CGExprConstant.cpp revision bb378cbf04e343fb15ae3611a153dde60671b514
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 "clang/AST/APValue.h" 18#include "clang/AST/ASTContext.h" 19#include "clang/AST/RecordLayout.h" 20#include "clang/AST/StmtVisitor.h" 21#include "clang/Basic/Builtins.h" 22#include "llvm/Constants.h" 23#include "llvm/Function.h" 24#include "llvm/GlobalVariable.h" 25#include "llvm/Support/Compiler.h" 26#include "llvm/Target/TargetData.h" 27using namespace clang; 28using namespace CodeGen; 29 30namespace { 31 32class VISIBILITY_HIDDEN ConstStructBuilder { 33 CodeGenModule &CGM; 34 CodeGenFunction *CGF; 35 36 bool Packed; 37 38 unsigned NextFieldOffsetInBytes; 39 40 unsigned LLVMStructAlignment; 41 42 std::vector<llvm::Constant *> Elements; 43 44 ConstStructBuilder(CodeGenModule &CGM, CodeGenFunction *CGF) 45 : CGM(CGM), CGF(CGF), Packed(false), NextFieldOffsetInBytes(0), 46 LLVMStructAlignment(1) { } 47 48 bool AppendField(const FieldDecl *Field, uint64_t FieldOffset, 49 const Expr *InitExpr) { 50 uint64_t FieldOffsetInBytes = FieldOffset / 8; 51 52 assert(NextFieldOffsetInBytes <= FieldOffsetInBytes 53 && "Field offset mismatch!"); 54 55 // Emit the field. 56 llvm::Constant *C = CGM.EmitConstantExpr(InitExpr, Field->getType(), CGF); 57 if (!C) 58 return false; 59 60 unsigned FieldAlignment = getAlignment(C); 61 62 // Round up the field offset to the alignment of the field type. 63 uint64_t AlignedNextFieldOffsetInBytes = 64 llvm::RoundUpToAlignment(NextFieldOffsetInBytes, FieldAlignment); 65 66 if (AlignedNextFieldOffsetInBytes > FieldOffsetInBytes) { 67 assert(!Packed && "Alignment is wrong even with a packed struct!"); 68 69 // Convert the struct to a packed struct. 70 ConvertStructToPacked(); 71 72 AlignedNextFieldOffsetInBytes = NextFieldOffsetInBytes; 73 } 74 75 if (AlignedNextFieldOffsetInBytes < FieldOffsetInBytes) { 76 // We need to append padding. 77 AppendPadding(FieldOffsetInBytes - NextFieldOffsetInBytes); 78 79 assert(NextFieldOffsetInBytes == FieldOffsetInBytes && 80 "Did not add enough padding!"); 81 82 AlignedNextFieldOffsetInBytes = NextFieldOffsetInBytes; 83 } 84 85 // Add the field. 86 Elements.push_back(C); 87 NextFieldOffsetInBytes = AlignedNextFieldOffsetInBytes + getSizeInBytes(C); 88 89 if (Packed) 90 assert(LLVMStructAlignment == 1 && "Packed struct not byte-aligned!"); 91 else 92 LLVMStructAlignment = std::max(LLVMStructAlignment, FieldAlignment); 93 94 return true; 95 } 96 97 bool AppendBitField(const FieldDecl *Field, uint64_t FieldOffset, 98 const Expr *InitExpr) { 99 llvm::ConstantInt *CI = 100 cast_or_null<llvm::ConstantInt>(CGM.EmitConstantExpr(InitExpr, 101 Field->getType(), 102 CGF)); 103 // FIXME: Can this ever happen? 104 if (!CI) 105 return false; 106 107 if (FieldOffset > NextFieldOffsetInBytes * 8) { 108 // We need to add padding. 109 uint64_t NumBytes = 110 llvm::RoundUpToAlignment(FieldOffset - 111 NextFieldOffsetInBytes * 8, 8) / 8; 112 113 AppendPadding(NumBytes); 114 } 115 116 uint64_t FieldSize = 117 Field->getBitWidth()->EvaluateAsInt(CGM.getContext()).getZExtValue(); 118 119 llvm::APInt FieldValue = CI->getValue(); 120 121 // Promote the size of FieldValue if necessary 122 // FIXME: This should never occur, but currently it can because initializer 123 // constants are cast to bool, and because clang is not enforcing bitfield 124 // width limits. 125 if (FieldSize > FieldValue.getBitWidth()) 126 FieldValue.zext(FieldSize); 127 128 // Truncate the size of FieldValue to the bit field size. 129 if (FieldSize < FieldValue.getBitWidth()) 130 FieldValue.trunc(FieldSize); 131 132 if (FieldOffset < NextFieldOffsetInBytes * 8) { 133 // Either part of the field or the entire field can go into the previous 134 // byte. 135 assert(!Elements.empty() && "Elements can't be empty!"); 136 137 unsigned BitsInPreviousByte = 138 NextFieldOffsetInBytes * 8 - FieldOffset; 139 140 bool FitsCompletelyInPreviousByte = 141 BitsInPreviousByte >= FieldValue.getBitWidth(); 142 143 llvm::APInt Tmp = FieldValue; 144 145 if (!FitsCompletelyInPreviousByte) { 146 unsigned NewFieldWidth = FieldSize - BitsInPreviousByte; 147 148 if (CGM.getTargetData().isBigEndian()) { 149 Tmp = Tmp.lshr(NewFieldWidth); 150 Tmp.trunc(BitsInPreviousByte); 151 152 // We want the remaining high bits. 153 FieldValue.trunc(NewFieldWidth); 154 } else { 155 Tmp.trunc(BitsInPreviousByte); 156 157 // We want the remaining low bits. 158 FieldValue = FieldValue.lshr(BitsInPreviousByte); 159 FieldValue.trunc(NewFieldWidth); 160 } 161 } 162 163 Tmp.zext(8); 164 if (CGM.getTargetData().isBigEndian()) { 165 if (FitsCompletelyInPreviousByte) 166 Tmp = Tmp.shl(BitsInPreviousByte - FieldValue.getBitWidth()); 167 } else { 168 Tmp = Tmp.shl(8 - BitsInPreviousByte); 169 } 170 171 // Or in the bits that go into the previous byte. 172 Tmp |= cast<llvm::ConstantInt>(Elements.back())->getValue(); 173 Elements.back() = llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp); 174 175 if (FitsCompletelyInPreviousByte) 176 return true; 177 } 178 179 while (FieldValue.getBitWidth() > 8) { 180 llvm::APInt Tmp; 181 182 if (CGM.getTargetData().isBigEndian()) { 183 // We want the high bits. 184 Tmp = FieldValue; 185 Tmp = Tmp.lshr(Tmp.getBitWidth() - 8); 186 Tmp.trunc(8); 187 } else { 188 // We want the low bits. 189 Tmp = FieldValue; 190 Tmp.trunc(8); 191 192 FieldValue = FieldValue.lshr(8); 193 } 194 195 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp)); 196 NextFieldOffsetInBytes++; 197 198 FieldValue.trunc(FieldValue.getBitWidth() - 8); 199 } 200 201 assert(FieldValue.getBitWidth() > 0 && 202 "Should have at least one bit left!"); 203 assert(FieldValue.getBitWidth() <= 8 && 204 "Should not have more than a byte left!"); 205 206 if (FieldValue.getBitWidth() < 8) { 207 if (CGM.getTargetData().isBigEndian()) { 208 unsigned BitWidth = FieldValue.getBitWidth(); 209 210 FieldValue.zext(8); 211 FieldValue = FieldValue << (8 - BitWidth); 212 } else 213 FieldValue.zext(8); 214 } 215 216 // Append the last element. 217 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), 218 FieldValue)); 219 NextFieldOffsetInBytes++; 220 return true; 221 } 222 223 void AppendPadding(uint64_t NumBytes) { 224 if (!NumBytes) 225 return; 226 227 const llvm::Type *Ty = llvm::Type::getInt8Ty(CGM.getLLVMContext()); 228 if (NumBytes > 1) 229 Ty = llvm::ArrayType::get(Ty, NumBytes); 230 231 llvm::Constant *C = llvm::Constant::getNullValue(Ty); 232 Elements.push_back(C); 233 assert(getAlignment(C) == 1 && "Padding must have 1 byte alignment!"); 234 235 NextFieldOffsetInBytes += getSizeInBytes(C); 236 } 237 238 void AppendTailPadding(uint64_t RecordSize) { 239 assert(RecordSize % 8 == 0 && "Invalid record size!"); 240 241 uint64_t RecordSizeInBytes = RecordSize / 8; 242 assert(NextFieldOffsetInBytes <= RecordSizeInBytes && "Size mismatch!"); 243 244 unsigned NumPadBytes = RecordSizeInBytes - NextFieldOffsetInBytes; 245 AppendPadding(NumPadBytes); 246 } 247 248 void ConvertStructToPacked() { 249 std::vector<llvm::Constant *> PackedElements; 250 uint64_t ElementOffsetInBytes = 0; 251 252 for (unsigned i = 0, e = Elements.size(); i != e; ++i) { 253 llvm::Constant *C = Elements[i]; 254 255 unsigned ElementAlign = 256 CGM.getTargetData().getABITypeAlignment(C->getType()); 257 uint64_t AlignedElementOffsetInBytes = 258 llvm::RoundUpToAlignment(ElementOffsetInBytes, ElementAlign); 259 260 if (AlignedElementOffsetInBytes > ElementOffsetInBytes) { 261 // We need some padding. 262 uint64_t NumBytes = 263 AlignedElementOffsetInBytes - ElementOffsetInBytes; 264 265 const llvm::Type *Ty = llvm::Type::getInt8Ty(CGF->getLLVMContext()); 266 if (NumBytes > 1) 267 Ty = llvm::ArrayType::get(Ty, NumBytes); 268 269 llvm::Constant *Padding = llvm::Constant::getNullValue(Ty); 270 PackedElements.push_back(Padding); 271 ElementOffsetInBytes += getSizeInBytes(Padding); 272 } 273 274 PackedElements.push_back(C); 275 ElementOffsetInBytes += getSizeInBytes(C); 276 } 277 278 assert(ElementOffsetInBytes == NextFieldOffsetInBytes && 279 "Packing the struct changed its size!"); 280 281 Elements = PackedElements; 282 LLVMStructAlignment = 1; 283 Packed = true; 284 } 285 286 bool Build(InitListExpr *ILE) { 287 RecordDecl *RD = ILE->getType()->getAs<RecordType>()->getDecl(); 288 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); 289 290 unsigned FieldNo = 0; 291 unsigned ElementNo = 0; 292 for (RecordDecl::field_iterator Field = RD->field_begin(), 293 FieldEnd = RD->field_end(); 294 ElementNo < ILE->getNumInits() && Field != FieldEnd; 295 ++Field, ++FieldNo) { 296 if (RD->isUnion() && ILE->getInitializedFieldInUnion() != *Field) 297 continue; 298 299 if (Field->isBitField()) { 300 if (!Field->getIdentifier()) 301 continue; 302 303 if (!AppendBitField(*Field, Layout.getFieldOffset(FieldNo), 304 ILE->getInit(ElementNo))) 305 return false; 306 } else { 307 if (!AppendField(*Field, Layout.getFieldOffset(FieldNo), 308 ILE->getInit(ElementNo))) 309 return false; 310 } 311 312 ElementNo++; 313 } 314 315 uint64_t LayoutSizeInBytes = Layout.getSize() / 8; 316 317 if (NextFieldOffsetInBytes > LayoutSizeInBytes) { 318 // If the struct is bigger than the size of the record type, 319 // we must have a flexible array member at the end. 320 assert(RD->hasFlexibleArrayMember() && 321 "Must have flexible array member if struct is bigger than type!"); 322 323 // No tail padding is necessary. 324 return true; 325 } 326 327 uint64_t LLVMSizeInBytes = llvm::RoundUpToAlignment(NextFieldOffsetInBytes, 328 LLVMStructAlignment); 329 330 // Check if we need to convert the struct to a packed struct. 331 if (NextFieldOffsetInBytes <= LayoutSizeInBytes && 332 LLVMSizeInBytes > LayoutSizeInBytes) { 333 assert(!Packed && "Size mismatch!"); 334 335 ConvertStructToPacked(); 336 assert(NextFieldOffsetInBytes == LayoutSizeInBytes && 337 "Converting to packed did not help!"); 338 } 339 340 // Append tail padding if necessary. 341 AppendTailPadding(Layout.getSize()); 342 343 assert(Layout.getSize() / 8 == NextFieldOffsetInBytes && 344 "Tail padding mismatch!"); 345 346 return true; 347 } 348 349 unsigned getAlignment(const llvm::Constant *C) const { 350 if (Packed) 351 return 1; 352 353 return CGM.getTargetData().getABITypeAlignment(C->getType()); 354 } 355 356 uint64_t getSizeInBytes(const llvm::Constant *C) const { 357 return CGM.getTargetData().getTypeAllocSize(C->getType()); 358 } 359 360public: 361 static llvm::Constant *BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF, 362 InitListExpr *ILE) { 363 ConstStructBuilder Builder(CGM, CGF); 364 365 if (!Builder.Build(ILE)) 366 return 0; 367 368 llvm::Constant *Result = 369 llvm::ConstantStruct::get(CGM.getLLVMContext(), 370 Builder.Elements, Builder.Packed); 371 372 assert(llvm::RoundUpToAlignment(Builder.NextFieldOffsetInBytes, 373 Builder.getAlignment(Result)) == 374 Builder.getSizeInBytes(Result) && "Size mismatch!"); 375 376 return Result; 377 } 378}; 379 380class VISIBILITY_HIDDEN ConstExprEmitter : 381 public StmtVisitor<ConstExprEmitter, llvm::Constant*> { 382 CodeGenModule &CGM; 383 CodeGenFunction *CGF; 384 llvm::LLVMContext &VMContext; 385public: 386 ConstExprEmitter(CodeGenModule &cgm, CodeGenFunction *cgf) 387 : CGM(cgm), CGF(cgf), VMContext(cgm.getLLVMContext()) { 388 } 389 390 //===--------------------------------------------------------------------===// 391 // Visitor Methods 392 //===--------------------------------------------------------------------===// 393 394 llvm::Constant *VisitStmt(Stmt *S) { 395 return 0; 396 } 397 398 llvm::Constant *VisitParenExpr(ParenExpr *PE) { 399 return Visit(PE->getSubExpr()); 400 } 401 402 llvm::Constant *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) { 403 return Visit(E->getInitializer()); 404 } 405 406 llvm::Constant *EmitMemberFunctionPointer(CXXMethodDecl *MD) { 407 assert(MD->isInstance() && "Member function must not be static!"); 408 409 const llvm::Type *PtrDiffTy = 410 CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType()); 411 412 llvm::Constant *Values[2]; 413 414 // Get the function pointer (or index if this is a virtual function). 415 if (MD->isVirtual()) { 416 int64_t Index = CGM.getVtableInfo().getMethodVtableIndex(MD); 417 418 Values[0] = llvm::ConstantInt::get(PtrDiffTy, Index + 1); 419 } else { 420 llvm::Constant *FuncPtr = CGM.GetAddrOfFunction(MD); 421 422 Values[0] = llvm::ConstantExpr::getPtrToInt(FuncPtr, PtrDiffTy); 423 } 424 425 // The adjustment will always be 0. 426 Values[1] = llvm::ConstantInt::get(PtrDiffTy, 0); 427 428 return llvm::ConstantStruct::get(CGM.getLLVMContext(), 429 Values, 2, /*Packed=*/false); 430 } 431 432 llvm::Constant *VisitUnaryAddrOf(UnaryOperator *E) { 433 if (const MemberPointerType *MPT = 434 E->getType()->getAs<MemberPointerType>()) { 435 QualType T = MPT->getPointeeType(); 436 if (T->isFunctionProtoType()) { 437 QualifiedDeclRefExpr *DRE = cast<QualifiedDeclRefExpr>(E->getSubExpr()); 438 439 return EmitMemberFunctionPointer(cast<CXXMethodDecl>(DRE->getDecl())); 440 } 441 442 // FIXME: Should we handle other member pointer types here too, 443 // or should they be handled by Expr::Evaluate? 444 } 445 446 return 0; 447 } 448 449 llvm::Constant *VisitBinSub(BinaryOperator *E) { 450 // This must be a pointer/pointer subtraction. This only happens for 451 // address of label. 452 if (!isa<AddrLabelExpr>(E->getLHS()->IgnoreParenNoopCasts(CGM.getContext())) || 453 !isa<AddrLabelExpr>(E->getRHS()->IgnoreParenNoopCasts(CGM.getContext()))) 454 return 0; 455 456 llvm::Constant *LHS = CGM.EmitConstantExpr(E->getLHS(), 457 E->getLHS()->getType(), CGF); 458 llvm::Constant *RHS = CGM.EmitConstantExpr(E->getRHS(), 459 E->getRHS()->getType(), CGF); 460 461 const llvm::Type *ResultType = ConvertType(E->getType()); 462 LHS = llvm::ConstantExpr::getPtrToInt(LHS, ResultType); 463 RHS = llvm::ConstantExpr::getPtrToInt(RHS, ResultType); 464 465 // No need to divide by element size, since addr of label is always void*, 466 // which has size 1 in GNUish. 467 return llvm::ConstantExpr::getSub(LHS, RHS); 468 } 469 470 llvm::Constant *VisitCastExpr(CastExpr* E) { 471 switch (E->getCastKind()) { 472 case CastExpr::CK_ToUnion: { 473 // GCC cast to union extension 474 assert(E->getType()->isUnionType() && 475 "Destination type is not union type!"); 476 const llvm::Type *Ty = ConvertType(E->getType()); 477 Expr *SubExpr = E->getSubExpr(); 478 479 llvm::Constant *C = 480 CGM.EmitConstantExpr(SubExpr, SubExpr->getType(), CGF); 481 if (!C) 482 return 0; 483 484 // Build a struct with the union sub-element as the first member, 485 // and padded to the appropriate size 486 std::vector<llvm::Constant*> Elts; 487 std::vector<const llvm::Type*> Types; 488 Elts.push_back(C); 489 Types.push_back(C->getType()); 490 unsigned CurSize = CGM.getTargetData().getTypeAllocSize(C->getType()); 491 unsigned TotalSize = CGM.getTargetData().getTypeAllocSize(Ty); 492 493 assert(CurSize <= TotalSize && "Union size mismatch!"); 494 if (unsigned NumPadBytes = TotalSize - CurSize) { 495 const llvm::Type *Ty = llvm::Type::getInt8Ty(VMContext); 496 if (NumPadBytes > 1) 497 Ty = llvm::ArrayType::get(Ty, NumPadBytes); 498 499 Elts.push_back(llvm::Constant::getNullValue(Ty)); 500 Types.push_back(Ty); 501 } 502 503 llvm::StructType* STy = 504 llvm::StructType::get(C->getType()->getContext(), Types, false); 505 return llvm::ConstantStruct::get(STy, Elts); 506 } 507 case CastExpr::CK_NullToMemberPointer: 508 return CGM.EmitNullConstant(E->getType()); 509 510 case CastExpr::CK_BaseToDerivedMemberPointer: { 511 Expr *SubExpr = E->getSubExpr(); 512 513 const MemberPointerType *SrcTy = 514 SubExpr->getType()->getAs<MemberPointerType>(); 515 const MemberPointerType *DestTy = 516 E->getType()->getAs<MemberPointerType>(); 517 518 const CXXRecordDecl *BaseClass = 519 cast<CXXRecordDecl>(cast<RecordType>(SrcTy->getClass())->getDecl()); 520 const CXXRecordDecl *DerivedClass = 521 cast<CXXRecordDecl>(cast<RecordType>(DestTy->getClass())->getDecl()); 522 523 if (SrcTy->getPointeeType()->isFunctionProtoType()) { 524 llvm::Constant *C = 525 CGM.EmitConstantExpr(SubExpr, SubExpr->getType(), CGF); 526 if (!C) 527 return 0; 528 529 llvm::ConstantStruct *CS = cast<llvm::ConstantStruct>(C); 530 531 // Check if we need to update the adjustment. 532 if (llvm::Constant *Offset = CGM.GetCXXBaseClassOffset(DerivedClass, 533 BaseClass)) { 534 llvm::Constant *Values[2]; 535 536 Values[0] = CS->getOperand(0); 537 Values[1] = llvm::ConstantExpr::getAdd(CS->getOperand(1), Offset); 538 return llvm::ConstantStruct::get(CGM.getLLVMContext(), Values, 2, 539 /*Packed=*/false); 540 } 541 542 return CS; 543 } 544 } 545 546 case CastExpr::CK_BitCast: 547 // This must be a member function pointer cast. 548 return Visit(E->getSubExpr()); 549 550 default: { 551 // FIXME: This should be handled by the CK_NoOp cast kind. 552 // Explicit and implicit no-op casts 553 QualType Ty = E->getType(), SubTy = E->getSubExpr()->getType(); 554 if (CGM.getContext().hasSameUnqualifiedType(Ty, SubTy)) 555 return Visit(E->getSubExpr()); 556 557 // Handle integer->integer casts for address-of-label differences. 558 if (Ty->isIntegerType() && SubTy->isIntegerType() && 559 CGF) { 560 llvm::Value *Src = Visit(E->getSubExpr()); 561 if (Src == 0) return 0; 562 563 // Use EmitScalarConversion to perform the conversion. 564 return cast<llvm::Constant>(CGF->EmitScalarConversion(Src, SubTy, Ty)); 565 } 566 567 return 0; 568 } 569 } 570 } 571 572 llvm::Constant *VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) { 573 return Visit(DAE->getExpr()); 574 } 575 576 llvm::Constant *EmitArrayInitialization(InitListExpr *ILE) { 577 std::vector<llvm::Constant*> Elts; 578 const llvm::ArrayType *AType = 579 cast<llvm::ArrayType>(ConvertType(ILE->getType())); 580 unsigned NumInitElements = ILE->getNumInits(); 581 // FIXME: Check for wide strings 582 // FIXME: Check for NumInitElements exactly equal to 1?? 583 if (NumInitElements > 0 && 584 (isa<StringLiteral>(ILE->getInit(0)) || 585 isa<ObjCEncodeExpr>(ILE->getInit(0))) && 586 ILE->getType()->getArrayElementTypeNoTypeQual()->isCharType()) 587 return Visit(ILE->getInit(0)); 588 const llvm::Type *ElemTy = AType->getElementType(); 589 unsigned NumElements = AType->getNumElements(); 590 591 // Initialising an array requires us to automatically 592 // initialise any elements that have not been initialised explicitly 593 unsigned NumInitableElts = std::min(NumInitElements, NumElements); 594 595 // Copy initializer elements. 596 unsigned i = 0; 597 bool RewriteType = false; 598 for (; i < NumInitableElts; ++i) { 599 Expr *Init = ILE->getInit(i); 600 llvm::Constant *C = CGM.EmitConstantExpr(Init, Init->getType(), CGF); 601 if (!C) 602 return 0; 603 RewriteType |= (C->getType() != ElemTy); 604 Elts.push_back(C); 605 } 606 607 // Initialize remaining array elements. 608 // FIXME: This doesn't handle member pointers correctly! 609 for (; i < NumElements; ++i) 610 Elts.push_back(llvm::Constant::getNullValue(ElemTy)); 611 612 if (RewriteType) { 613 // FIXME: Try to avoid packing the array 614 std::vector<const llvm::Type*> Types; 615 for (unsigned i = 0; i < Elts.size(); ++i) 616 Types.push_back(Elts[i]->getType()); 617 const llvm::StructType *SType = llvm::StructType::get(AType->getContext(), 618 Types, true); 619 return llvm::ConstantStruct::get(SType, Elts); 620 } 621 622 return llvm::ConstantArray::get(AType, Elts); 623 } 624 625 llvm::Constant *EmitStructInitialization(InitListExpr *ILE) { 626 return ConstStructBuilder::BuildStruct(CGM, CGF, ILE); 627 } 628 629 llvm::Constant *EmitUnionInitialization(InitListExpr *ILE) { 630 return ConstStructBuilder::BuildStruct(CGM, CGF, ILE); 631 } 632 633 llvm::Constant *EmitVectorInitialization(InitListExpr *ILE) { 634 const llvm::VectorType *VType = 635 cast<llvm::VectorType>(ConvertType(ILE->getType())); 636 const llvm::Type *ElemTy = VType->getElementType(); 637 std::vector<llvm::Constant*> Elts; 638 unsigned NumElements = VType->getNumElements(); 639 unsigned NumInitElements = ILE->getNumInits(); 640 641 unsigned NumInitableElts = std::min(NumInitElements, NumElements); 642 643 // Copy initializer elements. 644 unsigned i = 0; 645 for (; i < NumInitableElts; ++i) { 646 Expr *Init = ILE->getInit(i); 647 llvm::Constant *C = CGM.EmitConstantExpr(Init, Init->getType(), CGF); 648 if (!C) 649 return 0; 650 Elts.push_back(C); 651 } 652 653 for (; i < NumElements; ++i) 654 Elts.push_back(llvm::Constant::getNullValue(ElemTy)); 655 656 return llvm::ConstantVector::get(VType, Elts); 657 } 658 659 llvm::Constant *VisitImplicitValueInitExpr(ImplicitValueInitExpr* E) { 660 return CGM.EmitNullConstant(E->getType()); 661 } 662 663 llvm::Constant *VisitInitListExpr(InitListExpr *ILE) { 664 if (ILE->getType()->isScalarType()) { 665 // We have a scalar in braces. Just use the first element. 666 if (ILE->getNumInits() > 0) { 667 Expr *Init = ILE->getInit(0); 668 return CGM.EmitConstantExpr(Init, Init->getType(), CGF); 669 } 670 return CGM.EmitNullConstant(ILE->getType()); 671 } 672 673 if (ILE->getType()->isArrayType()) 674 return EmitArrayInitialization(ILE); 675 676 if (ILE->getType()->isStructureType()) 677 return EmitStructInitialization(ILE); 678 679 if (ILE->getType()->isUnionType()) 680 return EmitUnionInitialization(ILE); 681 682 if (ILE->getType()->isVectorType()) 683 return EmitVectorInitialization(ILE); 684 685 assert(0 && "Unable to handle InitListExpr"); 686 // Get rid of control reaches end of void function warning. 687 // Not reached. 688 return 0; 689 } 690 691 llvm::Constant *VisitStringLiteral(StringLiteral *E) { 692 assert(!E->getType()->isPointerType() && "Strings are always arrays"); 693 694 // This must be a string initializing an array in a static initializer. 695 // Don't emit it as the address of the string, emit the string data itself 696 // as an inline array. 697 return llvm::ConstantArray::get(VMContext, 698 CGM.GetStringForStringLiteral(E), false); 699 } 700 701 llvm::Constant *VisitObjCEncodeExpr(ObjCEncodeExpr *E) { 702 // This must be an @encode initializing an array in a static initializer. 703 // Don't emit it as the address of the string, emit the string data itself 704 // as an inline array. 705 std::string Str; 706 CGM.getContext().getObjCEncodingForType(E->getEncodedType(), Str); 707 const ConstantArrayType *CAT = cast<ConstantArrayType>(E->getType()); 708 709 // Resize the string to the right size, adding zeros at the end, or 710 // truncating as needed. 711 Str.resize(CAT->getSize().getZExtValue(), '\0'); 712 return llvm::ConstantArray::get(VMContext, Str, false); 713 } 714 715 llvm::Constant *VisitUnaryExtension(const UnaryOperator *E) { 716 return Visit(E->getSubExpr()); 717 } 718 719 // Utility methods 720 const llvm::Type *ConvertType(QualType T) { 721 return CGM.getTypes().ConvertType(T); 722 } 723 724public: 725 llvm::Constant *EmitLValue(Expr *E) { 726 switch (E->getStmtClass()) { 727 default: break; 728 case Expr::CompoundLiteralExprClass: { 729 // Note that due to the nature of compound literals, this is guaranteed 730 // to be the only use of the variable, so we just generate it here. 731 CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E); 732 llvm::Constant* C = Visit(CLE->getInitializer()); 733 // FIXME: "Leaked" on failure. 734 if (C) 735 C = new llvm::GlobalVariable(CGM.getModule(), C->getType(), 736 E->getType().isConstant(CGM.getContext()), 737 llvm::GlobalValue::InternalLinkage, 738 C, ".compoundliteral", 0, false, 739 E->getType().getAddressSpace()); 740 return C; 741 } 742 case Expr::DeclRefExprClass: 743 case Expr::QualifiedDeclRefExprClass: { 744 NamedDecl *Decl = cast<DeclRefExpr>(E)->getDecl(); 745 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Decl)) 746 return CGM.GetAddrOfFunction(FD); 747 if (const VarDecl* VD = dyn_cast<VarDecl>(Decl)) { 748 // We can never refer to a variable with local storage. 749 if (!VD->hasLocalStorage()) { 750 if (VD->isFileVarDecl() || VD->hasExternalStorage()) 751 return CGM.GetAddrOfGlobalVar(VD); 752 else if (VD->isBlockVarDecl()) { 753 assert(CGF && "Can't access static local vars without CGF"); 754 return CGF->GetAddrOfStaticLocalVar(VD); 755 } 756 } 757 } 758 break; 759 } 760 case Expr::StringLiteralClass: 761 return CGM.GetAddrOfConstantStringFromLiteral(cast<StringLiteral>(E)); 762 case Expr::ObjCEncodeExprClass: 763 return CGM.GetAddrOfConstantStringFromObjCEncode(cast<ObjCEncodeExpr>(E)); 764 case Expr::ObjCStringLiteralClass: { 765 ObjCStringLiteral* SL = cast<ObjCStringLiteral>(E); 766 llvm::Constant *C = CGM.getObjCRuntime().GenerateConstantString(SL); 767 return llvm::ConstantExpr::getBitCast(C, ConvertType(E->getType())); 768 } 769 case Expr::PredefinedExprClass: { 770 // __func__/__FUNCTION__ -> "". __PRETTY_FUNCTION__ -> "top level". 771 std::string Str; 772 if (cast<PredefinedExpr>(E)->getIdentType() == 773 PredefinedExpr::PrettyFunction) 774 Str = "top level"; 775 776 return CGM.GetAddrOfConstantCString(Str, ".tmp"); 777 } 778 case Expr::AddrLabelExprClass: { 779 assert(CGF && "Invalid address of label expression outside function."); 780 unsigned id = 781 CGF->GetIDForAddrOfLabel(cast<AddrLabelExpr>(E)->getLabel()); 782 llvm::Constant *C = 783 llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), id); 784 return llvm::ConstantExpr::getIntToPtr(C, ConvertType(E->getType())); 785 } 786 case Expr::CallExprClass: { 787 CallExpr* CE = cast<CallExpr>(E); 788 if (CE->isBuiltinCall(CGM.getContext()) != 789 Builtin::BI__builtin___CFStringMakeConstantString) 790 break; 791 const Expr *Arg = CE->getArg(0)->IgnoreParenCasts(); 792 const StringLiteral *Literal = cast<StringLiteral>(Arg); 793 // FIXME: need to deal with UCN conversion issues. 794 return CGM.GetAddrOfConstantCFString(Literal); 795 } 796 case Expr::BlockExprClass: { 797 std::string FunctionName; 798 if (CGF) 799 FunctionName = CGF->CurFn->getName(); 800 else 801 FunctionName = "global"; 802 803 return CGM.GetAddrOfGlobalBlock(cast<BlockExpr>(E), FunctionName.c_str()); 804 } 805 } 806 807 return 0; 808 } 809}; 810 811} // end anonymous namespace. 812 813llvm::Constant *CodeGenModule::EmitConstantExpr(const Expr *E, 814 QualType DestType, 815 CodeGenFunction *CGF) { 816 Expr::EvalResult Result; 817 818 bool Success = false; 819 820 if (DestType->isReferenceType()) 821 Success = E->EvaluateAsLValue(Result, Context); 822 else 823 Success = E->Evaluate(Result, Context); 824 825 if (Success) { 826 assert(!Result.HasSideEffects && 827 "Constant expr should not have any side effects!"); 828 switch (Result.Val.getKind()) { 829 case APValue::Uninitialized: 830 assert(0 && "Constant expressions should be initialized."); 831 return 0; 832 case APValue::LValue: { 833 const llvm::Type *DestTy = getTypes().ConvertTypeForMem(DestType); 834 llvm::Constant *Offset = 835 llvm::ConstantInt::get(llvm::Type::getInt64Ty(VMContext), 836 Result.Val.getLValueOffset()); 837 838 llvm::Constant *C; 839 if (const Expr *LVBase = Result.Val.getLValueBase()) { 840 C = ConstExprEmitter(*this, CGF).EmitLValue(const_cast<Expr*>(LVBase)); 841 842 // Apply offset if necessary. 843 if (!Offset->isNullValue()) { 844 const llvm::Type *Type = llvm::Type::getInt8PtrTy(VMContext); 845 llvm::Constant *Casted = llvm::ConstantExpr::getBitCast(C, Type); 846 Casted = llvm::ConstantExpr::getGetElementPtr(Casted, &Offset, 1); 847 C = llvm::ConstantExpr::getBitCast(Casted, C->getType()); 848 } 849 850 // Convert to the appropriate type; this could be an lvalue for 851 // an integer. 852 if (isa<llvm::PointerType>(DestTy)) 853 return llvm::ConstantExpr::getBitCast(C, DestTy); 854 855 return llvm::ConstantExpr::getPtrToInt(C, DestTy); 856 } else { 857 C = Offset; 858 859 // Convert to the appropriate type; this could be an lvalue for 860 // an integer. 861 if (isa<llvm::PointerType>(DestTy)) 862 return llvm::ConstantExpr::getIntToPtr(C, DestTy); 863 864 // If the types don't match this should only be a truncate. 865 if (C->getType() != DestTy) 866 return llvm::ConstantExpr::getTrunc(C, DestTy); 867 868 return C; 869 } 870 } 871 case APValue::Int: { 872 llvm::Constant *C = llvm::ConstantInt::get(VMContext, 873 Result.Val.getInt()); 874 875 if (C->getType() == llvm::Type::getInt1Ty(VMContext)) { 876 const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType()); 877 C = llvm::ConstantExpr::getZExt(C, BoolTy); 878 } 879 return C; 880 } 881 case APValue::ComplexInt: { 882 llvm::Constant *Complex[2]; 883 884 Complex[0] = llvm::ConstantInt::get(VMContext, 885 Result.Val.getComplexIntReal()); 886 Complex[1] = llvm::ConstantInt::get(VMContext, 887 Result.Val.getComplexIntImag()); 888 889 // FIXME: the target may want to specify that this is packed. 890 return llvm::ConstantStruct::get(VMContext, Complex, 2, false); 891 } 892 case APValue::Float: 893 return llvm::ConstantFP::get(VMContext, Result.Val.getFloat()); 894 case APValue::ComplexFloat: { 895 llvm::Constant *Complex[2]; 896 897 Complex[0] = llvm::ConstantFP::get(VMContext, 898 Result.Val.getComplexFloatReal()); 899 Complex[1] = llvm::ConstantFP::get(VMContext, 900 Result.Val.getComplexFloatImag()); 901 902 // FIXME: the target may want to specify that this is packed. 903 return llvm::ConstantStruct::get(VMContext, Complex, 2, false); 904 } 905 case APValue::Vector: { 906 llvm::SmallVector<llvm::Constant *, 4> Inits; 907 unsigned NumElts = Result.Val.getVectorLength(); 908 909 for (unsigned i = 0; i != NumElts; ++i) { 910 APValue &Elt = Result.Val.getVectorElt(i); 911 if (Elt.isInt()) 912 Inits.push_back(llvm::ConstantInt::get(VMContext, Elt.getInt())); 913 else 914 Inits.push_back(llvm::ConstantFP::get(VMContext, Elt.getFloat())); 915 } 916 return llvm::ConstantVector::get(&Inits[0], Inits.size()); 917 } 918 } 919 } 920 921 llvm::Constant* C = ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E)); 922 if (C && C->getType() == llvm::Type::getInt1Ty(VMContext)) { 923 const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType()); 924 C = llvm::ConstantExpr::getZExt(C, BoolTy); 925 } 926 return C; 927} 928 929static inline bool isDataMemberPointerType(QualType T) { 930 if (const MemberPointerType *MPT = T->getAs<MemberPointerType>()) 931 return !MPT->getPointeeType()->isFunctionType(); 932 933 return false; 934} 935 936llvm::Constant *CodeGenModule::EmitNullConstant(QualType T) { 937 // No need to check for member pointers when not compiling C++. 938 if (!getContext().getLangOptions().CPlusPlus) 939 return llvm::Constant::getNullValue(getTypes().ConvertTypeForMem(T)); 940 941 if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(T)) { 942 943 QualType ElementTy = CAT->getElementType(); 944 945 // FIXME: Handle arrays of structs that contain member pointers. 946 if (isDataMemberPointerType(Context.getBaseElementType(ElementTy))) { 947 llvm::Constant *Element = EmitNullConstant(ElementTy); 948 uint64_t NumElements = CAT->getSize().getZExtValue(); 949 std::vector<llvm::Constant *> Array(NumElements); 950 for (uint64_t i = 0; i != NumElements; ++i) 951 Array[i] = Element; 952 953 const llvm::ArrayType *ATy = 954 cast<llvm::ArrayType>(getTypes().ConvertTypeForMem(T)); 955 return llvm::ConstantArray::get(ATy, Array); 956 } 957 } 958 959 if (const RecordType *RT = T->getAs<RecordType>()) { 960 const RecordDecl *RD = RT->getDecl(); 961 // FIXME: It would be better if there was a way to explicitly compute the 962 // record layout instead of converting to a type. 963 Types.ConvertTagDeclType(RD); 964 965 const CGRecordLayout &Layout = Types.getCGRecordLayout(RD); 966 if (Layout.containsMemberPointer()) { 967 assert(0 && "FIXME: No support for structs with member pointers yet!"); 968 } 969 } 970 971 // FIXME: Handle structs that contain member pointers. 972 if (isDataMemberPointerType(T)) 973 return llvm::Constant::getAllOnesValue(getTypes().ConvertTypeForMem(T)); 974 975 return llvm::Constant::getNullValue(getTypes().ConvertTypeForMem(T)); 976} 977