CGExprAgg.cpp revision f6a1648197562e0b133440d612d9af297d0a86cc
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 "CGObjCRuntime.h" 17#include "clang/AST/ASTContext.h" 18#include "clang/AST/DeclCXX.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/Intrinsics.h" 24using namespace clang; 25using namespace CodeGen; 26 27//===----------------------------------------------------------------------===// 28// Aggregate Expression Emitter 29//===----------------------------------------------------------------------===// 30 31namespace { 32class AggExprEmitter : public StmtVisitor<AggExprEmitter> { 33 CodeGenFunction &CGF; 34 CGBuilderTy &Builder; 35 AggValueSlot Dest; 36 bool IgnoreResult; 37 38 ReturnValueSlot getReturnValueSlot() const { 39 // If the destination slot requires garbage collection, we can't 40 // use the real return value slot, because we have to use the GC 41 // API. 42 if (Dest.requiresGCollection()) return ReturnValueSlot(); 43 44 return ReturnValueSlot(Dest.getAddr(), Dest.isVolatile()); 45 } 46 47 AggValueSlot EnsureSlot(QualType T) { 48 if (!Dest.isIgnored()) return Dest; 49 return CGF.CreateAggTemp(T, "agg.tmp.ensured"); 50 } 51 52public: 53 AggExprEmitter(CodeGenFunction &cgf, AggValueSlot Dest, 54 bool ignore) 55 : CGF(cgf), Builder(CGF.Builder), Dest(Dest), 56 IgnoreResult(ignore) { 57 } 58 59 //===--------------------------------------------------------------------===// 60 // Utilities 61 //===--------------------------------------------------------------------===// 62 63 /// EmitAggLoadOfLValue - Given an expression with aggregate type that 64 /// represents a value lvalue, this method emits the address of the lvalue, 65 /// then loads the result into DestPtr. 66 void EmitAggLoadOfLValue(const Expr *E); 67 68 /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired. 69 void EmitFinalDestCopy(const Expr *E, LValue Src, bool Ignore = false); 70 void EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore = false); 71 72 void EmitGCMove(const Expr *E, RValue Src); 73 74 bool TypeRequiresGCollection(QualType T); 75 76 //===--------------------------------------------------------------------===// 77 // Visitor Methods 78 //===--------------------------------------------------------------------===// 79 80 void VisitStmt(Stmt *S) { 81 CGF.ErrorUnsupported(S, "aggregate expression"); 82 } 83 void VisitParenExpr(ParenExpr *PE) { Visit(PE->getSubExpr()); } 84 void VisitUnaryExtension(UnaryOperator *E) { Visit(E->getSubExpr()); } 85 86 // l-values. 87 void VisitDeclRefExpr(DeclRefExpr *DRE) { EmitAggLoadOfLValue(DRE); } 88 void VisitMemberExpr(MemberExpr *ME) { EmitAggLoadOfLValue(ME); } 89 void VisitUnaryDeref(UnaryOperator *E) { EmitAggLoadOfLValue(E); } 90 void VisitStringLiteral(StringLiteral *E) { EmitAggLoadOfLValue(E); } 91 void VisitCompoundLiteralExpr(CompoundLiteralExpr *E) { 92 EmitAggLoadOfLValue(E); 93 } 94 void VisitArraySubscriptExpr(ArraySubscriptExpr *E) { 95 EmitAggLoadOfLValue(E); 96 } 97 void VisitBlockDeclRefExpr(const BlockDeclRefExpr *E) { 98 EmitAggLoadOfLValue(E); 99 } 100 void VisitPredefinedExpr(const PredefinedExpr *E) { 101 EmitAggLoadOfLValue(E); 102 } 103 104 // Operators. 105 void VisitCastExpr(CastExpr *E); 106 void VisitCallExpr(const CallExpr *E); 107 void VisitStmtExpr(const StmtExpr *E); 108 void VisitBinaryOperator(const BinaryOperator *BO); 109 void VisitPointerToDataMemberBinaryOperator(const BinaryOperator *BO); 110 void VisitBinAssign(const BinaryOperator *E); 111 void VisitBinComma(const BinaryOperator *E); 112 113 void VisitObjCMessageExpr(ObjCMessageExpr *E); 114 void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) { 115 EmitAggLoadOfLValue(E); 116 } 117 void VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E); 118 119 void VisitConditionalOperator(const ConditionalOperator *CO); 120 void VisitChooseExpr(const ChooseExpr *CE); 121 void VisitInitListExpr(InitListExpr *E); 122 void VisitImplicitValueInitExpr(ImplicitValueInitExpr *E); 123 void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) { 124 Visit(DAE->getExpr()); 125 } 126 void VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E); 127 void VisitCXXConstructExpr(const CXXConstructExpr *E); 128 void VisitCXXExprWithTemporaries(CXXExprWithTemporaries *E); 129 void VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E); 130 void VisitCXXTypeidExpr(CXXTypeidExpr *E) { EmitAggLoadOfLValue(E); } 131 132 void VisitVAArgExpr(VAArgExpr *E); 133 134 void EmitInitializationToLValue(Expr *E, LValue Address, QualType T); 135 void EmitNullInitializationToLValue(LValue Address, QualType T); 136 // case Expr::ChooseExprClass: 137 void VisitCXXThrowExpr(const CXXThrowExpr *E) { CGF.EmitCXXThrowExpr(E); } 138}; 139} // end anonymous namespace. 140 141//===----------------------------------------------------------------------===// 142// Utilities 143//===----------------------------------------------------------------------===// 144 145/// EmitAggLoadOfLValue - Given an expression with aggregate type that 146/// represents a value lvalue, this method emits the address of the lvalue, 147/// then loads the result into DestPtr. 148void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) { 149 LValue LV = CGF.EmitLValue(E); 150 EmitFinalDestCopy(E, LV); 151} 152 153/// \brief True if the given aggregate type requires special GC API calls. 154bool AggExprEmitter::TypeRequiresGCollection(QualType T) { 155 // Only record types have members that might require garbage collection. 156 const RecordType *RecordTy = T->getAs<RecordType>(); 157 if (!RecordTy) return false; 158 159 // Don't mess with non-trivial C++ types. 160 RecordDecl *Record = RecordTy->getDecl(); 161 if (isa<CXXRecordDecl>(Record) && 162 (!cast<CXXRecordDecl>(Record)->hasTrivialCopyConstructor() || 163 !cast<CXXRecordDecl>(Record)->hasTrivialDestructor())) 164 return false; 165 166 // Check whether the type has an object member. 167 return Record->hasObjectMember(); 168} 169 170/// \brief Perform the final move to DestPtr if RequiresGCollection is set. 171/// 172/// The idea is that you do something like this: 173/// RValue Result = EmitSomething(..., getReturnValueSlot()); 174/// EmitGCMove(E, Result); 175/// If GC doesn't interfere, this will cause the result to be emitted 176/// directly into the return value slot. If GC does interfere, a final 177/// move will be performed. 178void AggExprEmitter::EmitGCMove(const Expr *E, RValue Src) { 179 if (Dest.requiresGCollection()) { 180 std::pair<uint64_t, unsigned> TypeInfo = 181 CGF.getContext().getTypeInfo(E->getType()); 182 unsigned long size = TypeInfo.first/8; 183 const llvm::Type *SizeTy = CGF.ConvertType(CGF.getContext().getSizeType()); 184 llvm::Value *SizeVal = llvm::ConstantInt::get(SizeTy, size); 185 CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF, Dest.getAddr(), 186 Src.getAggregateAddr(), 187 SizeVal); 188 } 189} 190 191/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired. 192void AggExprEmitter::EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore) { 193 assert(Src.isAggregate() && "value must be aggregate value!"); 194 195 // If Dest is ignored, then we're evaluating an aggregate expression 196 // in a context (like an expression statement) that doesn't care 197 // about the result. C says that an lvalue-to-rvalue conversion is 198 // performed in these cases; C++ says that it is not. In either 199 // case, we don't actually need to do anything unless the value is 200 // volatile. 201 if (Dest.isIgnored()) { 202 if (!Src.isVolatileQualified() || 203 CGF.CGM.getLangOptions().CPlusPlus || 204 (IgnoreResult && Ignore)) 205 return; 206 207 // If the source is volatile, we must read from it; to do that, we need 208 // some place to put it. 209 Dest = CGF.CreateAggTemp(E->getType(), "agg.tmp"); 210 } 211 212 if (Dest.requiresGCollection()) { 213 std::pair<uint64_t, unsigned> TypeInfo = 214 CGF.getContext().getTypeInfo(E->getType()); 215 unsigned long size = TypeInfo.first/8; 216 const llvm::Type *SizeTy = CGF.ConvertType(CGF.getContext().getSizeType()); 217 llvm::Value *SizeVal = llvm::ConstantInt::get(SizeTy, size); 218 CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF, 219 Dest.getAddr(), 220 Src.getAggregateAddr(), 221 SizeVal); 222 return; 223 } 224 // If the result of the assignment is used, copy the LHS there also. 225 // FIXME: Pass VolatileDest as well. I think we also need to merge volatile 226 // from the source as well, as we can't eliminate it if either operand 227 // is volatile, unless copy has volatile for both source and destination.. 228 CGF.EmitAggregateCopy(Dest.getAddr(), Src.getAggregateAddr(), E->getType(), 229 Dest.isVolatile()|Src.isVolatileQualified()); 230} 231 232/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired. 233void AggExprEmitter::EmitFinalDestCopy(const Expr *E, LValue Src, bool Ignore) { 234 assert(Src.isSimple() && "Can't have aggregate bitfield, vector, etc"); 235 236 EmitFinalDestCopy(E, RValue::getAggregate(Src.getAddress(), 237 Src.isVolatileQualified()), 238 Ignore); 239} 240 241//===----------------------------------------------------------------------===// 242// Visitor Methods 243//===----------------------------------------------------------------------===// 244 245void AggExprEmitter::VisitCastExpr(CastExpr *E) { 246 if (Dest.isIgnored() && E->getCastKind() != CK_Dynamic) { 247 Visit(E->getSubExpr()); 248 return; 249 } 250 251 switch (E->getCastKind()) { 252 case CK_Dynamic: { 253 assert(isa<CXXDynamicCastExpr>(E) && "CK_Dynamic without a dynamic_cast?"); 254 LValue LV = CGF.EmitCheckedLValue(E->getSubExpr()); 255 // FIXME: Do we also need to handle property references here? 256 if (LV.isSimple()) 257 CGF.EmitDynamicCast(LV.getAddress(), cast<CXXDynamicCastExpr>(E)); 258 else 259 CGF.CGM.ErrorUnsupported(E, "non-simple lvalue dynamic_cast"); 260 261 if (!Dest.isIgnored()) 262 CGF.CGM.ErrorUnsupported(E, "lvalue dynamic_cast with a destination"); 263 break; 264 } 265 266 case CK_ToUnion: { 267 // GCC union extension 268 QualType Ty = E->getSubExpr()->getType(); 269 QualType PtrTy = CGF.getContext().getPointerType(Ty); 270 llvm::Value *CastPtr = Builder.CreateBitCast(Dest.getAddr(), 271 CGF.ConvertType(PtrTy)); 272 EmitInitializationToLValue(E->getSubExpr(), CGF.MakeAddrLValue(CastPtr, Ty), 273 Ty); 274 break; 275 } 276 277 case CK_DerivedToBase: 278 case CK_BaseToDerived: 279 case CK_UncheckedDerivedToBase: { 280 assert(0 && "cannot perform hierarchy conversion in EmitAggExpr: " 281 "should have been unpacked before we got here"); 282 break; 283 } 284 285 case CK_GetObjCProperty: { 286 LValue LV = CGF.EmitLValue(E->getSubExpr()); 287 assert(LV.isPropertyRef()); 288 RValue RV = CGF.EmitLoadOfPropertyRefLValue(LV, getReturnValueSlot()); 289 EmitGCMove(E, RV); 290 break; 291 } 292 293 case CK_LValueToRValue: // hope for downstream optimization 294 case CK_NoOp: 295 case CK_UserDefinedConversion: 296 case CK_ConstructorConversion: 297 assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(), 298 E->getType()) && 299 "Implicit cast types must be compatible"); 300 Visit(E->getSubExpr()); 301 break; 302 303 case CK_LValueBitCast: 304 llvm_unreachable("should not be emitting lvalue bitcast as rvalue"); 305 break; 306 307 case CK_Dependent: 308 case CK_BitCast: 309 case CK_ArrayToPointerDecay: 310 case CK_FunctionToPointerDecay: 311 case CK_NullToPointer: 312 case CK_NullToMemberPointer: 313 case CK_BaseToDerivedMemberPointer: 314 case CK_DerivedToBaseMemberPointer: 315 case CK_MemberPointerToBoolean: 316 case CK_IntegralToPointer: 317 case CK_PointerToIntegral: 318 case CK_PointerToBoolean: 319 case CK_ToVoid: 320 case CK_VectorSplat: 321 case CK_IntegralCast: 322 case CK_IntegralToBoolean: 323 case CK_IntegralToFloating: 324 case CK_FloatingToIntegral: 325 case CK_FloatingToBoolean: 326 case CK_FloatingCast: 327 case CK_AnyPointerToObjCPointerCast: 328 case CK_AnyPointerToBlockPointerCast: 329 case CK_ObjCObjectLValueCast: 330 case CK_FloatingRealToComplex: 331 case CK_FloatingComplexToReal: 332 case CK_FloatingComplexToBoolean: 333 case CK_FloatingComplexCast: 334 case CK_FloatingComplexToIntegralComplex: 335 case CK_IntegralRealToComplex: 336 case CK_IntegralComplexToReal: 337 case CK_IntegralComplexToBoolean: 338 case CK_IntegralComplexCast: 339 case CK_IntegralComplexToFloatingComplex: 340 llvm_unreachable("cast kind invalid for aggregate types"); 341 } 342} 343 344void AggExprEmitter::VisitCallExpr(const CallExpr *E) { 345 if (E->getCallReturnType()->isReferenceType()) { 346 EmitAggLoadOfLValue(E); 347 return; 348 } 349 350 RValue RV = CGF.EmitCallExpr(E, getReturnValueSlot()); 351 EmitGCMove(E, RV); 352} 353 354void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) { 355 RValue RV = CGF.EmitObjCMessageExpr(E, getReturnValueSlot()); 356 EmitGCMove(E, RV); 357} 358 359void AggExprEmitter::VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E) { 360 llvm_unreachable("direct property access not surrounded by " 361 "lvalue-to-rvalue cast"); 362} 363 364void AggExprEmitter::VisitBinComma(const BinaryOperator *E) { 365 CGF.EmitAnyExpr(E->getLHS(), AggValueSlot::ignored(), true); 366 Visit(E->getRHS()); 367} 368 369void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) { 370 CGF.EmitCompoundStmt(*E->getSubStmt(), true, Dest); 371} 372 373void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) { 374 if (E->getOpcode() == BO_PtrMemD || E->getOpcode() == BO_PtrMemI) 375 VisitPointerToDataMemberBinaryOperator(E); 376 else 377 CGF.ErrorUnsupported(E, "aggregate binary expression"); 378} 379 380void AggExprEmitter::VisitPointerToDataMemberBinaryOperator( 381 const BinaryOperator *E) { 382 LValue LV = CGF.EmitPointerToDataMemberBinaryExpr(E); 383 EmitFinalDestCopy(E, LV); 384} 385 386void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) { 387 // For an assignment to work, the value on the right has 388 // to be compatible with the value on the left. 389 assert(CGF.getContext().hasSameUnqualifiedType(E->getLHS()->getType(), 390 E->getRHS()->getType()) 391 && "Invalid assignment"); 392 LValue LHS = CGF.EmitLValue(E->getLHS()); 393 394 // We have to special case property setters, otherwise we must have 395 // a simple lvalue (no aggregates inside vectors, bitfields). 396 if (LHS.isPropertyRef()) { 397 AggValueSlot Slot = EnsureSlot(E->getRHS()->getType()); 398 CGF.EmitAggExpr(E->getRHS(), Slot); 399 CGF.EmitStoreThroughPropertyRefLValue(Slot.asRValue(), LHS); 400 } else { 401 bool GCollection = false; 402 if (CGF.getContext().getLangOptions().getGCMode()) 403 GCollection = TypeRequiresGCollection(E->getLHS()->getType()); 404 405 // Codegen the RHS so that it stores directly into the LHS. 406 AggValueSlot LHSSlot = AggValueSlot::forLValue(LHS, true, 407 GCollection); 408 CGF.EmitAggExpr(E->getRHS(), LHSSlot, false); 409 EmitFinalDestCopy(E, LHS, true); 410 } 411} 412 413void AggExprEmitter::VisitConditionalOperator(const ConditionalOperator *E) { 414 if (!E->getLHS()) { 415 CGF.ErrorUnsupported(E, "conditional operator with missing LHS"); 416 return; 417 } 418 419 llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true"); 420 llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false"); 421 llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end"); 422 423 CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock); 424 425 CGF.BeginConditionalBranch(); 426 CGF.EmitBlock(LHSBlock); 427 428 // Save whether the destination's lifetime is externally managed. 429 bool DestLifetimeManaged = Dest.isLifetimeExternallyManaged(); 430 431 Visit(E->getLHS()); 432 CGF.EndConditionalBranch(); 433 CGF.EmitBranch(ContBlock); 434 435 CGF.BeginConditionalBranch(); 436 CGF.EmitBlock(RHSBlock); 437 438 // If the result of an agg expression is unused, then the emission 439 // of the LHS might need to create a destination slot. That's fine 440 // with us, and we can safely emit the RHS into the same slot, but 441 // we shouldn't claim that its lifetime is externally managed. 442 Dest.setLifetimeExternallyManaged(DestLifetimeManaged); 443 444 Visit(E->getRHS()); 445 CGF.EndConditionalBranch(); 446 CGF.EmitBranch(ContBlock); 447 448 CGF.EmitBlock(ContBlock); 449} 450 451void AggExprEmitter::VisitChooseExpr(const ChooseExpr *CE) { 452 Visit(CE->getChosenSubExpr(CGF.getContext())); 453} 454 455void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) { 456 llvm::Value *ArgValue = CGF.EmitVAListRef(VE->getSubExpr()); 457 llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType()); 458 459 if (!ArgPtr) { 460 CGF.ErrorUnsupported(VE, "aggregate va_arg expression"); 461 return; 462 } 463 464 EmitFinalDestCopy(VE, CGF.MakeAddrLValue(ArgPtr, VE->getType())); 465} 466 467void AggExprEmitter::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) { 468 // Ensure that we have a slot, but if we already do, remember 469 // whether its lifetime was externally managed. 470 bool WasManaged = Dest.isLifetimeExternallyManaged(); 471 Dest = EnsureSlot(E->getType()); 472 Dest.setLifetimeExternallyManaged(); 473 474 Visit(E->getSubExpr()); 475 476 // Set up the temporary's destructor if its lifetime wasn't already 477 // being managed. 478 if (!WasManaged) 479 CGF.EmitCXXTemporary(E->getTemporary(), Dest.getAddr()); 480} 481 482void 483AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *E) { 484 AggValueSlot Slot = EnsureSlot(E->getType()); 485 CGF.EmitCXXConstructExpr(E, Slot); 486} 487 488void AggExprEmitter::VisitCXXExprWithTemporaries(CXXExprWithTemporaries *E) { 489 CGF.EmitCXXExprWithTemporaries(E, Dest); 490} 491 492void AggExprEmitter::VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E) { 493 QualType T = E->getType(); 494 AggValueSlot Slot = EnsureSlot(T); 495 EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddr(), T), T); 496} 497 498void AggExprEmitter::VisitImplicitValueInitExpr(ImplicitValueInitExpr *E) { 499 QualType T = E->getType(); 500 AggValueSlot Slot = EnsureSlot(T); 501 EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddr(), T), T); 502} 503 504/// isSimpleZero - If emitting this value will obviously just cause a store of 505/// zero to memory, return true. This can return false if uncertain, so it just 506/// handles simple cases. 507static bool isSimpleZero(const Expr *E, CodeGenFunction &CGF) { 508 // (0) 509 if (const ParenExpr *PE = dyn_cast<ParenExpr>(E)) 510 return isSimpleZero(PE->getSubExpr(), CGF); 511 // 0 512 if (const IntegerLiteral *IL = dyn_cast<IntegerLiteral>(E)) 513 return IL->getValue() == 0; 514 // +0.0 515 if (const FloatingLiteral *FL = dyn_cast<FloatingLiteral>(E)) 516 return FL->getValue().isPosZero(); 517 // int() 518 if ((isa<ImplicitValueInitExpr>(E) || isa<CXXScalarValueInitExpr>(E)) && 519 CGF.getTypes().isZeroInitializable(E->getType())) 520 return true; 521 // (int*)0 - Null pointer expressions. 522 if (const CastExpr *ICE = dyn_cast<CastExpr>(E)) 523 return ICE->getCastKind() == CK_NullToPointer; 524 // '\0' 525 if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E)) 526 return CL->getValue() == 0; 527 528 // Otherwise, hard case: conservatively return false. 529 return false; 530} 531 532 533void 534AggExprEmitter::EmitInitializationToLValue(Expr* E, LValue LV, QualType T) { 535 // FIXME: Ignore result? 536 // FIXME: Are initializers affected by volatile? 537 if (Dest.isZeroed() && isSimpleZero(E, CGF)) { 538 // Storing "i32 0" to a zero'd memory location is a noop. 539 } else if (isa<ImplicitValueInitExpr>(E)) { 540 EmitNullInitializationToLValue(LV, T); 541 } else if (T->isReferenceType()) { 542 RValue RV = CGF.EmitReferenceBindingToExpr(E, /*InitializedDecl=*/0); 543 CGF.EmitStoreThroughLValue(RV, LV, T); 544 } else if (T->isAnyComplexType()) { 545 CGF.EmitComplexExprIntoAddr(E, LV.getAddress(), false); 546 } else if (CGF.hasAggregateLLVMType(T)) { 547 CGF.EmitAggExpr(E, AggValueSlot::forAddr(LV.getAddress(), false, true, 548 false, Dest.isZeroed())); 549 } else { 550 CGF.EmitStoreThroughLValue(CGF.EmitAnyExpr(E), LV, T); 551 } 552} 553 554void AggExprEmitter::EmitNullInitializationToLValue(LValue LV, QualType T) { 555 // If the destination slot is already zeroed out before the aggregate is 556 // copied into it, we don't have to emit any zeros here. 557 if (Dest.isZeroed() && CGF.getTypes().isZeroInitializable(T)) 558 return; 559 560 if (!CGF.hasAggregateLLVMType(T)) { 561 // For non-aggregates, we can store zero 562 llvm::Value *Null = llvm::Constant::getNullValue(CGF.ConvertType(T)); 563 CGF.EmitStoreThroughLValue(RValue::get(Null), LV, T); 564 } else { 565 // There's a potential optimization opportunity in combining 566 // memsets; that would be easy for arrays, but relatively 567 // difficult for structures with the current code. 568 CGF.EmitNullInitialization(LV.getAddress(), T); 569 } 570} 571 572void AggExprEmitter::VisitInitListExpr(InitListExpr *E) { 573#if 0 574 // FIXME: Assess perf here? Figure out what cases are worth optimizing here 575 // (Length of globals? Chunks of zeroed-out space?). 576 // 577 // If we can, prefer a copy from a global; this is a lot less code for long 578 // globals, and it's easier for the current optimizers to analyze. 579 if (llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, E->getType(), &CGF)) { 580 llvm::GlobalVariable* GV = 581 new llvm::GlobalVariable(CGF.CGM.getModule(), C->getType(), true, 582 llvm::GlobalValue::InternalLinkage, C, ""); 583 EmitFinalDestCopy(E, CGF.MakeAddrLValue(GV, E->getType())); 584 return; 585 } 586#endif 587 if (E->hadArrayRangeDesignator()) 588 CGF.ErrorUnsupported(E, "GNU array range designator extension"); 589 590 llvm::Value *DestPtr = Dest.getAddr(); 591 592 // Handle initialization of an array. 593 if (E->getType()->isArrayType()) { 594 const llvm::PointerType *APType = 595 cast<llvm::PointerType>(DestPtr->getType()); 596 const llvm::ArrayType *AType = 597 cast<llvm::ArrayType>(APType->getElementType()); 598 599 uint64_t NumInitElements = E->getNumInits(); 600 601 if (E->getNumInits() > 0) { 602 QualType T1 = E->getType(); 603 QualType T2 = E->getInit(0)->getType(); 604 if (CGF.getContext().hasSameUnqualifiedType(T1, T2)) { 605 EmitAggLoadOfLValue(E->getInit(0)); 606 return; 607 } 608 } 609 610 uint64_t NumArrayElements = AType->getNumElements(); 611 QualType ElementType = CGF.getContext().getCanonicalType(E->getType()); 612 ElementType = CGF.getContext().getAsArrayType(ElementType)->getElementType(); 613 614 // FIXME: were we intentionally ignoring address spaces and GC attributes? 615 616 for (uint64_t i = 0; i != NumArrayElements; ++i) { 617 // If we're done emitting initializers and the destination is known-zeroed 618 // then we're done. 619 if (i == NumInitElements && 620 Dest.isZeroed() && 621 CGF.getTypes().isZeroInitializable(ElementType)) 622 break; 623 624 llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array"); 625 LValue LV = CGF.MakeAddrLValue(NextVal, ElementType); 626 627 if (i < NumInitElements) 628 EmitInitializationToLValue(E->getInit(i), LV, ElementType); 629 else 630 EmitNullInitializationToLValue(LV, ElementType); 631 632 // If the GEP didn't get used because of a dead zero init or something 633 // else, clean it up for -O0 builds and general tidiness. 634 if (llvm::GetElementPtrInst *GEP = 635 dyn_cast<llvm::GetElementPtrInst>(NextVal)) 636 if (GEP->use_empty()) 637 GEP->eraseFromParent(); 638 } 639 return; 640 } 641 642 assert(E->getType()->isRecordType() && "Only support structs/unions here!"); 643 644 // Do struct initialization; this code just sets each individual member 645 // to the approprate value. This makes bitfield support automatic; 646 // the disadvantage is that the generated code is more difficult for 647 // the optimizer, especially with bitfields. 648 unsigned NumInitElements = E->getNumInits(); 649 RecordDecl *SD = E->getType()->getAs<RecordType>()->getDecl(); 650 651 if (E->getType()->isUnionType()) { 652 // Only initialize one field of a union. The field itself is 653 // specified by the initializer list. 654 if (!E->getInitializedFieldInUnion()) { 655 // Empty union; we have nothing to do. 656 657#ifndef NDEBUG 658 // Make sure that it's really an empty and not a failure of 659 // semantic analysis. 660 for (RecordDecl::field_iterator Field = SD->field_begin(), 661 FieldEnd = SD->field_end(); 662 Field != FieldEnd; ++Field) 663 assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed"); 664#endif 665 return; 666 } 667 668 // FIXME: volatility 669 FieldDecl *Field = E->getInitializedFieldInUnion(); 670 671 LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestPtr, Field, 0); 672 if (NumInitElements) { 673 // Store the initializer into the field 674 EmitInitializationToLValue(E->getInit(0), FieldLoc, Field->getType()); 675 } else { 676 // Default-initialize to null. 677 EmitNullInitializationToLValue(FieldLoc, Field->getType()); 678 } 679 680 return; 681 } 682 683 // Here we iterate over the fields; this makes it simpler to both 684 // default-initialize fields and skip over unnamed fields. 685 unsigned CurInitVal = 0; 686 for (RecordDecl::field_iterator Field = SD->field_begin(), 687 FieldEnd = SD->field_end(); 688 Field != FieldEnd; ++Field) { 689 // We're done once we hit the flexible array member 690 if (Field->getType()->isIncompleteArrayType()) 691 break; 692 693 if (Field->isUnnamedBitfield()) 694 continue; 695 696 // Don't emit GEP before a noop store of zero. 697 if (CurInitVal == NumInitElements && Dest.isZeroed() && 698 CGF.getTypes().isZeroInitializable(E->getType())) 699 break; 700 701 // FIXME: volatility 702 LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestPtr, *Field, 0); 703 // We never generate write-barries for initialized fields. 704 FieldLoc.setNonGC(true); 705 706 if (CurInitVal < NumInitElements) { 707 // Store the initializer into the field. 708 EmitInitializationToLValue(E->getInit(CurInitVal++), FieldLoc, 709 Field->getType()); 710 } else { 711 // We're out of initalizers; default-initialize to null 712 EmitNullInitializationToLValue(FieldLoc, Field->getType()); 713 } 714 715 // If the GEP didn't get used because of a dead zero init or something 716 // else, clean it up for -O0 builds and general tidiness. 717 if (FieldLoc.isSimple()) 718 if (llvm::GetElementPtrInst *GEP = 719 dyn_cast<llvm::GetElementPtrInst>(FieldLoc.getAddress())) 720 if (GEP->use_empty()) 721 GEP->eraseFromParent(); 722 } 723} 724 725//===----------------------------------------------------------------------===// 726// Entry Points into this File 727//===----------------------------------------------------------------------===// 728 729/// GetNumNonZeroBytesInInit - Get an approximate count of the number of 730/// non-zero bytes that will be stored when outputting the initializer for the 731/// specified initializer expression. 732static uint64_t GetNumNonZeroBytesInInit(const Expr *E, CodeGenFunction &CGF) { 733 if (const ParenExpr *PE = dyn_cast<ParenExpr>(E)) 734 return GetNumNonZeroBytesInInit(PE->getSubExpr(), CGF); 735 736 // 0 and 0.0 won't require any non-zero stores! 737 if (isSimpleZero(E, CGF)) return 0; 738 739 // If this is an initlist expr, sum up the size of sizes of the (present) 740 // elements. If this is something weird, assume the whole thing is non-zero. 741 const InitListExpr *ILE = dyn_cast<InitListExpr>(E); 742 if (ILE == 0 || !CGF.getTypes().isZeroInitializable(ILE->getType())) 743 return CGF.getContext().getTypeSize(E->getType())/8; 744 745 // InitListExprs for structs have to be handled carefully. If there are 746 // reference members, we need to consider the size of the reference, not the 747 // referencee. InitListExprs for unions and arrays can't have references. 748 if (const RecordType *RT = E->getType()->getAs<RecordType>()) { 749 if (!RT->isUnionType()) { 750 RecordDecl *SD = E->getType()->getAs<RecordType>()->getDecl(); 751 uint64_t NumNonZeroBytes = 0; 752 753 unsigned ILEElement = 0; 754 for (RecordDecl::field_iterator Field = SD->field_begin(), 755 FieldEnd = SD->field_end(); Field != FieldEnd; ++Field) { 756 // We're done once we hit the flexible array member or run out of 757 // InitListExpr elements. 758 if (Field->getType()->isIncompleteArrayType() || 759 ILEElement == ILE->getNumInits()) 760 break; 761 if (Field->isUnnamedBitfield()) 762 continue; 763 764 const Expr *E = ILE->getInit(ILEElement++); 765 766 // Reference values are always non-null and have the width of a pointer. 767 if (Field->getType()->isReferenceType()) 768 NumNonZeroBytes += CGF.getContext().Target.getPointerWidth(0); 769 else 770 NumNonZeroBytes += GetNumNonZeroBytesInInit(E, CGF); 771 } 772 773 return NumNonZeroBytes; 774 } 775 } 776 777 778 uint64_t NumNonZeroBytes = 0; 779 for (unsigned i = 0, e = ILE->getNumInits(); i != e; ++i) 780 NumNonZeroBytes += GetNumNonZeroBytesInInit(ILE->getInit(i), CGF); 781 return NumNonZeroBytes; 782} 783 784/// CheckAggExprForMemSetUse - If the initializer is large and has a lot of 785/// zeros in it, emit a memset and avoid storing the individual zeros. 786/// 787static void CheckAggExprForMemSetUse(AggValueSlot &Slot, const Expr *E, 788 CodeGenFunction &CGF) { 789 // If the slot is already known to be zeroed, nothing to do. Don't mess with 790 // volatile stores. 791 if (Slot.isZeroed() || Slot.isVolatile() || Slot.getAddr() == 0) return; 792 793 // If the type is 16-bytes or smaller, prefer individual stores over memset. 794 std::pair<uint64_t, unsigned> TypeInfo = 795 CGF.getContext().getTypeInfo(E->getType()); 796 if (TypeInfo.first/8 <= 16) 797 return; 798 799 // Check to see if over 3/4 of the initializer are known to be zero. If so, 800 // we prefer to emit memset + individual stores for the rest. 801 uint64_t NumNonZeroBytes = GetNumNonZeroBytesInInit(E, CGF); 802 if (NumNonZeroBytes*4 > TypeInfo.first/8) 803 return; 804 805 // Okay, it seems like a good idea to use an initial memset, emit the call. 806 llvm::Constant *SizeVal = CGF.Builder.getInt64(TypeInfo.first/8); 807 llvm::ConstantInt *AlignVal = CGF.Builder.getInt32(TypeInfo.second/8); 808 809 llvm::Value *Loc = Slot.getAddr(); 810 const llvm::Type *BP = llvm::Type::getInt8PtrTy(CGF.getLLVMContext()); 811 812 Loc = CGF.Builder.CreateBitCast(Loc, BP); 813 CGF.Builder.CreateCall5(CGF.CGM.getMemSetFn(Loc->getType(), 814 SizeVal->getType()), 815 Loc, CGF.Builder.getInt8(0), SizeVal, AlignVal, 816 CGF.Builder.getFalse()); 817 818 // Tell the AggExprEmitter that the slot is known zero. 819 Slot.setZeroed(); 820} 821 822 823 824 825/// EmitAggExpr - Emit the computation of the specified expression of aggregate 826/// type. The result is computed into DestPtr. Note that if DestPtr is null, 827/// the value of the aggregate expression is not needed. If VolatileDest is 828/// true, DestPtr cannot be 0. 829/// 830/// \param IsInitializer - true if this evaluation is initializing an 831/// object whose lifetime is already being managed. 832// 833// FIXME: Take Qualifiers object. 834void CodeGenFunction::EmitAggExpr(const Expr *E, AggValueSlot Slot, 835 bool IgnoreResult) { 836 assert(E && hasAggregateLLVMType(E->getType()) && 837 "Invalid aggregate expression to emit"); 838 assert((Slot.getAddr() != 0 || Slot.isIgnored()) && 839 "slot has bits but no address"); 840 841 // Optimize the slot if possible. 842 CheckAggExprForMemSetUse(Slot, E, *this); 843 844 AggExprEmitter(*this, Slot, IgnoreResult).Visit(const_cast<Expr*>(E)); 845} 846 847LValue CodeGenFunction::EmitAggExprToLValue(const Expr *E) { 848 assert(hasAggregateLLVMType(E->getType()) && "Invalid argument!"); 849 llvm::Value *Temp = CreateMemTemp(E->getType()); 850 LValue LV = MakeAddrLValue(Temp, E->getType()); 851 EmitAggExpr(E, AggValueSlot::forAddr(Temp, LV.isVolatileQualified(), false)); 852 return LV; 853} 854 855void CodeGenFunction::EmitAggregateCopy(llvm::Value *DestPtr, 856 llvm::Value *SrcPtr, QualType Ty, 857 bool isVolatile) { 858 assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex"); 859 860 if (getContext().getLangOptions().CPlusPlus) { 861 if (const RecordType *RT = Ty->getAs<RecordType>()) { 862 CXXRecordDecl *Record = cast<CXXRecordDecl>(RT->getDecl()); 863 assert((Record->hasTrivialCopyConstructor() || 864 Record->hasTrivialCopyAssignment()) && 865 "Trying to aggregate-copy a type without a trivial copy " 866 "constructor or assignment operator"); 867 // Ignore empty classes in C++. 868 if (Record->isEmpty()) 869 return; 870 } 871 } 872 873 // Aggregate assignment turns into llvm.memcpy. This is almost valid per 874 // C99 6.5.16.1p3, which states "If the value being stored in an object is 875 // read from another object that overlaps in anyway the storage of the first 876 // object, then the overlap shall be exact and the two objects shall have 877 // qualified or unqualified versions of a compatible type." 878 // 879 // memcpy is not defined if the source and destination pointers are exactly 880 // equal, but other compilers do this optimization, and almost every memcpy 881 // implementation handles this case safely. If there is a libc that does not 882 // safely handle this, we can add a target hook. 883 884 // Get size and alignment info for this aggregate. 885 std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty); 886 887 // FIXME: Handle variable sized types. 888 889 // FIXME: If we have a volatile struct, the optimizer can remove what might 890 // appear to be `extra' memory ops: 891 // 892 // volatile struct { int i; } a, b; 893 // 894 // int main() { 895 // a = b; 896 // a = b; 897 // } 898 // 899 // we need to use a different call here. We use isVolatile to indicate when 900 // either the source or the destination is volatile. 901 902 const llvm::PointerType *DPT = cast<llvm::PointerType>(DestPtr->getType()); 903 const llvm::Type *DBP = 904 llvm::Type::getInt8PtrTy(VMContext, DPT->getAddressSpace()); 905 DestPtr = Builder.CreateBitCast(DestPtr, DBP, "tmp"); 906 907 const llvm::PointerType *SPT = cast<llvm::PointerType>(SrcPtr->getType()); 908 const llvm::Type *SBP = 909 llvm::Type::getInt8PtrTy(VMContext, SPT->getAddressSpace()); 910 SrcPtr = Builder.CreateBitCast(SrcPtr, SBP, "tmp"); 911 912 if (const RecordType *RecordTy = Ty->getAs<RecordType>()) { 913 RecordDecl *Record = RecordTy->getDecl(); 914 if (Record->hasObjectMember()) { 915 unsigned long size = TypeInfo.first/8; 916 const llvm::Type *SizeTy = ConvertType(getContext().getSizeType()); 917 llvm::Value *SizeVal = llvm::ConstantInt::get(SizeTy, size); 918 CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr, 919 SizeVal); 920 return; 921 } 922 } else if (getContext().getAsArrayType(Ty)) { 923 QualType BaseType = getContext().getBaseElementType(Ty); 924 if (const RecordType *RecordTy = BaseType->getAs<RecordType>()) { 925 if (RecordTy->getDecl()->hasObjectMember()) { 926 unsigned long size = TypeInfo.first/8; 927 const llvm::Type *SizeTy = ConvertType(getContext().getSizeType()); 928 llvm::Value *SizeVal = llvm::ConstantInt::get(SizeTy, size); 929 CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr, 930 SizeVal); 931 return; 932 } 933 } 934 } 935 936 Builder.CreateCall5(CGM.getMemCpyFn(DestPtr->getType(), SrcPtr->getType(), 937 IntPtrTy), 938 DestPtr, SrcPtr, 939 // TypeInfo.first describes size in bits. 940 llvm::ConstantInt::get(IntPtrTy, TypeInfo.first/8), 941 Builder.getInt32(TypeInfo.second/8), 942 Builder.getInt1(isVolatile)); 943} 944