CGExprConstant.cpp revision e20de512d88cf42a26ef994687d87fc6f5826625
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/StmtVisitor.h" 20#include "llvm/Constants.h" 21#include "llvm/Function.h" 22#include "llvm/GlobalVariable.h" 23#include "llvm/Support/Compiler.h" 24#include "llvm/Target/TargetData.h" 25using namespace clang; 26using namespace CodeGen; 27 28namespace { 29class VISIBILITY_HIDDEN ConstExprEmitter : 30 public StmtVisitor<ConstExprEmitter, llvm::Constant*> { 31 CodeGenModule &CGM; 32 CodeGenFunction *CGF; 33public: 34 ConstExprEmitter(CodeGenModule &cgm, CodeGenFunction *cgf) 35 : CGM(cgm), CGF(cgf) { 36 } 37 38 //===--------------------------------------------------------------------===// 39 // Visitor Methods 40 //===--------------------------------------------------------------------===// 41 42 llvm::Constant *VisitStmt(Stmt *S) { 43 CGM.ErrorUnsupported(S, "constant expression"); 44 QualType T = cast<Expr>(S)->getType(); 45 return llvm::UndefValue::get(CGM.getTypes().ConvertType(T)); 46 } 47 48 llvm::Constant *VisitParenExpr(ParenExpr *PE) { 49 return Visit(PE->getSubExpr()); 50 } 51 52 llvm::Constant *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) { 53 return Visit(E->getInitializer()); 54 } 55 56 llvm::Constant *VisitCastExpr(CastExpr* E) { 57 // GCC cast to union extension 58 if (E->getType()->isUnionType()) { 59 const llvm::Type *Ty = ConvertType(E->getType()); 60 return EmitUnion(CGM.EmitConstantExpr(E->getSubExpr(), CGF), Ty); 61 } 62 63 llvm::Constant *C = Visit(E->getSubExpr()); 64 return EmitConversion(C, E->getSubExpr()->getType(), E->getType()); 65 } 66 67 llvm::Constant *VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) { 68 return Visit(DAE->getExpr()); 69 } 70 71 llvm::Constant *EmitArrayInitialization(InitListExpr *ILE) { 72 std::vector<llvm::Constant*> Elts; 73 const llvm::ArrayType *AType = 74 cast<llvm::ArrayType>(ConvertType(ILE->getType())); 75 unsigned NumInitElements = ILE->getNumInits(); 76 // FIXME: Check for wide strings 77 if (NumInitElements > 0 && isa<StringLiteral>(ILE->getInit(0)) && 78 ILE->getType()->getArrayElementTypeNoTypeQual()->isCharType()) 79 return Visit(ILE->getInit(0)); 80 const llvm::Type *ElemTy = AType->getElementType(); 81 unsigned NumElements = AType->getNumElements(); 82 83 // Initialising an array requires us to automatically 84 // initialise any elements that have not been initialised explicitly 85 unsigned NumInitableElts = std::min(NumInitElements, NumElements); 86 87 // Copy initializer elements. 88 unsigned i = 0; 89 bool RewriteType = false; 90 for (; i < NumInitableElts; ++i) { 91 llvm::Constant *C = CGM.EmitConstantExpr(ILE->getInit(i), CGF); 92 if (!C) 93 return 0; 94 RewriteType |= (C->getType() != ElemTy); 95 Elts.push_back(C); 96 } 97 98 // Initialize remaining array elements. 99 for (; i < NumElements; ++i) 100 Elts.push_back(llvm::Constant::getNullValue(ElemTy)); 101 102 if (RewriteType) { 103 // FIXME: Try to avoid packing the array 104 std::vector<const llvm::Type*> Types; 105 for (unsigned i = 0; i < Elts.size(); ++i) 106 Types.push_back(Elts[i]->getType()); 107 const llvm::StructType *SType = llvm::StructType::get(Types, true); 108 return llvm::ConstantStruct::get(SType, Elts); 109 } 110 111 return llvm::ConstantArray::get(AType, Elts); 112 } 113 114 void InsertBitfieldIntoStruct(std::vector<llvm::Constant*>& Elts, 115 FieldDecl* Field, Expr* E) { 116 // Calculate the value to insert 117 llvm::Constant *C = CGM.EmitConstantExpr(E, CGF); 118 if (!C) 119 return; 120 121 llvm::ConstantInt *CI = dyn_cast<llvm::ConstantInt>(C); 122 if (!CI) { 123 CGM.ErrorUnsupported(E, "bitfield initialization"); 124 return; 125 } 126 llvm::APInt V = CI->getValue(); 127 128 // Calculate information about the relevant field 129 const llvm::Type* Ty = CI->getType(); 130 const llvm::TargetData &TD = CGM.getTypes().getTargetData(); 131 unsigned size = TD.getTypePaddedSizeInBits(Ty); 132 unsigned fieldOffset = CGM.getTypes().getLLVMFieldNo(Field) * size; 133 CodeGenTypes::BitFieldInfo bitFieldInfo = 134 CGM.getTypes().getBitFieldInfo(Field); 135 fieldOffset += bitFieldInfo.Begin; 136 137 // Find where to start the insertion 138 // FIXME: This is O(n^2) in the number of bit-fields! 139 // FIXME: This won't work if the struct isn't completely packed! 140 unsigned offset = 0, i = 0; 141 while (offset < (fieldOffset & -8)) 142 offset += TD.getTypePaddedSizeInBits(Elts[i++]->getType()); 143 144 // Advance over 0 sized elements (must terminate in bounds since 145 // the bitfield must have a size). 146 while (TD.getTypePaddedSizeInBits(Elts[i]->getType()) == 0) 147 ++i; 148 149 // Promote the size of V if necessary 150 // FIXME: This should never occur, but currently it can because 151 // initializer constants are cast to bool, and because clang is 152 // not enforcing bitfield width limits. 153 if (bitFieldInfo.Size > V.getBitWidth()) 154 V.zext(bitFieldInfo.Size); 155 156 // Insert the bits into the struct 157 // FIXME: This algorthm is only correct on X86! 158 // FIXME: THis algorthm assumes bit-fields only have byte-size elements! 159 unsigned bitsToInsert = bitFieldInfo.Size; 160 unsigned curBits = std::min(8 - (fieldOffset & 7), bitsToInsert); 161 unsigned byte = V.getLoBits(curBits).getZExtValue() << (fieldOffset & 7); 162 do { 163 llvm::Constant* byteC = llvm::ConstantInt::get(llvm::Type::Int8Ty, byte); 164 Elts[i] = llvm::ConstantExpr::getOr(Elts[i], byteC); 165 ++i; 166 V = V.lshr(curBits); 167 bitsToInsert -= curBits; 168 169 if (!bitsToInsert) 170 break; 171 172 curBits = bitsToInsert > 8 ? 8 : bitsToInsert; 173 byte = V.getLoBits(curBits).getZExtValue(); 174 } while (true); 175 } 176 177 llvm::Constant *EmitStructInitialization(InitListExpr *ILE) { 178 const llvm::StructType *SType = 179 cast<llvm::StructType>(ConvertType(ILE->getType())); 180 RecordDecl *RD = ILE->getType()->getAsRecordType()->getDecl(); 181 std::vector<llvm::Constant*> Elts; 182 183 // Initialize the whole structure to zero. 184 for (unsigned i = 0; i < SType->getNumElements(); ++i) { 185 const llvm::Type *FieldTy = SType->getElementType(i); 186 Elts.push_back(llvm::Constant::getNullValue(FieldTy)); 187 } 188 189 // Copy initializer elements. Skip padding fields. 190 unsigned EltNo = 0; // Element no in ILE 191 int FieldNo = 0; // Field no in RecordDecl 192 bool RewriteType = false; 193 for (RecordDecl::field_iterator Field = RD->field_begin(), 194 FieldEnd = RD->field_end(); 195 EltNo < ILE->getNumInits() && Field != FieldEnd; ++Field) { 196 FieldNo++; 197 if (!Field->getIdentifier()) 198 continue; 199 200 if (Field->isBitField()) { 201 InsertBitfieldIntoStruct(Elts, *Field, ILE->getInit(EltNo)); 202 } else { 203 unsigned FieldNo = CGM.getTypes().getLLVMFieldNo(*Field); 204 llvm::Constant *C = CGM.EmitConstantExpr(ILE->getInit(EltNo), CGF); 205 if (!C) return 0; 206 RewriteType |= (C->getType() != Elts[FieldNo]->getType()); 207 Elts[FieldNo] = C; 208 } 209 EltNo++; 210 } 211 212 if (RewriteType) { 213 // FIXME: Make this work for non-packed structs 214 assert(SType->isPacked() && "Cannot recreate unpacked structs"); 215 std::vector<const llvm::Type*> Types; 216 for (unsigned i = 0; i < Elts.size(); ++i) 217 Types.push_back(Elts[i]->getType()); 218 SType = llvm::StructType::get(Types, true); 219 } 220 221 return llvm::ConstantStruct::get(SType, Elts); 222 } 223 224 llvm::Constant *EmitUnion(llvm::Constant *C, const llvm::Type *Ty) { 225 if (!C) 226 return 0; 227 228 // Build a struct with the union sub-element as the first member, 229 // and padded to the appropriate size 230 std::vector<llvm::Constant*> Elts; 231 std::vector<const llvm::Type*> Types; 232 Elts.push_back(C); 233 Types.push_back(C->getType()); 234 unsigned CurSize = CGM.getTargetData().getTypePaddedSize(C->getType()); 235 unsigned TotalSize = CGM.getTargetData().getTypePaddedSize(Ty); 236 while (CurSize < TotalSize) { 237 Elts.push_back(llvm::Constant::getNullValue(llvm::Type::Int8Ty)); 238 Types.push_back(llvm::Type::Int8Ty); 239 CurSize++; 240 } 241 242 // This always generates a packed struct 243 // FIXME: Try to generate an unpacked struct when we can 244 llvm::StructType* STy = llvm::StructType::get(Types, true); 245 return llvm::ConstantStruct::get(STy, Elts); 246 } 247 248 llvm::Constant *EmitUnionInitialization(InitListExpr *ILE) { 249 const llvm::Type *Ty = ConvertType(ILE->getType()); 250 251 // If this is an empty initializer list, we value-initialize the 252 // union. 253 if (ILE->getNumInits() == 0) 254 return llvm::Constant::getNullValue(Ty); 255 256 FieldDecl* curField = ILE->getInitializedFieldInUnion(); 257 if (!curField) { 258 // There's no field to initialize, so value-initialize the union. 259#ifndef NDEBUG 260 // Make sure that it's really an empty and not a failure of 261 // semantic analysis. 262 RecordDecl *RD = ILE->getType()->getAsRecordType()->getDecl(); 263 for (RecordDecl::field_iterator Field = RD->field_begin(), 264 FieldEnd = RD->field_end(); 265 Field != FieldEnd; ++Field) 266 assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed"); 267#endif 268 return llvm::Constant::getNullValue(Ty); 269 } 270 271 if (curField->isBitField()) { 272 // Create a dummy struct for bit-field insertion 273 unsigned NumElts = CGM.getTargetData().getTypePaddedSize(Ty) / 8; 274 llvm::Constant* NV = llvm::Constant::getNullValue(llvm::Type::Int8Ty); 275 std::vector<llvm::Constant*> Elts(NumElts, NV); 276 277 InsertBitfieldIntoStruct(Elts, curField, ILE->getInit(0)); 278 const llvm::ArrayType *RetTy = 279 llvm::ArrayType::get(NV->getType(), NumElts); 280 return llvm::ConstantArray::get(RetTy, Elts); 281 } 282 283 return EmitUnion(CGM.EmitConstantExpr(ILE->getInit(0), CGF), Ty); 284 } 285 286 llvm::Constant *EmitVectorInitialization(InitListExpr *ILE) { 287 const llvm::VectorType *VType = 288 cast<llvm::VectorType>(ConvertType(ILE->getType())); 289 const llvm::Type *ElemTy = VType->getElementType(); 290 std::vector<llvm::Constant*> Elts; 291 unsigned NumElements = VType->getNumElements(); 292 unsigned NumInitElements = ILE->getNumInits(); 293 294 unsigned NumInitableElts = std::min(NumInitElements, NumElements); 295 296 // Copy initializer elements. 297 unsigned i = 0; 298 for (; i < NumInitableElts; ++i) { 299 llvm::Constant *C = CGM.EmitConstantExpr(ILE->getInit(i), CGF); 300 if (!C) 301 return 0; 302 Elts.push_back(C); 303 } 304 305 for (; i < NumElements; ++i) 306 Elts.push_back(llvm::Constant::getNullValue(ElemTy)); 307 308 return llvm::ConstantVector::get(VType, Elts); 309 } 310 311 llvm::Constant *VisitImplicitValueInitExpr(ImplicitValueInitExpr* E) { 312 const llvm::Type* RetTy = CGM.getTypes().ConvertType(E->getType()); 313 return llvm::Constant::getNullValue(RetTy); 314 } 315 316 llvm::Constant *VisitInitListExpr(InitListExpr *ILE) { 317 if (ILE->getType()->isScalarType()) { 318 // We have a scalar in braces. Just use the first element. 319 if (ILE->getNumInits() > 0) 320 return CGM.EmitConstantExpr(ILE->getInit(0), CGF); 321 322 const llvm::Type* RetTy = CGM.getTypes().ConvertType(ILE->getType()); 323 return llvm::Constant::getNullValue(RetTy); 324 } 325 326 if (ILE->getType()->isArrayType()) 327 return EmitArrayInitialization(ILE); 328 329 if (ILE->getType()->isStructureType()) 330 return EmitStructInitialization(ILE); 331 332 if (ILE->getType()->isUnionType()) 333 return EmitUnionInitialization(ILE); 334 335 if (ILE->getType()->isVectorType()) 336 return EmitVectorInitialization(ILE); 337 338 assert(0 && "Unable to handle InitListExpr"); 339 // Get rid of control reaches end of void function warning. 340 // Not reached. 341 return 0; 342 } 343 344 llvm::Constant *VisitImplicitCastExpr(ImplicitCastExpr *ICExpr) { 345 Expr* SExpr = ICExpr->getSubExpr(); 346 QualType SType = SExpr->getType(); 347 llvm::Constant *C; // the intermediate expression 348 QualType T; // the type of the intermediate expression 349 if (SType->isArrayType()) { 350 // Arrays decay to a pointer to the first element 351 // VLAs would require special handling, but they can't occur here 352 C = EmitLValue(SExpr); 353 llvm::Constant *Idx0 = llvm::ConstantInt::get(llvm::Type::Int32Ty, 0); 354 llvm::Constant *Ops[] = {Idx0, Idx0}; 355 C = llvm::ConstantExpr::getGetElementPtr(C, Ops, 2); 356 T = CGM.getContext().getArrayDecayedType(SType); 357 } else if (SType->isFunctionType()) { 358 // Function types decay to a pointer to the function 359 C = EmitLValue(SExpr); 360 T = CGM.getContext().getPointerType(SType); 361 } else { 362 C = Visit(SExpr); 363 T = SType; 364 } 365 366 // Perform the conversion; note that an implicit cast can both promote 367 // and convert an array/function 368 return EmitConversion(C, T, ICExpr->getType()); 369 } 370 371 llvm::Constant *VisitStringLiteral(StringLiteral *E) { 372 assert(!E->getType()->isPointerType() && "Strings are always arrays"); 373 374 // Otherwise this must be a string initializing an array in a static 375 // initializer. Don't emit it as the address of the string, emit the string 376 // data itself as an inline array. 377 return llvm::ConstantArray::get(CGM.GetStringForStringLiteral(E), false); 378 } 379 380 llvm::Constant *VisitUnaryExtension(const UnaryOperator *E) { 381 return Visit(E->getSubExpr()); 382 } 383 384 llvm::Constant *VisitBlockExpr(const BlockExpr *E) { 385 const char *Name = ""; 386 if (const NamedDecl *ND = dyn_cast<NamedDecl>(CGF->CurFuncDecl)) 387 Name = ND->getNameAsString().c_str(); 388 return CGM.GetAddrOfGlobalBlock(E, Name); 389 } 390 391 // Utility methods 392 const llvm::Type *ConvertType(QualType T) { 393 return CGM.getTypes().ConvertType(T); 394 } 395 396 llvm::Constant *EmitConversionToBool(llvm::Constant *Src, QualType SrcType) { 397 assert(SrcType->isCanonical() && "EmitConversion strips typedefs"); 398 399 if (SrcType->isRealFloatingType()) { 400 // Compare against 0.0 for fp scalars. 401 llvm::Constant *Zero = llvm::Constant::getNullValue(Src->getType()); 402 return llvm::ConstantExpr::getFCmp(llvm::FCmpInst::FCMP_UNE, Src, Zero); 403 } 404 405 assert((SrcType->isIntegerType() || SrcType->isPointerType()) && 406 "Unknown scalar type to convert"); 407 408 // Compare against an integer or pointer null. 409 llvm::Constant *Zero = llvm::Constant::getNullValue(Src->getType()); 410 return llvm::ConstantExpr::getICmp(llvm::ICmpInst::ICMP_NE, Src, Zero); 411 } 412 413 llvm::Constant *EmitConversion(llvm::Constant *Src, QualType SrcType, 414 QualType DstType) { 415 if (!Src) 416 return 0; 417 418 SrcType = CGM.getContext().getCanonicalType(SrcType); 419 DstType = CGM.getContext().getCanonicalType(DstType); 420 if (SrcType == DstType) return Src; 421 422 // Handle conversions to bool first, they are special: comparisons against 0. 423 if (DstType->isBooleanType()) 424 return EmitConversionToBool(Src, SrcType); 425 426 const llvm::Type *DstTy = ConvertType(DstType); 427 428 // Ignore conversions like int -> uint. 429 if (Src->getType() == DstTy) 430 return Src; 431 432 // Handle pointer conversions next: pointers can only be converted to/from 433 // other pointers and integers. 434 if (isa<llvm::PointerType>(DstTy)) { 435 // The source value may be an integer, or a pointer. 436 if (isa<llvm::PointerType>(Src->getType())) 437 return llvm::ConstantExpr::getBitCast(Src, DstTy); 438 assert(SrcType->isIntegerType() &&"Not ptr->ptr or int->ptr conversion?"); 439 return llvm::ConstantExpr::getIntToPtr(Src, DstTy); 440 } 441 442 if (isa<llvm::PointerType>(Src->getType())) { 443 // Must be an ptr to int cast. 444 assert(isa<llvm::IntegerType>(DstTy) && "not ptr->int?"); 445 return llvm::ConstantExpr::getPtrToInt(Src, DstTy); 446 } 447 448 // A scalar source can be splatted to a vector of the same element type 449 if (isa<llvm::VectorType>(DstTy) && !isa<VectorType>(SrcType)) { 450 assert((cast<llvm::VectorType>(DstTy)->getElementType() 451 == Src->getType()) && 452 "Vector element type must match scalar type to splat."); 453 unsigned NumElements = DstType->getAsVectorType()->getNumElements(); 454 llvm::SmallVector<llvm::Constant*, 16> Elements; 455 for (unsigned i = 0; i < NumElements; i++) 456 Elements.push_back(Src); 457 458 return llvm::ConstantVector::get(&Elements[0], NumElements); 459 } 460 461 if (isa<llvm::VectorType>(Src->getType()) || 462 isa<llvm::VectorType>(DstTy)) { 463 return llvm::ConstantExpr::getBitCast(Src, DstTy); 464 } 465 466 // Finally, we have the arithmetic types: real int/float. 467 if (isa<llvm::IntegerType>(Src->getType())) { 468 bool InputSigned = SrcType->isSignedIntegerType(); 469 if (isa<llvm::IntegerType>(DstTy)) 470 return llvm::ConstantExpr::getIntegerCast(Src, DstTy, InputSigned); 471 else if (InputSigned) 472 return llvm::ConstantExpr::getSIToFP(Src, DstTy); 473 else 474 return llvm::ConstantExpr::getUIToFP(Src, DstTy); 475 } 476 477 assert(Src->getType()->isFloatingPoint() && "Unknown real conversion"); 478 if (isa<llvm::IntegerType>(DstTy)) { 479 if (DstType->isSignedIntegerType()) 480 return llvm::ConstantExpr::getFPToSI(Src, DstTy); 481 else 482 return llvm::ConstantExpr::getFPToUI(Src, DstTy); 483 } 484 485 assert(DstTy->isFloatingPoint() && "Unknown real conversion"); 486 if (DstTy->getTypeID() < Src->getType()->getTypeID()) 487 return llvm::ConstantExpr::getFPTrunc(Src, DstTy); 488 else 489 return llvm::ConstantExpr::getFPExtend(Src, DstTy); 490 } 491 492public: 493 llvm::Constant *EmitLValue(Expr *E) { 494 switch (E->getStmtClass()) { 495 default: break; 496 case Expr::ParenExprClass: 497 // Elide parenthesis 498 return EmitLValue(cast<ParenExpr>(E)->getSubExpr()); 499 case Expr::CompoundLiteralExprClass: { 500 // Note that due to the nature of compound literals, this is guaranteed 501 // to be the only use of the variable, so we just generate it here. 502 CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E); 503 llvm::Constant* C = Visit(CLE->getInitializer()); 504 // FIXME: "Leaked" on failure. 505 if (C) 506 C = new llvm::GlobalVariable(C->getType(), 507 E->getType().isConstQualified(), 508 llvm::GlobalValue::InternalLinkage, 509 C, ".compoundliteral", &CGM.getModule()); 510 return C; 511 } 512 case Expr::DeclRefExprClass: 513 case Expr::QualifiedDeclRefExprClass: { 514 NamedDecl *Decl = cast<DeclRefExpr>(E)->getDecl(); 515 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Decl)) 516 return CGM.GetAddrOfFunction(FD); 517 if (const VarDecl* VD = dyn_cast<VarDecl>(Decl)) { 518 if (VD->isFileVarDecl()) 519 return CGM.GetAddrOfGlobalVar(VD); 520 else if (VD->isBlockVarDecl()) { 521 assert(CGF && "Can't access static local vars without CGF"); 522 return CGF->GetAddrOfStaticLocalVar(VD); 523 } 524 } 525 break; 526 } 527 case Expr::MemberExprClass: { 528 MemberExpr* ME = cast<MemberExpr>(E); 529 llvm::Constant *Base; 530 if (ME->isArrow()) 531 Base = Visit(ME->getBase()); 532 else 533 Base = EmitLValue(ME->getBase()); 534 if (!Base) 535 return 0; 536 537 FieldDecl *Field = dyn_cast<FieldDecl>(ME->getMemberDecl()); 538 // FIXME: Handle other kinds of member expressions. 539 assert(Field && "No code generation for non-field member expressions"); 540 unsigned FieldNumber = CGM.getTypes().getLLVMFieldNo(Field); 541 llvm::Constant *Zero = llvm::ConstantInt::get(llvm::Type::Int32Ty, 0); 542 llvm::Constant *Idx = llvm::ConstantInt::get(llvm::Type::Int32Ty, 543 FieldNumber); 544 llvm::Value *Ops[] = {Zero, Idx}; 545 return llvm::ConstantExpr::getGetElementPtr(Base, Ops, 2); 546 } 547 case Expr::ArraySubscriptExprClass: { 548 ArraySubscriptExpr* ASExpr = cast<ArraySubscriptExpr>(E); 549 assert(!ASExpr->getBase()->getType()->isVectorType() && 550 "Taking the address of a vector component is illegal!"); 551 552 llvm::Constant *Base = Visit(ASExpr->getBase()); 553 llvm::Constant *Index = Visit(ASExpr->getIdx()); 554 if (!Base || !Index) 555 return 0; 556 return llvm::ConstantExpr::getGetElementPtr(Base, &Index, 1); 557 } 558 case Expr::StringLiteralClass: 559 return CGM.GetAddrOfConstantStringFromLiteral(cast<StringLiteral>(E)); 560 case Expr::ObjCStringLiteralClass: { 561 ObjCStringLiteral* SL = cast<ObjCStringLiteral>(E); 562 std::string S(SL->getString()->getStrData(), 563 SL->getString()->getByteLength()); 564 llvm::Constant *C = CGM.getObjCRuntime().GenerateConstantString(S); 565 return llvm::ConstantExpr::getBitCast(C, ConvertType(E->getType())); 566 } 567 case Expr::UnaryOperatorClass: { 568 UnaryOperator *Exp = cast<UnaryOperator>(E); 569 switch (Exp->getOpcode()) { 570 default: break; 571 case UnaryOperator::Extension: 572 // Extension is just a wrapper for expressions 573 return EmitLValue(Exp->getSubExpr()); 574 case UnaryOperator::Real: 575 case UnaryOperator::Imag: { 576 // The address of __real or __imag is just a GEP off the address 577 // of the internal expression 578 llvm::Constant* C = EmitLValue(Exp->getSubExpr()); 579 llvm::Constant *Zero = llvm::ConstantInt::get(llvm::Type::Int32Ty, 0); 580 llvm::Constant *Idx = llvm::ConstantInt::get(llvm::Type::Int32Ty, 581 Exp->getOpcode() == UnaryOperator::Imag); 582 llvm::Value *Ops[] = {Zero, Idx}; 583 return llvm::ConstantExpr::getGetElementPtr(C, Ops, 2); 584 } 585 case UnaryOperator::Deref: 586 // The address of a deref is just the value of the expression 587 return Visit(Exp->getSubExpr()); 588 } 589 break; 590 } 591 592 case Expr::PredefinedExprClass: { 593 // __func__/__FUNCTION__ -> "". __PRETTY_FUNCTION__ -> "top level". 594 std::string Str; 595 if (cast<PredefinedExpr>(E)->getIdentType() == 596 PredefinedExpr::PrettyFunction) 597 Str = "top level"; 598 599 return CGM.GetAddrOfConstantCString(Str, ".tmp"); 600 } 601 case Expr::AddrLabelExprClass: { 602 assert(CGF && "Invalid address of label expression outside function."); 603 unsigned id = CGF->GetIDForAddrOfLabel(cast<AddrLabelExpr>(E)->getLabel()); 604 llvm::Constant *C = llvm::ConstantInt::get(llvm::Type::Int32Ty, id); 605 return llvm::ConstantExpr::getIntToPtr(C, ConvertType(E->getType())); 606 } 607 case Expr::CallExprClass: { 608 CallExpr* CE = cast<CallExpr>(E); 609 if (CE->isBuiltinCall(CGM.getContext()) != 610 Builtin::BI__builtin___CFStringMakeConstantString) 611 break; 612 const Expr *Arg = CE->getArg(0)->IgnoreParenCasts(); 613 const StringLiteral *Literal = cast<StringLiteral>(Arg); 614 std::string S(Literal->getStrData(), Literal->getByteLength()); 615 return CGM.GetAddrOfConstantCFString(S); 616 } 617 case Expr::BlockExprClass: { 618 return CGF->BuildBlockLiteralTmp(cast<BlockExpr>(E)); 619 } 620 } 621 622 return 0; 623 } 624}; 625 626} // end anonymous namespace. 627 628llvm::Constant *CodeGenModule::EmitConstantExpr(const Expr *E, 629 CodeGenFunction *CGF) { 630 Expr::EvalResult Result; 631 632 if (E->Evaluate(Result, Context)) { 633 assert(!Result.HasSideEffects && 634 "Constant expr should not have any side effects!"); 635 switch (Result.Val.getKind()) { 636 case APValue::Uninitialized: 637 assert(0 && "Constant expressions should be initialized."); 638 return 0; 639 case APValue::LValue: { 640 const llvm::Type *DestType = getTypes().ConvertTypeForMem(E->getType()); 641 llvm::Constant *Offset = 642 llvm::ConstantInt::get(llvm::Type::Int64Ty, 643 Result.Val.getLValueOffset()); 644 645 llvm::Constant *C; 646 if (const Expr *LVBase = Result.Val.getLValueBase()) { 647 C = ConstExprEmitter(*this, CGF).EmitLValue(const_cast<Expr*>(LVBase)); 648 649 // Apply offset if necessary. 650 if (!Offset->isNullValue()) { 651 const llvm::Type *Type = 652 llvm::PointerType::getUnqual(llvm::Type::Int8Ty); 653 llvm::Constant *Casted = llvm::ConstantExpr::getBitCast(C, Type); 654 Casted = llvm::ConstantExpr::getGetElementPtr(Casted, &Offset, 1); 655 C = llvm::ConstantExpr::getBitCast(Casted, C->getType()); 656 } 657 658 // Convert to the appropriate type; this could be an lvalue for 659 // an integer. 660 if (isa<llvm::PointerType>(DestType)) 661 return llvm::ConstantExpr::getBitCast(C, DestType); 662 663 return llvm::ConstantExpr::getPtrToInt(C, DestType); 664 } else { 665 C = Offset; 666 667 // Convert to the appropriate type; this could be an lvalue for 668 // an integer. 669 if (isa<llvm::PointerType>(DestType)) 670 return llvm::ConstantExpr::getIntToPtr(C, DestType); 671 672 // If the types don't match this should only be a truncate. 673 if (C->getType() != DestType) 674 return llvm::ConstantExpr::getTrunc(C, DestType); 675 676 return C; 677 } 678 } 679 case APValue::Int: { 680 llvm::Constant *C = llvm::ConstantInt::get(Result.Val.getInt()); 681 682 if (C->getType() == llvm::Type::Int1Ty) { 683 const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType()); 684 C = llvm::ConstantExpr::getZExt(C, BoolTy); 685 } 686 return C; 687 } 688 case APValue::ComplexInt: { 689 llvm::Constant *Complex[2]; 690 691 Complex[0] = llvm::ConstantInt::get(Result.Val.getComplexIntReal()); 692 Complex[1] = llvm::ConstantInt::get(Result.Val.getComplexIntImag()); 693 694 return llvm::ConstantStruct::get(Complex, 2); 695 } 696 case APValue::Float: 697 return llvm::ConstantFP::get(Result.Val.getFloat()); 698 case APValue::ComplexFloat: { 699 llvm::Constant *Complex[2]; 700 701 Complex[0] = llvm::ConstantFP::get(Result.Val.getComplexFloatReal()); 702 Complex[1] = llvm::ConstantFP::get(Result.Val.getComplexFloatImag()); 703 704 return llvm::ConstantStruct::get(Complex, 2); 705 } 706 case APValue::Vector: { 707 llvm::SmallVector<llvm::Constant *, 4> Inits; 708 unsigned NumElts = Result.Val.getVectorLength(); 709 710 for (unsigned i = 0; i != NumElts; ++i) { 711 APValue &Elt = Result.Val.getVectorElt(i); 712 if (Elt.isInt()) 713 Inits.push_back(llvm::ConstantInt::get(Elt.getInt())); 714 else 715 Inits.push_back(llvm::ConstantFP::get(Elt.getFloat())); 716 } 717 return llvm::ConstantVector::get(&Inits[0], Inits.size()); 718 } 719 } 720 } 721 722 llvm::Constant* C = ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E)); 723 if (C && 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