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"
16 #include "CGObjCRuntime.h"
17 #include "CGRecordLayout.h"
18 #include "CodeGenModule.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/IR/Constants.h"
25 #include "llvm/IR/DataLayout.h"
26 #include "llvm/IR/Function.h"
27 #include "llvm/IR/GlobalVariable.h"
28 using namespace clang;
29 using namespace CodeGen;
31 //===----------------------------------------------------------------------===//
33 //===----------------------------------------------------------------------===//
36 class ConstExprEmitter;
37 class ConstStructBuilder {
42 CharUnits NextFieldOffsetInChars;
43 CharUnits LLVMStructAlignment;
44 SmallVector<llvm::Constant *, 32> Elements;
46 static llvm::Constant *BuildStruct(CodeGenModule &CGM, CodeGenFunction *CFG,
47 ConstExprEmitter *Emitter,
48 llvm::ConstantStruct *Base,
49 InitListExpr *Updater);
50 static llvm::Constant *BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF,
52 static llvm::Constant *BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF,
53 const APValue &Value, QualType ValTy);
56 ConstStructBuilder(CodeGenModule &CGM, CodeGenFunction *CGF)
57 : CGM(CGM), CGF(CGF), Packed(false),
58 NextFieldOffsetInChars(CharUnits::Zero()),
59 LLVMStructAlignment(CharUnits::One()) { }
61 void AppendField(const FieldDecl *Field, uint64_t FieldOffset,
62 llvm::Constant *InitExpr);
64 void AppendBytes(CharUnits FieldOffsetInChars, llvm::Constant *InitCst);
66 void AppendBitField(const FieldDecl *Field, uint64_t FieldOffset,
67 llvm::ConstantInt *InitExpr);
69 void AppendPadding(CharUnits PadSize);
71 void AppendTailPadding(CharUnits RecordSize);
73 void ConvertStructToPacked();
75 bool Build(InitListExpr *ILE);
76 bool Build(ConstExprEmitter *Emitter, llvm::ConstantStruct *Base,
77 InitListExpr *Updater);
78 void Build(const APValue &Val, const RecordDecl *RD, bool IsPrimaryBase,
79 const CXXRecordDecl *VTableClass, CharUnits BaseOffset);
80 llvm::Constant *Finalize(QualType Ty);
82 CharUnits getAlignment(const llvm::Constant *C) const {
83 if (Packed) return CharUnits::One();
84 return CharUnits::fromQuantity(
85 CGM.getDataLayout().getABITypeAlignment(C->getType()));
88 CharUnits getSizeInChars(const llvm::Constant *C) const {
89 return CharUnits::fromQuantity(
90 CGM.getDataLayout().getTypeAllocSize(C->getType()));
94 void ConstStructBuilder::
95 AppendField(const FieldDecl *Field, uint64_t FieldOffset,
96 llvm::Constant *InitCst) {
97 const ASTContext &Context = CGM.getContext();
99 CharUnits FieldOffsetInChars = Context.toCharUnitsFromBits(FieldOffset);
101 AppendBytes(FieldOffsetInChars, InitCst);
104 void ConstStructBuilder::
105 AppendBytes(CharUnits FieldOffsetInChars, llvm::Constant *InitCst) {
107 assert(NextFieldOffsetInChars <= FieldOffsetInChars
108 && "Field offset mismatch!");
110 CharUnits FieldAlignment = getAlignment(InitCst);
112 // Round up the field offset to the alignment of the field type.
113 CharUnits AlignedNextFieldOffsetInChars =
114 NextFieldOffsetInChars.RoundUpToAlignment(FieldAlignment);
116 if (AlignedNextFieldOffsetInChars < FieldOffsetInChars) {
117 // We need to append padding.
118 AppendPadding(FieldOffsetInChars - NextFieldOffsetInChars);
120 assert(NextFieldOffsetInChars == FieldOffsetInChars &&
121 "Did not add enough padding!");
123 AlignedNextFieldOffsetInChars =
124 NextFieldOffsetInChars.RoundUpToAlignment(FieldAlignment);
127 if (AlignedNextFieldOffsetInChars > FieldOffsetInChars) {
128 assert(!Packed && "Alignment is wrong even with a packed struct!");
130 // Convert the struct to a packed struct.
131 ConvertStructToPacked();
133 // After we pack the struct, we may need to insert padding.
134 if (NextFieldOffsetInChars < FieldOffsetInChars) {
135 // We need to append padding.
136 AppendPadding(FieldOffsetInChars - NextFieldOffsetInChars);
138 assert(NextFieldOffsetInChars == FieldOffsetInChars &&
139 "Did not add enough padding!");
141 AlignedNextFieldOffsetInChars = NextFieldOffsetInChars;
145 Elements.push_back(InitCst);
146 NextFieldOffsetInChars = AlignedNextFieldOffsetInChars +
147 getSizeInChars(InitCst);
150 assert(LLVMStructAlignment == CharUnits::One() &&
151 "Packed struct not byte-aligned!");
153 LLVMStructAlignment = std::max(LLVMStructAlignment, FieldAlignment);
156 void ConstStructBuilder::AppendBitField(const FieldDecl *Field,
157 uint64_t FieldOffset,
158 llvm::ConstantInt *CI) {
159 const ASTContext &Context = CGM.getContext();
160 const uint64_t CharWidth = Context.getCharWidth();
161 uint64_t NextFieldOffsetInBits = Context.toBits(NextFieldOffsetInChars);
162 if (FieldOffset > NextFieldOffsetInBits) {
163 // We need to add padding.
164 CharUnits PadSize = Context.toCharUnitsFromBits(
165 llvm::RoundUpToAlignment(FieldOffset - NextFieldOffsetInBits,
166 Context.getTargetInfo().getCharAlign()));
168 AppendPadding(PadSize);
171 uint64_t FieldSize = Field->getBitWidthValue(Context);
173 llvm::APInt FieldValue = CI->getValue();
175 // Promote the size of FieldValue if necessary
176 // FIXME: This should never occur, but currently it can because initializer
177 // constants are cast to bool, and because clang is not enforcing bitfield
179 if (FieldSize > FieldValue.getBitWidth())
180 FieldValue = FieldValue.zext(FieldSize);
182 // Truncate the size of FieldValue to the bit field size.
183 if (FieldSize < FieldValue.getBitWidth())
184 FieldValue = FieldValue.trunc(FieldSize);
186 NextFieldOffsetInBits = Context.toBits(NextFieldOffsetInChars);
187 if (FieldOffset < NextFieldOffsetInBits) {
188 // Either part of the field or the entire field can go into the previous
190 assert(!Elements.empty() && "Elements can't be empty!");
192 unsigned BitsInPreviousByte = NextFieldOffsetInBits - FieldOffset;
194 bool FitsCompletelyInPreviousByte =
195 BitsInPreviousByte >= FieldValue.getBitWidth();
197 llvm::APInt Tmp = FieldValue;
199 if (!FitsCompletelyInPreviousByte) {
200 unsigned NewFieldWidth = FieldSize - BitsInPreviousByte;
202 if (CGM.getDataLayout().isBigEndian()) {
203 Tmp = Tmp.lshr(NewFieldWidth);
204 Tmp = Tmp.trunc(BitsInPreviousByte);
206 // We want the remaining high bits.
207 FieldValue = FieldValue.trunc(NewFieldWidth);
209 Tmp = Tmp.trunc(BitsInPreviousByte);
211 // We want the remaining low bits.
212 FieldValue = FieldValue.lshr(BitsInPreviousByte);
213 FieldValue = FieldValue.trunc(NewFieldWidth);
217 Tmp = Tmp.zext(CharWidth);
218 if (CGM.getDataLayout().isBigEndian()) {
219 if (FitsCompletelyInPreviousByte)
220 Tmp = Tmp.shl(BitsInPreviousByte - FieldValue.getBitWidth());
222 Tmp = Tmp.shl(CharWidth - BitsInPreviousByte);
225 // 'or' in the bits that go into the previous byte.
226 llvm::Value *LastElt = Elements.back();
227 if (llvm::ConstantInt *Val = dyn_cast<llvm::ConstantInt>(LastElt))
228 Tmp |= Val->getValue();
230 assert(isa<llvm::UndefValue>(LastElt));
231 // If there is an undef field that we're adding to, it can either be a
232 // scalar undef (in which case, we just replace it with our field) or it
233 // is an array. If it is an array, we have to pull one byte off the
234 // array so that the other undef bytes stay around.
235 if (!isa<llvm::IntegerType>(LastElt->getType())) {
236 // The undef padding will be a multibyte array, create a new smaller
237 // padding and then an hole for our i8 to get plopped into.
238 assert(isa<llvm::ArrayType>(LastElt->getType()) &&
239 "Expected array padding of undefs");
240 llvm::ArrayType *AT = cast<llvm::ArrayType>(LastElt->getType());
241 assert(AT->getElementType()->isIntegerTy(CharWidth) &&
242 AT->getNumElements() != 0 &&
243 "Expected non-empty array padding of undefs");
245 // Remove the padding array.
246 NextFieldOffsetInChars -= CharUnits::fromQuantity(AT->getNumElements());
249 // Add the padding back in two chunks.
250 AppendPadding(CharUnits::fromQuantity(AT->getNumElements()-1));
251 AppendPadding(CharUnits::One());
252 assert(isa<llvm::UndefValue>(Elements.back()) &&
253 Elements.back()->getType()->isIntegerTy(CharWidth) &&
254 "Padding addition didn't work right");
258 Elements.back() = llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp);
260 if (FitsCompletelyInPreviousByte)
264 while (FieldValue.getBitWidth() > CharWidth) {
267 if (CGM.getDataLayout().isBigEndian()) {
268 // We want the high bits.
270 FieldValue.lshr(FieldValue.getBitWidth() - CharWidth).trunc(CharWidth);
272 // We want the low bits.
273 Tmp = FieldValue.trunc(CharWidth);
275 FieldValue = FieldValue.lshr(CharWidth);
278 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp));
279 ++NextFieldOffsetInChars;
281 FieldValue = FieldValue.trunc(FieldValue.getBitWidth() - CharWidth);
284 assert(FieldValue.getBitWidth() > 0 &&
285 "Should have at least one bit left!");
286 assert(FieldValue.getBitWidth() <= CharWidth &&
287 "Should not have more than a byte left!");
289 if (FieldValue.getBitWidth() < CharWidth) {
290 if (CGM.getDataLayout().isBigEndian()) {
291 unsigned BitWidth = FieldValue.getBitWidth();
293 FieldValue = FieldValue.zext(CharWidth) << (CharWidth - BitWidth);
295 FieldValue = FieldValue.zext(CharWidth);
298 // Append the last element.
299 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(),
301 ++NextFieldOffsetInChars;
304 void ConstStructBuilder::AppendPadding(CharUnits PadSize) {
305 if (PadSize.isZero())
308 llvm::Type *Ty = CGM.Int8Ty;
309 if (PadSize > CharUnits::One())
310 Ty = llvm::ArrayType::get(Ty, PadSize.getQuantity());
312 llvm::Constant *C = llvm::UndefValue::get(Ty);
313 Elements.push_back(C);
314 assert(getAlignment(C) == CharUnits::One() &&
315 "Padding must have 1 byte alignment!");
317 NextFieldOffsetInChars += getSizeInChars(C);
320 void ConstStructBuilder::AppendTailPadding(CharUnits RecordSize) {
321 assert(NextFieldOffsetInChars <= RecordSize &&
324 AppendPadding(RecordSize - NextFieldOffsetInChars);
327 void ConstStructBuilder::ConvertStructToPacked() {
328 SmallVector<llvm::Constant *, 16> PackedElements;
329 CharUnits ElementOffsetInChars = CharUnits::Zero();
331 for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
332 llvm::Constant *C = Elements[i];
334 CharUnits ElementAlign = CharUnits::fromQuantity(
335 CGM.getDataLayout().getABITypeAlignment(C->getType()));
336 CharUnits AlignedElementOffsetInChars =
337 ElementOffsetInChars.RoundUpToAlignment(ElementAlign);
339 if (AlignedElementOffsetInChars > ElementOffsetInChars) {
340 // We need some padding.
342 AlignedElementOffsetInChars - ElementOffsetInChars;
344 llvm::Type *Ty = CGM.Int8Ty;
345 if (NumChars > CharUnits::One())
346 Ty = llvm::ArrayType::get(Ty, NumChars.getQuantity());
348 llvm::Constant *Padding = llvm::UndefValue::get(Ty);
349 PackedElements.push_back(Padding);
350 ElementOffsetInChars += getSizeInChars(Padding);
353 PackedElements.push_back(C);
354 ElementOffsetInChars += getSizeInChars(C);
357 assert(ElementOffsetInChars == NextFieldOffsetInChars &&
358 "Packing the struct changed its size!");
360 Elements.swap(PackedElements);
361 LLVMStructAlignment = CharUnits::One();
365 bool ConstStructBuilder::Build(InitListExpr *ILE) {
366 RecordDecl *RD = ILE->getType()->getAs<RecordType>()->getDecl();
367 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
369 unsigned FieldNo = 0;
370 unsigned ElementNo = 0;
372 for (RecordDecl::field_iterator Field = RD->field_begin(),
373 FieldEnd = RD->field_end(); Field != FieldEnd; ++Field, ++FieldNo) {
374 // If this is a union, skip all the fields that aren't being initialized.
375 if (RD->isUnion() && ILE->getInitializedFieldInUnion() != *Field)
378 // Don't emit anonymous bitfields, they just affect layout.
379 if (Field->isUnnamedBitfield())
382 // Get the initializer. A struct can include fields without initializers,
383 // we just use explicit null values for them.
384 llvm::Constant *EltInit;
385 if (ElementNo < ILE->getNumInits())
386 EltInit = CGM.EmitConstantExpr(ILE->getInit(ElementNo++),
387 Field->getType(), CGF);
389 EltInit = CGM.EmitNullConstant(Field->getType());
394 if (!Field->isBitField()) {
395 // Handle non-bitfield members.
396 AppendField(*Field, Layout.getFieldOffset(FieldNo), EltInit);
398 // Otherwise we have a bitfield.
399 if (auto *CI = dyn_cast<llvm::ConstantInt>(EltInit)) {
400 AppendBitField(*Field, Layout.getFieldOffset(FieldNo), CI);
402 // We are trying to initialize a bitfield with a non-trivial constant,
403 // this must require run-time code.
414 BaseInfo(const CXXRecordDecl *Decl, CharUnits Offset, unsigned Index)
415 : Decl(Decl), Offset(Offset), Index(Index) {
418 const CXXRecordDecl *Decl;
422 bool operator<(const BaseInfo &O) const { return Offset < O.Offset; }
426 void ConstStructBuilder::Build(const APValue &Val, const RecordDecl *RD,
428 const CXXRecordDecl *VTableClass,
430 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
432 if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) {
433 // Add a vtable pointer, if we need one and it hasn't already been added.
434 if (CD->isDynamicClass() && !IsPrimaryBase) {
435 llvm::Constant *VTableAddressPoint =
436 CGM.getCXXABI().getVTableAddressPointForConstExpr(
437 BaseSubobject(CD, Offset), VTableClass);
438 AppendBytes(Offset, VTableAddressPoint);
441 // Accumulate and sort bases, in order to visit them in address order, which
442 // may not be the same as declaration order.
443 SmallVector<BaseInfo, 8> Bases;
444 Bases.reserve(CD->getNumBases());
446 for (CXXRecordDecl::base_class_const_iterator Base = CD->bases_begin(),
447 BaseEnd = CD->bases_end(); Base != BaseEnd; ++Base, ++BaseNo) {
448 assert(!Base->isVirtual() && "should not have virtual bases here");
449 const CXXRecordDecl *BD = Base->getType()->getAsCXXRecordDecl();
450 CharUnits BaseOffset = Layout.getBaseClassOffset(BD);
451 Bases.push_back(BaseInfo(BD, BaseOffset, BaseNo));
453 std::stable_sort(Bases.begin(), Bases.end());
455 for (unsigned I = 0, N = Bases.size(); I != N; ++I) {
456 BaseInfo &Base = Bases[I];
458 bool IsPrimaryBase = Layout.getPrimaryBase() == Base.Decl;
459 Build(Val.getStructBase(Base.Index), Base.Decl, IsPrimaryBase,
460 VTableClass, Offset + Base.Offset);
464 unsigned FieldNo = 0;
465 uint64_t OffsetBits = CGM.getContext().toBits(Offset);
467 for (RecordDecl::field_iterator Field = RD->field_begin(),
468 FieldEnd = RD->field_end(); Field != FieldEnd; ++Field, ++FieldNo) {
469 // If this is a union, skip all the fields that aren't being initialized.
470 if (RD->isUnion() && Val.getUnionField() != *Field)
473 // Don't emit anonymous bitfields, they just affect layout.
474 if (Field->isUnnamedBitfield())
477 // Emit the value of the initializer.
478 const APValue &FieldValue =
479 RD->isUnion() ? Val.getUnionValue() : Val.getStructField(FieldNo);
480 llvm::Constant *EltInit =
481 CGM.EmitConstantValueForMemory(FieldValue, Field->getType(), CGF);
482 assert(EltInit && "EmitConstantValue can't fail");
484 if (!Field->isBitField()) {
485 // Handle non-bitfield members.
486 AppendField(*Field, Layout.getFieldOffset(FieldNo) + OffsetBits, EltInit);
488 // Otherwise we have a bitfield.
489 AppendBitField(*Field, Layout.getFieldOffset(FieldNo) + OffsetBits,
490 cast<llvm::ConstantInt>(EltInit));
495 llvm::Constant *ConstStructBuilder::Finalize(QualType Ty) {
496 RecordDecl *RD = Ty->getAs<RecordType>()->getDecl();
497 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
499 CharUnits LayoutSizeInChars = Layout.getSize();
501 if (NextFieldOffsetInChars > LayoutSizeInChars) {
502 // If the struct is bigger than the size of the record type,
503 // we must have a flexible array member at the end.
504 assert(RD->hasFlexibleArrayMember() &&
505 "Must have flexible array member if struct is bigger than type!");
507 // No tail padding is necessary.
509 // Append tail padding if necessary.
510 CharUnits LLVMSizeInChars =
511 NextFieldOffsetInChars.RoundUpToAlignment(LLVMStructAlignment);
513 if (LLVMSizeInChars != LayoutSizeInChars)
514 AppendTailPadding(LayoutSizeInChars);
517 NextFieldOffsetInChars.RoundUpToAlignment(LLVMStructAlignment);
519 // Check if we need to convert the struct to a packed struct.
520 if (NextFieldOffsetInChars <= LayoutSizeInChars &&
521 LLVMSizeInChars > LayoutSizeInChars) {
522 assert(!Packed && "Size mismatch!");
524 ConvertStructToPacked();
525 assert(NextFieldOffsetInChars <= LayoutSizeInChars &&
526 "Converting to packed did not help!");
530 NextFieldOffsetInChars.RoundUpToAlignment(LLVMStructAlignment);
532 assert(LayoutSizeInChars == LLVMSizeInChars &&
533 "Tail padding mismatch!");
536 // Pick the type to use. If the type is layout identical to the ConvertType
537 // type then use it, otherwise use whatever the builder produced for us.
538 llvm::StructType *STy =
539 llvm::ConstantStruct::getTypeForElements(CGM.getLLVMContext(),
541 llvm::Type *ValTy = CGM.getTypes().ConvertType(Ty);
542 if (llvm::StructType *ValSTy = dyn_cast<llvm::StructType>(ValTy)) {
543 if (ValSTy->isLayoutIdentical(STy))
547 llvm::Constant *Result = llvm::ConstantStruct::get(STy, Elements);
549 assert(NextFieldOffsetInChars.RoundUpToAlignment(getAlignment(Result)) ==
550 getSizeInChars(Result) && "Size mismatch!");
555 llvm::Constant *ConstStructBuilder::BuildStruct(CodeGenModule &CGM,
556 CodeGenFunction *CGF,
557 ConstExprEmitter *Emitter,
558 llvm::ConstantStruct *Base,
559 InitListExpr *Updater) {
560 ConstStructBuilder Builder(CGM, CGF);
561 if (!Builder.Build(Emitter, Base, Updater))
563 return Builder.Finalize(Updater->getType());
566 llvm::Constant *ConstStructBuilder::BuildStruct(CodeGenModule &CGM,
567 CodeGenFunction *CGF,
569 ConstStructBuilder Builder(CGM, CGF);
571 if (!Builder.Build(ILE))
574 return Builder.Finalize(ILE->getType());
577 llvm::Constant *ConstStructBuilder::BuildStruct(CodeGenModule &CGM,
578 CodeGenFunction *CGF,
581 ConstStructBuilder Builder(CGM, CGF);
583 const RecordDecl *RD = ValTy->castAs<RecordType>()->getDecl();
584 const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD);
585 Builder.Build(Val, RD, false, CD, CharUnits::Zero());
587 return Builder.Finalize(ValTy);
591 //===----------------------------------------------------------------------===//
593 //===----------------------------------------------------------------------===//
595 /// This class only needs to handle two cases:
596 /// 1) Literals (this is used by APValue emission to emit literals).
597 /// 2) Arrays, structs and unions (outside C++11 mode, we don't currently
598 /// constant fold these types).
599 class ConstExprEmitter :
600 public StmtVisitor<ConstExprEmitter, llvm::Constant*> {
602 CodeGenFunction *CGF;
603 llvm::LLVMContext &VMContext;
605 ConstExprEmitter(CodeGenModule &cgm, CodeGenFunction *cgf)
606 : CGM(cgm), CGF(cgf), VMContext(cgm.getLLVMContext()) {
609 //===--------------------------------------------------------------------===//
611 //===--------------------------------------------------------------------===//
613 llvm::Constant *VisitStmt(Stmt *S) {
617 llvm::Constant *VisitParenExpr(ParenExpr *PE) {
618 return Visit(PE->getSubExpr());
622 VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *PE) {
623 return Visit(PE->getReplacement());
626 llvm::Constant *VisitGenericSelectionExpr(GenericSelectionExpr *GE) {
627 return Visit(GE->getResultExpr());
630 llvm::Constant *VisitChooseExpr(ChooseExpr *CE) {
631 return Visit(CE->getChosenSubExpr());
634 llvm::Constant *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
635 return Visit(E->getInitializer());
638 llvm::Constant *VisitCastExpr(CastExpr* E) {
639 if (const auto *ECE = dyn_cast<ExplicitCastExpr>(E))
640 CGM.EmitExplicitCastExprType(ECE, CGF);
641 Expr *subExpr = E->getSubExpr();
642 llvm::Constant *C = CGM.EmitConstantExpr(subExpr, subExpr->getType(), CGF);
643 if (!C) return nullptr;
645 llvm::Type *destType = ConvertType(E->getType());
647 switch (E->getCastKind()) {
649 // GCC cast to union extension
650 assert(E->getType()->isUnionType() &&
651 "Destination type is not union type!");
653 // Build a struct with the union sub-element as the first member,
654 // and padded to the appropriate size
655 SmallVector<llvm::Constant*, 2> Elts;
656 SmallVector<llvm::Type*, 2> Types;
658 Types.push_back(C->getType());
659 unsigned CurSize = CGM.getDataLayout().getTypeAllocSize(C->getType());
660 unsigned TotalSize = CGM.getDataLayout().getTypeAllocSize(destType);
662 assert(CurSize <= TotalSize && "Union size mismatch!");
663 if (unsigned NumPadBytes = TotalSize - CurSize) {
664 llvm::Type *Ty = CGM.Int8Ty;
666 Ty = llvm::ArrayType::get(Ty, NumPadBytes);
668 Elts.push_back(llvm::UndefValue::get(Ty));
672 llvm::StructType* STy =
673 llvm::StructType::get(C->getType()->getContext(), Types, false);
674 return llvm::ConstantStruct::get(STy, Elts);
677 case CK_AddressSpaceConversion:
678 return llvm::ConstantExpr::getAddrSpaceCast(C, destType);
680 case CK_LValueToRValue:
681 case CK_AtomicToNonAtomic:
682 case CK_NonAtomicToAtomic:
684 case CK_ConstructorConversion:
687 case CK_Dependent: llvm_unreachable("saw dependent cast!");
689 case CK_BuiltinFnToFnPtr:
690 llvm_unreachable("builtin functions are handled elsewhere");
692 case CK_ReinterpretMemberPointer:
693 case CK_DerivedToBaseMemberPointer:
694 case CK_BaseToDerivedMemberPointer:
695 return CGM.getCXXABI().EmitMemberPointerConversion(E, C);
697 // These will never be supported.
698 case CK_ObjCObjectLValueCast:
699 case CK_ARCProduceObject:
700 case CK_ARCConsumeObject:
701 case CK_ARCReclaimReturnedObject:
702 case CK_ARCExtendBlockObject:
703 case CK_CopyAndAutoreleaseBlockObject:
706 // These don't need to be handled here because Evaluate knows how to
707 // evaluate them in the cases where they can be folded.
711 case CK_LValueBitCast:
712 case CK_NullToMemberPointer:
713 case CK_UserDefinedConversion:
714 case CK_CPointerToObjCPointerCast:
715 case CK_BlockPointerToObjCPointerCast:
716 case CK_AnyPointerToBlockPointerCast:
717 case CK_ArrayToPointerDecay:
718 case CK_FunctionToPointerDecay:
719 case CK_BaseToDerived:
720 case CK_DerivedToBase:
721 case CK_UncheckedDerivedToBase:
722 case CK_MemberPointerToBoolean:
724 case CK_FloatingRealToComplex:
725 case CK_FloatingComplexToReal:
726 case CK_FloatingComplexToBoolean:
727 case CK_FloatingComplexCast:
728 case CK_FloatingComplexToIntegralComplex:
729 case CK_IntegralRealToComplex:
730 case CK_IntegralComplexToReal:
731 case CK_IntegralComplexToBoolean:
732 case CK_IntegralComplexCast:
733 case CK_IntegralComplexToFloatingComplex:
734 case CK_PointerToIntegral:
735 case CK_PointerToBoolean:
736 case CK_NullToPointer:
737 case CK_IntegralCast:
738 case CK_BooleanToSignedIntegral:
739 case CK_IntegralToPointer:
740 case CK_IntegralToBoolean:
741 case CK_IntegralToFloating:
742 case CK_FloatingToIntegral:
743 case CK_FloatingToBoolean:
744 case CK_FloatingCast:
745 case CK_ZeroToOCLEvent:
748 llvm_unreachable("Invalid CastKind");
751 llvm::Constant *VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
752 return Visit(DAE->getExpr());
755 llvm::Constant *VisitCXXDefaultInitExpr(CXXDefaultInitExpr *DIE) {
756 // No need for a DefaultInitExprScope: we don't handle 'this' in a
757 // constant expression.
758 return Visit(DIE->getExpr());
761 llvm::Constant *VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E) {
762 return Visit(E->GetTemporaryExpr());
765 llvm::Constant *EmitArrayInitialization(InitListExpr *ILE) {
766 if (ILE->isStringLiteralInit())
767 return Visit(ILE->getInit(0));
769 llvm::ArrayType *AType =
770 cast<llvm::ArrayType>(ConvertType(ILE->getType()));
771 llvm::Type *ElemTy = AType->getElementType();
772 unsigned NumInitElements = ILE->getNumInits();
773 unsigned NumElements = AType->getNumElements();
775 // Initialising an array requires us to automatically
776 // initialise any elements that have not been initialised explicitly
777 unsigned NumInitableElts = std::min(NumInitElements, NumElements);
779 // Initialize remaining array elements.
780 // FIXME: This doesn't handle member pointers correctly!
781 llvm::Constant *fillC;
782 if (Expr *filler = ILE->getArrayFiller())
783 fillC = CGM.EmitConstantExpr(filler, filler->getType(), CGF);
785 fillC = llvm::Constant::getNullValue(ElemTy);
789 // Try to use a ConstantAggregateZero if we can.
790 if (fillC->isNullValue() && !NumInitableElts)
791 return llvm::ConstantAggregateZero::get(AType);
793 // Copy initializer elements.
794 std::vector<llvm::Constant*> Elts;
795 Elts.reserve(NumInitableElts + NumElements);
797 bool RewriteType = false;
798 for (unsigned i = 0; i < NumInitableElts; ++i) {
799 Expr *Init = ILE->getInit(i);
800 llvm::Constant *C = CGM.EmitConstantExpr(Init, Init->getType(), CGF);
803 RewriteType |= (C->getType() != ElemTy);
807 RewriteType |= (fillC->getType() != ElemTy);
808 Elts.resize(NumElements, fillC);
811 // FIXME: Try to avoid packing the array
812 std::vector<llvm::Type*> Types;
813 Types.reserve(NumInitableElts + NumElements);
814 for (unsigned i = 0, e = Elts.size(); i < e; ++i)
815 Types.push_back(Elts[i]->getType());
816 llvm::StructType *SType = llvm::StructType::get(AType->getContext(),
818 return llvm::ConstantStruct::get(SType, Elts);
821 return llvm::ConstantArray::get(AType, Elts);
824 llvm::Constant *EmitRecordInitialization(InitListExpr *ILE) {
825 return ConstStructBuilder::BuildStruct(CGM, CGF, ILE);
828 llvm::Constant *VisitImplicitValueInitExpr(ImplicitValueInitExpr* E) {
829 return CGM.EmitNullConstant(E->getType());
832 llvm::Constant *VisitInitListExpr(InitListExpr *ILE) {
833 if (ILE->getType()->isArrayType())
834 return EmitArrayInitialization(ILE);
836 if (ILE->getType()->isRecordType())
837 return EmitRecordInitialization(ILE);
842 llvm::Constant *EmitDesignatedInitUpdater(llvm::Constant *Base,
843 InitListExpr *Updater) {
844 QualType ExprType = Updater->getType();
846 if (ExprType->isArrayType()) {
847 llvm::ArrayType *AType = cast<llvm::ArrayType>(ConvertType(ExprType));
848 llvm::Type *ElemType = AType->getElementType();
850 unsigned NumInitElements = Updater->getNumInits();
851 unsigned NumElements = AType->getNumElements();
853 std::vector<llvm::Constant *> Elts;
854 Elts.reserve(NumElements);
856 if (llvm::ConstantDataArray *DataArray =
857 dyn_cast<llvm::ConstantDataArray>(Base))
858 for (unsigned i = 0; i != NumElements; ++i)
859 Elts.push_back(DataArray->getElementAsConstant(i));
860 else if (llvm::ConstantArray *Array =
861 dyn_cast<llvm::ConstantArray>(Base))
862 for (unsigned i = 0; i != NumElements; ++i)
863 Elts.push_back(Array->getOperand(i));
865 return nullptr; // FIXME: other array types not implemented
867 llvm::Constant *fillC = nullptr;
868 if (Expr *filler = Updater->getArrayFiller())
869 if (!isa<NoInitExpr>(filler))
870 fillC = CGM.EmitConstantExpr(filler, filler->getType(), CGF);
871 bool RewriteType = (fillC && fillC->getType() != ElemType);
873 for (unsigned i = 0; i != NumElements; ++i) {
874 Expr *Init = nullptr;
875 if (i < NumInitElements)
876 Init = Updater->getInit(i);
880 else if (!Init || isa<NoInitExpr>(Init))
882 else if (InitListExpr *ChildILE = dyn_cast<InitListExpr>(Init))
883 Elts[i] = EmitDesignatedInitUpdater(Elts[i], ChildILE);
885 Elts[i] = CGM.EmitConstantExpr(Init, Init->getType(), CGF);
889 RewriteType |= (Elts[i]->getType() != ElemType);
893 std::vector<llvm::Type *> Types;
894 Types.reserve(NumElements);
895 for (unsigned i = 0; i != NumElements; ++i)
896 Types.push_back(Elts[i]->getType());
897 llvm::StructType *SType = llvm::StructType::get(AType->getContext(),
899 return llvm::ConstantStruct::get(SType, Elts);
902 return llvm::ConstantArray::get(AType, Elts);
905 if (ExprType->isRecordType())
906 return ConstStructBuilder::BuildStruct(CGM, CGF, this,
907 dyn_cast<llvm::ConstantStruct>(Base), Updater);
912 llvm::Constant *VisitDesignatedInitUpdateExpr(DesignatedInitUpdateExpr *E) {
913 return EmitDesignatedInitUpdater(
914 CGM.EmitConstantExpr(E->getBase(), E->getType(), CGF),
918 llvm::Constant *VisitCXXConstructExpr(CXXConstructExpr *E) {
919 if (!E->getConstructor()->isTrivial())
922 QualType Ty = E->getType();
924 // FIXME: We should not have to call getBaseElementType here.
925 const RecordType *RT =
926 CGM.getContext().getBaseElementType(Ty)->getAs<RecordType>();
927 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
929 // If the class doesn't have a trivial destructor, we can't emit it as a
931 if (!RD->hasTrivialDestructor())
934 // Only copy and default constructors can be trivial.
937 if (E->getNumArgs()) {
938 assert(E->getNumArgs() == 1 && "trivial ctor with > 1 argument");
939 assert(E->getConstructor()->isCopyOrMoveConstructor() &&
940 "trivial ctor has argument but isn't a copy/move ctor");
942 Expr *Arg = E->getArg(0);
943 assert(CGM.getContext().hasSameUnqualifiedType(Ty, Arg->getType()) &&
944 "argument to copy ctor is of wrong type");
949 return CGM.EmitNullConstant(Ty);
952 llvm::Constant *VisitStringLiteral(StringLiteral *E) {
953 return CGM.GetConstantArrayFromStringLiteral(E);
956 llvm::Constant *VisitObjCEncodeExpr(ObjCEncodeExpr *E) {
957 // This must be an @encode initializing an array in a static initializer.
958 // Don't emit it as the address of the string, emit the string data itself
959 // as an inline array.
961 CGM.getContext().getObjCEncodingForType(E->getEncodedType(), Str);
962 QualType T = E->getType();
963 if (T->getTypeClass() == Type::TypeOfExpr)
964 T = cast<TypeOfExprType>(T)->getUnderlyingExpr()->getType();
965 const ConstantArrayType *CAT = cast<ConstantArrayType>(T);
967 // Resize the string to the right size, adding zeros at the end, or
968 // truncating as needed.
969 Str.resize(CAT->getSize().getZExtValue(), '\0');
970 return llvm::ConstantDataArray::getString(VMContext, Str, false);
973 llvm::Constant *VisitUnaryExtension(const UnaryOperator *E) {
974 return Visit(E->getSubExpr());
978 llvm::Type *ConvertType(QualType T) {
979 return CGM.getTypes().ConvertType(T);
983 ConstantAddress EmitLValue(APValue::LValueBase LVBase) {
984 if (const ValueDecl *Decl = LVBase.dyn_cast<const ValueDecl*>()) {
985 if (Decl->hasAttr<WeakRefAttr>())
986 return CGM.GetWeakRefReference(Decl);
987 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Decl))
988 return ConstantAddress(CGM.GetAddrOfFunction(FD), CharUnits::One());
989 if (const VarDecl* VD = dyn_cast<VarDecl>(Decl)) {
990 // We can never refer to a variable with local storage.
991 if (!VD->hasLocalStorage()) {
992 CharUnits Align = CGM.getContext().getDeclAlign(VD);
993 if (VD->isFileVarDecl() || VD->hasExternalStorage())
994 return ConstantAddress(CGM.GetAddrOfGlobalVar(VD), Align);
995 else if (VD->isLocalVarDecl()) {
996 auto Ptr = CGM.getOrCreateStaticVarDecl(
997 *VD, CGM.getLLVMLinkageVarDefinition(VD, /*isConstant=*/false));
998 return ConstantAddress(Ptr, Align);
1002 return ConstantAddress::invalid();
1005 Expr *E = const_cast<Expr*>(LVBase.get<const Expr*>());
1006 switch (E->getStmtClass()) {
1008 case Expr::CompoundLiteralExprClass: {
1009 // Note that due to the nature of compound literals, this is guaranteed
1010 // to be the only use of the variable, so we just generate it here.
1011 CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E);
1012 llvm::Constant* C = CGM.EmitConstantExpr(CLE->getInitializer(),
1013 CLE->getType(), CGF);
1014 // FIXME: "Leaked" on failure.
1015 if (!C) return ConstantAddress::invalid();
1017 CharUnits Align = CGM.getContext().getTypeAlignInChars(E->getType());
1019 auto GV = new llvm::GlobalVariable(CGM.getModule(), C->getType(),
1020 E->getType().isConstant(CGM.getContext()),
1021 llvm::GlobalValue::InternalLinkage,
1022 C, ".compoundliteral", nullptr,
1023 llvm::GlobalVariable::NotThreadLocal,
1024 CGM.getContext().getTargetAddressSpace(E->getType()));
1025 GV->setAlignment(Align.getQuantity());
1026 return ConstantAddress(GV, Align);
1028 case Expr::StringLiteralClass:
1029 return CGM.GetAddrOfConstantStringFromLiteral(cast<StringLiteral>(E));
1030 case Expr::ObjCEncodeExprClass:
1031 return CGM.GetAddrOfConstantStringFromObjCEncode(cast<ObjCEncodeExpr>(E));
1032 case Expr::ObjCStringLiteralClass: {
1033 ObjCStringLiteral* SL = cast<ObjCStringLiteral>(E);
1035 CGM.getObjCRuntime().GenerateConstantString(SL->getString());
1036 return C.getElementBitCast(ConvertType(E->getType()));
1038 case Expr::PredefinedExprClass: {
1039 unsigned Type = cast<PredefinedExpr>(E)->getIdentType();
1041 LValue Res = CGF->EmitPredefinedLValue(cast<PredefinedExpr>(E));
1042 return cast<ConstantAddress>(Res.getAddress());
1043 } else if (Type == PredefinedExpr::PrettyFunction) {
1044 return CGM.GetAddrOfConstantCString("top level", ".tmp");
1047 return CGM.GetAddrOfConstantCString("", ".tmp");
1049 case Expr::AddrLabelExprClass: {
1050 assert(CGF && "Invalid address of label expression outside function.");
1051 llvm::Constant *Ptr =
1052 CGF->GetAddrOfLabel(cast<AddrLabelExpr>(E)->getLabel());
1053 Ptr = llvm::ConstantExpr::getBitCast(Ptr, ConvertType(E->getType()));
1054 return ConstantAddress(Ptr, CharUnits::One());
1056 case Expr::CallExprClass: {
1057 CallExpr* CE = cast<CallExpr>(E);
1058 unsigned builtin = CE->getBuiltinCallee();
1060 Builtin::BI__builtin___CFStringMakeConstantString &&
1062 Builtin::BI__builtin___NSStringMakeConstantString)
1064 const Expr *Arg = CE->getArg(0)->IgnoreParenCasts();
1065 const StringLiteral *Literal = cast<StringLiteral>(Arg);
1067 Builtin::BI__builtin___NSStringMakeConstantString) {
1068 return CGM.getObjCRuntime().GenerateConstantString(Literal);
1070 // FIXME: need to deal with UCN conversion issues.
1071 return CGM.GetAddrOfConstantCFString(Literal);
1073 case Expr::BlockExprClass: {
1074 std::string FunctionName;
1076 FunctionName = CGF->CurFn->getName();
1078 FunctionName = "global";
1080 // This is not really an l-value.
1081 llvm::Constant *Ptr =
1082 CGM.GetAddrOfGlobalBlock(cast<BlockExpr>(E), FunctionName.c_str());
1083 return ConstantAddress(Ptr, CGM.getPointerAlign());
1085 case Expr::CXXTypeidExprClass: {
1086 CXXTypeidExpr *Typeid = cast<CXXTypeidExpr>(E);
1088 if (Typeid->isTypeOperand())
1089 T = Typeid->getTypeOperand(CGM.getContext());
1091 T = Typeid->getExprOperand()->getType();
1092 return ConstantAddress(CGM.GetAddrOfRTTIDescriptor(T),
1093 CGM.getPointerAlign());
1095 case Expr::CXXUuidofExprClass: {
1096 return CGM.GetAddrOfUuidDescriptor(cast<CXXUuidofExpr>(E));
1098 case Expr::MaterializeTemporaryExprClass: {
1099 MaterializeTemporaryExpr *MTE = cast<MaterializeTemporaryExpr>(E);
1100 assert(MTE->getStorageDuration() == SD_Static);
1101 SmallVector<const Expr *, 2> CommaLHSs;
1102 SmallVector<SubobjectAdjustment, 2> Adjustments;
1103 const Expr *Inner = MTE->GetTemporaryExpr()
1104 ->skipRValueSubobjectAdjustments(CommaLHSs, Adjustments);
1105 return CGM.GetAddrOfGlobalTemporary(MTE, Inner);
1109 return ConstantAddress::invalid();
1113 } // end anonymous namespace.
1115 bool ConstStructBuilder::Build(ConstExprEmitter *Emitter,
1116 llvm::ConstantStruct *Base,
1117 InitListExpr *Updater) {
1118 assert(Base && "base expression should not be empty");
1120 QualType ExprType = Updater->getType();
1121 RecordDecl *RD = ExprType->getAs<RecordType>()->getDecl();
1122 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
1123 const llvm::StructLayout *BaseLayout = CGM.getDataLayout().getStructLayout(
1125 unsigned FieldNo = -1;
1126 unsigned ElementNo = 0;
1128 for (FieldDecl *Field : RD->fields()) {
1131 if (RD->isUnion() && Updater->getInitializedFieldInUnion() != Field)
1134 // Skip anonymous bitfields.
1135 if (Field->isUnnamedBitfield())
1138 llvm::Constant *EltInit = Base->getOperand(ElementNo);
1140 // Bail out if the type of the ConstantStruct does not have the same layout
1141 // as the type of the InitListExpr.
1142 if (CGM.getTypes().ConvertType(Field->getType()) != EltInit->getType() ||
1143 Layout.getFieldOffset(ElementNo) !=
1144 BaseLayout->getElementOffsetInBits(ElementNo))
1147 // Get the initializer. If we encounter an empty field or a NoInitExpr,
1148 // we use values from the base expression.
1149 Expr *Init = nullptr;
1150 if (ElementNo < Updater->getNumInits())
1151 Init = Updater->getInit(ElementNo);
1153 if (!Init || isa<NoInitExpr>(Init))
1155 else if (InitListExpr *ChildILE = dyn_cast<InitListExpr>(Init))
1156 EltInit = Emitter->EmitDesignatedInitUpdater(EltInit, ChildILE);
1158 EltInit = CGM.EmitConstantExpr(Init, Field->getType(), CGF);
1165 if (!Field->isBitField())
1166 AppendField(Field, Layout.getFieldOffset(FieldNo), EltInit);
1167 else if (llvm::ConstantInt *CI = dyn_cast<llvm::ConstantInt>(EltInit))
1168 AppendBitField(Field, Layout.getFieldOffset(FieldNo), CI);
1170 // Initializing a bitfield with a non-trivial constant?
1177 llvm::Constant *CodeGenModule::EmitConstantInit(const VarDecl &D,
1178 CodeGenFunction *CGF) {
1179 // Make a quick check if variable can be default NULL initialized
1180 // and avoid going through rest of code which may do, for c++11,
1181 // initialization of memory to all NULLs.
1182 if (!D.hasLocalStorage()) {
1183 QualType Ty = D.getType();
1184 if (Ty->isArrayType())
1185 Ty = Context.getBaseElementType(Ty);
1186 if (Ty->isRecordType())
1187 if (const CXXConstructExpr *E =
1188 dyn_cast_or_null<CXXConstructExpr>(D.getInit())) {
1189 const CXXConstructorDecl *CD = E->getConstructor();
1190 if (CD->isTrivial() && CD->isDefaultConstructor())
1191 return EmitNullConstant(D.getType());
1195 if (const APValue *Value = D.evaluateValue())
1196 return EmitConstantValueForMemory(*Value, D.getType(), CGF);
1198 // FIXME: Implement C++11 [basic.start.init]p2: if the initializer of a
1199 // reference is a constant expression, and the reference binds to a temporary,
1200 // then constant initialization is performed. ConstExprEmitter will
1201 // incorrectly emit a prvalue constant in this case, and the calling code
1202 // interprets that as the (pointer) value of the reference, rather than the
1203 // desired value of the referee.
1204 if (D.getType()->isReferenceType())
1207 const Expr *E = D.getInit();
1208 assert(E && "No initializer to emit");
1210 llvm::Constant* C = ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E));
1211 if (C && C->getType()->isIntegerTy(1)) {
1212 llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType());
1213 C = llvm::ConstantExpr::getZExt(C, BoolTy);
1218 llvm::Constant *CodeGenModule::EmitConstantExpr(const Expr *E,
1220 CodeGenFunction *CGF) {
1221 Expr::EvalResult Result;
1223 bool Success = false;
1225 if (DestType->isReferenceType())
1226 Success = E->EvaluateAsLValue(Result, Context);
1228 Success = E->EvaluateAsRValue(Result, Context);
1230 llvm::Constant *C = nullptr;
1231 if (Success && !Result.HasSideEffects)
1232 C = EmitConstantValue(Result.Val, DestType, CGF);
1234 C = ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E));
1236 if (C && C->getType()->isIntegerTy(1)) {
1237 llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType());
1238 C = llvm::ConstantExpr::getZExt(C, BoolTy);
1243 llvm::Constant *CodeGenModule::EmitConstantValue(const APValue &Value,
1245 CodeGenFunction *CGF) {
1246 // For an _Atomic-qualified constant, we may need to add tail padding.
1247 if (auto *AT = DestType->getAs<AtomicType>()) {
1248 QualType InnerType = AT->getValueType();
1249 auto *Inner = EmitConstantValue(Value, InnerType, CGF);
1251 uint64_t InnerSize = Context.getTypeSize(InnerType);
1252 uint64_t OuterSize = Context.getTypeSize(DestType);
1253 if (InnerSize == OuterSize)
1256 assert(InnerSize < OuterSize && "emitted over-large constant for atomic");
1257 llvm::Constant *Elts[] = {
1259 llvm::ConstantAggregateZero::get(
1260 llvm::ArrayType::get(Int8Ty, (OuterSize - InnerSize) / 8))
1262 return llvm::ConstantStruct::getAnon(Elts);
1265 switch (Value.getKind()) {
1266 case APValue::Uninitialized:
1267 llvm_unreachable("Constant expressions should be initialized.");
1268 case APValue::LValue: {
1269 llvm::Type *DestTy = getTypes().ConvertTypeForMem(DestType);
1270 llvm::Constant *Offset =
1271 llvm::ConstantInt::get(Int64Ty, Value.getLValueOffset().getQuantity());
1273 llvm::Constant *C = nullptr;
1274 if (APValue::LValueBase LVBase = Value.getLValueBase()) {
1275 // An array can be represented as an lvalue referring to the base.
1276 if (isa<llvm::ArrayType>(DestTy)) {
1277 assert(Offset->isNullValue() && "offset on array initializer");
1278 return ConstExprEmitter(*this, CGF).Visit(
1279 const_cast<Expr*>(LVBase.get<const Expr*>()));
1282 C = ConstExprEmitter(*this, CGF).EmitLValue(LVBase).getPointer();
1284 // Apply offset if necessary.
1285 if (!Offset->isNullValue()) {
1286 unsigned AS = C->getType()->getPointerAddressSpace();
1287 llvm::Type *CharPtrTy = Int8Ty->getPointerTo(AS);
1288 llvm::Constant *Casted = llvm::ConstantExpr::getBitCast(C, CharPtrTy);
1289 Casted = llvm::ConstantExpr::getGetElementPtr(Int8Ty, Casted, Offset);
1290 C = llvm::ConstantExpr::getPointerCast(Casted, C->getType());
1293 // Convert to the appropriate type; this could be an lvalue for
1295 if (isa<llvm::PointerType>(DestTy))
1296 return llvm::ConstantExpr::getPointerCast(C, DestTy);
1298 return llvm::ConstantExpr::getPtrToInt(C, DestTy);
1302 // Convert to the appropriate type; this could be an lvalue for
1304 if (isa<llvm::PointerType>(DestTy))
1305 return llvm::ConstantExpr::getIntToPtr(C, DestTy);
1307 // If the types don't match this should only be a truncate.
1308 if (C->getType() != DestTy)
1309 return llvm::ConstantExpr::getTrunc(C, DestTy);
1315 return llvm::ConstantInt::get(VMContext, Value.getInt());
1316 case APValue::ComplexInt: {
1317 llvm::Constant *Complex[2];
1319 Complex[0] = llvm::ConstantInt::get(VMContext,
1320 Value.getComplexIntReal());
1321 Complex[1] = llvm::ConstantInt::get(VMContext,
1322 Value.getComplexIntImag());
1324 // FIXME: the target may want to specify that this is packed.
1325 llvm::StructType *STy = llvm::StructType::get(Complex[0]->getType(),
1326 Complex[1]->getType(),
1328 return llvm::ConstantStruct::get(STy, Complex);
1330 case APValue::Float: {
1331 const llvm::APFloat &Init = Value.getFloat();
1332 if (&Init.getSemantics() == &llvm::APFloat::IEEEhalf &&
1333 !Context.getLangOpts().NativeHalfType &&
1334 !Context.getLangOpts().HalfArgsAndReturns)
1335 return llvm::ConstantInt::get(VMContext, Init.bitcastToAPInt());
1337 return llvm::ConstantFP::get(VMContext, Init);
1339 case APValue::ComplexFloat: {
1340 llvm::Constant *Complex[2];
1342 Complex[0] = llvm::ConstantFP::get(VMContext,
1343 Value.getComplexFloatReal());
1344 Complex[1] = llvm::ConstantFP::get(VMContext,
1345 Value.getComplexFloatImag());
1347 // FIXME: the target may want to specify that this is packed.
1348 llvm::StructType *STy = llvm::StructType::get(Complex[0]->getType(),
1349 Complex[1]->getType(),
1351 return llvm::ConstantStruct::get(STy, Complex);
1353 case APValue::Vector: {
1354 unsigned NumElts = Value.getVectorLength();
1355 SmallVector<llvm::Constant *, 4> Inits(NumElts);
1357 for (unsigned I = 0; I != NumElts; ++I) {
1358 const APValue &Elt = Value.getVectorElt(I);
1360 Inits[I] = llvm::ConstantInt::get(VMContext, Elt.getInt());
1361 else if (Elt.isFloat())
1362 Inits[I] = llvm::ConstantFP::get(VMContext, Elt.getFloat());
1364 llvm_unreachable("unsupported vector element type");
1366 return llvm::ConstantVector::get(Inits);
1368 case APValue::AddrLabelDiff: {
1369 const AddrLabelExpr *LHSExpr = Value.getAddrLabelDiffLHS();
1370 const AddrLabelExpr *RHSExpr = Value.getAddrLabelDiffRHS();
1371 llvm::Constant *LHS = EmitConstantExpr(LHSExpr, LHSExpr->getType(), CGF);
1372 llvm::Constant *RHS = EmitConstantExpr(RHSExpr, RHSExpr->getType(), CGF);
1374 // Compute difference
1375 llvm::Type *ResultType = getTypes().ConvertType(DestType);
1376 LHS = llvm::ConstantExpr::getPtrToInt(LHS, IntPtrTy);
1377 RHS = llvm::ConstantExpr::getPtrToInt(RHS, IntPtrTy);
1378 llvm::Constant *AddrLabelDiff = llvm::ConstantExpr::getSub(LHS, RHS);
1380 // LLVM is a bit sensitive about the exact format of the
1381 // address-of-label difference; make sure to truncate after
1383 return llvm::ConstantExpr::getTruncOrBitCast(AddrLabelDiff, ResultType);
1385 case APValue::Struct:
1386 case APValue::Union:
1387 return ConstStructBuilder::BuildStruct(*this, CGF, Value, DestType);
1388 case APValue::Array: {
1389 const ArrayType *CAT = Context.getAsArrayType(DestType);
1390 unsigned NumElements = Value.getArraySize();
1391 unsigned NumInitElts = Value.getArrayInitializedElts();
1393 // Emit array filler, if there is one.
1394 llvm::Constant *Filler = nullptr;
1395 if (Value.hasArrayFiller())
1396 Filler = EmitConstantValueForMemory(Value.getArrayFiller(),
1397 CAT->getElementType(), CGF);
1399 // Emit initializer elements.
1400 llvm::Type *CommonElementType =
1401 getTypes().ConvertType(CAT->getElementType());
1403 // Try to use a ConstantAggregateZero if we can.
1404 if (Filler && Filler->isNullValue() && !NumInitElts) {
1405 llvm::ArrayType *AType =
1406 llvm::ArrayType::get(CommonElementType, NumElements);
1407 return llvm::ConstantAggregateZero::get(AType);
1410 std::vector<llvm::Constant*> Elts;
1411 Elts.reserve(NumElements);
1412 for (unsigned I = 0; I < NumElements; ++I) {
1413 llvm::Constant *C = Filler;
1414 if (I < NumInitElts)
1415 C = EmitConstantValueForMemory(Value.getArrayInitializedElt(I),
1416 CAT->getElementType(), CGF);
1418 assert(Filler && "Missing filler for implicit elements of initializer");
1420 CommonElementType = C->getType();
1421 else if (C->getType() != CommonElementType)
1422 CommonElementType = nullptr;
1426 if (!CommonElementType) {
1427 // FIXME: Try to avoid packing the array
1428 std::vector<llvm::Type*> Types;
1429 Types.reserve(NumElements);
1430 for (unsigned i = 0, e = Elts.size(); i < e; ++i)
1431 Types.push_back(Elts[i]->getType());
1432 llvm::StructType *SType = llvm::StructType::get(VMContext, Types, true);
1433 return llvm::ConstantStruct::get(SType, Elts);
1436 llvm::ArrayType *AType =
1437 llvm::ArrayType::get(CommonElementType, NumElements);
1438 return llvm::ConstantArray::get(AType, Elts);
1440 case APValue::MemberPointer:
1441 return getCXXABI().EmitMemberPointer(Value, DestType);
1443 llvm_unreachable("Unknown APValue kind");
1447 CodeGenModule::EmitConstantValueForMemory(const APValue &Value,
1449 CodeGenFunction *CGF) {
1450 llvm::Constant *C = EmitConstantValue(Value, DestType, CGF);
1451 if (C->getType()->isIntegerTy(1)) {
1452 llvm::Type *BoolTy = getTypes().ConvertTypeForMem(DestType);
1453 C = llvm::ConstantExpr::getZExt(C, BoolTy);
1459 CodeGenModule::GetAddrOfConstantCompoundLiteral(const CompoundLiteralExpr *E) {
1460 assert(E->isFileScope() && "not a file-scope compound literal expr");
1461 return ConstExprEmitter(*this, nullptr).EmitLValue(E);
1465 CodeGenModule::getMemberPointerConstant(const UnaryOperator *uo) {
1466 // Member pointer constants always have a very particular form.
1467 const MemberPointerType *type = cast<MemberPointerType>(uo->getType());
1468 const ValueDecl *decl = cast<DeclRefExpr>(uo->getSubExpr())->getDecl();
1470 // A member function pointer.
1471 if (const CXXMethodDecl *method = dyn_cast<CXXMethodDecl>(decl))
1472 return getCXXABI().EmitMemberFunctionPointer(method);
1474 // Otherwise, a member data pointer.
1475 uint64_t fieldOffset = getContext().getFieldOffset(decl);
1476 CharUnits chars = getContext().toCharUnitsFromBits((int64_t) fieldOffset);
1477 return getCXXABI().EmitMemberDataPointer(type, chars);
1480 static llvm::Constant *EmitNullConstantForBase(CodeGenModule &CGM,
1481 llvm::Type *baseType,
1482 const CXXRecordDecl *base);
1484 static llvm::Constant *EmitNullConstant(CodeGenModule &CGM,
1485 const CXXRecordDecl *record,
1486 bool asCompleteObject) {
1487 const CGRecordLayout &layout = CGM.getTypes().getCGRecordLayout(record);
1488 llvm::StructType *structure =
1489 (asCompleteObject ? layout.getLLVMType()
1490 : layout.getBaseSubobjectLLVMType());
1492 unsigned numElements = structure->getNumElements();
1493 std::vector<llvm::Constant *> elements(numElements);
1495 // Fill in all the bases.
1496 for (const auto &I : record->bases()) {
1497 if (I.isVirtual()) {
1498 // Ignore virtual bases; if we're laying out for a complete
1499 // object, we'll lay these out later.
1503 const CXXRecordDecl *base =
1504 cast<CXXRecordDecl>(I.getType()->castAs<RecordType>()->getDecl());
1506 // Ignore empty bases.
1507 if (base->isEmpty())
1510 unsigned fieldIndex = layout.getNonVirtualBaseLLVMFieldNo(base);
1511 llvm::Type *baseType = structure->getElementType(fieldIndex);
1512 elements[fieldIndex] = EmitNullConstantForBase(CGM, baseType, base);
1515 // Fill in all the fields.
1516 for (const auto *Field : record->fields()) {
1517 // Fill in non-bitfields. (Bitfields always use a zero pattern, which we
1518 // will fill in later.)
1519 if (!Field->isBitField()) {
1520 unsigned fieldIndex = layout.getLLVMFieldNo(Field);
1521 elements[fieldIndex] = CGM.EmitNullConstant(Field->getType());
1524 // For unions, stop after the first named field.
1525 if (record->isUnion()) {
1526 if (Field->getIdentifier())
1528 if (const auto *FieldRD =
1529 dyn_cast_or_null<RecordDecl>(Field->getType()->getAsTagDecl()))
1530 if (FieldRD->findFirstNamedDataMember())
1535 // Fill in the virtual bases, if we're working with the complete object.
1536 if (asCompleteObject) {
1537 for (const auto &I : record->vbases()) {
1538 const CXXRecordDecl *base =
1539 cast<CXXRecordDecl>(I.getType()->castAs<RecordType>()->getDecl());
1541 // Ignore empty bases.
1542 if (base->isEmpty())
1545 unsigned fieldIndex = layout.getVirtualBaseIndex(base);
1547 // We might have already laid this field out.
1548 if (elements[fieldIndex]) continue;
1550 llvm::Type *baseType = structure->getElementType(fieldIndex);
1551 elements[fieldIndex] = EmitNullConstantForBase(CGM, baseType, base);
1555 // Now go through all other fields and zero them out.
1556 for (unsigned i = 0; i != numElements; ++i) {
1558 elements[i] = llvm::Constant::getNullValue(structure->getElementType(i));
1561 return llvm::ConstantStruct::get(structure, elements);
1564 /// Emit the null constant for a base subobject.
1565 static llvm::Constant *EmitNullConstantForBase(CodeGenModule &CGM,
1566 llvm::Type *baseType,
1567 const CXXRecordDecl *base) {
1568 const CGRecordLayout &baseLayout = CGM.getTypes().getCGRecordLayout(base);
1570 // Just zero out bases that don't have any pointer to data members.
1571 if (baseLayout.isZeroInitializableAsBase())
1572 return llvm::Constant::getNullValue(baseType);
1574 // Otherwise, we can just use its null constant.
1575 return EmitNullConstant(CGM, base, /*asCompleteObject=*/false);
1578 llvm::Constant *CodeGenModule::EmitNullConstant(QualType T) {
1579 if (getTypes().isZeroInitializable(T))
1580 return llvm::Constant::getNullValue(getTypes().ConvertTypeForMem(T));
1582 if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(T)) {
1583 llvm::ArrayType *ATy =
1584 cast<llvm::ArrayType>(getTypes().ConvertTypeForMem(T));
1586 QualType ElementTy = CAT->getElementType();
1588 llvm::Constant *Element = EmitNullConstant(ElementTy);
1589 unsigned NumElements = CAT->getSize().getZExtValue();
1590 SmallVector<llvm::Constant *, 8> Array(NumElements, Element);
1591 return llvm::ConstantArray::get(ATy, Array);
1594 if (const RecordType *RT = T->getAs<RecordType>()) {
1595 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
1596 return ::EmitNullConstant(*this, RD, /*complete object*/ true);
1599 assert(T->isMemberDataPointerType() &&
1600 "Should only see pointers to data members here!");
1602 return getCXXABI().EmitNullMemberPointer(T->castAs<MemberPointerType>());
1606 CodeGenModule::EmitNullConstantForBase(const CXXRecordDecl *Record) {
1607 return ::EmitNullConstant(*this, Record, false);