CGExprConstant.cpp revision 3498bdb9e9cb300de74c7b51c92608e2902b2348
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 65 return EmitConversion(C, E->getSubExpr()->getType(), E->getType()); 66 } 67 68 llvm::Constant *VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) { 69 return Visit(DAE->getExpr()); 70 } 71 72 llvm::Constant *EmitArrayInitialization(InitListExpr *ILE) { 73 std::vector<llvm::Constant*> Elts; 74 const llvm::ArrayType *AType = 75 cast<llvm::ArrayType>(ConvertType(ILE->getType())); 76 unsigned NumInitElements = ILE->getNumInits(); 77 // FIXME: Check for wide strings 78 if (NumInitElements > 0 && isa<StringLiteral>(ILE->getInit(0)) && 79 ILE->getType()->getArrayElementTypeNoTypeQual()->isCharType()) 80 return Visit(ILE->getInit(0)); 81 const llvm::Type *ElemTy = AType->getElementType(); 82 unsigned NumElements = AType->getNumElements(); 83 84 // Initialising an array requires us to automatically 85 // initialise any elements that have not been initialised explicitly 86 unsigned NumInitableElts = std::min(NumInitElements, NumElements); 87 88 // Copy initializer elements. 89 unsigned i = 0; 90 bool RewriteType = false; 91 for (; i < NumInitableElts; ++i) { 92 llvm::Constant *C = CGM.EmitConstantExpr(ILE->getInit(i), CGF); 93 RewriteType |= (C->getType() != ElemTy); 94 Elts.push_back(C); 95 } 96 97 // Initialize remaining array elements. 98 for (; i < NumElements; ++i) 99 Elts.push_back(llvm::Constant::getNullValue(ElemTy)); 100 101 if (RewriteType) { 102 // FIXME: Try to avoid packing the array 103 std::vector<const llvm::Type*> Types; 104 for (unsigned i = 0; i < Elts.size(); ++i) 105 Types.push_back(Elts[i]->getType()); 106 const llvm::StructType *SType = llvm::StructType::get(Types, true); 107 return llvm::ConstantStruct::get(SType, Elts); 108 } 109 110 return llvm::ConstantArray::get(AType, Elts); 111 } 112 113 void InsertBitfieldIntoStruct(std::vector<llvm::Constant*>& Elts, 114 FieldDecl* Field, Expr* E) { 115 // Calculate the value to insert 116 llvm::Constant *C = CGM.EmitConstantExpr(E, CGF); 117 llvm::ConstantInt *CI = dyn_cast<llvm::ConstantInt>(C); 118 if (!CI) { 119 CGM.ErrorUnsupported(E, "bitfield initialization"); 120 return; 121 } 122 llvm::APInt V = CI->getValue(); 123 124 // Calculate information about the relevant field 125 const llvm::Type* Ty = CI->getType(); 126 const llvm::TargetData &TD = CGM.getTypes().getTargetData(); 127 unsigned size = TD.getTypeStoreSizeInBits(Ty); 128 unsigned fieldOffset = CGM.getTypes().getLLVMFieldNo(Field) * size; 129 CodeGenTypes::BitFieldInfo bitFieldInfo = 130 CGM.getTypes().getBitFieldInfo(Field); 131 fieldOffset += bitFieldInfo.Begin; 132 133 // Find where to start the insertion 134 // FIXME: This is O(n^2) in the number of bit-fields! 135 // FIXME: This won't work if the struct isn't completely packed! 136 unsigned offset = 0, i = 0; 137 while (offset < (fieldOffset & -8)) 138 offset += TD.getTypeStoreSizeInBits(Elts[i++]->getType()); 139 140 // Advance over 0 sized elements (must terminate in bounds since 141 // the bitfield must have a size). 142 while (TD.getTypeStoreSizeInBits(Elts[i]->getType()) == 0) 143 ++i; 144 145 // Promote the size of V if necessary 146 // FIXME: This should never occur, but currently it can because 147 // initializer constants are cast to bool, and because clang is 148 // not enforcing bitfield width limits. 149 if (bitFieldInfo.Size > V.getBitWidth()) 150 V.zext(bitFieldInfo.Size); 151 152 // Insert the bits into the struct 153 // FIXME: This algorthm is only correct on X86! 154 // FIXME: THis algorthm assumes bit-fields only have byte-size elements! 155 unsigned bitsToInsert = bitFieldInfo.Size; 156 unsigned curBits = std::min(8 - (fieldOffset & 7), bitsToInsert); 157 unsigned byte = V.getLoBits(curBits).getZExtValue() << (fieldOffset & 7); 158 do { 159 llvm::Constant* byteC = llvm::ConstantInt::get(llvm::Type::Int8Ty, byte); 160 Elts[i] = llvm::ConstantExpr::getOr(Elts[i], byteC); 161 ++i; 162 V = V.lshr(curBits); 163 bitsToInsert -= curBits; 164 165 if (!bitsToInsert) 166 break; 167 168 curBits = bitsToInsert > 8 ? 8 : bitsToInsert; 169 byte = V.getLoBits(curBits).getZExtValue(); 170 } while (true); 171 } 172 173 llvm::Constant *EmitStructInitialization(InitListExpr *ILE) { 174 const llvm::StructType *SType = 175 cast<llvm::StructType>(ConvertType(ILE->getType())); 176 RecordDecl *RD = ILE->getType()->getAsRecordType()->getDecl(); 177 std::vector<llvm::Constant*> Elts; 178 179 // Initialize the whole structure to zero. 180 for (unsigned i = 0; i < SType->getNumElements(); ++i) { 181 const llvm::Type *FieldTy = SType->getElementType(i); 182 Elts.push_back(llvm::Constant::getNullValue(FieldTy)); 183 } 184 185 // Copy initializer elements. Skip padding fields. 186 unsigned EltNo = 0; // Element no in ILE 187 int FieldNo = 0; // Field no in RecordDecl 188 bool RewriteType = false; 189 for (RecordDecl::field_iterator Field = RD->field_begin(), 190 FieldEnd = RD->field_end(); 191 EltNo < ILE->getNumInits() && Field != FieldEnd; ++Field) { 192 FieldNo++; 193 if (!Field->getIdentifier()) 194 continue; 195 196 if (Field->isBitField()) { 197 InsertBitfieldIntoStruct(Elts, *Field, ILE->getInit(EltNo)); 198 } else { 199 unsigned FieldNo = CGM.getTypes().getLLVMFieldNo(*Field); 200 llvm::Constant *C = CGM.EmitConstantExpr(ILE->getInit(EltNo), CGF); 201 RewriteType |= (C->getType() != Elts[FieldNo]->getType()); 202 Elts[FieldNo] = C; 203 } 204 EltNo++; 205 } 206 207 if (RewriteType) { 208 // FIXME: Make this work for non-packed structs 209 assert(SType->isPacked() && "Cannot recreate unpacked structs"); 210 std::vector<const llvm::Type*> Types; 211 for (unsigned i = 0; i < Elts.size(); ++i) 212 Types.push_back(Elts[i]->getType()); 213 SType = llvm::StructType::get(Types, true); 214 } 215 216 return llvm::ConstantStruct::get(SType, Elts); 217 } 218 219 llvm::Constant *EmitUnion(llvm::Constant *C, const llvm::Type *Ty) { 220 // Build a struct with the union sub-element as the first member, 221 // and padded to the appropriate size 222 std::vector<llvm::Constant*> Elts; 223 std::vector<const llvm::Type*> Types; 224 Elts.push_back(C); 225 Types.push_back(C->getType()); 226 unsigned CurSize = CGM.getTargetData().getTypeStoreSize(C->getType()); 227 unsigned TotalSize = CGM.getTargetData().getTypeStoreSize(Ty); 228 while (CurSize < TotalSize) { 229 Elts.push_back(llvm::Constant::getNullValue(llvm::Type::Int8Ty)); 230 Types.push_back(llvm::Type::Int8Ty); 231 CurSize++; 232 } 233 234 // This always generates a packed struct 235 // FIXME: Try to generate an unpacked struct when we can 236 llvm::StructType* STy = llvm::StructType::get(Types, true); 237 return llvm::ConstantStruct::get(STy, Elts); 238 } 239 240 llvm::Constant *EmitUnionInitialization(InitListExpr *ILE) { 241 RecordDecl *RD = ILE->getType()->getAsRecordType()->getDecl(); 242 const llvm::Type *Ty = ConvertType(ILE->getType()); 243 244 // If this is an empty initializer list, we value-initialize the 245 // union. 246 if (ILE->getNumInits() == 0) 247 return llvm::Constant::getNullValue(Ty); 248 249 FieldDecl* curField = ILE->getInitializedFieldInUnion(); 250 if (!curField) { 251 // There's no field to initialize, so value-initialize the union. 252#ifndef NDEBUG 253 // Make sure that it's really an empty and not a failure of 254 // semantic analysis. 255 for (RecordDecl::field_iterator Field = RD->field_begin(), 256 FieldEnd = RD->field_end(); 257 Field != FieldEnd; ++Field) 258 assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed"); 259#endif 260 return llvm::Constant::getNullValue(Ty); 261 } 262 263 if (curField->isBitField()) { 264 // Create a dummy struct for bit-field insertion 265 unsigned NumElts = CGM.getTargetData().getTypePaddedSize(Ty) / 8; 266 llvm::Constant* NV = llvm::Constant::getNullValue(llvm::Type::Int8Ty); 267 std::vector<llvm::Constant*> Elts(NumElts, NV); 268 269 InsertBitfieldIntoStruct(Elts, curField, ILE->getInit(0)); 270 const llvm::ArrayType *RetTy = 271 llvm::ArrayType::get(NV->getType(), NumElts); 272 return llvm::ConstantArray::get(RetTy, Elts); 273 } 274 275 return EmitUnion(CGM.EmitConstantExpr(ILE->getInit(0), CGF), Ty); 276 } 277 278 llvm::Constant *EmitVectorInitialization(InitListExpr *ILE) { 279 const llvm::VectorType *VType = 280 cast<llvm::VectorType>(ConvertType(ILE->getType())); 281 const llvm::Type *ElemTy = VType->getElementType(); 282 std::vector<llvm::Constant*> Elts; 283 unsigned NumElements = VType->getNumElements(); 284 unsigned NumInitElements = ILE->getNumInits(); 285 286 unsigned NumInitableElts = std::min(NumInitElements, NumElements); 287 288 // Copy initializer elements. 289 unsigned i = 0; 290 for (; i < NumInitableElts; ++i) { 291 llvm::Constant *C = CGM.EmitConstantExpr(ILE->getInit(i), CGF); 292 Elts.push_back(C); 293 } 294 295 for (; i < NumElements; ++i) 296 Elts.push_back(llvm::Constant::getNullValue(ElemTy)); 297 298 return llvm::ConstantVector::get(VType, Elts); 299 } 300 301 llvm::Constant *VisitInitListExpr(InitListExpr *ILE) { 302 if (ILE->getType()->isScalarType()) { 303 // We have a scalar in braces. Just use the first element. 304 if (ILE->getNumInits() > 0) 305 return CGM.EmitConstantExpr(ILE->getInit(0), CGF); 306 307 const llvm::Type* RetTy = CGM.getTypes().ConvertType(ILE->getType()); 308 return llvm::Constant::getNullValue(RetTy); 309 } 310 311 if (ILE->getType()->isArrayType()) 312 return EmitArrayInitialization(ILE); 313 314 if (ILE->getType()->isStructureType()) 315 return EmitStructInitialization(ILE); 316 317 if (ILE->getType()->isUnionType()) 318 return EmitUnionInitialization(ILE); 319 320 if (ILE->getType()->isVectorType()) 321 return EmitVectorInitialization(ILE); 322 323 assert(0 && "Unable to handle InitListExpr"); 324 // Get rid of control reaches end of void function warning. 325 // Not reached. 326 return 0; 327 } 328 329 llvm::Constant *VisitImplicitCastExpr(ImplicitCastExpr *ICExpr) { 330 Expr* SExpr = ICExpr->getSubExpr(); 331 QualType SType = SExpr->getType(); 332 llvm::Constant *C; // the intermediate expression 333 QualType T; // the type of the intermediate expression 334 if (SType->isArrayType()) { 335 // Arrays decay to a pointer to the first element 336 // VLAs would require special handling, but they can't occur here 337 C = EmitLValue(SExpr); 338 llvm::Constant *Idx0 = llvm::ConstantInt::get(llvm::Type::Int32Ty, 0); 339 llvm::Constant *Ops[] = {Idx0, Idx0}; 340 C = llvm::ConstantExpr::getGetElementPtr(C, Ops, 2); 341 T = CGM.getContext().getArrayDecayedType(SType); 342 } else if (SType->isFunctionType()) { 343 // Function types decay to a pointer to the function 344 C = EmitLValue(SExpr); 345 T = CGM.getContext().getPointerType(SType); 346 } else { 347 C = Visit(SExpr); 348 T = SType; 349 } 350 351 // Perform the conversion; note that an implicit cast can both promote 352 // and convert an array/function 353 return EmitConversion(C, T, ICExpr->getType()); 354 } 355 356 llvm::Constant *VisitStringLiteral(StringLiteral *E) { 357 assert(!E->getType()->isPointerType() && "Strings are always arrays"); 358 359 // Otherwise this must be a string initializing an array in a static 360 // initializer. Don't emit it as the address of the string, emit the string 361 // data itself as an inline array. 362 return llvm::ConstantArray::get(CGM.GetStringForStringLiteral(E), false); 363 } 364 365 llvm::Constant *VisitUnaryExtension(const UnaryOperator *E) { 366 return Visit(E->getSubExpr()); 367 } 368 369 // Utility methods 370 const llvm::Type *ConvertType(QualType T) { 371 return CGM.getTypes().ConvertType(T); 372 } 373 374 llvm::Constant *EmitConversionToBool(llvm::Constant *Src, QualType SrcType) { 375 assert(SrcType->isCanonical() && "EmitConversion strips typedefs"); 376 377 if (SrcType->isRealFloatingType()) { 378 // Compare against 0.0 for fp scalars. 379 llvm::Constant *Zero = llvm::Constant::getNullValue(Src->getType()); 380 return llvm::ConstantExpr::getFCmp(llvm::FCmpInst::FCMP_UNE, Src, Zero); 381 } 382 383 assert((SrcType->isIntegerType() || SrcType->isPointerType()) && 384 "Unknown scalar type to convert"); 385 386 // Compare against an integer or pointer null. 387 llvm::Constant *Zero = llvm::Constant::getNullValue(Src->getType()); 388 return llvm::ConstantExpr::getICmp(llvm::ICmpInst::ICMP_NE, Src, Zero); 389 } 390 391 llvm::Constant *EmitConversion(llvm::Constant *Src, QualType SrcType, 392 QualType DstType) { 393 SrcType = CGM.getContext().getCanonicalType(SrcType); 394 DstType = CGM.getContext().getCanonicalType(DstType); 395 if (SrcType == DstType) return Src; 396 397 // Handle conversions to bool first, they are special: comparisons against 0. 398 if (DstType->isBooleanType()) 399 return EmitConversionToBool(Src, SrcType); 400 401 const llvm::Type *DstTy = ConvertType(DstType); 402 403 // Ignore conversions like int -> uint. 404 if (Src->getType() == DstTy) 405 return Src; 406 407 // Handle pointer conversions next: pointers can only be converted to/from 408 // other pointers and integers. 409 if (isa<llvm::PointerType>(DstTy)) { 410 // The source value may be an integer, or a pointer. 411 if (isa<llvm::PointerType>(Src->getType())) 412 return llvm::ConstantExpr::getBitCast(Src, DstTy); 413 assert(SrcType->isIntegerType() &&"Not ptr->ptr or int->ptr conversion?"); 414 return llvm::ConstantExpr::getIntToPtr(Src, DstTy); 415 } 416 417 if (isa<llvm::PointerType>(Src->getType())) { 418 // Must be an ptr to int cast. 419 assert(isa<llvm::IntegerType>(DstTy) && "not ptr->int?"); 420 return llvm::ConstantExpr::getPtrToInt(Src, DstTy); 421 } 422 423 // A scalar source can be splatted to a vector of the same element type 424 if (isa<llvm::VectorType>(DstTy) && !isa<VectorType>(SrcType)) { 425 assert((cast<llvm::VectorType>(DstTy)->getElementType() 426 == Src->getType()) && 427 "Vector element type must match scalar type to splat."); 428 unsigned NumElements = DstType->getAsVectorType()->getNumElements(); 429 llvm::SmallVector<llvm::Constant*, 16> Elements; 430 for (unsigned i = 0; i < NumElements; i++) 431 Elements.push_back(Src); 432 433 return llvm::ConstantVector::get(&Elements[0], NumElements); 434 } 435 436 if (isa<llvm::VectorType>(Src->getType()) || 437 isa<llvm::VectorType>(DstTy)) { 438 return llvm::ConstantExpr::getBitCast(Src, DstTy); 439 } 440 441 // Finally, we have the arithmetic types: real int/float. 442 if (isa<llvm::IntegerType>(Src->getType())) { 443 bool InputSigned = SrcType->isSignedIntegerType(); 444 if (isa<llvm::IntegerType>(DstTy)) 445 return llvm::ConstantExpr::getIntegerCast(Src, DstTy, InputSigned); 446 else if (InputSigned) 447 return llvm::ConstantExpr::getSIToFP(Src, DstTy); 448 else 449 return llvm::ConstantExpr::getUIToFP(Src, DstTy); 450 } 451 452 assert(Src->getType()->isFloatingPoint() && "Unknown real conversion"); 453 if (isa<llvm::IntegerType>(DstTy)) { 454 if (DstType->isSignedIntegerType()) 455 return llvm::ConstantExpr::getFPToSI(Src, DstTy); 456 else 457 return llvm::ConstantExpr::getFPToUI(Src, DstTy); 458 } 459 460 assert(DstTy->isFloatingPoint() && "Unknown real conversion"); 461 if (DstTy->getTypeID() < Src->getType()->getTypeID()) 462 return llvm::ConstantExpr::getFPTrunc(Src, DstTy); 463 else 464 return llvm::ConstantExpr::getFPExtend(Src, DstTy); 465 } 466 467public: 468 llvm::Constant *EmitLValue(Expr *E) { 469 switch (E->getStmtClass()) { 470 default: break; 471 case Expr::ParenExprClass: 472 // Elide parenthesis 473 return EmitLValue(cast<ParenExpr>(E)->getSubExpr()); 474 case Expr::CompoundLiteralExprClass: { 475 // Note that due to the nature of compound literals, this is guaranteed 476 // to be the only use of the variable, so we just generate it here. 477 CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E); 478 llvm::Constant* C = Visit(CLE->getInitializer()); 479 C = new llvm::GlobalVariable(C->getType(),E->getType().isConstQualified(), 480 llvm::GlobalValue::InternalLinkage, 481 C, ".compoundliteral", &CGM.getModule()); 482 return C; 483 } 484 case Expr::DeclRefExprClass: 485 case Expr::QualifiedDeclRefExprClass: { 486 NamedDecl *Decl = cast<DeclRefExpr>(E)->getDecl(); 487 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Decl)) 488 return CGM.GetAddrOfFunction(FD); 489 if (const VarDecl* VD = dyn_cast<VarDecl>(Decl)) { 490 if (VD->isFileVarDecl()) 491 return CGM.GetAddrOfGlobalVar(VD); 492 else if (VD->isBlockVarDecl()) { 493 assert(CGF && "Can't access static local vars without CGF"); 494 return CGF->GetAddrOfStaticLocalVar(VD); 495 } 496 } 497 break; 498 } 499 case Expr::MemberExprClass: { 500 MemberExpr* ME = cast<MemberExpr>(E); 501 llvm::Constant *Base; 502 if (ME->isArrow()) 503 Base = Visit(ME->getBase()); 504 else 505 Base = EmitLValue(ME->getBase()); 506 507 FieldDecl *Field = dyn_cast<FieldDecl>(ME->getMemberDecl()); 508 // FIXME: Handle other kinds of member expressions. 509 assert(Field && "No code generation for non-field member expressions"); 510 unsigned FieldNumber = CGM.getTypes().getLLVMFieldNo(Field); 511 llvm::Constant *Zero = llvm::ConstantInt::get(llvm::Type::Int32Ty, 0); 512 llvm::Constant *Idx = llvm::ConstantInt::get(llvm::Type::Int32Ty, 513 FieldNumber); 514 llvm::Value *Ops[] = {Zero, Idx}; 515 return llvm::ConstantExpr::getGetElementPtr(Base, Ops, 2); 516 } 517 case Expr::ArraySubscriptExprClass: { 518 ArraySubscriptExpr* ASExpr = cast<ArraySubscriptExpr>(E); 519 llvm::Constant *Base = Visit(ASExpr->getBase()); 520 llvm::Constant *Index = Visit(ASExpr->getIdx()); 521 assert(!ASExpr->getBase()->getType()->isVectorType() && 522 "Taking the address of a vector component is illegal!"); 523 return llvm::ConstantExpr::getGetElementPtr(Base, &Index, 1); 524 } 525 case Expr::StringLiteralClass: 526 return CGM.GetAddrOfConstantStringFromLiteral(cast<StringLiteral>(E)); 527 case Expr::ObjCStringLiteralClass: { 528 ObjCStringLiteral* SL = cast<ObjCStringLiteral>(E); 529 std::string S(SL->getString()->getStrData(), 530 SL->getString()->getByteLength()); 531 llvm::Constant *C = CGM.getObjCRuntime().GenerateConstantString(S); 532 return llvm::ConstantExpr::getBitCast(C, ConvertType(E->getType())); 533 } 534 case Expr::UnaryOperatorClass: { 535 UnaryOperator *Exp = cast<UnaryOperator>(E); 536 switch (Exp->getOpcode()) { 537 default: break; 538 case UnaryOperator::Extension: 539 // Extension is just a wrapper for expressions 540 return EmitLValue(Exp->getSubExpr()); 541 case UnaryOperator::Real: 542 case UnaryOperator::Imag: { 543 // The address of __real or __imag is just a GEP off the address 544 // of the internal expression 545 llvm::Constant* C = EmitLValue(Exp->getSubExpr()); 546 llvm::Constant *Zero = llvm::ConstantInt::get(llvm::Type::Int32Ty, 0); 547 llvm::Constant *Idx = llvm::ConstantInt::get(llvm::Type::Int32Ty, 548 Exp->getOpcode() == UnaryOperator::Imag); 549 llvm::Value *Ops[] = {Zero, Idx}; 550 return llvm::ConstantExpr::getGetElementPtr(C, Ops, 2); 551 } 552 case UnaryOperator::Deref: 553 // The address of a deref is just the value of the expression 554 return Visit(Exp->getSubExpr()); 555 } 556 break; 557 } 558 559 case Expr::PredefinedExprClass: { 560 // __func__/__FUNCTION__ -> "". __PRETTY_FUNCTION__ -> "top level". 561 std::string Str; 562 if (cast<PredefinedExpr>(E)->getIdentType() == 563 PredefinedExpr::PrettyFunction) 564 Str = "top level"; 565 566 return CGM.GetAddrOfConstantCString(Str, ".tmp"); 567 } 568 case Expr::AddrLabelExprClass: { 569 assert(CGF && "Invalid address of label expression outside function."); 570 unsigned id = CGF->GetIDForAddrOfLabel(cast<AddrLabelExpr>(E)->getLabel()); 571 llvm::Constant *C = llvm::ConstantInt::get(llvm::Type::Int32Ty, id); 572 return llvm::ConstantExpr::getIntToPtr(C, ConvertType(E->getType())); 573 } 574 case Expr::CallExprClass: { 575 CallExpr* CE = cast<CallExpr>(E); 576 if (CE->isBuiltinCall() != Builtin::BI__builtin___CFStringMakeConstantString) 577 break; 578 const Expr *Arg = CE->getArg(0)->IgnoreParenCasts(); 579 const StringLiteral *Literal = cast<StringLiteral>(Arg); 580 std::string S(Literal->getStrData(), Literal->getByteLength()); 581 return CGM.GetAddrOfConstantCFString(S); 582 } 583 } 584 CGM.ErrorUnsupported(E, "constant l-value expression"); 585 llvm::Type *Ty = llvm::PointerType::getUnqual(ConvertType(E->getType())); 586 return llvm::UndefValue::get(Ty); 587 } 588}; 589 590} // end anonymous namespace. 591 592llvm::Constant *CodeGenModule::EmitConstantExpr(const Expr *E, 593 CodeGenFunction *CGF) { 594 QualType type = Context.getCanonicalType(E->getType()); 595 596 Expr::EvalResult Result; 597 598 if (E->Evaluate(Result, Context)) { 599 assert(!Result.HasSideEffects && 600 "Constant expr should not have any side effects!"); 601 switch (Result.Val.getKind()) { 602 case APValue::Uninitialized: 603 assert(0 && "Constant expressions should be uninitialized."); 604 return llvm::UndefValue::get(getTypes().ConvertType(type)); 605 case APValue::LValue: { 606 llvm::Constant *Offset = 607 llvm::ConstantInt::get(llvm::Type::Int64Ty, 608 Result.Val.getLValueOffset()); 609 610 if (const Expr *LVBase = Result.Val.getLValueBase()) { 611 llvm::Constant *C = 612 ConstExprEmitter(*this, CGF).EmitLValue(const_cast<Expr*>(LVBase)); 613 614 const llvm::Type *Type = 615 llvm::PointerType::getUnqual(llvm::Type::Int8Ty); 616 const llvm::Type *DestType = getTypes().ConvertTypeForMem(E->getType()); 617 618 // FIXME: It's a little ugly that we need to cast to a pointer, 619 // apply the GEP and then cast back. 620 C = llvm::ConstantExpr::getBitCast(C, Type); 621 C = llvm::ConstantExpr::getGetElementPtr(C, &Offset, 1); 622 623 return llvm::ConstantExpr::getBitCast(C, DestType); 624 } 625 626 return llvm::ConstantExpr::getIntToPtr(Offset, 627 getTypes().ConvertType(type)); 628 } 629 case APValue::Int: { 630 llvm::Constant *C = llvm::ConstantInt::get(Result.Val.getInt()); 631 632 if (C->getType() == llvm::Type::Int1Ty) { 633 const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType()); 634 C = llvm::ConstantExpr::getZExt(C, BoolTy); 635 } 636 return C; 637 } 638 case APValue::ComplexInt: { 639 llvm::Constant *Complex[2]; 640 641 Complex[0] = llvm::ConstantInt::get(Result.Val.getComplexIntReal()); 642 Complex[1] = llvm::ConstantInt::get(Result.Val.getComplexIntImag()); 643 644 return llvm::ConstantStruct::get(Complex, 2); 645 } 646 case APValue::Float: 647 return llvm::ConstantFP::get(Result.Val.getFloat()); 648 case APValue::ComplexFloat: { 649 llvm::Constant *Complex[2]; 650 651 Complex[0] = llvm::ConstantFP::get(Result.Val.getComplexFloatReal()); 652 Complex[1] = llvm::ConstantFP::get(Result.Val.getComplexFloatImag()); 653 654 return llvm::ConstantStruct::get(Complex, 2); 655 } 656 case APValue::Vector: { 657 llvm::SmallVector<llvm::Constant *, 4> Inits; 658 unsigned NumElts = Result.Val.getVectorLength(); 659 660 for (unsigned i = 0; i != NumElts; ++i) { 661 APValue &Elt = Result.Val.getVectorElt(i); 662 if (Elt.isInt()) 663 Inits.push_back(llvm::ConstantInt::get(Elt.getInt())); 664 else 665 Inits.push_back(llvm::ConstantFP::get(Elt.getFloat())); 666 } 667 return llvm::ConstantVector::get(&Inits[0], Inits.size()); 668 } 669 } 670 } 671 672 llvm::Constant* C = ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E)); 673 if (C->getType() == llvm::Type::Int1Ty) { 674 const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType()); 675 C = llvm::ConstantExpr::getZExt(C, BoolTy); 676 } 677 return C; 678} 679