1 //===--- CGExprConstant.cpp - Emit LLVM Code from Constant Expressions ----===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This contains code to emit Constant Expr nodes as LLVM code.
12 //===----------------------------------------------------------------------===//
14 #include "CodeGenFunction.h"
15 #include "CodeGenModule.h"
17 #include "CGObjCRuntime.h"
18 #include "CGRecordLayout.h"
19 #include "clang/AST/APValue.h"
20 #include "clang/AST/ASTContext.h"
21 #include "clang/AST/RecordLayout.h"
22 #include "clang/AST/StmtVisitor.h"
23 #include "clang/Basic/Builtins.h"
24 #include "llvm/Constants.h"
25 #include "llvm/Function.h"
26 #include "llvm/GlobalVariable.h"
27 #include "llvm/DataLayout.h"
28 using namespace clang;
29 using namespace CodeGen;
31 //===----------------------------------------------------------------------===//
33 //===----------------------------------------------------------------------===//
36 class ConstStructBuilder {
41 CharUnits NextFieldOffsetInChars;
42 CharUnits LLVMStructAlignment;
43 SmallVector<llvm::Constant *, 32> Elements;
45 static llvm::Constant *BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF,
47 static llvm::Constant *BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF,
48 const APValue &Value, QualType ValTy);
51 ConstStructBuilder(CodeGenModule &CGM, CodeGenFunction *CGF)
52 : CGM(CGM), CGF(CGF), Packed(false),
53 NextFieldOffsetInChars(CharUnits::Zero()),
54 LLVMStructAlignment(CharUnits::One()) { }
56 void AppendVTablePointer(BaseSubobject Base, llvm::Constant *VTable,
57 const CXXRecordDecl *VTableClass);
59 void AppendField(const FieldDecl *Field, uint64_t FieldOffset,
60 llvm::Constant *InitExpr);
62 void AppendBytes(CharUnits FieldOffsetInChars, llvm::Constant *InitCst);
64 void AppendBitField(const FieldDecl *Field, uint64_t FieldOffset,
65 llvm::ConstantInt *InitExpr);
67 void AppendPadding(CharUnits PadSize);
69 void AppendTailPadding(CharUnits RecordSize);
71 void ConvertStructToPacked();
73 bool Build(InitListExpr *ILE);
74 void Build(const APValue &Val, const RecordDecl *RD, bool IsPrimaryBase,
75 llvm::Constant *VTable, const CXXRecordDecl *VTableClass,
76 CharUnits BaseOffset);
77 llvm::Constant *Finalize(QualType Ty);
79 CharUnits getAlignment(const llvm::Constant *C) const {
80 if (Packed) return CharUnits::One();
81 return CharUnits::fromQuantity(
82 CGM.getDataLayout().getABITypeAlignment(C->getType()));
85 CharUnits getSizeInChars(const llvm::Constant *C) const {
86 return CharUnits::fromQuantity(
87 CGM.getDataLayout().getTypeAllocSize(C->getType()));
91 void ConstStructBuilder::AppendVTablePointer(BaseSubobject Base,
92 llvm::Constant *VTable,
93 const CXXRecordDecl *VTableClass) {
94 // Find the appropriate vtable within the vtable group.
95 uint64_t AddressPoint =
96 CGM.getVTableContext().getVTableLayout(VTableClass).getAddressPoint(Base);
97 llvm::Value *Indices[] = {
98 llvm::ConstantInt::get(CGM.Int64Ty, 0),
99 llvm::ConstantInt::get(CGM.Int64Ty, AddressPoint)
101 llvm::Constant *VTableAddressPoint =
102 llvm::ConstantExpr::getInBoundsGetElementPtr(VTable, Indices);
104 // Add the vtable at the start of the object.
105 AppendBytes(Base.getBaseOffset(), VTableAddressPoint);
108 void ConstStructBuilder::
109 AppendField(const FieldDecl *Field, uint64_t FieldOffset,
110 llvm::Constant *InitCst) {
111 const ASTContext &Context = CGM.getContext();
113 CharUnits FieldOffsetInChars = Context.toCharUnitsFromBits(FieldOffset);
115 AppendBytes(FieldOffsetInChars, InitCst);
118 void ConstStructBuilder::
119 AppendBytes(CharUnits FieldOffsetInChars, llvm::Constant *InitCst) {
121 assert(NextFieldOffsetInChars <= FieldOffsetInChars
122 && "Field offset mismatch!");
124 CharUnits FieldAlignment = getAlignment(InitCst);
126 // Round up the field offset to the alignment of the field type.
127 CharUnits AlignedNextFieldOffsetInChars =
128 NextFieldOffsetInChars.RoundUpToAlignment(FieldAlignment);
130 if (AlignedNextFieldOffsetInChars > FieldOffsetInChars) {
131 assert(!Packed && "Alignment is wrong even with a packed struct!");
133 // Convert the struct to a packed struct.
134 ConvertStructToPacked();
136 AlignedNextFieldOffsetInChars = NextFieldOffsetInChars;
139 if (AlignedNextFieldOffsetInChars < FieldOffsetInChars) {
140 // We need to append padding.
141 AppendPadding(FieldOffsetInChars - NextFieldOffsetInChars);
143 assert(NextFieldOffsetInChars == FieldOffsetInChars &&
144 "Did not add enough padding!");
146 AlignedNextFieldOffsetInChars = NextFieldOffsetInChars;
150 Elements.push_back(InitCst);
151 NextFieldOffsetInChars = AlignedNextFieldOffsetInChars +
152 getSizeInChars(InitCst);
155 assert(LLVMStructAlignment == CharUnits::One() &&
156 "Packed struct not byte-aligned!");
158 LLVMStructAlignment = std::max(LLVMStructAlignment, FieldAlignment);
161 void ConstStructBuilder::AppendBitField(const FieldDecl *Field,
162 uint64_t FieldOffset,
163 llvm::ConstantInt *CI) {
164 const ASTContext &Context = CGM.getContext();
165 const uint64_t CharWidth = Context.getCharWidth();
166 uint64_t NextFieldOffsetInBits = Context.toBits(NextFieldOffsetInChars);
167 if (FieldOffset > NextFieldOffsetInBits) {
168 // We need to add padding.
169 CharUnits PadSize = Context.toCharUnitsFromBits(
170 llvm::RoundUpToAlignment(FieldOffset - NextFieldOffsetInBits,
171 Context.getTargetInfo().getCharAlign()));
173 AppendPadding(PadSize);
176 uint64_t FieldSize = Field->getBitWidthValue(Context);
178 llvm::APInt FieldValue = CI->getValue();
180 // Promote the size of FieldValue if necessary
181 // FIXME: This should never occur, but currently it can because initializer
182 // constants are cast to bool, and because clang is not enforcing bitfield
184 if (FieldSize > FieldValue.getBitWidth())
185 FieldValue = FieldValue.zext(FieldSize);
187 // Truncate the size of FieldValue to the bit field size.
188 if (FieldSize < FieldValue.getBitWidth())
189 FieldValue = FieldValue.trunc(FieldSize);
191 NextFieldOffsetInBits = Context.toBits(NextFieldOffsetInChars);
192 if (FieldOffset < NextFieldOffsetInBits) {
193 // Either part of the field or the entire field can go into the previous
195 assert(!Elements.empty() && "Elements can't be empty!");
197 unsigned BitsInPreviousByte = NextFieldOffsetInBits - FieldOffset;
199 bool FitsCompletelyInPreviousByte =
200 BitsInPreviousByte >= FieldValue.getBitWidth();
202 llvm::APInt Tmp = FieldValue;
204 if (!FitsCompletelyInPreviousByte) {
205 unsigned NewFieldWidth = FieldSize - BitsInPreviousByte;
207 if (CGM.getDataLayout().isBigEndian()) {
208 Tmp = Tmp.lshr(NewFieldWidth);
209 Tmp = Tmp.trunc(BitsInPreviousByte);
211 // We want the remaining high bits.
212 FieldValue = FieldValue.trunc(NewFieldWidth);
214 Tmp = Tmp.trunc(BitsInPreviousByte);
216 // We want the remaining low bits.
217 FieldValue = FieldValue.lshr(BitsInPreviousByte);
218 FieldValue = FieldValue.trunc(NewFieldWidth);
222 Tmp = Tmp.zext(CharWidth);
223 if (CGM.getDataLayout().isBigEndian()) {
224 if (FitsCompletelyInPreviousByte)
225 Tmp = Tmp.shl(BitsInPreviousByte - FieldValue.getBitWidth());
227 Tmp = Tmp.shl(CharWidth - BitsInPreviousByte);
230 // 'or' in the bits that go into the previous byte.
231 llvm::Value *LastElt = Elements.back();
232 if (llvm::ConstantInt *Val = dyn_cast<llvm::ConstantInt>(LastElt))
233 Tmp |= Val->getValue();
235 assert(isa<llvm::UndefValue>(LastElt));
236 // If there is an undef field that we're adding to, it can either be a
237 // scalar undef (in which case, we just replace it with our field) or it
238 // is an array. If it is an array, we have to pull one byte off the
239 // array so that the other undef bytes stay around.
240 if (!isa<llvm::IntegerType>(LastElt->getType())) {
241 // The undef padding will be a multibyte array, create a new smaller
242 // padding and then an hole for our i8 to get plopped into.
243 assert(isa<llvm::ArrayType>(LastElt->getType()) &&
244 "Expected array padding of undefs");
245 llvm::ArrayType *AT = cast<llvm::ArrayType>(LastElt->getType());
246 assert(AT->getElementType()->isIntegerTy(CharWidth) &&
247 AT->getNumElements() != 0 &&
248 "Expected non-empty array padding of undefs");
250 // Remove the padding array.
251 NextFieldOffsetInChars -= CharUnits::fromQuantity(AT->getNumElements());
254 // Add the padding back in two chunks.
255 AppendPadding(CharUnits::fromQuantity(AT->getNumElements()-1));
256 AppendPadding(CharUnits::One());
257 assert(isa<llvm::UndefValue>(Elements.back()) &&
258 Elements.back()->getType()->isIntegerTy(CharWidth) &&
259 "Padding addition didn't work right");
263 Elements.back() = llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp);
265 if (FitsCompletelyInPreviousByte)
269 while (FieldValue.getBitWidth() > CharWidth) {
272 if (CGM.getDataLayout().isBigEndian()) {
273 // We want the high bits.
275 FieldValue.lshr(FieldValue.getBitWidth() - CharWidth).trunc(CharWidth);
277 // We want the low bits.
278 Tmp = FieldValue.trunc(CharWidth);
280 FieldValue = FieldValue.lshr(CharWidth);
283 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp));
284 ++NextFieldOffsetInChars;
286 FieldValue = FieldValue.trunc(FieldValue.getBitWidth() - CharWidth);
289 assert(FieldValue.getBitWidth() > 0 &&
290 "Should have at least one bit left!");
291 assert(FieldValue.getBitWidth() <= CharWidth &&
292 "Should not have more than a byte left!");
294 if (FieldValue.getBitWidth() < CharWidth) {
295 if (CGM.getDataLayout().isBigEndian()) {
296 unsigned BitWidth = FieldValue.getBitWidth();
298 FieldValue = FieldValue.zext(CharWidth) << (CharWidth - BitWidth);
300 FieldValue = FieldValue.zext(CharWidth);
303 // Append the last element.
304 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(),
306 ++NextFieldOffsetInChars;
309 void ConstStructBuilder::AppendPadding(CharUnits PadSize) {
310 if (PadSize.isZero())
313 llvm::Type *Ty = CGM.Int8Ty;
314 if (PadSize > CharUnits::One())
315 Ty = llvm::ArrayType::get(Ty, PadSize.getQuantity());
317 llvm::Constant *C = llvm::UndefValue::get(Ty);
318 Elements.push_back(C);
319 assert(getAlignment(C) == CharUnits::One() &&
320 "Padding must have 1 byte alignment!");
322 NextFieldOffsetInChars += getSizeInChars(C);
325 void ConstStructBuilder::AppendTailPadding(CharUnits RecordSize) {
326 assert(NextFieldOffsetInChars <= RecordSize &&
329 AppendPadding(RecordSize - NextFieldOffsetInChars);
332 void ConstStructBuilder::ConvertStructToPacked() {
333 SmallVector<llvm::Constant *, 16> PackedElements;
334 CharUnits ElementOffsetInChars = CharUnits::Zero();
336 for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
337 llvm::Constant *C = Elements[i];
339 CharUnits ElementAlign = CharUnits::fromQuantity(
340 CGM.getDataLayout().getABITypeAlignment(C->getType()));
341 CharUnits AlignedElementOffsetInChars =
342 ElementOffsetInChars.RoundUpToAlignment(ElementAlign);
344 if (AlignedElementOffsetInChars > ElementOffsetInChars) {
345 // We need some padding.
347 AlignedElementOffsetInChars - ElementOffsetInChars;
349 llvm::Type *Ty = CGM.Int8Ty;
350 if (NumChars > CharUnits::One())
351 Ty = llvm::ArrayType::get(Ty, NumChars.getQuantity());
353 llvm::Constant *Padding = llvm::UndefValue::get(Ty);
354 PackedElements.push_back(Padding);
355 ElementOffsetInChars += getSizeInChars(Padding);
358 PackedElements.push_back(C);
359 ElementOffsetInChars += getSizeInChars(C);
362 assert(ElementOffsetInChars == NextFieldOffsetInChars &&
363 "Packing the struct changed its size!");
365 Elements.swap(PackedElements);
366 LLVMStructAlignment = CharUnits::One();
370 bool ConstStructBuilder::Build(InitListExpr *ILE) {
371 if (ILE->initializesStdInitializerList()) {
372 //CGM.ErrorUnsupported(ILE, "global std::initializer_list");
376 RecordDecl *RD = ILE->getType()->getAs<RecordType>()->getDecl();
377 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
379 unsigned FieldNo = 0;
380 unsigned ElementNo = 0;
381 const FieldDecl *LastFD = 0;
382 bool IsMsStruct = RD->isMsStruct(CGM.getContext());
384 for (RecordDecl::field_iterator Field = RD->field_begin(),
385 FieldEnd = RD->field_end(); Field != FieldEnd; ++Field, ++FieldNo) {
387 // Zero-length bitfields following non-bitfield members are
389 if (CGM.getContext().ZeroBitfieldFollowsNonBitfield(*Field, LastFD)) {
396 // If this is a union, skip all the fields that aren't being initialized.
397 if (RD->isUnion() && ILE->getInitializedFieldInUnion() != *Field)
400 // Don't emit anonymous bitfields, they just affect layout.
401 if (Field->isUnnamedBitfield()) {
406 // Get the initializer. A struct can include fields without initializers,
407 // we just use explicit null values for them.
408 llvm::Constant *EltInit;
409 if (ElementNo < ILE->getNumInits())
410 EltInit = CGM.EmitConstantExpr(ILE->getInit(ElementNo++),
411 Field->getType(), CGF);
413 EltInit = CGM.EmitNullConstant(Field->getType());
418 if (!Field->isBitField()) {
419 // Handle non-bitfield members.
420 AppendField(*Field, Layout.getFieldOffset(FieldNo), EltInit);
422 // Otherwise we have a bitfield.
423 AppendBitField(*Field, Layout.getFieldOffset(FieldNo),
424 cast<llvm::ConstantInt>(EltInit));
433 BaseInfo(const CXXRecordDecl *Decl, CharUnits Offset, unsigned Index)
434 : Decl(Decl), Offset(Offset), Index(Index) {
437 const CXXRecordDecl *Decl;
441 bool operator<(const BaseInfo &O) const { return Offset < O.Offset; }
445 void ConstStructBuilder::Build(const APValue &Val, const RecordDecl *RD,
446 bool IsPrimaryBase, llvm::Constant *VTable,
447 const CXXRecordDecl *VTableClass,
449 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
451 if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) {
452 // Add a vtable pointer, if we need one and it hasn't already been added.
453 if (CD->isDynamicClass() && !IsPrimaryBase)
454 AppendVTablePointer(BaseSubobject(CD, Offset), VTable, VTableClass);
456 // Accumulate and sort bases, in order to visit them in address order, which
457 // may not be the same as declaration order.
458 llvm::SmallVector<BaseInfo, 8> Bases;
459 Bases.reserve(CD->getNumBases());
461 for (CXXRecordDecl::base_class_const_iterator Base = CD->bases_begin(),
462 BaseEnd = CD->bases_end(); Base != BaseEnd; ++Base, ++BaseNo) {
463 assert(!Base->isVirtual() && "should not have virtual bases here");
464 const CXXRecordDecl *BD = Base->getType()->getAsCXXRecordDecl();
465 CharUnits BaseOffset = Layout.getBaseClassOffset(BD);
466 Bases.push_back(BaseInfo(BD, BaseOffset, BaseNo));
468 std::stable_sort(Bases.begin(), Bases.end());
470 for (unsigned I = 0, N = Bases.size(); I != N; ++I) {
471 BaseInfo &Base = Bases[I];
473 bool IsPrimaryBase = Layout.getPrimaryBase() == Base.Decl;
474 Build(Val.getStructBase(Base.Index), Base.Decl, IsPrimaryBase,
475 VTable, VTableClass, Offset + Base.Offset);
479 unsigned FieldNo = 0;
480 const FieldDecl *LastFD = 0;
481 bool IsMsStruct = RD->isMsStruct(CGM.getContext());
482 uint64_t OffsetBits = CGM.getContext().toBits(Offset);
484 for (RecordDecl::field_iterator Field = RD->field_begin(),
485 FieldEnd = RD->field_end(); Field != FieldEnd; ++Field, ++FieldNo) {
487 // Zero-length bitfields following non-bitfield members are
489 if (CGM.getContext().ZeroBitfieldFollowsNonBitfield(*Field, LastFD)) {
496 // If this is a union, skip all the fields that aren't being initialized.
497 if (RD->isUnion() && Val.getUnionField() != *Field)
500 // Don't emit anonymous bitfields, they just affect layout.
501 if (Field->isUnnamedBitfield()) {
506 // Emit the value of the initializer.
507 const APValue &FieldValue =
508 RD->isUnion() ? Val.getUnionValue() : Val.getStructField(FieldNo);
509 llvm::Constant *EltInit =
510 CGM.EmitConstantValueForMemory(FieldValue, Field->getType(), CGF);
511 assert(EltInit && "EmitConstantValue can't fail");
513 if (!Field->isBitField()) {
514 // Handle non-bitfield members.
515 AppendField(*Field, Layout.getFieldOffset(FieldNo) + OffsetBits, EltInit);
517 // Otherwise we have a bitfield.
518 AppendBitField(*Field, Layout.getFieldOffset(FieldNo) + OffsetBits,
519 cast<llvm::ConstantInt>(EltInit));
524 llvm::Constant *ConstStructBuilder::Finalize(QualType Ty) {
525 RecordDecl *RD = Ty->getAs<RecordType>()->getDecl();
526 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
528 CharUnits LayoutSizeInChars = Layout.getSize();
530 if (NextFieldOffsetInChars > LayoutSizeInChars) {
531 // If the struct is bigger than the size of the record type,
532 // we must have a flexible array member at the end.
533 assert(RD->hasFlexibleArrayMember() &&
534 "Must have flexible array member if struct is bigger than type!");
536 // No tail padding is necessary.
538 // Append tail padding if necessary.
539 AppendTailPadding(LayoutSizeInChars);
541 CharUnits LLVMSizeInChars =
542 NextFieldOffsetInChars.RoundUpToAlignment(LLVMStructAlignment);
544 // Check if we need to convert the struct to a packed struct.
545 if (NextFieldOffsetInChars <= LayoutSizeInChars &&
546 LLVMSizeInChars > LayoutSizeInChars) {
547 assert(!Packed && "Size mismatch!");
549 ConvertStructToPacked();
550 assert(NextFieldOffsetInChars <= LayoutSizeInChars &&
551 "Converting to packed did not help!");
554 assert(LayoutSizeInChars == NextFieldOffsetInChars &&
555 "Tail padding mismatch!");
558 // Pick the type to use. If the type is layout identical to the ConvertType
559 // type then use it, otherwise use whatever the builder produced for us.
560 llvm::StructType *STy =
561 llvm::ConstantStruct::getTypeForElements(CGM.getLLVMContext(),
563 llvm::Type *ValTy = CGM.getTypes().ConvertType(Ty);
564 if (llvm::StructType *ValSTy = dyn_cast<llvm::StructType>(ValTy)) {
565 if (ValSTy->isLayoutIdentical(STy))
569 llvm::Constant *Result = llvm::ConstantStruct::get(STy, Elements);
571 assert(NextFieldOffsetInChars.RoundUpToAlignment(getAlignment(Result)) ==
572 getSizeInChars(Result) && "Size mismatch!");
577 llvm::Constant *ConstStructBuilder::BuildStruct(CodeGenModule &CGM,
578 CodeGenFunction *CGF,
580 ConstStructBuilder Builder(CGM, CGF);
582 if (!Builder.Build(ILE))
585 return Builder.Finalize(ILE->getType());
588 llvm::Constant *ConstStructBuilder::BuildStruct(CodeGenModule &CGM,
589 CodeGenFunction *CGF,
592 ConstStructBuilder Builder(CGM, CGF);
594 const RecordDecl *RD = ValTy->castAs<RecordType>()->getDecl();
595 const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD);
596 llvm::Constant *VTable = 0;
597 if (CD && CD->isDynamicClass())
598 VTable = CGM.getVTables().GetAddrOfVTable(CD);
600 Builder.Build(Val, RD, false, VTable, CD, CharUnits::Zero());
602 return Builder.Finalize(ValTy);
606 //===----------------------------------------------------------------------===//
608 //===----------------------------------------------------------------------===//
610 /// This class only needs to handle two cases:
611 /// 1) Literals (this is used by APValue emission to emit literals).
612 /// 2) Arrays, structs and unions (outside C++11 mode, we don't currently
613 /// constant fold these types).
614 class ConstExprEmitter :
615 public StmtVisitor<ConstExprEmitter, llvm::Constant*> {
617 CodeGenFunction *CGF;
618 llvm::LLVMContext &VMContext;
620 ConstExprEmitter(CodeGenModule &cgm, CodeGenFunction *cgf)
621 : CGM(cgm), CGF(cgf), VMContext(cgm.getLLVMContext()) {
624 //===--------------------------------------------------------------------===//
626 //===--------------------------------------------------------------------===//
628 llvm::Constant *VisitStmt(Stmt *S) {
632 llvm::Constant *VisitParenExpr(ParenExpr *PE) {
633 return Visit(PE->getSubExpr());
637 VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *PE) {
638 return Visit(PE->getReplacement());
641 llvm::Constant *VisitGenericSelectionExpr(GenericSelectionExpr *GE) {
642 return Visit(GE->getResultExpr());
645 llvm::Constant *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
646 return Visit(E->getInitializer());
649 llvm::Constant *VisitCastExpr(CastExpr* E) {
650 Expr *subExpr = E->getSubExpr();
651 llvm::Constant *C = CGM.EmitConstantExpr(subExpr, subExpr->getType(), CGF);
654 llvm::Type *destType = ConvertType(E->getType());
656 switch (E->getCastKind()) {
658 // GCC cast to union extension
659 assert(E->getType()->isUnionType() &&
660 "Destination type is not union type!");
662 // Build a struct with the union sub-element as the first member,
663 // and padded to the appropriate size
664 SmallVector<llvm::Constant*, 2> Elts;
665 SmallVector<llvm::Type*, 2> Types;
667 Types.push_back(C->getType());
668 unsigned CurSize = CGM.getDataLayout().getTypeAllocSize(C->getType());
669 unsigned TotalSize = CGM.getDataLayout().getTypeAllocSize(destType);
671 assert(CurSize <= TotalSize && "Union size mismatch!");
672 if (unsigned NumPadBytes = TotalSize - CurSize) {
673 llvm::Type *Ty = CGM.Int8Ty;
675 Ty = llvm::ArrayType::get(Ty, NumPadBytes);
677 Elts.push_back(llvm::UndefValue::get(Ty));
681 llvm::StructType* STy =
682 llvm::StructType::get(C->getType()->getContext(), Types, false);
683 return llvm::ConstantStruct::get(STy, Elts);
686 case CK_LValueToRValue:
687 case CK_AtomicToNonAtomic:
688 case CK_NonAtomicToAtomic:
692 case CK_Dependent: llvm_unreachable("saw dependent cast!");
694 case CK_BuiltinFnToFnPtr:
695 llvm_unreachable("builtin functions are handled elsewhere");
697 case CK_ReinterpretMemberPointer:
698 case CK_DerivedToBaseMemberPointer:
699 case CK_BaseToDerivedMemberPointer:
700 return CGM.getCXXABI().EmitMemberPointerConversion(E, C);
702 // These will never be supported.
703 case CK_ObjCObjectLValueCast:
704 case CK_ARCProduceObject:
705 case CK_ARCConsumeObject:
706 case CK_ARCReclaimReturnedObject:
707 case CK_ARCExtendBlockObject:
708 case CK_CopyAndAutoreleaseBlockObject:
711 // These don't need to be handled here because Evaluate knows how to
712 // evaluate them in the cases where they can be folded.
716 case CK_LValueBitCast:
717 case CK_NullToMemberPointer:
718 case CK_UserDefinedConversion:
719 case CK_ConstructorConversion:
720 case CK_CPointerToObjCPointerCast:
721 case CK_BlockPointerToObjCPointerCast:
722 case CK_AnyPointerToBlockPointerCast:
723 case CK_ArrayToPointerDecay:
724 case CK_FunctionToPointerDecay:
725 case CK_BaseToDerived:
726 case CK_DerivedToBase:
727 case CK_UncheckedDerivedToBase:
728 case CK_MemberPointerToBoolean:
730 case CK_FloatingRealToComplex:
731 case CK_FloatingComplexToReal:
732 case CK_FloatingComplexToBoolean:
733 case CK_FloatingComplexCast:
734 case CK_FloatingComplexToIntegralComplex:
735 case CK_IntegralRealToComplex:
736 case CK_IntegralComplexToReal:
737 case CK_IntegralComplexToBoolean:
738 case CK_IntegralComplexCast:
739 case CK_IntegralComplexToFloatingComplex:
740 case CK_PointerToIntegral:
741 case CK_PointerToBoolean:
742 case CK_NullToPointer:
743 case CK_IntegralCast:
744 case CK_IntegralToPointer:
745 case CK_IntegralToBoolean:
746 case CK_IntegralToFloating:
747 case CK_FloatingToIntegral:
748 case CK_FloatingToBoolean:
749 case CK_FloatingCast:
752 llvm_unreachable("Invalid CastKind");
755 llvm::Constant *VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
756 return Visit(DAE->getExpr());
759 llvm::Constant *VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E) {
760 return Visit(E->GetTemporaryExpr());
763 llvm::Constant *EmitArrayInitialization(InitListExpr *ILE) {
764 if (ILE->isStringLiteralInit())
765 return Visit(ILE->getInit(0));
767 llvm::ArrayType *AType =
768 cast<llvm::ArrayType>(ConvertType(ILE->getType()));
769 llvm::Type *ElemTy = AType->getElementType();
770 unsigned NumInitElements = ILE->getNumInits();
771 unsigned NumElements = AType->getNumElements();
773 // Initialising an array requires us to automatically
774 // initialise any elements that have not been initialised explicitly
775 unsigned NumInitableElts = std::min(NumInitElements, NumElements);
777 // Copy initializer elements.
778 std::vector<llvm::Constant*> Elts;
779 Elts.reserve(NumInitableElts + NumElements);
781 bool RewriteType = false;
782 for (unsigned i = 0; i < NumInitableElts; ++i) {
783 Expr *Init = ILE->getInit(i);
784 llvm::Constant *C = CGM.EmitConstantExpr(Init, Init->getType(), CGF);
787 RewriteType |= (C->getType() != ElemTy);
791 // Initialize remaining array elements.
792 // FIXME: This doesn't handle member pointers correctly!
793 llvm::Constant *fillC;
794 if (Expr *filler = ILE->getArrayFiller())
795 fillC = CGM.EmitConstantExpr(filler, filler->getType(), CGF);
797 fillC = llvm::Constant::getNullValue(ElemTy);
800 RewriteType |= (fillC->getType() != ElemTy);
801 Elts.resize(NumElements, fillC);
804 // FIXME: Try to avoid packing the array
805 std::vector<llvm::Type*> Types;
806 Types.reserve(NumInitableElts + NumElements);
807 for (unsigned i = 0, e = Elts.size(); i < e; ++i)
808 Types.push_back(Elts[i]->getType());
809 llvm::StructType *SType = llvm::StructType::get(AType->getContext(),
811 return llvm::ConstantStruct::get(SType, Elts);
814 return llvm::ConstantArray::get(AType, Elts);
817 llvm::Constant *EmitRecordInitialization(InitListExpr *ILE) {
818 return ConstStructBuilder::BuildStruct(CGM, CGF, ILE);
821 llvm::Constant *VisitImplicitValueInitExpr(ImplicitValueInitExpr* E) {
822 return CGM.EmitNullConstant(E->getType());
825 llvm::Constant *VisitInitListExpr(InitListExpr *ILE) {
826 if (ILE->getType()->isArrayType())
827 return EmitArrayInitialization(ILE);
829 if (ILE->getType()->isRecordType())
830 return EmitRecordInitialization(ILE);
835 llvm::Constant *VisitCXXConstructExpr(CXXConstructExpr *E) {
836 if (!E->getConstructor()->isTrivial())
839 QualType Ty = E->getType();
841 // FIXME: We should not have to call getBaseElementType here.
842 const RecordType *RT =
843 CGM.getContext().getBaseElementType(Ty)->getAs<RecordType>();
844 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
846 // If the class doesn't have a trivial destructor, we can't emit it as a
848 if (!RD->hasTrivialDestructor())
851 // Only copy and default constructors can be trivial.
854 if (E->getNumArgs()) {
855 assert(E->getNumArgs() == 1 && "trivial ctor with > 1 argument");
856 assert(E->getConstructor()->isCopyOrMoveConstructor() &&
857 "trivial ctor has argument but isn't a copy/move ctor");
859 Expr *Arg = E->getArg(0);
860 assert(CGM.getContext().hasSameUnqualifiedType(Ty, Arg->getType()) &&
861 "argument to copy ctor is of wrong type");
866 return CGM.EmitNullConstant(Ty);
869 llvm::Constant *VisitStringLiteral(StringLiteral *E) {
870 return CGM.GetConstantArrayFromStringLiteral(E);
873 llvm::Constant *VisitObjCEncodeExpr(ObjCEncodeExpr *E) {
874 // This must be an @encode initializing an array in a static initializer.
875 // Don't emit it as the address of the string, emit the string data itself
876 // as an inline array.
878 CGM.getContext().getObjCEncodingForType(E->getEncodedType(), Str);
879 const ConstantArrayType *CAT = cast<ConstantArrayType>(E->getType());
881 // Resize the string to the right size, adding zeros at the end, or
882 // truncating as needed.
883 Str.resize(CAT->getSize().getZExtValue(), '\0');
884 return llvm::ConstantDataArray::getString(VMContext, Str, false);
887 llvm::Constant *VisitUnaryExtension(const UnaryOperator *E) {
888 return Visit(E->getSubExpr());
892 llvm::Type *ConvertType(QualType T) {
893 return CGM.getTypes().ConvertType(T);
897 llvm::Constant *EmitLValue(APValue::LValueBase LVBase) {
898 if (const ValueDecl *Decl = LVBase.dyn_cast<const ValueDecl*>()) {
899 if (Decl->hasAttr<WeakRefAttr>())
900 return CGM.GetWeakRefReference(Decl);
901 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Decl))
902 return CGM.GetAddrOfFunction(FD);
903 if (const VarDecl* VD = dyn_cast<VarDecl>(Decl)) {
904 // We can never refer to a variable with local storage.
905 if (!VD->hasLocalStorage()) {
906 if (VD->isFileVarDecl() || VD->hasExternalStorage())
907 return CGM.GetAddrOfGlobalVar(VD);
908 else if (VD->isLocalVarDecl()) {
909 assert(CGF && "Can't access static local vars without CGF");
910 return CGF->GetAddrOfStaticLocalVar(VD);
917 Expr *E = const_cast<Expr*>(LVBase.get<const Expr*>());
918 switch (E->getStmtClass()) {
920 case Expr::CompoundLiteralExprClass: {
921 // Note that due to the nature of compound literals, this is guaranteed
922 // to be the only use of the variable, so we just generate it here.
923 CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E);
924 llvm::Constant* C = CGM.EmitConstantExpr(CLE->getInitializer(),
925 CLE->getType(), CGF);
926 // FIXME: "Leaked" on failure.
928 C = new llvm::GlobalVariable(CGM.getModule(), C->getType(),
929 E->getType().isConstant(CGM.getContext()),
930 llvm::GlobalValue::InternalLinkage,
931 C, ".compoundliteral", 0,
932 llvm::GlobalVariable::NotThreadLocal,
933 CGM.getContext().getTargetAddressSpace(E->getType()));
936 case Expr::StringLiteralClass:
937 return CGM.GetAddrOfConstantStringFromLiteral(cast<StringLiteral>(E));
938 case Expr::ObjCEncodeExprClass:
939 return CGM.GetAddrOfConstantStringFromObjCEncode(cast<ObjCEncodeExpr>(E));
940 case Expr::ObjCStringLiteralClass: {
941 ObjCStringLiteral* SL = cast<ObjCStringLiteral>(E);
943 CGM.getObjCRuntime().GenerateConstantString(SL->getString());
944 return llvm::ConstantExpr::getBitCast(C, ConvertType(E->getType()));
946 case Expr::PredefinedExprClass: {
947 unsigned Type = cast<PredefinedExpr>(E)->getIdentType();
949 LValue Res = CGF->EmitPredefinedLValue(cast<PredefinedExpr>(E));
950 return cast<llvm::Constant>(Res.getAddress());
951 } else if (Type == PredefinedExpr::PrettyFunction) {
952 return CGM.GetAddrOfConstantCString("top level", ".tmp");
955 return CGM.GetAddrOfConstantCString("", ".tmp");
957 case Expr::AddrLabelExprClass: {
958 assert(CGF && "Invalid address of label expression outside function.");
959 llvm::Constant *Ptr =
960 CGF->GetAddrOfLabel(cast<AddrLabelExpr>(E)->getLabel());
961 return llvm::ConstantExpr::getBitCast(Ptr, ConvertType(E->getType()));
963 case Expr::CallExprClass: {
964 CallExpr* CE = cast<CallExpr>(E);
965 unsigned builtin = CE->isBuiltinCall();
967 Builtin::BI__builtin___CFStringMakeConstantString &&
969 Builtin::BI__builtin___NSStringMakeConstantString)
971 const Expr *Arg = CE->getArg(0)->IgnoreParenCasts();
972 const StringLiteral *Literal = cast<StringLiteral>(Arg);
974 Builtin::BI__builtin___NSStringMakeConstantString) {
975 return CGM.getObjCRuntime().GenerateConstantString(Literal);
977 // FIXME: need to deal with UCN conversion issues.
978 return CGM.GetAddrOfConstantCFString(Literal);
980 case Expr::BlockExprClass: {
981 std::string FunctionName;
983 FunctionName = CGF->CurFn->getName();
985 FunctionName = "global";
987 return CGM.GetAddrOfGlobalBlock(cast<BlockExpr>(E), FunctionName.c_str());
989 case Expr::CXXTypeidExprClass: {
990 CXXTypeidExpr *Typeid = cast<CXXTypeidExpr>(E);
992 if (Typeid->isTypeOperand())
993 T = Typeid->getTypeOperand();
995 T = Typeid->getExprOperand()->getType();
996 return CGM.GetAddrOfRTTIDescriptor(T);
998 case Expr::CXXUuidofExprClass: {
999 return CGM.GetAddrOfUuidDescriptor(cast<CXXUuidofExpr>(E));
1007 } // end anonymous namespace.
1009 llvm::Constant *CodeGenModule::EmitConstantInit(const VarDecl &D,
1010 CodeGenFunction *CGF) {
1011 if (const APValue *Value = D.evaluateValue())
1012 return EmitConstantValueForMemory(*Value, D.getType(), CGF);
1014 // FIXME: Implement C++11 [basic.start.init]p2: if the initializer of a
1015 // reference is a constant expression, and the reference binds to a temporary,
1016 // then constant initialization is performed. ConstExprEmitter will
1017 // incorrectly emit a prvalue constant in this case, and the calling code
1018 // interprets that as the (pointer) value of the reference, rather than the
1019 // desired value of the referee.
1020 if (D.getType()->isReferenceType())
1023 const Expr *E = D.getInit();
1024 assert(E && "No initializer to emit");
1026 llvm::Constant* C = ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E));
1027 if (C && C->getType()->isIntegerTy(1)) {
1028 llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType());
1029 C = llvm::ConstantExpr::getZExt(C, BoolTy);
1034 llvm::Constant *CodeGenModule::EmitConstantExpr(const Expr *E,
1036 CodeGenFunction *CGF) {
1037 Expr::EvalResult Result;
1039 bool Success = false;
1041 if (DestType->isReferenceType())
1042 Success = E->EvaluateAsLValue(Result, Context);
1044 Success = E->EvaluateAsRValue(Result, Context);
1046 llvm::Constant *C = 0;
1047 if (Success && !Result.HasSideEffects)
1048 C = EmitConstantValue(Result.Val, DestType, CGF);
1050 C = ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E));
1052 if (C && C->getType()->isIntegerTy(1)) {
1053 llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType());
1054 C = llvm::ConstantExpr::getZExt(C, BoolTy);
1059 llvm::Constant *CodeGenModule::EmitConstantValue(const APValue &Value,
1061 CodeGenFunction *CGF) {
1062 switch (Value.getKind()) {
1063 case APValue::Uninitialized:
1064 llvm_unreachable("Constant expressions should be initialized.");
1065 case APValue::LValue: {
1066 llvm::Type *DestTy = getTypes().ConvertTypeForMem(DestType);
1067 llvm::Constant *Offset =
1068 llvm::ConstantInt::get(Int64Ty, Value.getLValueOffset().getQuantity());
1071 if (APValue::LValueBase LVBase = Value.getLValueBase()) {
1072 // An array can be represented as an lvalue referring to the base.
1073 if (isa<llvm::ArrayType>(DestTy)) {
1074 assert(Offset->isNullValue() && "offset on array initializer");
1075 return ConstExprEmitter(*this, CGF).Visit(
1076 const_cast<Expr*>(LVBase.get<const Expr*>()));
1079 C = ConstExprEmitter(*this, CGF).EmitLValue(LVBase);
1081 // Apply offset if necessary.
1082 if (!Offset->isNullValue()) {
1083 llvm::Constant *Casted = llvm::ConstantExpr::getBitCast(C, Int8PtrTy);
1084 Casted = llvm::ConstantExpr::getGetElementPtr(Casted, Offset);
1085 C = llvm::ConstantExpr::getBitCast(Casted, C->getType());
1088 // Convert to the appropriate type; this could be an lvalue for
1090 if (isa<llvm::PointerType>(DestTy))
1091 return llvm::ConstantExpr::getBitCast(C, DestTy);
1093 return llvm::ConstantExpr::getPtrToInt(C, DestTy);
1097 // Convert to the appropriate type; this could be an lvalue for
1099 if (isa<llvm::PointerType>(DestTy))
1100 return llvm::ConstantExpr::getIntToPtr(C, DestTy);
1102 // If the types don't match this should only be a truncate.
1103 if (C->getType() != DestTy)
1104 return llvm::ConstantExpr::getTrunc(C, DestTy);
1110 return llvm::ConstantInt::get(VMContext, Value.getInt());
1111 case APValue::ComplexInt: {
1112 llvm::Constant *Complex[2];
1114 Complex[0] = llvm::ConstantInt::get(VMContext,
1115 Value.getComplexIntReal());
1116 Complex[1] = llvm::ConstantInt::get(VMContext,
1117 Value.getComplexIntImag());
1119 // FIXME: the target may want to specify that this is packed.
1120 llvm::StructType *STy = llvm::StructType::get(Complex[0]->getType(),
1121 Complex[1]->getType(),
1123 return llvm::ConstantStruct::get(STy, Complex);
1125 case APValue::Float: {
1126 const llvm::APFloat &Init = Value.getFloat();
1127 if (&Init.getSemantics() == &llvm::APFloat::IEEEhalf)
1128 return llvm::ConstantInt::get(VMContext, Init.bitcastToAPInt());
1130 return llvm::ConstantFP::get(VMContext, Init);
1132 case APValue::ComplexFloat: {
1133 llvm::Constant *Complex[2];
1135 Complex[0] = llvm::ConstantFP::get(VMContext,
1136 Value.getComplexFloatReal());
1137 Complex[1] = llvm::ConstantFP::get(VMContext,
1138 Value.getComplexFloatImag());
1140 // FIXME: the target may want to specify that this is packed.
1141 llvm::StructType *STy = llvm::StructType::get(Complex[0]->getType(),
1142 Complex[1]->getType(),
1144 return llvm::ConstantStruct::get(STy, Complex);
1146 case APValue::Vector: {
1147 SmallVector<llvm::Constant *, 4> Inits;
1148 unsigned NumElts = Value.getVectorLength();
1150 for (unsigned i = 0; i != NumElts; ++i) {
1151 const APValue &Elt = Value.getVectorElt(i);
1153 Inits.push_back(llvm::ConstantInt::get(VMContext, Elt.getInt()));
1155 Inits.push_back(llvm::ConstantFP::get(VMContext, Elt.getFloat()));
1157 return llvm::ConstantVector::get(Inits);
1159 case APValue::AddrLabelDiff: {
1160 const AddrLabelExpr *LHSExpr = Value.getAddrLabelDiffLHS();
1161 const AddrLabelExpr *RHSExpr = Value.getAddrLabelDiffRHS();
1162 llvm::Constant *LHS = EmitConstantExpr(LHSExpr, LHSExpr->getType(), CGF);
1163 llvm::Constant *RHS = EmitConstantExpr(RHSExpr, RHSExpr->getType(), CGF);
1165 // Compute difference
1166 llvm::Type *ResultType = getTypes().ConvertType(DestType);
1167 LHS = llvm::ConstantExpr::getPtrToInt(LHS, IntPtrTy);
1168 RHS = llvm::ConstantExpr::getPtrToInt(RHS, IntPtrTy);
1169 llvm::Constant *AddrLabelDiff = llvm::ConstantExpr::getSub(LHS, RHS);
1171 // LLVM is a bit sensitive about the exact format of the
1172 // address-of-label difference; make sure to truncate after
1174 return llvm::ConstantExpr::getTruncOrBitCast(AddrLabelDiff, ResultType);
1176 case APValue::Struct:
1177 case APValue::Union:
1178 return ConstStructBuilder::BuildStruct(*this, CGF, Value, DestType);
1179 case APValue::Array: {
1180 const ArrayType *CAT = Context.getAsArrayType(DestType);
1181 unsigned NumElements = Value.getArraySize();
1182 unsigned NumInitElts = Value.getArrayInitializedElts();
1184 std::vector<llvm::Constant*> Elts;
1185 Elts.reserve(NumElements);
1187 // Emit array filler, if there is one.
1188 llvm::Constant *Filler = 0;
1189 if (Value.hasArrayFiller())
1190 Filler = EmitConstantValueForMemory(Value.getArrayFiller(),
1191 CAT->getElementType(), CGF);
1193 // Emit initializer elements.
1194 llvm::Type *CommonElementType = 0;
1195 for (unsigned I = 0; I < NumElements; ++I) {
1196 llvm::Constant *C = Filler;
1197 if (I < NumInitElts)
1198 C = EmitConstantValueForMemory(Value.getArrayInitializedElt(I),
1199 CAT->getElementType(), CGF);
1201 CommonElementType = C->getType();
1202 else if (C->getType() != CommonElementType)
1203 CommonElementType = 0;
1207 if (!CommonElementType) {
1208 // FIXME: Try to avoid packing the array
1209 std::vector<llvm::Type*> Types;
1210 Types.reserve(NumElements);
1211 for (unsigned i = 0, e = Elts.size(); i < e; ++i)
1212 Types.push_back(Elts[i]->getType());
1213 llvm::StructType *SType = llvm::StructType::get(VMContext, Types, true);
1214 return llvm::ConstantStruct::get(SType, Elts);
1217 llvm::ArrayType *AType =
1218 llvm::ArrayType::get(CommonElementType, NumElements);
1219 return llvm::ConstantArray::get(AType, Elts);
1221 case APValue::MemberPointer:
1222 return getCXXABI().EmitMemberPointer(Value, DestType);
1224 llvm_unreachable("Unknown APValue kind");
1228 CodeGenModule::EmitConstantValueForMemory(const APValue &Value,
1230 CodeGenFunction *CGF) {
1231 llvm::Constant *C = EmitConstantValue(Value, DestType, CGF);
1232 if (C->getType()->isIntegerTy(1)) {
1233 llvm::Type *BoolTy = getTypes().ConvertTypeForMem(DestType);
1234 C = llvm::ConstantExpr::getZExt(C, BoolTy);
1240 CodeGenModule::GetAddrOfConstantCompoundLiteral(const CompoundLiteralExpr *E) {
1241 assert(E->isFileScope() && "not a file-scope compound literal expr");
1242 return ConstExprEmitter(*this, 0).EmitLValue(E);
1246 CodeGenModule::getMemberPointerConstant(const UnaryOperator *uo) {
1247 // Member pointer constants always have a very particular form.
1248 const MemberPointerType *type = cast<MemberPointerType>(uo->getType());
1249 const ValueDecl *decl = cast<DeclRefExpr>(uo->getSubExpr())->getDecl();
1251 // A member function pointer.
1252 if (const CXXMethodDecl *method = dyn_cast<CXXMethodDecl>(decl))
1253 return getCXXABI().EmitMemberPointer(method);
1255 // Otherwise, a member data pointer.
1256 uint64_t fieldOffset = getContext().getFieldOffset(decl);
1257 CharUnits chars = getContext().toCharUnitsFromBits((int64_t) fieldOffset);
1258 return getCXXABI().EmitMemberDataPointer(type, chars);
1262 FillInNullDataMemberPointers(CodeGenModule &CGM, QualType T,
1263 SmallVectorImpl<llvm::Constant *> &Elements,
1264 uint64_t StartOffset) {
1265 assert(StartOffset % CGM.getContext().getCharWidth() == 0 &&
1266 "StartOffset not byte aligned!");
1268 if (CGM.getTypes().isZeroInitializable(T))
1271 if (const ConstantArrayType *CAT =
1272 CGM.getContext().getAsConstantArrayType(T)) {
1273 QualType ElementTy = CAT->getElementType();
1274 uint64_t ElementSize = CGM.getContext().getTypeSize(ElementTy);
1276 for (uint64_t I = 0, E = CAT->getSize().getZExtValue(); I != E; ++I) {
1277 FillInNullDataMemberPointers(CGM, ElementTy, Elements,
1278 StartOffset + I * ElementSize);
1280 } else if (const RecordType *RT = T->getAs<RecordType>()) {
1281 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
1282 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
1284 // Go through all bases and fill in any null pointer to data members.
1285 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
1286 E = RD->bases_end(); I != E; ++I) {
1287 if (I->isVirtual()) {
1288 // Ignore virtual bases.
1292 const CXXRecordDecl *BaseDecl =
1293 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
1295 // Ignore empty bases.
1296 if (BaseDecl->isEmpty())
1299 // Ignore bases that don't have any pointer to data members.
1300 if (CGM.getTypes().isZeroInitializable(BaseDecl))
1303 uint64_t BaseOffset =
1304 CGM.getContext().toBits(Layout.getBaseClassOffset(BaseDecl));
1305 FillInNullDataMemberPointers(CGM, I->getType(),
1306 Elements, StartOffset + BaseOffset);
1309 // Visit all fields.
1310 unsigned FieldNo = 0;
1311 for (RecordDecl::field_iterator I = RD->field_begin(),
1312 E = RD->field_end(); I != E; ++I, ++FieldNo) {
1313 QualType FieldType = I->getType();
1315 if (CGM.getTypes().isZeroInitializable(FieldType))
1318 uint64_t FieldOffset = StartOffset + Layout.getFieldOffset(FieldNo);
1319 FillInNullDataMemberPointers(CGM, FieldType, Elements, FieldOffset);
1322 assert(T->isMemberPointerType() && "Should only see member pointers here!");
1323 assert(!T->getAs<MemberPointerType>()->getPointeeType()->isFunctionType() &&
1324 "Should only see pointers to data members here!");
1326 CharUnits StartIndex = CGM.getContext().toCharUnitsFromBits(StartOffset);
1327 CharUnits EndIndex = StartIndex + CGM.getContext().getTypeSizeInChars(T);
1329 // FIXME: hardcodes Itanium member pointer representation!
1330 llvm::Constant *NegativeOne =
1331 llvm::ConstantInt::get(CGM.Int8Ty, -1ULL, /*isSigned*/true);
1333 // Fill in the null data member pointer.
1334 for (CharUnits I = StartIndex; I != EndIndex; ++I)
1335 Elements[I.getQuantity()] = NegativeOne;
1339 static llvm::Constant *EmitNullConstantForBase(CodeGenModule &CGM,
1340 llvm::Type *baseType,
1341 const CXXRecordDecl *base);
1343 static llvm::Constant *EmitNullConstant(CodeGenModule &CGM,
1344 const CXXRecordDecl *record,
1345 bool asCompleteObject) {
1346 const CGRecordLayout &layout = CGM.getTypes().getCGRecordLayout(record);
1347 llvm::StructType *structure =
1348 (asCompleteObject ? layout.getLLVMType()
1349 : layout.getBaseSubobjectLLVMType());
1351 unsigned numElements = structure->getNumElements();
1352 std::vector<llvm::Constant *> elements(numElements);
1354 // Fill in all the bases.
1355 for (CXXRecordDecl::base_class_const_iterator
1356 I = record->bases_begin(), E = record->bases_end(); I != E; ++I) {
1357 if (I->isVirtual()) {
1358 // Ignore virtual bases; if we're laying out for a complete
1359 // object, we'll lay these out later.
1363 const CXXRecordDecl *base =
1364 cast<CXXRecordDecl>(I->getType()->castAs<RecordType>()->getDecl());
1366 // Ignore empty bases.
1367 if (base->isEmpty())
1370 unsigned fieldIndex = layout.getNonVirtualBaseLLVMFieldNo(base);
1371 llvm::Type *baseType = structure->getElementType(fieldIndex);
1372 elements[fieldIndex] = EmitNullConstantForBase(CGM, baseType, base);
1375 // Fill in all the fields.
1376 for (RecordDecl::field_iterator I = record->field_begin(),
1377 E = record->field_end(); I != E; ++I) {
1378 const FieldDecl *field = *I;
1380 // Fill in non-bitfields. (Bitfields always use a zero pattern, which we
1381 // will fill in later.)
1382 if (!field->isBitField()) {
1383 unsigned fieldIndex = layout.getLLVMFieldNo(field);
1384 elements[fieldIndex] = CGM.EmitNullConstant(field->getType());
1387 // For unions, stop after the first named field.
1388 if (record->isUnion() && field->getDeclName())
1392 // Fill in the virtual bases, if we're working with the complete object.
1393 if (asCompleteObject) {
1394 for (CXXRecordDecl::base_class_const_iterator
1395 I = record->vbases_begin(), E = record->vbases_end(); I != E; ++I) {
1396 const CXXRecordDecl *base =
1397 cast<CXXRecordDecl>(I->getType()->castAs<RecordType>()->getDecl());
1399 // Ignore empty bases.
1400 if (base->isEmpty())
1403 unsigned fieldIndex = layout.getVirtualBaseIndex(base);
1405 // We might have already laid this field out.
1406 if (elements[fieldIndex]) continue;
1408 llvm::Type *baseType = structure->getElementType(fieldIndex);
1409 elements[fieldIndex] = EmitNullConstantForBase(CGM, baseType, base);
1413 // Now go through all other fields and zero them out.
1414 for (unsigned i = 0; i != numElements; ++i) {
1416 elements[i] = llvm::Constant::getNullValue(structure->getElementType(i));
1419 return llvm::ConstantStruct::get(structure, elements);
1422 /// Emit the null constant for a base subobject.
1423 static llvm::Constant *EmitNullConstantForBase(CodeGenModule &CGM,
1424 llvm::Type *baseType,
1425 const CXXRecordDecl *base) {
1426 const CGRecordLayout &baseLayout = CGM.getTypes().getCGRecordLayout(base);
1428 // Just zero out bases that don't have any pointer to data members.
1429 if (baseLayout.isZeroInitializableAsBase())
1430 return llvm::Constant::getNullValue(baseType);
1432 // If the base type is a struct, we can just use its null constant.
1433 if (isa<llvm::StructType>(baseType)) {
1434 return EmitNullConstant(CGM, base, /*complete*/ false);
1437 // Otherwise, some bases are represented as arrays of i8 if the size
1438 // of the base is smaller than its corresponding LLVM type. Figure
1439 // out how many elements this base array has.
1440 llvm::ArrayType *baseArrayType = cast<llvm::ArrayType>(baseType);
1441 unsigned numBaseElements = baseArrayType->getNumElements();
1443 // Fill in null data member pointers.
1444 SmallVector<llvm::Constant *, 16> baseElements(numBaseElements);
1445 FillInNullDataMemberPointers(CGM, CGM.getContext().getTypeDeclType(base),
1448 // Now go through all other elements and zero them out.
1449 if (numBaseElements) {
1450 llvm::Constant *i8_zero = llvm::Constant::getNullValue(CGM.Int8Ty);
1451 for (unsigned i = 0; i != numBaseElements; ++i) {
1452 if (!baseElements[i])
1453 baseElements[i] = i8_zero;
1457 return llvm::ConstantArray::get(baseArrayType, baseElements);
1460 llvm::Constant *CodeGenModule::EmitNullConstant(QualType T) {
1461 if (getTypes().isZeroInitializable(T))
1462 return llvm::Constant::getNullValue(getTypes().ConvertTypeForMem(T));
1464 if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(T)) {
1465 llvm::ArrayType *ATy =
1466 cast<llvm::ArrayType>(getTypes().ConvertTypeForMem(T));
1468 QualType ElementTy = CAT->getElementType();
1470 llvm::Constant *Element = EmitNullConstant(ElementTy);
1471 unsigned NumElements = CAT->getSize().getZExtValue();
1473 if (Element->isNullValue())
1474 return llvm::ConstantAggregateZero::get(ATy);
1476 SmallVector<llvm::Constant *, 8> Array(NumElements, Element);
1477 return llvm::ConstantArray::get(ATy, Array);
1480 if (const RecordType *RT = T->getAs<RecordType>()) {
1481 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
1482 return ::EmitNullConstant(*this, RD, /*complete object*/ true);
1485 assert(T->isMemberPointerType() && "Should only see member pointers here!");
1486 assert(!T->getAs<MemberPointerType>()->getPointeeType()->isFunctionType() &&
1487 "Should only see pointers to data members here!");
1489 // Itanium C++ ABI 2.3:
1490 // A NULL pointer is represented as -1.
1491 return getCXXABI().EmitNullMemberPointer(T->castAs<MemberPointerType>());
1495 CodeGenModule::EmitNullConstantForBase(const CXXRecordDecl *Record) {
1496 return ::EmitNullConstant(*this, Record, false);