CGExprConstant.cpp revision 47a434ff3d49e7906eda88e8e8242e4297725b32
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 std::vector<llvm::Constant *> Elements; 41 42 ConstStructBuilder(CodeGenModule &CGM, CodeGenFunction *CGF) 43 : CGM(CGM), CGF(CGF), Packed(false), NextFieldOffsetInBytes(0) { } 44 45 bool AppendField(const FieldDecl *Field, uint64_t FieldOffset, 46 const Expr *InitExpr) { 47 uint64_t FieldOffsetInBytes = FieldOffset / 8; 48 49 assert(NextFieldOffsetInBytes <= FieldOffsetInBytes 50 && "Field offset mismatch!"); 51 52 // Emit the field. 53 llvm::Constant *C = CGM.EmitConstantExpr(InitExpr, Field->getType(), CGF); 54 if (!C) 55 return false; 56 57 unsigned FieldAlignment = getAlignment(C); 58 59 // Round up the field offset to the alignment of the field type. 60 uint64_t AlignedNextFieldOffsetInBytes = 61 llvm::RoundUpToAlignment(NextFieldOffsetInBytes, FieldAlignment); 62 63 if (AlignedNextFieldOffsetInBytes > FieldOffsetInBytes) { 64 std::vector<llvm::Constant *> PackedElements; 65 66 assert(!Packed && "Alignment is wrong even with a packed struct!"); 67 68 // Convert the struct to a packed struct. 69 uint64_t ElementOffsetInBytes = 0; 70 71 for (unsigned i = 0, e = Elements.size(); i != e; ++i) { 72 llvm::Constant *C = Elements[i]; 73 74 unsigned ElementAlign = 75 CGM.getTargetData().getABITypeAlignment(C->getType()); 76 uint64_t AlignedElementOffsetInBytes = 77 llvm::RoundUpToAlignment(ElementOffsetInBytes, ElementAlign); 78 79 if (AlignedElementOffsetInBytes > ElementOffsetInBytes) { 80 // We need some padding. 81 uint64_t NumBytes = 82 AlignedElementOffsetInBytes - ElementOffsetInBytes; 83 84 const llvm::Type *Ty = llvm::Type::Int8Ty; 85 if (NumBytes > 1) 86 Ty = llvm::ArrayType::get(Ty, NumBytes); 87 88 llvm::Constant *Padding = llvm::Constant::getNullValue(Ty); 89 PackedElements.push_back(Padding); 90 ElementOffsetInBytes += getSizeInBytes(Padding); 91 } 92 93 PackedElements.push_back(C); 94 ElementOffsetInBytes += getSizeInBytes(C); 95 } 96 97 assert(ElementOffsetInBytes == NextFieldOffsetInBytes && 98 "Packing the struct changed its size!"); 99 100 Elements = PackedElements; 101 Packed = true; 102 AlignedNextFieldOffsetInBytes = NextFieldOffsetInBytes; 103 } 104 105 if (AlignedNextFieldOffsetInBytes < FieldOffsetInBytes) { 106 // We need to append padding. 107 AppendPadding(FieldOffsetInBytes - NextFieldOffsetInBytes); 108 109 assert(NextFieldOffsetInBytes == FieldOffsetInBytes && 110 "Did not add enough padding!"); 111 112 AlignedNextFieldOffsetInBytes = NextFieldOffsetInBytes; 113 } 114 115 // Add the field. 116 Elements.push_back(C); 117 NextFieldOffsetInBytes = AlignedNextFieldOffsetInBytes + getSizeInBytes(C); 118 119 return true; 120 } 121 122 bool AppendBitField(const FieldDecl *Field, uint64_t FieldOffset, 123 const Expr *InitExpr) { 124 llvm::ConstantInt *CI = 125 cast_or_null<llvm::ConstantInt>(CGM.EmitConstantExpr(InitExpr, 126 Field->getType(), 127 CGF)); 128 // FIXME: Can this ever happen? 129 if (!CI) 130 return false; 131 132 if (FieldOffset > NextFieldOffsetInBytes * 8) { 133 // We need to add padding. 134 uint64_t NumBytes = 135 llvm::RoundUpToAlignment(FieldOffset - 136 NextFieldOffsetInBytes * 8, 8) / 8; 137 138 AppendPadding(NumBytes); 139 } 140 141 uint64_t FieldSize = 142 Field->getBitWidth()->EvaluateAsInt(CGM.getContext()).getZExtValue(); 143 144 llvm::APInt FieldValue = CI->getValue(); 145 146 // Promote the size of FieldValue if necessary 147 // FIXME: This should never occur, but currently it can because initializer 148 // constants are cast to bool, and because clang is not enforcing bitfield 149 // width limits. 150 if (FieldSize > FieldValue.getBitWidth()) 151 FieldValue.zext(FieldSize); 152 153 // Truncate the size of FieldValue to the bit field size. 154 if (FieldSize < FieldValue.getBitWidth()) 155 FieldValue.trunc(FieldSize); 156 157 if (FieldOffset < NextFieldOffsetInBytes * 8) { 158 // Either part of the field or the entire field can go into the previous 159 // byte. 160 assert(!Elements.empty() && "Elements can't be empty!"); 161 162 unsigned BitsInPreviousByte = 163 NextFieldOffsetInBytes * 8 - FieldOffset; 164 165 bool FitsCompletelyInPreviousByte = 166 BitsInPreviousByte >= FieldValue.getBitWidth(); 167 168 llvm::APInt Tmp = FieldValue; 169 170 if (!FitsCompletelyInPreviousByte) { 171 unsigned NewFieldWidth = FieldSize - BitsInPreviousByte; 172 173 if (CGM.getTargetData().isBigEndian()) { 174 Tmp = Tmp.lshr(NewFieldWidth); 175 Tmp.trunc(BitsInPreviousByte); 176 177 // We want the remaining high bits. 178 FieldValue.trunc(NewFieldWidth); 179 } else { 180 Tmp.trunc(BitsInPreviousByte); 181 182 // We want the remaining low bits. 183 FieldValue = FieldValue.lshr(BitsInPreviousByte); 184 FieldValue.trunc(NewFieldWidth); 185 } 186 } 187 188 Tmp.zext(8); 189 if (CGM.getTargetData().isBigEndian()) { 190 if (FitsCompletelyInPreviousByte) 191 Tmp = Tmp.shl(BitsInPreviousByte - FieldValue.getBitWidth()); 192 } else { 193 Tmp = Tmp.shl(8 - BitsInPreviousByte); 194 } 195 196 // Or in the bits that go into the previous byte. 197 Tmp |= cast<llvm::ConstantInt>(Elements.back())->getValue(); 198 Elements.back() = llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp); 199 200 if (FitsCompletelyInPreviousByte) 201 return true; 202 } 203 204 while (FieldValue.getBitWidth() > 8) { 205 llvm::APInt Tmp; 206 207 if (CGM.getTargetData().isBigEndian()) { 208 // We want the high bits. 209 Tmp = FieldValue; 210 Tmp = Tmp.lshr(Tmp.getBitWidth() - 8); 211 Tmp.trunc(8); 212 } else { 213 // We want the low bits. 214 Tmp = FieldValue; 215 Tmp.trunc(8); 216 217 FieldValue = FieldValue.lshr(8); 218 } 219 220 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp)); 221 NextFieldOffsetInBytes++; 222 223 FieldValue.trunc(FieldValue.getBitWidth() - 8); 224 } 225 226 assert(FieldValue.getBitWidth() > 0 && 227 "Should have at least one bit left!"); 228 assert(FieldValue.getBitWidth() <= 8 && 229 "Should not have more than a byte left!"); 230 231 if (FieldValue.getBitWidth() < 8) { 232 if (CGM.getTargetData().isBigEndian()) { 233 unsigned BitWidth = FieldValue.getBitWidth(); 234 235 FieldValue.zext(8); 236 FieldValue = FieldValue << (8 - BitWidth); 237 } else 238 FieldValue.zext(8); 239 } 240 241 // Append the last element. 242 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), 243 FieldValue)); 244 NextFieldOffsetInBytes++; 245 return true; 246 } 247 248 void AppendPadding(uint64_t NumBytes) { 249 if (!NumBytes) 250 return; 251 252 const llvm::Type *Ty = llvm::Type::Int8Ty; 253 if (NumBytes > 1) 254 Ty = llvm::ArrayType::get(Ty, NumBytes); 255 256 llvm::Constant *C = llvm::Constant::getNullValue(Ty); 257 Elements.push_back(C); 258 assert(getAlignment(C) == 1 && "Padding must have 1 byte alignment!"); 259 260 NextFieldOffsetInBytes += getSizeInBytes(C); 261 } 262 263 void AppendTailPadding(uint64_t RecordSize) { 264 assert(RecordSize % 8 == 0 && "Invalid record size!"); 265 266 uint64_t RecordSizeInBytes = RecordSize / 8; 267 assert(NextFieldOffsetInBytes <= RecordSizeInBytes && "Size mismatch!"); 268 269 unsigned NumPadBytes = RecordSizeInBytes - NextFieldOffsetInBytes; 270 AppendPadding(NumPadBytes); 271 } 272 273 bool Build(InitListExpr *ILE) { 274 RecordDecl *RD = ILE->getType()->getAs<RecordType>()->getDecl(); 275 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); 276 277 unsigned FieldNo = 0; 278 unsigned ElementNo = 0; 279 for (RecordDecl::field_iterator Field = RD->field_begin(), 280 FieldEnd = RD->field_end(); 281 ElementNo < ILE->getNumInits() && Field != FieldEnd; 282 ++Field, ++FieldNo) { 283 if (RD->isUnion() && ILE->getInitializedFieldInUnion() != *Field) 284 continue; 285 286 if (Field->isBitField()) { 287 if (!Field->getIdentifier()) 288 continue; 289 290 if (!AppendBitField(*Field, Layout.getFieldOffset(FieldNo), 291 ILE->getInit(ElementNo))) 292 return false; 293 } else { 294 if (!AppendField(*Field, Layout.getFieldOffset(FieldNo), 295 ILE->getInit(ElementNo))) 296 return false; 297 } 298 299 ElementNo++; 300 } 301 302 uint64_t LayoutSizeInBytes = Layout.getSize() / 8; 303 304 if (NextFieldOffsetInBytes > LayoutSizeInBytes) { 305 // If the struct is bigger than the size of the record type, 306 // we must have a flexible array member at the end. 307 assert(RD->hasFlexibleArrayMember() && 308 "Must have flexible array member if struct is bigger than type!"); 309 310 // No tail padding is necessary. 311 return true; 312 } 313 314 // Append tail padding if necessary. 315 AppendTailPadding(Layout.getSize()); 316 317 assert(Layout.getSize() / 8 == NextFieldOffsetInBytes && 318 "Tail padding mismatch!"); 319 320 return true; 321 } 322 323 unsigned getAlignment(const llvm::Constant *C) const { 324 if (Packed) 325 return 1; 326 327 return CGM.getTargetData().getABITypeAlignment(C->getType()); 328 } 329 330 uint64_t getSizeInBytes(const llvm::Constant *C) const { 331 return CGM.getTargetData().getTypeAllocSize(C->getType()); 332 } 333 334public: 335 static llvm::Constant *BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF, 336 InitListExpr *ILE) { 337 ConstStructBuilder Builder(CGM, CGF); 338 339 if (!Builder.Build(ILE)) 340 return 0; 341 342 llvm::Constant *Result = 343 llvm::ConstantStruct::get(CGF->getLLVMContext(), 344 Builder.Elements, Builder.Packed); 345 346 assert(llvm::RoundUpToAlignment(Builder.NextFieldOffsetInBytes, 347 Builder.getAlignment(Result)) == 348 Builder.getSizeInBytes(Result) && "Size mismatch!"); 349 350 return Result; 351 } 352}; 353 354class VISIBILITY_HIDDEN ConstExprEmitter : 355 public StmtVisitor<ConstExprEmitter, llvm::Constant*> { 356 CodeGenModule &CGM; 357 CodeGenFunction *CGF; 358 llvm::LLVMContext &VMContext; 359public: 360 ConstExprEmitter(CodeGenModule &cgm, CodeGenFunction *cgf) 361 : CGM(cgm), CGF(cgf), VMContext(cgm.getLLVMContext()) { 362 } 363 364 //===--------------------------------------------------------------------===// 365 // Visitor Methods 366 //===--------------------------------------------------------------------===// 367 368 llvm::Constant *VisitStmt(Stmt *S) { 369 return 0; 370 } 371 372 llvm::Constant *VisitParenExpr(ParenExpr *PE) { 373 return Visit(PE->getSubExpr()); 374 } 375 376 llvm::Constant *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) { 377 return Visit(E->getInitializer()); 378 } 379 380 llvm::Constant *VisitCastExpr(CastExpr* E) { 381 // GCC cast to union extension 382 if (E->getType()->isUnionType()) { 383 const llvm::Type *Ty = ConvertType(E->getType()); 384 Expr *SubExpr = E->getSubExpr(); 385 386 llvm::Constant *C = 387 CGM.EmitConstantExpr(SubExpr, SubExpr->getType(), CGF); 388 if (!C) 389 return 0; 390 391 // Build a struct with the union sub-element as the first member, 392 // and padded to the appropriate size 393 std::vector<llvm::Constant*> Elts; 394 std::vector<const llvm::Type*> Types; 395 Elts.push_back(C); 396 Types.push_back(C->getType()); 397 unsigned CurSize = CGM.getTargetData().getTypeAllocSize(C->getType()); 398 unsigned TotalSize = CGM.getTargetData().getTypeAllocSize(Ty); 399 400 assert(CurSize <= TotalSize && "Union size mismatch!"); 401 if (unsigned NumPadBytes = TotalSize - CurSize) { 402 const llvm::Type *Ty = llvm::Type::Int8Ty; 403 if (NumPadBytes > 1) 404 Ty = llvm::ArrayType::get(Ty, NumPadBytes); 405 406 Elts.push_back(llvm::Constant::getNullValue(Ty)); 407 Types.push_back(Ty); 408 } 409 410 llvm::StructType* STy = llvm::StructType::get(C->getType()->getContext(), 411 Types, false); 412 return llvm::ConstantStruct::get(STy, Elts); 413 } 414 415 // Explicit and implicit no-op casts 416 QualType Ty = E->getType(), SubTy = E->getSubExpr()->getType(); 417 if (CGM.getContext().hasSameUnqualifiedType(Ty, SubTy)) { 418 return Visit(E->getSubExpr()); 419 } 420 return 0; 421 } 422 423 llvm::Constant *VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) { 424 return Visit(DAE->getExpr()); 425 } 426 427 llvm::Constant *EmitArrayInitialization(InitListExpr *ILE) { 428 std::vector<llvm::Constant*> Elts; 429 const llvm::ArrayType *AType = 430 cast<llvm::ArrayType>(ConvertType(ILE->getType())); 431 unsigned NumInitElements = ILE->getNumInits(); 432 // FIXME: Check for wide strings 433 // FIXME: Check for NumInitElements exactly equal to 1?? 434 if (NumInitElements > 0 && 435 (isa<StringLiteral>(ILE->getInit(0)) || 436 isa<ObjCEncodeExpr>(ILE->getInit(0))) && 437 ILE->getType()->getArrayElementTypeNoTypeQual()->isCharType()) 438 return Visit(ILE->getInit(0)); 439 const llvm::Type *ElemTy = AType->getElementType(); 440 unsigned NumElements = AType->getNumElements(); 441 442 // Initialising an array requires us to automatically 443 // initialise any elements that have not been initialised explicitly 444 unsigned NumInitableElts = std::min(NumInitElements, NumElements); 445 446 // Copy initializer elements. 447 unsigned i = 0; 448 bool RewriteType = false; 449 for (; i < NumInitableElts; ++i) { 450 Expr *Init = ILE->getInit(i); 451 llvm::Constant *C = CGM.EmitConstantExpr(Init, Init->getType(), CGF); 452 if (!C) 453 return 0; 454 RewriteType |= (C->getType() != ElemTy); 455 Elts.push_back(C); 456 } 457 458 // Initialize remaining array elements. 459 // FIXME: This doesn't handle member pointers correctly! 460 for (; i < NumElements; ++i) 461 Elts.push_back(llvm::Constant::getNullValue(ElemTy)); 462 463 if (RewriteType) { 464 // FIXME: Try to avoid packing the array 465 std::vector<const llvm::Type*> Types; 466 for (unsigned i = 0; i < Elts.size(); ++i) 467 Types.push_back(Elts[i]->getType()); 468 const llvm::StructType *SType = llvm::StructType::get(AType->getContext(), 469 Types, true); 470 return llvm::ConstantStruct::get(SType, Elts); 471 } 472 473 return llvm::ConstantArray::get(AType, Elts); 474 } 475 476 llvm::Constant *EmitStructInitialization(InitListExpr *ILE) { 477 return ConstStructBuilder::BuildStruct(CGM, CGF, ILE); 478 } 479 480 llvm::Constant *EmitUnionInitialization(InitListExpr *ILE) { 481 return ConstStructBuilder::BuildStruct(CGM, CGF, ILE); 482 } 483 484 llvm::Constant *EmitVectorInitialization(InitListExpr *ILE) { 485 const llvm::VectorType *VType = 486 cast<llvm::VectorType>(ConvertType(ILE->getType())); 487 const llvm::Type *ElemTy = VType->getElementType(); 488 std::vector<llvm::Constant*> Elts; 489 unsigned NumElements = VType->getNumElements(); 490 unsigned NumInitElements = ILE->getNumInits(); 491 492 unsigned NumInitableElts = std::min(NumInitElements, NumElements); 493 494 // Copy initializer elements. 495 unsigned i = 0; 496 for (; i < NumInitableElts; ++i) { 497 Expr *Init = ILE->getInit(i); 498 llvm::Constant *C = CGM.EmitConstantExpr(Init, Init->getType(), CGF); 499 if (!C) 500 return 0; 501 Elts.push_back(C); 502 } 503 504 for (; i < NumElements; ++i) 505 Elts.push_back(llvm::Constant::getNullValue(ElemTy)); 506 507 return llvm::ConstantVector::get(VType, Elts); 508 } 509 510 llvm::Constant *VisitImplicitValueInitExpr(ImplicitValueInitExpr* E) { 511 return CGM.EmitNullConstant(E->getType()); 512 } 513 514 llvm::Constant *VisitInitListExpr(InitListExpr *ILE) { 515 if (ILE->getType()->isScalarType()) { 516 // We have a scalar in braces. Just use the first element. 517 if (ILE->getNumInits() > 0) { 518 Expr *Init = ILE->getInit(0); 519 return CGM.EmitConstantExpr(Init, Init->getType(), CGF); 520 } 521 return CGM.EmitNullConstant(ILE->getType()); 522 } 523 524 if (ILE->getType()->isArrayType()) 525 return EmitArrayInitialization(ILE); 526 527 if (ILE->getType()->isStructureType()) 528 return EmitStructInitialization(ILE); 529 530 if (ILE->getType()->isUnionType()) 531 return EmitUnionInitialization(ILE); 532 533 if (ILE->getType()->isVectorType()) 534 return EmitVectorInitialization(ILE); 535 536 assert(0 && "Unable to handle InitListExpr"); 537 // Get rid of control reaches end of void function warning. 538 // Not reached. 539 return 0; 540 } 541 542 llvm::Constant *VisitStringLiteral(StringLiteral *E) { 543 assert(!E->getType()->isPointerType() && "Strings are always arrays"); 544 545 // This must be a string initializing an array in a static initializer. 546 // Don't emit it as the address of the string, emit the string data itself 547 // as an inline array. 548 return llvm::ConstantArray::get(CGM.GetStringForStringLiteral(E), false); 549 } 550 551 llvm::Constant *VisitObjCEncodeExpr(ObjCEncodeExpr *E) { 552 // This must be an @encode initializing an array in a static initializer. 553 // Don't emit it as the address of the string, emit the string data itself 554 // as an inline array. 555 std::string Str; 556 CGM.getContext().getObjCEncodingForType(E->getEncodedType(), Str); 557 const ConstantArrayType *CAT = cast<ConstantArrayType>(E->getType()); 558 559 // Resize the string to the right size, adding zeros at the end, or 560 // truncating as needed. 561 Str.resize(CAT->getSize().getZExtValue(), '\0'); 562 return llvm::ConstantArray::get(Str, false); 563 } 564 565 llvm::Constant *VisitUnaryExtension(const UnaryOperator *E) { 566 return Visit(E->getSubExpr()); 567 } 568 569 // Utility methods 570 const llvm::Type *ConvertType(QualType T) { 571 return CGM.getTypes().ConvertType(T); 572 } 573 574public: 575 llvm::Constant *EmitLValue(Expr *E) { 576 switch (E->getStmtClass()) { 577 default: break; 578 case Expr::CompoundLiteralExprClass: { 579 // Note that due to the nature of compound literals, this is guaranteed 580 // to be the only use of the variable, so we just generate it here. 581 CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E); 582 llvm::Constant* C = Visit(CLE->getInitializer()); 583 // FIXME: "Leaked" on failure. 584 if (C) 585 C = new llvm::GlobalVariable(CGM.getModule(), C->getType(), 586 E->getType().isConstQualified(), 587 llvm::GlobalValue::InternalLinkage, 588 C, ".compoundliteral"); 589 return C; 590 } 591 case Expr::DeclRefExprClass: 592 case Expr::QualifiedDeclRefExprClass: { 593 NamedDecl *Decl = cast<DeclRefExpr>(E)->getDecl(); 594 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Decl)) 595 return CGM.GetAddrOfFunction(GlobalDecl(FD)); 596 if (const VarDecl* VD = dyn_cast<VarDecl>(Decl)) { 597 // We can never refer to a variable with local storage. 598 if (!VD->hasLocalStorage()) { 599 if (VD->isFileVarDecl() || VD->hasExternalStorage()) 600 return CGM.GetAddrOfGlobalVar(VD); 601 else if (VD->isBlockVarDecl()) { 602 assert(CGF && "Can't access static local vars without CGF"); 603 return CGF->GetAddrOfStaticLocalVar(VD); 604 } 605 } 606 } 607 break; 608 } 609 case Expr::StringLiteralClass: 610 return CGM.GetAddrOfConstantStringFromLiteral(cast<StringLiteral>(E)); 611 case Expr::ObjCEncodeExprClass: 612 return CGM.GetAddrOfConstantStringFromObjCEncode(cast<ObjCEncodeExpr>(E)); 613 case Expr::ObjCStringLiteralClass: { 614 ObjCStringLiteral* SL = cast<ObjCStringLiteral>(E); 615 llvm::Constant *C = CGM.getObjCRuntime().GenerateConstantString(SL); 616 return llvm::ConstantExpr::getBitCast(C, ConvertType(E->getType())); 617 } 618 case Expr::PredefinedExprClass: { 619 // __func__/__FUNCTION__ -> "". __PRETTY_FUNCTION__ -> "top level". 620 std::string Str; 621 if (cast<PredefinedExpr>(E)->getIdentType() == 622 PredefinedExpr::PrettyFunction) 623 Str = "top level"; 624 625 return CGM.GetAddrOfConstantCString(Str, ".tmp"); 626 } 627 case Expr::AddrLabelExprClass: { 628 assert(CGF && "Invalid address of label expression outside function."); 629 unsigned id = CGF->GetIDForAddrOfLabel(cast<AddrLabelExpr>(E)->getLabel()); 630 llvm::Constant *C = llvm::ConstantInt::get(llvm::Type::Int32Ty, id); 631 return llvm::ConstantExpr::getIntToPtr(C, ConvertType(E->getType())); 632 } 633 case Expr::CallExprClass: { 634 CallExpr* CE = cast<CallExpr>(E); 635 if (CE->isBuiltinCall(CGM.getContext()) != 636 Builtin::BI__builtin___CFStringMakeConstantString) 637 break; 638 const Expr *Arg = CE->getArg(0)->IgnoreParenCasts(); 639 const StringLiteral *Literal = cast<StringLiteral>(Arg); 640 // FIXME: need to deal with UCN conversion issues. 641 return CGM.GetAddrOfConstantCFString(Literal); 642 } 643 case Expr::BlockExprClass: { 644 std::string FunctionName; 645 if (CGF) 646 FunctionName = CGF->CurFn->getName(); 647 else 648 FunctionName = "global"; 649 650 return CGM.GetAddrOfGlobalBlock(cast<BlockExpr>(E), FunctionName.c_str()); 651 } 652 } 653 654 return 0; 655 } 656}; 657 658} // end anonymous namespace. 659 660llvm::Constant *CodeGenModule::EmitConstantExpr(const Expr *E, 661 QualType DestType, 662 CodeGenFunction *CGF) { 663 Expr::EvalResult Result; 664 665 bool Success = false; 666 667 if (DestType->isReferenceType()) 668 Success = E->EvaluateAsLValue(Result, Context); 669 else 670 Success = E->Evaluate(Result, Context); 671 672 if (Success) { 673 assert(!Result.HasSideEffects && 674 "Constant expr should not have any side effects!"); 675 switch (Result.Val.getKind()) { 676 case APValue::Uninitialized: 677 assert(0 && "Constant expressions should be initialized."); 678 return 0; 679 case APValue::LValue: { 680 const llvm::Type *DestTy = getTypes().ConvertTypeForMem(DestType); 681 llvm::Constant *Offset = 682 llvm::ConstantInt::get(llvm::Type::Int64Ty, 683 Result.Val.getLValueOffset()); 684 685 llvm::Constant *C; 686 if (const Expr *LVBase = Result.Val.getLValueBase()) { 687 C = ConstExprEmitter(*this, CGF).EmitLValue(const_cast<Expr*>(LVBase)); 688 689 // Apply offset if necessary. 690 if (!Offset->isNullValue()) { 691 const llvm::Type *Type = 692 llvm::PointerType::getUnqual(llvm::Type::Int8Ty); 693 llvm::Constant *Casted = llvm::ConstantExpr::getBitCast(C, Type); 694 Casted = llvm::ConstantExpr::getGetElementPtr(Casted, &Offset, 1); 695 C = llvm::ConstantExpr::getBitCast(Casted, C->getType()); 696 } 697 698 // Convert to the appropriate type; this could be an lvalue for 699 // an integer. 700 if (isa<llvm::PointerType>(DestTy)) 701 return llvm::ConstantExpr::getBitCast(C, DestTy); 702 703 return llvm::ConstantExpr::getPtrToInt(C, DestTy); 704 } else { 705 C = Offset; 706 707 // Convert to the appropriate type; this could be an lvalue for 708 // an integer. 709 if (isa<llvm::PointerType>(DestTy)) 710 return llvm::ConstantExpr::getIntToPtr(C, DestTy); 711 712 // If the types don't match this should only be a truncate. 713 if (C->getType() != DestTy) 714 return llvm::ConstantExpr::getTrunc(C, DestTy); 715 716 return C; 717 } 718 } 719 case APValue::Int: { 720 llvm::Constant *C = llvm::ConstantInt::get(VMContext, 721 Result.Val.getInt()); 722 723 if (C->getType() == llvm::Type::Int1Ty) { 724 const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType()); 725 C = llvm::ConstantExpr::getZExt(C, BoolTy); 726 } 727 return C; 728 } 729 case APValue::ComplexInt: { 730 llvm::Constant *Complex[2]; 731 732 Complex[0] = llvm::ConstantInt::get(VMContext, 733 Result.Val.getComplexIntReal()); 734 Complex[1] = llvm::ConstantInt::get(VMContext, 735 Result.Val.getComplexIntImag()); 736 737 return llvm::ConstantStruct::get(VMContext, Complex, 2); 738 } 739 case APValue::Float: 740 return llvm::ConstantFP::get(VMContext, Result.Val.getFloat()); 741 case APValue::ComplexFloat: { 742 llvm::Constant *Complex[2]; 743 744 Complex[0] = llvm::ConstantFP::get(VMContext, 745 Result.Val.getComplexFloatReal()); 746 Complex[1] = llvm::ConstantFP::get(VMContext, 747 Result.Val.getComplexFloatImag()); 748 749 return llvm::ConstantStruct::get(VMContext, Complex, 2); 750 } 751 case APValue::Vector: { 752 llvm::SmallVector<llvm::Constant *, 4> Inits; 753 unsigned NumElts = Result.Val.getVectorLength(); 754 755 for (unsigned i = 0; i != NumElts; ++i) { 756 APValue &Elt = Result.Val.getVectorElt(i); 757 if (Elt.isInt()) 758 Inits.push_back(llvm::ConstantInt::get(VMContext, Elt.getInt())); 759 else 760 Inits.push_back(llvm::ConstantFP::get(VMContext, Elt.getFloat())); 761 } 762 return llvm::ConstantVector::get(&Inits[0], Inits.size()); 763 } 764 } 765 } 766 767 llvm::Constant* C = ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E)); 768 if (C && C->getType() == llvm::Type::Int1Ty) { 769 const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType()); 770 C = llvm::ConstantExpr::getZExt(C, BoolTy); 771 } 772 return C; 773} 774 775llvm::Constant *CodeGenModule::EmitNullConstant(QualType T) { 776 // Always return an LLVM null constant for now; this will change when we 777 // get support for IRGen of member pointers. 778 return llvm::Constant::getNullValue(getTypes().ConvertTypeForMem(T)); 779} 780