CGExprAgg.cpp revision d57a871339c7c98d58d93108b806f59bdf4e13e2
1//===--- CGExprAgg.cpp - Emit LLVM Code from Aggregate 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 Aggregate Expr nodes as LLVM code. 11// 12//===----------------------------------------------------------------------===// 13 14#include "CodeGenFunction.h" 15#include "CodeGenModule.h" 16#include "clang/AST/ASTContext.h" 17#include "clang/AST/StmtVisitor.h" 18#include "llvm/Constants.h" 19#include "llvm/Function.h" 20#include "llvm/GlobalVariable.h" 21#include "llvm/Support/Compiler.h" 22#include "llvm/Intrinsics.h" 23using namespace clang; 24using namespace CodeGen; 25 26//===----------------------------------------------------------------------===// 27// Aggregate Expression Emitter 28//===----------------------------------------------------------------------===// 29 30namespace { 31class VISIBILITY_HIDDEN AggExprEmitter : public StmtVisitor<AggExprEmitter> { 32 CodeGenFunction &CGF; 33 CGBuilderTy &Builder; 34 llvm::Value *DestPtr; 35 bool VolatileDest; 36public: 37 AggExprEmitter(CodeGenFunction &cgf, llvm::Value *destPtr, bool volatileDest) 38 : CGF(cgf), Builder(CGF.Builder), 39 DestPtr(destPtr), VolatileDest(volatileDest) { 40 } 41 42 //===--------------------------------------------------------------------===// 43 // Utilities 44 //===--------------------------------------------------------------------===// 45 46 /// EmitAggLoadOfLValue - Given an expression with aggregate type that 47 /// represents a value lvalue, this method emits the address of the lvalue, 48 /// then loads the result into DestPtr. 49 void EmitAggLoadOfLValue(const Expr *E); 50 51 void EmitNonConstInit(InitListExpr *E); 52 53 //===--------------------------------------------------------------------===// 54 // Visitor Methods 55 //===--------------------------------------------------------------------===// 56 57 void VisitStmt(Stmt *S) { 58 CGF.ErrorUnsupported(S, "aggregate expression"); 59 } 60 void VisitParenExpr(ParenExpr *PE) { Visit(PE->getSubExpr()); } 61 62 // l-values. 63 void VisitDeclRefExpr(DeclRefExpr *DRE) { EmitAggLoadOfLValue(DRE); } 64 void VisitMemberExpr(MemberExpr *ME) { EmitAggLoadOfLValue(ME); } 65 void VisitUnaryDeref(UnaryOperator *E) { EmitAggLoadOfLValue(E); } 66 void VisitStringLiteral(StringLiteral *E) { EmitAggLoadOfLValue(E); } 67 void VisitCompoundLiteralExpr(CompoundLiteralExpr *E) 68 { EmitAggLoadOfLValue(E); } 69 70 void VisitArraySubscriptExpr(ArraySubscriptExpr *E) { 71 EmitAggLoadOfLValue(E); 72 } 73 74 // Operators. 75 // case Expr::UnaryOperatorClass: 76 // case Expr::CastExprClass: 77 void VisitImplicitCastExpr(ImplicitCastExpr *E); 78 void VisitCallExpr(const CallExpr *E); 79 void VisitStmtExpr(const StmtExpr *E); 80 void VisitBinaryOperator(const BinaryOperator *BO); 81 void VisitBinAssign(const BinaryOperator *E); 82 void VisitOverloadExpr(const OverloadExpr *E); 83 void VisitBinComma(const BinaryOperator *E); 84 85 void VisitObjCMessageExpr(ObjCMessageExpr *E); 86 void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) { 87 EmitAggLoadOfLValue(E); 88 } 89 void VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E); 90 91 void VisitConditionalOperator(const ConditionalOperator *CO); 92 void VisitInitListExpr(InitListExpr *E); 93 void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) { 94 Visit(DAE->getExpr()); 95 } 96 void VisitVAArgExpr(VAArgExpr *E); 97 98 void EmitInitializationToLValue(Expr *E, LValue Address); 99 void EmitNullInitializationToLValue(LValue Address, QualType T); 100 // case Expr::ChooseExprClass: 101 102}; 103} // end anonymous namespace. 104 105//===----------------------------------------------------------------------===// 106// Utilities 107//===----------------------------------------------------------------------===// 108 109/// EmitAggLoadOfLValue - Given an expression with aggregate type that 110/// represents a value lvalue, this method emits the address of the lvalue, 111/// then loads the result into DestPtr. 112void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) { 113 LValue LV = CGF.EmitLValue(E); 114 assert(LV.isSimple() && "Can't have aggregate bitfield, vector, etc"); 115 llvm::Value *SrcPtr = LV.getAddress(); 116 117 // If the result is ignored, don't copy from the value. 118 if (DestPtr == 0) 119 // FIXME: If the source is volatile, we must read from it. 120 return; 121 122 CGF.EmitAggregateCopy(DestPtr, SrcPtr, E->getType()); 123} 124 125//===----------------------------------------------------------------------===// 126// Visitor Methods 127//===----------------------------------------------------------------------===// 128 129void AggExprEmitter::VisitImplicitCastExpr(ImplicitCastExpr *E) { 130 assert(CGF.getContext().typesAreCompatible( 131 E->getSubExpr()->getType().getUnqualifiedType(), 132 E->getType().getUnqualifiedType()) && 133 "Implicit cast types must be compatible"); 134 Visit(E->getSubExpr()); 135} 136 137void AggExprEmitter::VisitCallExpr(const CallExpr *E) { 138 RValue RV = CGF.EmitCallExpr(E); 139 assert(RV.isAggregate() && "Return value must be aggregate value!"); 140 141 // If the result is ignored, don't copy from the value. 142 if (DestPtr == 0) 143 // FIXME: If the source is volatile, we must read from it. 144 return; 145 146 CGF.EmitAggregateCopy(DestPtr, RV.getAggregateAddr(), E->getType()); 147} 148 149void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) { 150 RValue RV = CGF.EmitObjCMessageExpr(E); 151 assert(RV.isAggregate() && "Return value must be aggregate value!"); 152 153 // If the result is ignored, don't copy from the value. 154 if (DestPtr == 0) 155 // FIXME: If the source is volatile, we must read from it. 156 return; 157 158 CGF.EmitAggregateCopy(DestPtr, RV.getAggregateAddr(), E->getType()); 159} 160 161void AggExprEmitter::VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E) { 162 RValue RV = CGF.EmitObjCPropertyGet(E); 163 assert(RV.isAggregate() && "Return value must be aggregate value!"); 164 165 // If the result is ignored, don't copy from the value. 166 if (DestPtr == 0) 167 // FIXME: If the source is volatile, we must read from it. 168 return; 169 170 CGF.EmitAggregateCopy(DestPtr, RV.getAggregateAddr(), E->getType()); 171} 172 173void AggExprEmitter::VisitOverloadExpr(const OverloadExpr *E) { 174 RValue RV = CGF.EmitCallExpr(E->getFn(), E->arg_begin(), 175 E->arg_end(CGF.getContext())); 176 177 assert(RV.isAggregate() && "Return value must be aggregate value!"); 178 179 // If the result is ignored, don't copy from the value. 180 if (DestPtr == 0) 181 // FIXME: If the source is volatile, we must read from it. 182 return; 183 184 CGF.EmitAggregateCopy(DestPtr, RV.getAggregateAddr(), E->getType()); 185} 186 187void AggExprEmitter::VisitBinComma(const BinaryOperator *E) { 188 CGF.EmitAnyExpr(E->getLHS()); 189 CGF.EmitAggExpr(E->getRHS(), DestPtr, false); 190} 191 192void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) { 193 CGF.EmitCompoundStmt(*E->getSubStmt(), true, DestPtr, VolatileDest); 194} 195 196void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) { 197 CGF.ErrorUnsupported(E, "aggregate binary expression"); 198} 199 200void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) { 201 // For an assignment to work, the value on the right has 202 // to be compatible with the value on the left. 203 assert(CGF.getContext().typesAreCompatible( 204 E->getLHS()->getType().getUnqualifiedType(), 205 E->getRHS()->getType().getUnqualifiedType()) 206 && "Invalid assignment"); 207 LValue LHS = CGF.EmitLValue(E->getLHS()); 208 209 // We have to special case property setters, otherwise we must have 210 // a simple lvalue (no aggregates inside vectors, bitfields). 211 if (LHS.isPropertyRef()) { 212 // FIXME: Volatility? 213 llvm::Value *AggLoc = DestPtr; 214 if (!AggLoc) 215 AggLoc = CGF.CreateTempAlloca(CGF.ConvertType(E->getRHS()->getType())); 216 CGF.EmitAggExpr(E->getRHS(), AggLoc, false); 217 CGF.EmitObjCPropertySet(LHS.getPropertyRefExpr(), 218 RValue::getAggregate(AggLoc)); 219 } else { 220 // Codegen the RHS so that it stores directly into the LHS. 221 CGF.EmitAggExpr(E->getRHS(), LHS.getAddress(), false /*FIXME: VOLATILE LHS*/); 222 223 if (DestPtr == 0) 224 return; 225 226 // If the result of the assignment is used, copy the RHS there also. 227 CGF.EmitAggregateCopy(DestPtr, LHS.getAddress(), E->getType()); 228 } 229} 230 231void AggExprEmitter::VisitConditionalOperator(const ConditionalOperator *E) { 232 llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.?"); 233 llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.:"); 234 llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.cont"); 235 236 llvm::Value *Cond = CGF.EvaluateExprAsBool(E->getCond()); 237 Builder.CreateCondBr(Cond, LHSBlock, RHSBlock); 238 239 CGF.EmitBlock(LHSBlock); 240 241 // Handle the GNU extension for missing LHS. 242 assert(E->getLHS() && "Must have LHS for aggregate value"); 243 244 Visit(E->getLHS()); 245 CGF.EmitBranch(ContBlock); 246 247 CGF.EmitBlock(RHSBlock); 248 249 Visit(E->getRHS()); 250 CGF.EmitBranch(ContBlock); 251 252 CGF.EmitBlock(ContBlock); 253} 254 255void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) { 256 llvm::Value *ArgValue = CGF.EmitLValue(VE->getSubExpr()).getAddress(); 257 llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType()); 258 259 if (!ArgPtr) 260 CGF.ErrorUnsupported(VE, "aggregate va_arg expression"); 261 262 if (DestPtr) 263 // FIXME: volatility 264 CGF.EmitAggregateCopy(DestPtr, ArgPtr, VE->getType()); 265} 266 267void AggExprEmitter::EmitNonConstInit(InitListExpr *E) { 268 if (E->hadDesignators()) { 269 CGF.ErrorUnsupported(E, "initializer list with designators"); 270 return; 271 } 272 273 const llvm::PointerType *APType = 274 cast<llvm::PointerType>(DestPtr->getType()); 275 const llvm::Type *DestType = APType->getElementType(); 276 277 if (const llvm::ArrayType *AType = dyn_cast<llvm::ArrayType>(DestType)) { 278 unsigned NumInitElements = E->getNumInits(); 279 280 unsigned i; 281 for (i = 0; i != NumInitElements; ++i) { 282 llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array"); 283 Expr *Init = E->getInit(i); 284 if (isa<InitListExpr>(Init)) 285 CGF.EmitAggExpr(Init, NextVal, VolatileDest); 286 else 287 // FIXME: volatility 288 Builder.CreateStore(CGF.EmitScalarExpr(Init), NextVal); 289 } 290 291 // Emit remaining default initializers 292 unsigned NumArrayElements = AType->getNumElements(); 293 QualType QType = E->getInit(0)->getType(); 294 const llvm::Type *EType = AType->getElementType(); 295 for (/*Do not initialize i*/; i < NumArrayElements; ++i) { 296 llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array"); 297 if (EType->isSingleValueType()) 298 // FIXME: volatility 299 Builder.CreateStore(llvm::Constant::getNullValue(EType), NextVal); 300 else 301 CGF.EmitAggregateClear(NextVal, QType); 302 } 303 } else 304 assert(false && "Invalid initializer"); 305} 306 307void AggExprEmitter::EmitInitializationToLValue(Expr* E, LValue LV) { 308 // FIXME: Are initializers affected by volatile? 309 if (E->getType()->isComplexType()) { 310 CGF.EmitComplexExprIntoAddr(E, LV.getAddress(), false); 311 } else if (CGF.hasAggregateLLVMType(E->getType())) { 312 CGF.EmitAnyExpr(E, LV.getAddress(), false); 313 } else { 314 CGF.EmitStoreThroughLValue(CGF.EmitAnyExpr(E), LV, E->getType()); 315 } 316} 317 318void AggExprEmitter::EmitNullInitializationToLValue(LValue LV, QualType T) { 319 if (!CGF.hasAggregateLLVMType(T)) { 320 // For non-aggregates, we can store zero 321 llvm::Value *Null = llvm::Constant::getNullValue(CGF.ConvertType(T)); 322 CGF.EmitStoreThroughLValue(RValue::get(Null), LV, T); 323 } else { 324 // Otherwise, just memset the whole thing to zero. This is legal 325 // because in LLVM, all default initializers are guaranteed to have a 326 // bit pattern of all zeros. 327 // There's a potential optimization opportunity in combining 328 // memsets; that would be easy for arrays, but relatively 329 // difficult for structures with the current code. 330 llvm::Value *MemSet = CGF.CGM.getIntrinsic(llvm::Intrinsic::memset_i64); 331 uint64_t Size = CGF.getContext().getTypeSize(T); 332 333 const llvm::Type *BP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty); 334 llvm::Value* DestPtr = Builder.CreateBitCast(LV.getAddress(), BP, "tmp"); 335 Builder.CreateCall4(MemSet, DestPtr, 336 llvm::ConstantInt::get(llvm::Type::Int8Ty, 0), 337 llvm::ConstantInt::get(llvm::Type::Int64Ty, Size/8), 338 llvm::ConstantInt::get(llvm::Type::Int32Ty, 0)); 339 } 340} 341 342void AggExprEmitter::VisitInitListExpr(InitListExpr *E) { 343 if (E->hadDesignators()) { 344 CGF.ErrorUnsupported(E, "initializer list with designators"); 345 return; 346 } 347 348 // FIXME: For constant expressions, call into const expr emitter so 349 // that we can emit a memcpy instead of storing the individual 350 // members. This is purely for perf; both codepaths lead to 351 // equivalent (although not necessarily identical) code. It's worth 352 // noting that LLVM keeps on getting smarter, though, so it might 353 // not be worth bothering. 354 355 // Handle initialization of an array. 356 if (E->getType()->isArrayType()) { 357 const llvm::PointerType *APType = 358 cast<llvm::PointerType>(DestPtr->getType()); 359 const llvm::ArrayType *AType = 360 cast<llvm::ArrayType>(APType->getElementType()); 361 362 uint64_t NumInitElements = E->getNumInits(); 363 364 if (E->getNumInits() > 0) { 365 QualType T1 = E->getType(); 366 QualType T2 = E->getInit(0)->getType(); 367 if (CGF.getContext().getCanonicalType(T1).getUnqualifiedType() == 368 CGF.getContext().getCanonicalType(T2).getUnqualifiedType()) { 369 EmitAggLoadOfLValue(E->getInit(0)); 370 return; 371 } 372 } 373 374 uint64_t NumArrayElements = AType->getNumElements(); 375 QualType ElementType = CGF.getContext().getCanonicalType(E->getType()); 376 ElementType =CGF.getContext().getAsArrayType(ElementType)->getElementType(); 377 378 unsigned CVRqualifier = ElementType.getCVRQualifiers(); 379 380 for (uint64_t i = 0; i != NumArrayElements; ++i) { 381 llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array"); 382 if (i < NumInitElements) 383 EmitInitializationToLValue(E->getInit(i), 384 LValue::MakeAddr(NextVal, CVRqualifier)); 385 else 386 EmitNullInitializationToLValue(LValue::MakeAddr(NextVal, CVRqualifier), 387 ElementType); 388 } 389 return; 390 } 391 392 assert(E->getType()->isRecordType() && "Only support structs/unions here!"); 393 394 // Do struct initialization; this code just sets each individual member 395 // to the approprate value. This makes bitfield support automatic; 396 // the disadvantage is that the generated code is more difficult for 397 // the optimizer, especially with bitfields. 398 unsigned NumInitElements = E->getNumInits(); 399 RecordDecl *SD = E->getType()->getAsRecordType()->getDecl(); 400 unsigned NumMembers = SD->getNumMembers() - SD->hasFlexibleArrayMember(); 401 unsigned CurInitVal = 0; 402 bool isUnion = E->getType()->isUnionType(); 403 404 // Here we iterate over the fields; this makes it simpler to both 405 // default-initialize fields and skip over unnamed fields. 406 for (unsigned CurFieldNo = 0; CurFieldNo != NumMembers; ++CurFieldNo) { 407 FieldDecl *CurField = SD->getMember(CurFieldNo); 408 if (CurField->getIdentifier() == 0) { 409 // Initializers can't initialize unnamed fields, e.g. "int : 20;" 410 continue; 411 } 412 // FIXME: volatility 413 LValue FieldLoc = CGF.EmitLValueForField(DestPtr, CurField, isUnion,0); 414 if (CurInitVal < NumInitElements) { 415 // Store the initializer into the field 416 // This will probably have to get a bit smarter when we support 417 // designators in initializers 418 EmitInitializationToLValue(E->getInit(CurInitVal++), FieldLoc); 419 } else { 420 // We're out of initalizers; default-initialize to null 421 EmitNullInitializationToLValue(FieldLoc, CurField->getType()); 422 } 423 424 // Unions only initialize one field. 425 // (things can get weird with designators, but they aren't 426 // supported yet.) 427 if (E->getType()->isUnionType()) 428 break; 429 } 430} 431 432//===----------------------------------------------------------------------===// 433// Entry Points into this File 434//===----------------------------------------------------------------------===// 435 436/// EmitAggExpr - Emit the computation of the specified expression of 437/// aggregate type. The result is computed into DestPtr. Note that if 438/// DestPtr is null, the value of the aggregate expression is not needed. 439void CodeGenFunction::EmitAggExpr(const Expr *E, llvm::Value *DestPtr, 440 bool VolatileDest) { 441 assert(E && hasAggregateLLVMType(E->getType()) && 442 "Invalid aggregate expression to emit"); 443 444 AggExprEmitter(*this, DestPtr, VolatileDest).Visit(const_cast<Expr*>(E)); 445} 446 447void CodeGenFunction::EmitAggregateClear(llvm::Value *DestPtr, QualType Ty) { 448 assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex"); 449 450 EmitMemSetToZero(DestPtr, Ty); 451} 452 453void CodeGenFunction::EmitAggregateCopy(llvm::Value *DestPtr, 454 llvm::Value *SrcPtr, QualType Ty) { 455 assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex"); 456 457 // Aggregate assignment turns into llvm.memmove. 458 const llvm::Type *BP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty); 459 if (DestPtr->getType() != BP) 460 DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp"); 461 if (SrcPtr->getType() != BP) 462 SrcPtr = Builder.CreateBitCast(SrcPtr, BP, "tmp"); 463 464 // Get size and alignment info for this aggregate. 465 std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty); 466 467 // FIXME: Handle variable sized types. 468 const llvm::Type *IntPtr = llvm::IntegerType::get(LLVMPointerWidth); 469 470 Builder.CreateCall4(CGM.getMemMoveFn(), 471 DestPtr, SrcPtr, 472 // TypeInfo.first describes size in bits. 473 llvm::ConstantInt::get(IntPtr, TypeInfo.first/8), 474 llvm::ConstantInt::get(llvm::Type::Int32Ty, 475 TypeInfo.second/8)); 476} 477