::UndefValue>(Elements.back()) && 217 Elements.back()->getType()->isIntegerTy(8) && 218 "Padding addition didn't work right"); 219 } 220 } 221 222 Elements.back() = llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp); 223 224 if (FitsCompletelyInPreviousByte) 225 return; 226 } 227 228 while (FieldValue.getBitWidth() > 8) { 229 llvm::APInt Tmp; 230 231 if (CGM.getTargetData().isBigEndian()) { 232 // We want the high bits. 233 Tmp = FieldValue; 234 Tmp = Tmp.lshr(Tmp.getBitWidth() - 8); 235 Tmp.trunc(8); 236 } else { 237 // We want the low bits. 238 Tmp = FieldValue; 239 Tmp.trunc(8); 240 241 FieldValue = FieldValue.lshr(8); 242 } 243 244 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp)); 245 NextFieldOffsetInBytes++; 246 247 FieldValue.trunc(FieldValue.getBitWidth() - 8); 248 } 249 250 assert(FieldValue.getBitWidth() > 0 && 251 "Should have at least one bit left!"); 252 assert(FieldValue.getBitWidth() <= 8 && 253 "Should not have more than a byte left!"); 254 255 if (FieldValue.getBitWidth() < 8) { 256 if (CGM.getTargetData().isBigEndian()) { 257 unsigned BitWidth = FieldValue.getBitWidth(); 258 259 FieldValue.zext(8); 260 FieldValue = FieldValue << (8 - BitWidth); 261 } else 262 FieldValue.zext(8); 263 } 264 265 // Append the last element. 266 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), 267 FieldValue)); 268 NextFieldOffsetInBytes++; 269} 270 271void ConstStructBuilder::AppendPadding(uint64_t NumBytes) { 272 if (!NumBytes) 273 return; 274 275 const llvm::Type *Ty = llvm::Type::getInt8Ty(CGM.getLLVMContext()); 276 if (NumBytes > 1) 277 Ty = llvm::ArrayType::get(Ty, NumBytes); 278 279 llvm::Constant *C = llvm::UndefValue::get(Ty); 280 Elements.push_back(C); 281 assert(getAlignment(C) == 1 && "Padding must have 1 byte alignment!"); 282 283 NextFieldOffsetInBytes += getSizeInBytes(C); 284} 285 286void ConstStructBuilder::AppendTailPadding(uint64_t RecordSize) { 287 assert(RecordSize % 8 == 0 && "Invalid record size!"); 288 289 uint64_t RecordSizeInBytes = RecordSize / 8; 290 assert(NextFieldOffsetInBytes <= RecordSizeInBytes && "Size mismatch!"); 291 292 unsigned NumPadBytes = RecordSizeInBytes - NextFieldOffsetInBytes; 293 AppendPadding(NumPadBytes); 294} 295 296void ConstStructBuilder::ConvertStructToPacked() { 297 std::vector<llvm::Constant *> PackedElements; 298 uint64_t ElementOffsetInBytes = 0; 299 300 for (unsigned i = 0, e = Elements.size(); i != e; ++i) { 301 llvm::Constant *C = Elements[i]; 302 303 unsigned ElementAlign = 304 CGM.getTargetData().getABITypeAlignment(C->getType()); 305 uint64_t AlignedElementOffsetInBytes = 306 llvm::RoundUpToAlignment(ElementOffsetInBytes, ElementAlign); 307 308 if (AlignedElementOffsetInBytes > ElementOffsetInBytes) { 309 // We need some padding. 310 uint64_t NumBytes = 311 AlignedElementOffsetInBytes - ElementOffsetInBytes; 312 313 const llvm::Type *Ty = llvm::Type::getInt8Ty(CGM.getLLVMContext()); 314 if (NumBytes > 1) 315 Ty = llvm::ArrayType::get(Ty, NumBytes); 316 317 llvm::Constant *Padding = llvm::UndefValue::get(Ty); 318 PackedElements.push_back(Padding); 319 ElementOffsetInBytes += getSizeInBytes(Padding); 320 } 321 322 PackedElements.push_back(C); 323 ElementOffsetInBytes += getSizeInBytes(C); 324 } 325 326 assert(ElementOffsetInBytes == NextFieldOffsetInBytes && 327 "Packing the struct changed its size!"); 328 329 Elements = PackedElements; 330 LLVMStructAlignment = 1; 331 Packed = true; 332} 333 334bool ConstStructBuilder::Build(InitListExpr *ILE) { 335 RecordDecl *RD = ILE->getType()->getAs<RecordType>()->getDecl(); 336 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); 337 338 unsigned FieldNo = 0; 339 unsigned ElementNo = 0; 340 for (RecordDecl::field_iterator Field = RD->field_begin(), 341 FieldEnd = RD->field_end(); Field != FieldEnd; ++Field, ++FieldNo) { 342 343 // If this is a union, skip all the fields that aren't being initialized. 344 if (RD->isUnion() && ILE->getInitializedFieldInUnion() != *Field) 345 continue; 346 347 // Don't emit anonymous bitfields, they just affect layout. 348 if (Field->isBitField() && !Field->getIdentifier()) 349 continue; 350 351 // Get the initializer. A struct can include fields without initializers, 352 // we just use explicit null values for them. 353 llvm::Constant *EltInit; 354 if (ElementNo < ILE->getNumInits()) 355 EltInit = CGM.EmitConstantExpr(ILE->getInit(ElementNo++), 356 Field->getType(), CGF); 357 else 358 EltInit = CGM.EmitNullConstant(Field->getType()); 359 360 if (!EltInit) 361 return false; 362 363 if (!Field->isBitField()) { 364 // Handle non-bitfield members. 365 if (!AppendField(*Field, Layout.getFieldOffset(FieldNo), EltInit)) 366 return false; 367 } else { 368 // Otherwise we have a bitfield. 369 AppendBitField(*Field, Layout.getFieldOffset(FieldNo), 370 cast<llvm::ConstantInt>(EltInit)); 371 } 372 } 373 374 uint64_t LayoutSizeInBytes = Layout.getSize() / 8; 375 376 if (NextFieldOffsetInBytes > LayoutSizeInBytes) { 377 // If the struct is bigger than the size of the record type, 378 // we must have a flexible array member at the end. 379 assert(RD->hasFlexibleArrayMember() && 380 "Must have flexible array member if struct is bigger than type!"); 381 382 // No tail padding is necessary. 383 return true; 384 } 385 386 uint64_t LLVMSizeInBytes = llvm::RoundUpToAlignment(NextFieldOffsetInBytes, 387 LLVMStructAlignment); 388 389 // Check if we need to convert the struct to a packed struct. 390 if (NextFieldOffsetInBytes <= LayoutSizeInBytes && 391 LLVMSizeInBytes > LayoutSizeInBytes) { 392 assert(!Packed && "Size mismatch!"); 393 394 ConvertStructToPacked(); 395 assert(NextFieldOffsetInBytes <= LayoutSizeInBytes && 396 "Converting to packed did not help!"); 397 } 398 399 // Append tail padding if necessary. 400 AppendTailPadding(Layout.getSize()); 401 402 assert(Layout.getSize() / 8 == NextFieldOffsetInBytes && 403 "Tail padding mismatch!"); 404 405 return true; 406} 407 408llvm::Constant *ConstStructBuilder:: 409 BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF, InitListExpr *ILE) { 410 ConstStructBuilder Builder(CGM, CGF); 411 412 if (!Builder.Build(ILE)) 413 return 0; 414 415 llvm::Constant *Result = 416 llvm::ConstantStruct::get(CGM.getLLVMContext(), 417 Builder.Elements, Builder.Packed); 418 419 assert(llvm::RoundUpToAlignment(Builder.NextFieldOffsetInBytes, 420 Builder.getAlignment(Result)) == 421 Builder.getSizeInBytes(Result) && "Size mismatch!"); 422 423 return Result; 424} 425 426 427//===----------------------------------------------------------------------===// 428// ConstExprEmitter 429//===----------------------------------------------------------------------===// 430 431class ConstExprEmitter : 432 public StmtVisitor<ConstExprEmitter, llvm::Constant*> { 433 CodeGenModule &CGM; 434 CodeGenFunction *CGF; 435 llvm::LLVMContext &VMContext; 436public: 437 ConstExprEmitter(CodeGenModule &cgm, CodeGenFunction *cgf) 438 : CGM(cgm), CGF(cgf), VMContext(cgm.getLLVMContext()) { 439 } 440 441 //===--------------------------------------------------------------------===// 442 // Visitor Methods 443 //===--------------------------------------------------------------------===// 444 445 llvm::Constant *VisitStmt(Stmt *S) { 446 return 0; 447 } 448 449 llvm::Constant *VisitParenExpr(ParenExpr *PE) { 450 return Visit(PE->getSubExpr()); 451 } 452 453 llvm::Constant *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) { 454 return Visit(E->getInitializer()); 455 } 456 457 llvm::Constant *EmitMemberFunctionPointer(CXXMethodDecl *MD) { 458 assert(MD->isInstance() && "Member function must not be static!"); 459 460 MD = MD->getCanonicalDecl(); 461 462 const llvm::Type *PtrDiffTy = 463 CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType()); 464 465 llvm::Constant *Values[2]; 466 467 Values[0] = CGM.GetCXXMemberFunctionPointerValue(MD); 468 469 // The adjustment will always be 0. 470 Values[1] = llvm::ConstantInt::get(PtrDiffTy, 0); 471 472 return llvm::ConstantStruct::get(CGM.getLLVMContext(), 473 Values, 2, /*Packed=*/false); 474 } 475 476 llvm::Constant *VisitUnaryAddrOf(UnaryOperator *E) { 477 if (const MemberPointerType *MPT = 478 E->getType()->getAs<MemberPointerType>()) { 479 QualType T = MPT->getPointeeType(); 480 DeclRefExpr *DRE = cast<DeclRefExpr>(E->getSubExpr()); 481 482 NamedDecl *ND = DRE->getDecl(); 483 if (T->isFunctionProtoType()) 484 return EmitMemberFunctionPointer(cast<CXXMethodDecl>(ND)); 485 486 // We have a pointer to data member. 487 return CGM.EmitPointerToDataMember(cast<FieldDecl>(ND)); 488 } 489 490 return 0; 491 } 492 493 llvm::Constant *VisitBinSub(BinaryOperator *E) { 494 // This must be a pointer/pointer subtraction. This only happens for 495 // address of label. 496 if (!isa<AddrLabelExpr>(E->getLHS()->IgnoreParenNoopCasts(CGM.getContext())) || 497 !isa<AddrLabelExpr>(E->getRHS()->IgnoreParenNoopCasts(CGM.getContext()))) 498 return 0; 499 500 llvm::Constant *LHS = CGM.EmitConstantExpr(E->getLHS(), 501 E->getLHS()->getType(), CGF); 502 llvm::Constant *RHS = CGM.EmitConstantExpr(E->getRHS(), 503 E->getRHS()->getType(), CGF); 504 505 const llvm::Type *ResultType = ConvertType(E->getType()); 506 LHS = llvm::ConstantExpr::getPtrToInt(LHS, ResultType); 507 RHS = llvm::ConstantExpr::getPtrToInt(RHS, ResultType); 508 509 // No need to divide by element size, since addr of label is always void*, 510 // which has size 1 in GNUish. 511 return llvm::ConstantExpr::getSub(LHS, RHS); 512 } 513 514 llvm::Constant *VisitCastExpr(CastExpr* E) { 515 switch (E->getCastKind()) { 516 case CastExpr::CK_ToUnion: { 517 // GCC cast to union extension 518 assert(E->getType()->isUnionType() && 519 "Destination type is not union type!"); 520 const llvm::Type *Ty = ConvertType(E->getType()); 521 Expr *SubExpr = E->getSubExpr(); 522 523 llvm::Constant *C = 524 CGM.EmitConstantExpr(SubExpr, SubExpr->getType(), CGF); 525 if (!C) 526 return 0; 527 528 // Build a struct with the union sub-element as the first member, 529 // and padded to the appropriate size 530 std::vector<llvm::Constant*> Elts; 531 std::vector<const llvm::Type*> Types; 532 Elts.push_back(C); 533 Types.push_back(C->getType()); 534 unsigned CurSize = CGM.getTargetData().getTypeAllocSize(C->getType()); 535 unsigned TotalSize = CGM.getTargetData().getTypeAllocSize(Ty); 536 537 assert(CurSize <= TotalSize && "Union size mismatch!"); 538 if (unsigned NumPadBytes = TotalSize - CurSize) { 539 const llvm::Type *Ty = llvm::Type::getInt8Ty(VMContext); 540 if (NumPadBytes > 1) 541 Ty = llvm::ArrayType::get(Ty, NumPadBytes); 542 543 Elts.push_back(llvm::UndefValue::get(Ty)); 544 Types.push_back(Ty); 545 } 546 547 llvm::StructType* STy = 548 llvm::StructType::get(C->getType()->getContext(), Types, false); 549 return llvm::ConstantStruct::get(STy, Elts); 550 } 551 case CastExpr::CK_NullToMemberPointer: 552 return CGM.EmitNullConstant(E->getType()); 553 554 case CastExpr::CK_BaseToDerivedMemberPointer: { 555 Expr *SubExpr = E->getSubExpr(); 556 557 const MemberPointerType *SrcTy = 558 SubExpr->getType()->getAs<MemberPointerType>(); 559 const MemberPointerType *DestTy = 560 E->getType()->getAs<MemberPointerType>(); 561 562 const CXXRecordDecl *DerivedClass = 563 cast<CXXRecordDecl>(cast<RecordType>(DestTy->getClass())->getDecl()); 564 565 if (SrcTy->getPointeeType()->isFunctionProtoType()) { 566 llvm::Constant *C = 567 CGM.EmitConstantExpr(SubExpr, SubExpr->getType(), CGF); 568 if (!C) 569 return 0; 570 571 llvm::ConstantStruct *CS = cast<llvm::ConstantStruct>(C); 572 573 // Check if we need to update the adjustment. 574 if (llvm::Constant *Offset = 575 CGM.GetNonVirtualBaseClassOffset(DerivedClass, 576 E->path_begin(), 577 E->path_end())) { 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->EmitPredefinedLValue(cast<PredefinedExpr>(E)); 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()->isIntegerTy(1)) { 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()->isIntegerTy(1)) { 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 if (I->isVirtual()) { 1013 // FIXME: We should initialize null pointer to data members in virtual 1014 // bases here. 1015 continue; 1016 } 1017 1018 const CXXRecordDecl *BaseDecl = 1019 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); 1020 1021 // Ignore empty bases. 1022 if (BaseDecl->isEmpty()) 1023 continue; 1024 1025 // Ignore bases that don't have any pointer to data members. 1026 if (!CGM.getTypes().ContainsPointerToDataMember(BaseDecl)) 1027 continue; 1028 1029 uint64_t BaseOffset = Layout.getBaseClassOffset(BaseDecl); 1030 FillInNullDataMemberPointers(CGM, I->getType(), 1031 Elements, StartOffset + BaseOffset); 1032 } 1033 1034 // Visit all fields. 1035 unsigned FieldNo = 0; 1036 for (RecordDecl::field_iterator I = RD->field_begin(), 1037 E = RD->field_end(); I != E; ++I, ++FieldNo) { 1038 QualType FieldType = I->getType(); 1039 1040 if (!CGM.getTypes().ContainsPointerToDataMember(FieldType)) 1041 continue; 1042 1043 uint64_t FieldOffset = StartOffset + Layout.getFieldOffset(FieldNo); 1044 FillInNullDataMemberPointers(CGM, FieldType, Elements, FieldOffset); 1045 } 1046 } else { 1047 assert(T->isMemberPointerType() && "Should only see member pointers here!"); 1048 assert(!T->getAs<MemberPointerType>()->getPointeeType()->isFunctionType() && 1049 "Should only see pointers to data members here!"); 1050 1051 uint64_t StartIndex = StartOffset / 8; 1052 uint64_t EndIndex = StartIndex + CGM.getContext().getTypeSize(T) / 8; 1053 1054 llvm::Constant *NegativeOne = 1055 llvm::ConstantInt::get(llvm::Type::getInt8Ty(CGM.getLLVMContext()), 1056 -1ULL, /*isSigned=*/true); 1057 1058 // Fill in the null data member pointer. 1059 for (uint64_t I = StartIndex; I != EndIndex; ++I) 1060 Elements[I] = NegativeOne; 1061 } 1062} 1063 1064llvm::Constant *CodeGenModule::EmitNullConstant(QualType T) { 1065 if (!getTypes().ContainsPointerToDataMember(T)) 1066 return llvm::Constant::getNullValue(getTypes().ConvertTypeForMem(T)); 1067 1068 if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(T)) { 1069 1070 QualType ElementTy = CAT->getElementType(); 1071 1072 llvm::Constant *Element = EmitNullConstant(ElementTy); 1073 unsigned NumElements = CAT->getSize().getZExtValue(); 1074 std::vector<llvm::Constant *> Array(NumElements); 1075 for (unsigned i = 0; i != NumElements; ++i) 1076 Array[i] = Element; 1077 1078 const llvm::ArrayType *ATy = 1079 cast<llvm::ArrayType>(getTypes().ConvertTypeForMem(T)); 1080 return llvm::ConstantArray::get(ATy, Array); 1081 } 1082 1083 if (const RecordType *RT = T->getAs<RecordType>()) { 1084 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); 1085 const llvm::StructType *STy = 1086 cast<llvm::StructType>(getTypes().ConvertTypeForMem(T)); 1087 unsigned NumElements = STy->getNumElements(); 1088 std::vector<llvm::Constant *> Elements(NumElements); 1089 1090 const CGRecordLayout &Layout = getTypes().getCGRecordLayout(RD); 1091 1092 // Go through all bases and fill in any null pointer to data members. 1093 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 1094 E = RD->bases_end(); I != E; ++I) { 1095 if (I->isVirtual()) { 1096 // FIXME: We should initialize null pointer to data members in virtual 1097 // bases here. 1098 continue; 1099 } 1100 1101 const CXXRecordDecl *BaseDecl = 1102 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); 1103 1104 // Ignore empty bases. 1105 if (BaseDecl->isEmpty()) 1106 continue; 1107 1108 // Ignore bases that don't have any pointer to data members. 1109 if (!getTypes().ContainsPointerToDataMember(BaseDecl)) 1110 continue; 1111 1112 // Currently, all bases are arrays of i8. Figure out how many elements 1113 // this base array has. 1114 unsigned BaseFieldNo = Layout.getNonVirtualBaseLLVMFieldNo(BaseDecl); 1115 const llvm::ArrayType *BaseArrayTy = 1116 cast<llvm::ArrayType>(STy->getElementType(BaseFieldNo)); 1117 1118 unsigned NumBaseElements = BaseArrayTy->getNumElements(); 1119 std::vector<llvm::Constant *> BaseElements(NumBaseElements); 1120 1121 // Now fill in null data member pointers. 1122 FillInNullDataMemberPointers(*this, I->getType(), BaseElements, 0); 1123 1124 // Now go through all other elements and zero them out. 1125 if (NumBaseElements) { 1126 llvm::Constant *Zero = 1127 llvm::ConstantInt::get(llvm::Type::getInt8Ty(getLLVMContext()), 0); 1128 1129 for (unsigned I = 0; I != NumBaseElements; ++I) { 1130 if (!BaseElements[I]) 1131 BaseElements[I] = Zero; 1132 } 1133 } 1134 1135 Elements[BaseFieldNo] = llvm::ConstantArray::get(BaseArrayTy, 1136 BaseElements); 1137 } 1138 1139 for (RecordDecl::field_iterator I = RD->field_begin(), 1140 E = RD->field_end(); I != E; ++I) { 1141 const FieldDecl *FD = *I; 1142 1143 // Ignore bit fields. 1144 if (FD->isBitField()) 1145 continue; 1146 1147 unsigned FieldNo = Layout.getLLVMFieldNo(FD); 1148 Elements[FieldNo] = EmitNullConstant(FD->getType()); 1149 } 1150 1151 // Now go through all other fields and zero them out. 1152 for (unsigned i = 0; i != NumElements; ++i) { 1153 if (!Elements[i]) 1154 Elements[i] = llvm::Constant::getNullValue(STy->getElementType(i)); 1155 } 1156 1157 return llvm::ConstantStruct::get(STy, Elements); 1158 } 1159 1160 assert(T->isMemberPointerType() && "Should only see member pointers here!"); 1161 assert(!T->getAs<MemberPointerType>()->getPointeeType()->isFunctionType() && 1162 "Should only see pointers to data members here!"); 1163 1164 // Itanium C++ ABI 2.3: 1165 // A NULL pointer is represented as -1. 1166 return llvm::ConstantInt::get(getTypes().ConvertTypeForMem(T), -1ULL, 1167 /*isSigned=*/true); 1168} 1169 1170llvm::Constant * 1171CodeGenModule::EmitPointerToDataMember(const FieldDecl *FD) { 1172 1173 // Itanium C++ ABI 2.3: 1174 // A pointer to data member is an offset from the base address of the class 1175 // object containing it, represented as a ptrdiff_t 1176 1177 const CXXRecordDecl *ClassDecl = cast<CXXRecordDecl>(FD->getParent()); 1178 QualType ClassType = 1179 getContext().getTypeDeclType(const_cast<CXXRecordDecl *>(ClassDecl)); 1180 1181 const llvm::StructType *ClassLTy = 1182 cast<llvm::StructType>(getTypes().ConvertType(ClassType)); 1183 1184 const CGRecordLayout &RL = 1185 getTypes().getCGRecordLayout(FD->getParent()); 1186 unsigned FieldNo = RL.getLLVMFieldNo(FD); 1187 uint64_t Offset = 1188 getTargetData().getStructLayout(ClassLTy)->getElementOffset(FieldNo); 1189 1190 const llvm::Type *PtrDiffTy = 1191 getTypes().ConvertType(getContext().getPointerDiffType()); 1192 1193 return llvm::ConstantInt::get(PtrDiffTy, Offset); 1194} 1195