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 "TargetInfo.h"
20 #include "clang/AST/APValue.h"
21 #include "clang/AST/ASTContext.h"
22 #include "clang/AST/RecordLayout.h"
23 #include "clang/AST/StmtVisitor.h"
24 #include "clang/Basic/Builtins.h"
25 #include "llvm/IR/Constants.h"
26 #include "llvm/IR/DataLayout.h"
27 #include "llvm/IR/Function.h"
28 #include "llvm/IR/GlobalVariable.h"
29 using namespace clang;
30 using namespace CodeGen;
32 //===----------------------------------------------------------------------===//
34 //===----------------------------------------------------------------------===//
37 class ConstExprEmitter;
38 class ConstStructBuilder {
43 CharUnits NextFieldOffsetInChars;
44 CharUnits LLVMStructAlignment;
45 SmallVector<llvm::Constant *, 32> Elements;
47 static llvm::Constant *BuildStruct(CodeGenModule &CGM, CodeGenFunction *CFG,
48 ConstExprEmitter *Emitter,
49 llvm::ConstantStruct *Base,
50 InitListExpr *Updater);
51 static llvm::Constant *BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF,
53 static llvm::Constant *BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF,
54 const APValue &Value, QualType ValTy);
57 ConstStructBuilder(CodeGenModule &CGM, CodeGenFunction *CGF)
58 : CGM(CGM), CGF(CGF), Packed(false),
59 NextFieldOffsetInChars(CharUnits::Zero()),
60 LLVMStructAlignment(CharUnits::One()) { }
62 void AppendField(const FieldDecl *Field, uint64_t FieldOffset,
63 llvm::Constant *InitExpr);
65 void AppendBytes(CharUnits FieldOffsetInChars, llvm::Constant *InitCst);
67 void AppendBitField(const FieldDecl *Field, uint64_t FieldOffset,
68 llvm::ConstantInt *InitExpr);
70 void AppendPadding(CharUnits PadSize);
72 void AppendTailPadding(CharUnits RecordSize);
74 void ConvertStructToPacked();
76 bool Build(InitListExpr *ILE);
77 bool Build(ConstExprEmitter *Emitter, llvm::ConstantStruct *Base,
78 InitListExpr *Updater);
79 void Build(const APValue &Val, const RecordDecl *RD, bool IsPrimaryBase,
80 const CXXRecordDecl *VTableClass, CharUnits BaseOffset);
81 llvm::Constant *Finalize(QualType Ty);
83 CharUnits getAlignment(const llvm::Constant *C) const {
84 if (Packed) return CharUnits::One();
85 return CharUnits::fromQuantity(
86 CGM.getDataLayout().getABITypeAlignment(C->getType()));
89 CharUnits getSizeInChars(const llvm::Constant *C) const {
90 return CharUnits::fromQuantity(
91 CGM.getDataLayout().getTypeAllocSize(C->getType()));
95 void ConstStructBuilder::
96 AppendField(const FieldDecl *Field, uint64_t FieldOffset,
97 llvm::Constant *InitCst) {
98 const ASTContext &Context = CGM.getContext();
100 CharUnits FieldOffsetInChars = Context.toCharUnitsFromBits(FieldOffset);
102 AppendBytes(FieldOffsetInChars, InitCst);
105 void ConstStructBuilder::
106 AppendBytes(CharUnits FieldOffsetInChars, llvm::Constant *InitCst) {
108 assert(NextFieldOffsetInChars <= FieldOffsetInChars
109 && "Field offset mismatch!");
111 CharUnits FieldAlignment = getAlignment(InitCst);
113 // Round up the field offset to the alignment of the field type.
114 CharUnits AlignedNextFieldOffsetInChars =
115 NextFieldOffsetInChars.alignTo(FieldAlignment);
117 if (AlignedNextFieldOffsetInChars < FieldOffsetInChars) {
118 // We need to append padding.
119 AppendPadding(FieldOffsetInChars - NextFieldOffsetInChars);
121 assert(NextFieldOffsetInChars == FieldOffsetInChars &&
122 "Did not add enough padding!");
124 AlignedNextFieldOffsetInChars =
125 NextFieldOffsetInChars.alignTo(FieldAlignment);
128 if (AlignedNextFieldOffsetInChars > FieldOffsetInChars) {
129 assert(!Packed && "Alignment is wrong even with a packed struct!");
131 // Convert the struct to a packed struct.
132 ConvertStructToPacked();
134 // After we pack the struct, we may need to insert padding.
135 if (NextFieldOffsetInChars < FieldOffsetInChars) {
136 // We need to append padding.
137 AppendPadding(FieldOffsetInChars - NextFieldOffsetInChars);
139 assert(NextFieldOffsetInChars == FieldOffsetInChars &&
140 "Did not add enough padding!");
142 AlignedNextFieldOffsetInChars = NextFieldOffsetInChars;
146 Elements.push_back(InitCst);
147 NextFieldOffsetInChars = AlignedNextFieldOffsetInChars +
148 getSizeInChars(InitCst);
151 assert(LLVMStructAlignment == CharUnits::One() &&
152 "Packed struct not byte-aligned!");
154 LLVMStructAlignment = std::max(LLVMStructAlignment, FieldAlignment);
157 void ConstStructBuilder::AppendBitField(const FieldDecl *Field,
158 uint64_t FieldOffset,
159 llvm::ConstantInt *CI) {
160 const ASTContext &Context = CGM.getContext();
161 const uint64_t CharWidth = Context.getCharWidth();
162 uint64_t NextFieldOffsetInBits = Context.toBits(NextFieldOffsetInChars);
163 if (FieldOffset > NextFieldOffsetInBits) {
164 // We need to add padding.
165 CharUnits PadSize = Context.toCharUnitsFromBits(
166 llvm::alignTo(FieldOffset - NextFieldOffsetInBits,
167 Context.getTargetInfo().getCharAlign()));
169 AppendPadding(PadSize);
172 uint64_t FieldSize = Field->getBitWidthValue(Context);
174 llvm::APInt FieldValue = CI->getValue();
176 // Promote the size of FieldValue if necessary
177 // FIXME: This should never occur, but currently it can because initializer
178 // constants are cast to bool, and because clang is not enforcing bitfield
180 if (FieldSize > FieldValue.getBitWidth())
181 FieldValue = FieldValue.zext(FieldSize);
183 // Truncate the size of FieldValue to the bit field size.
184 if (FieldSize < FieldValue.getBitWidth())
185 FieldValue = FieldValue.trunc(FieldSize);
187 NextFieldOffsetInBits = Context.toBits(NextFieldOffsetInChars);
188 if (FieldOffset < NextFieldOffsetInBits) {
189 // Either part of the field or the entire field can go into the previous
191 assert(!Elements.empty() && "Elements can't be empty!");
193 unsigned BitsInPreviousByte = NextFieldOffsetInBits - FieldOffset;
195 bool FitsCompletelyInPreviousByte =
196 BitsInPreviousByte >= FieldValue.getBitWidth();
198 llvm::APInt Tmp = FieldValue;
200 if (!FitsCompletelyInPreviousByte) {
201 unsigned NewFieldWidth = FieldSize - BitsInPreviousByte;
203 if (CGM.getDataLayout().isBigEndian()) {
204 Tmp = Tmp.lshr(NewFieldWidth);
205 Tmp = Tmp.trunc(BitsInPreviousByte);
207 // We want the remaining high bits.
208 FieldValue = FieldValue.trunc(NewFieldWidth);
210 Tmp = Tmp.trunc(BitsInPreviousByte);
212 // We want the remaining low bits.
213 FieldValue = FieldValue.lshr(BitsInPreviousByte);
214 FieldValue = FieldValue.trunc(NewFieldWidth);
218 Tmp = Tmp.zext(CharWidth);
219 if (CGM.getDataLayout().isBigEndian()) {
220 if (FitsCompletelyInPreviousByte)
221 Tmp = Tmp.shl(BitsInPreviousByte - FieldValue.getBitWidth());
223 Tmp = Tmp.shl(CharWidth - BitsInPreviousByte);
226 // 'or' in the bits that go into the previous byte.
227 llvm::Value *LastElt = Elements.back();
228 if (llvm::ConstantInt *Val = dyn_cast<llvm::ConstantInt>(LastElt))
229 Tmp |= Val->getValue();
231 assert(isa<llvm::UndefValue>(LastElt));
232 // If there is an undef field that we're adding to, it can either be a
233 // scalar undef (in which case, we just replace it with our field) or it
234 // is an array. If it is an array, we have to pull one byte off the
235 // array so that the other undef bytes stay around.
236 if (!isa<llvm::IntegerType>(LastElt->getType())) {
237 // The undef padding will be a multibyte array, create a new smaller
238 // padding and then an hole for our i8 to get plopped into.
239 assert(isa<llvm::ArrayType>(LastElt->getType()) &&
240 "Expected array padding of undefs");
241 llvm::ArrayType *AT = cast<llvm::ArrayType>(LastElt->getType());
242 assert(AT->getElementType()->isIntegerTy(CharWidth) &&
243 AT->getNumElements() != 0 &&
244 "Expected non-empty array padding of undefs");
246 // Remove the padding array.
247 NextFieldOffsetInChars -= CharUnits::fromQuantity(AT->getNumElements());
250 // Add the padding back in two chunks.
251 AppendPadding(CharUnits::fromQuantity(AT->getNumElements()-1));
252 AppendPadding(CharUnits::One());
253 assert(isa<llvm::UndefValue>(Elements.back()) &&
254 Elements.back()->getType()->isIntegerTy(CharWidth) &&
255 "Padding addition didn't work right");
259 Elements.back() = llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp);
261 if (FitsCompletelyInPreviousByte)
265 while (FieldValue.getBitWidth() > CharWidth) {
268 if (CGM.getDataLayout().isBigEndian()) {
269 // We want the high bits.
271 FieldValue.lshr(FieldValue.getBitWidth() - CharWidth).trunc(CharWidth);
273 // We want the low bits.
274 Tmp = FieldValue.trunc(CharWidth);
276 FieldValue = FieldValue.lshr(CharWidth);
279 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp));
280 ++NextFieldOffsetInChars;
282 FieldValue = FieldValue.trunc(FieldValue.getBitWidth() - CharWidth);
285 assert(FieldValue.getBitWidth() > 0 &&
286 "Should have at least one bit left!");
287 assert(FieldValue.getBitWidth() <= CharWidth &&
288 "Should not have more than a byte left!");
290 if (FieldValue.getBitWidth() < CharWidth) {
291 if (CGM.getDataLayout().isBigEndian()) {
292 unsigned BitWidth = FieldValue.getBitWidth();
294 FieldValue = FieldValue.zext(CharWidth) << (CharWidth - BitWidth);
296 FieldValue = FieldValue.zext(CharWidth);
299 // Append the last element.
300 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(),
302 ++NextFieldOffsetInChars;
305 void ConstStructBuilder::AppendPadding(CharUnits PadSize) {
306 if (PadSize.isZero())
309 llvm::Type *Ty = CGM.Int8Ty;
310 if (PadSize > CharUnits::One())
311 Ty = llvm::ArrayType::get(Ty, PadSize.getQuantity());
313 llvm::Constant *C = llvm::UndefValue::get(Ty);
314 Elements.push_back(C);
315 assert(getAlignment(C) == CharUnits::One() &&
316 "Padding must have 1 byte alignment!");
318 NextFieldOffsetInChars += getSizeInChars(C);
321 void ConstStructBuilder::AppendTailPadding(CharUnits RecordSize) {
322 assert(NextFieldOffsetInChars <= RecordSize &&
325 AppendPadding(RecordSize - NextFieldOffsetInChars);
328 void ConstStructBuilder::ConvertStructToPacked() {
329 SmallVector<llvm::Constant *, 16> PackedElements;
330 CharUnits ElementOffsetInChars = CharUnits::Zero();
332 for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
333 llvm::Constant *C = Elements[i];
335 CharUnits ElementAlign = CharUnits::fromQuantity(
336 CGM.getDataLayout().getABITypeAlignment(C->getType()));
337 CharUnits AlignedElementOffsetInChars =
338 ElementOffsetInChars.alignTo(ElementAlign);
340 if (AlignedElementOffsetInChars > ElementOffsetInChars) {
341 // We need some padding.
343 AlignedElementOffsetInChars - ElementOffsetInChars;
345 llvm::Type *Ty = CGM.Int8Ty;
346 if (NumChars > CharUnits::One())
347 Ty = llvm::ArrayType::get(Ty, NumChars.getQuantity());
349 llvm::Constant *Padding = llvm::UndefValue::get(Ty);
350 PackedElements.push_back(Padding);
351 ElementOffsetInChars += getSizeInChars(Padding);
354 PackedElements.push_back(C);
355 ElementOffsetInChars += getSizeInChars(C);
358 assert(ElementOffsetInChars == NextFieldOffsetInChars &&
359 "Packing the struct changed its size!");
361 Elements.swap(PackedElements);
362 LLVMStructAlignment = CharUnits::One();
366 bool ConstStructBuilder::Build(InitListExpr *ILE) {
367 RecordDecl *RD = ILE->getType()->getAs<RecordType>()->getDecl();
368 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
370 unsigned FieldNo = 0;
371 unsigned ElementNo = 0;
373 // Bail out if we have base classes. We could support these, but they only
374 // arise in C++1z where we will have already constant folded most interesting
375 // cases. FIXME: There are still a few more cases we can handle this way.
376 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD))
377 if (CXXRD->getNumBases())
380 for (RecordDecl::field_iterator Field = RD->field_begin(),
381 FieldEnd = RD->field_end(); Field != FieldEnd; ++Field, ++FieldNo) {
382 // If this is a union, skip all the fields that aren't being initialized.
383 if (RD->isUnion() && ILE->getInitializedFieldInUnion() != *Field)
386 // Don't emit anonymous bitfields, they just affect layout.
387 if (Field->isUnnamedBitfield())
390 // Get the initializer. A struct can include fields without initializers,
391 // we just use explicit null values for them.
392 llvm::Constant *EltInit;
393 if (ElementNo < ILE->getNumInits())
394 EltInit = CGM.EmitConstantExpr(ILE->getInit(ElementNo++),
395 Field->getType(), CGF);
397 EltInit = CGM.EmitNullConstant(Field->getType());
402 if (!Field->isBitField()) {
403 // Handle non-bitfield members.
404 AppendField(*Field, Layout.getFieldOffset(FieldNo), EltInit);
406 // Otherwise we have a bitfield.
407 if (auto *CI = dyn_cast<llvm::ConstantInt>(EltInit)) {
408 AppendBitField(*Field, Layout.getFieldOffset(FieldNo), CI);
410 // We are trying to initialize a bitfield with a non-trivial constant,
411 // this must require run-time code.
422 BaseInfo(const CXXRecordDecl *Decl, CharUnits Offset, unsigned Index)
423 : Decl(Decl), Offset(Offset), Index(Index) {
426 const CXXRecordDecl *Decl;
430 bool operator<(const BaseInfo &O) const { return Offset < O.Offset; }
434 void ConstStructBuilder::Build(const APValue &Val, const RecordDecl *RD,
436 const CXXRecordDecl *VTableClass,
438 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
440 if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) {
441 // Add a vtable pointer, if we need one and it hasn't already been added.
442 if (CD->isDynamicClass() && !IsPrimaryBase) {
443 llvm::Constant *VTableAddressPoint =
444 CGM.getCXXABI().getVTableAddressPointForConstExpr(
445 BaseSubobject(CD, Offset), VTableClass);
446 AppendBytes(Offset, VTableAddressPoint);
449 // Accumulate and sort bases, in order to visit them in address order, which
450 // may not be the same as declaration order.
451 SmallVector<BaseInfo, 8> Bases;
452 Bases.reserve(CD->getNumBases());
454 for (CXXRecordDecl::base_class_const_iterator Base = CD->bases_begin(),
455 BaseEnd = CD->bases_end(); Base != BaseEnd; ++Base, ++BaseNo) {
456 assert(!Base->isVirtual() && "should not have virtual bases here");
457 const CXXRecordDecl *BD = Base->getType()->getAsCXXRecordDecl();
458 CharUnits BaseOffset = Layout.getBaseClassOffset(BD);
459 Bases.push_back(BaseInfo(BD, BaseOffset, BaseNo));
461 std::stable_sort(Bases.begin(), Bases.end());
463 for (unsigned I = 0, N = Bases.size(); I != N; ++I) {
464 BaseInfo &Base = Bases[I];
466 bool IsPrimaryBase = Layout.getPrimaryBase() == Base.Decl;
467 Build(Val.getStructBase(Base.Index), Base.Decl, IsPrimaryBase,
468 VTableClass, Offset + Base.Offset);
472 unsigned FieldNo = 0;
473 uint64_t OffsetBits = CGM.getContext().toBits(Offset);
475 for (RecordDecl::field_iterator Field = RD->field_begin(),
476 FieldEnd = RD->field_end(); Field != FieldEnd; ++Field, ++FieldNo) {
477 // If this is a union, skip all the fields that aren't being initialized.
478 if (RD->isUnion() && Val.getUnionField() != *Field)
481 // Don't emit anonymous bitfields, they just affect layout.
482 if (Field->isUnnamedBitfield())
485 // Emit the value of the initializer.
486 const APValue &FieldValue =
487 RD->isUnion() ? Val.getUnionValue() : Val.getStructField(FieldNo);
488 llvm::Constant *EltInit =
489 CGM.EmitConstantValueForMemory(FieldValue, Field->getType(), CGF);
490 assert(EltInit && "EmitConstantValue can't fail");
492 if (!Field->isBitField()) {
493 // Handle non-bitfield members.
494 AppendField(*Field, Layout.getFieldOffset(FieldNo) + OffsetBits, EltInit);
496 // Otherwise we have a bitfield.
497 AppendBitField(*Field, Layout.getFieldOffset(FieldNo) + OffsetBits,
498 cast<llvm::ConstantInt>(EltInit));
503 llvm::Constant *ConstStructBuilder::Finalize(QualType Ty) {
504 RecordDecl *RD = Ty->getAs<RecordType>()->getDecl();
505 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
507 CharUnits LayoutSizeInChars = Layout.getSize();
509 if (NextFieldOffsetInChars > LayoutSizeInChars) {
510 // If the struct is bigger than the size of the record type,
511 // we must have a flexible array member at the end.
512 assert(RD->hasFlexibleArrayMember() &&
513 "Must have flexible array member if struct is bigger than type!");
515 // No tail padding is necessary.
517 // Append tail padding if necessary.
518 CharUnits LLVMSizeInChars =
519 NextFieldOffsetInChars.alignTo(LLVMStructAlignment);
521 if (LLVMSizeInChars != LayoutSizeInChars)
522 AppendTailPadding(LayoutSizeInChars);
524 LLVMSizeInChars = NextFieldOffsetInChars.alignTo(LLVMStructAlignment);
526 // Check if we need to convert the struct to a packed struct.
527 if (NextFieldOffsetInChars <= LayoutSizeInChars &&
528 LLVMSizeInChars > LayoutSizeInChars) {
529 assert(!Packed && "Size mismatch!");
531 ConvertStructToPacked();
532 assert(NextFieldOffsetInChars <= LayoutSizeInChars &&
533 "Converting to packed did not help!");
536 LLVMSizeInChars = NextFieldOffsetInChars.alignTo(LLVMStructAlignment);
538 assert(LayoutSizeInChars == LLVMSizeInChars &&
539 "Tail padding mismatch!");
542 // Pick the type to use. If the type is layout identical to the ConvertType
543 // type then use it, otherwise use whatever the builder produced for us.
544 llvm::StructType *STy =
545 llvm::ConstantStruct::getTypeForElements(CGM.getLLVMContext(),
547 llvm::Type *ValTy = CGM.getTypes().ConvertType(Ty);
548 if (llvm::StructType *ValSTy = dyn_cast<llvm::StructType>(ValTy)) {
549 if (ValSTy->isLayoutIdentical(STy))
553 llvm::Constant *Result = llvm::ConstantStruct::get(STy, Elements);
555 assert(NextFieldOffsetInChars.alignTo(getAlignment(Result)) ==
556 getSizeInChars(Result) &&
562 llvm::Constant *ConstStructBuilder::BuildStruct(CodeGenModule &CGM,
563 CodeGenFunction *CGF,
564 ConstExprEmitter *Emitter,
565 llvm::ConstantStruct *Base,
566 InitListExpr *Updater) {
567 ConstStructBuilder Builder(CGM, CGF);
568 if (!Builder.Build(Emitter, Base, Updater))
570 return Builder.Finalize(Updater->getType());
573 llvm::Constant *ConstStructBuilder::BuildStruct(CodeGenModule &CGM,
574 CodeGenFunction *CGF,
576 ConstStructBuilder Builder(CGM, CGF);
578 if (!Builder.Build(ILE))
581 return Builder.Finalize(ILE->getType());
584 llvm::Constant *ConstStructBuilder::BuildStruct(CodeGenModule &CGM,
585 CodeGenFunction *CGF,
588 ConstStructBuilder Builder(CGM, CGF);
590 const RecordDecl *RD = ValTy->castAs<RecordType>()->getDecl();
591 const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD);
592 Builder.Build(Val, RD, false, CD, CharUnits::Zero());
594 return Builder.Finalize(ValTy);
598 //===----------------------------------------------------------------------===//
600 //===----------------------------------------------------------------------===//
602 /// This class only needs to handle two cases:
603 /// 1) Literals (this is used by APValue emission to emit literals).
604 /// 2) Arrays, structs and unions (outside C++11 mode, we don't currently
605 /// constant fold these types).
606 class ConstExprEmitter :
607 public StmtVisitor<ConstExprEmitter, llvm::Constant*> {
609 CodeGenFunction *CGF;
610 llvm::LLVMContext &VMContext;
612 ConstExprEmitter(CodeGenModule &cgm, CodeGenFunction *cgf)
613 : CGM(cgm), CGF(cgf), VMContext(cgm.getLLVMContext()) {
616 //===--------------------------------------------------------------------===//
618 //===--------------------------------------------------------------------===//
620 llvm::Constant *VisitStmt(Stmt *S) {
624 llvm::Constant *VisitParenExpr(ParenExpr *PE) {
625 return Visit(PE->getSubExpr());
629 VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *PE) {
630 return Visit(PE->getReplacement());
633 llvm::Constant *VisitGenericSelectionExpr(GenericSelectionExpr *GE) {
634 return Visit(GE->getResultExpr());
637 llvm::Constant *VisitChooseExpr(ChooseExpr *CE) {
638 return Visit(CE->getChosenSubExpr());
641 llvm::Constant *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
642 return Visit(E->getInitializer());
645 llvm::Constant *VisitCastExpr(CastExpr* E) {
646 if (const auto *ECE = dyn_cast<ExplicitCastExpr>(E))
647 CGM.EmitExplicitCastExprType(ECE, CGF);
648 Expr *subExpr = E->getSubExpr();
649 llvm::Constant *C = CGM.EmitConstantExpr(subExpr, subExpr->getType(), CGF);
650 if (!C) return nullptr;
652 llvm::Type *destType = ConvertType(E->getType());
654 switch (E->getCastKind()) {
656 // GCC cast to union extension
657 assert(E->getType()->isUnionType() &&
658 "Destination type is not union type!");
660 // Build a struct with the union sub-element as the first member,
661 // and padded to the appropriate size
662 SmallVector<llvm::Constant*, 2> Elts;
663 SmallVector<llvm::Type*, 2> Types;
665 Types.push_back(C->getType());
666 unsigned CurSize = CGM.getDataLayout().getTypeAllocSize(C->getType());
667 unsigned TotalSize = CGM.getDataLayout().getTypeAllocSize(destType);
669 assert(CurSize <= TotalSize && "Union size mismatch!");
670 if (unsigned NumPadBytes = TotalSize - CurSize) {
671 llvm::Type *Ty = CGM.Int8Ty;
673 Ty = llvm::ArrayType::get(Ty, NumPadBytes);
675 Elts.push_back(llvm::UndefValue::get(Ty));
679 llvm::StructType* STy =
680 llvm::StructType::get(C->getType()->getContext(), Types, false);
681 return llvm::ConstantStruct::get(STy, Elts);
684 case CK_AddressSpaceConversion:
685 return llvm::ConstantExpr::getAddrSpaceCast(C, destType);
687 case CK_LValueToRValue:
688 case CK_AtomicToNonAtomic:
689 case CK_NonAtomicToAtomic:
691 case CK_ConstructorConversion:
694 case CK_IntToOCLSampler:
695 llvm_unreachable("global sampler variables are not generated");
697 case CK_Dependent: llvm_unreachable("saw dependent cast!");
699 case CK_BuiltinFnToFnPtr:
700 llvm_unreachable("builtin functions are handled elsewhere");
702 case CK_ReinterpretMemberPointer:
703 case CK_DerivedToBaseMemberPointer:
704 case CK_BaseToDerivedMemberPointer:
705 return CGM.getCXXABI().EmitMemberPointerConversion(E, C);
707 // These will never be supported.
708 case CK_ObjCObjectLValueCast:
709 case CK_ARCProduceObject:
710 case CK_ARCConsumeObject:
711 case CK_ARCReclaimReturnedObject:
712 case CK_ARCExtendBlockObject:
713 case CK_CopyAndAutoreleaseBlockObject:
716 // These don't need to be handled here because Evaluate knows how to
717 // evaluate them in the cases where they can be folded.
721 case CK_LValueBitCast:
722 case CK_NullToMemberPointer:
723 case CK_UserDefinedConversion:
724 case CK_CPointerToObjCPointerCast:
725 case CK_BlockPointerToObjCPointerCast:
726 case CK_AnyPointerToBlockPointerCast:
727 case CK_ArrayToPointerDecay:
728 case CK_FunctionToPointerDecay:
729 case CK_BaseToDerived:
730 case CK_DerivedToBase:
731 case CK_UncheckedDerivedToBase:
732 case CK_MemberPointerToBoolean:
734 case CK_FloatingRealToComplex:
735 case CK_FloatingComplexToReal:
736 case CK_FloatingComplexToBoolean:
737 case CK_FloatingComplexCast:
738 case CK_FloatingComplexToIntegralComplex:
739 case CK_IntegralRealToComplex:
740 case CK_IntegralComplexToReal:
741 case CK_IntegralComplexToBoolean:
742 case CK_IntegralComplexCast:
743 case CK_IntegralComplexToFloatingComplex:
744 case CK_PointerToIntegral:
745 case CK_PointerToBoolean:
746 case CK_NullToPointer:
747 case CK_IntegralCast:
748 case CK_BooleanToSignedIntegral:
749 case CK_IntegralToPointer:
750 case CK_IntegralToBoolean:
751 case CK_IntegralToFloating:
752 case CK_FloatingToIntegral:
753 case CK_FloatingToBoolean:
754 case CK_FloatingCast:
755 case CK_ZeroToOCLEvent:
756 case CK_ZeroToOCLQueue:
759 llvm_unreachable("Invalid CastKind");
762 llvm::Constant *VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
763 return Visit(DAE->getExpr());
766 llvm::Constant *VisitCXXDefaultInitExpr(CXXDefaultInitExpr *DIE) {
767 // No need for a DefaultInitExprScope: we don't handle 'this' in a
768 // constant expression.
769 return Visit(DIE->getExpr());
772 llvm::Constant *VisitExprWithCleanups(ExprWithCleanups *E) {
773 if (!E->cleanupsHaveSideEffects())
774 return Visit(E->getSubExpr());
778 llvm::Constant *VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E) {
779 return Visit(E->GetTemporaryExpr());
782 llvm::Constant *EmitArrayInitialization(InitListExpr *ILE) {
783 llvm::ArrayType *AType =
784 cast<llvm::ArrayType>(ConvertType(ILE->getType()));
785 llvm::Type *ElemTy = AType->getElementType();
786 unsigned NumInitElements = ILE->getNumInits();
787 unsigned NumElements = AType->getNumElements();
789 // Initialising an array requires us to automatically
790 // initialise any elements that have not been initialised explicitly
791 unsigned NumInitableElts = std::min(NumInitElements, NumElements);
793 // Initialize remaining array elements.
794 // FIXME: This doesn't handle member pointers correctly!
795 llvm::Constant *fillC;
796 if (Expr *filler = ILE->getArrayFiller())
797 fillC = CGM.EmitConstantExpr(filler, filler->getType(), CGF);
799 fillC = llvm::Constant::getNullValue(ElemTy);
803 // Try to use a ConstantAggregateZero if we can.
804 if (fillC->isNullValue() && !NumInitableElts)
805 return llvm::ConstantAggregateZero::get(AType);
807 // Copy initializer elements.
808 std::vector<llvm::Constant*> Elts;
809 Elts.reserve(NumInitableElts + NumElements);
811 bool RewriteType = false;
812 for (unsigned i = 0; i < NumInitableElts; ++i) {
813 Expr *Init = ILE->getInit(i);
814 llvm::Constant *C = CGM.EmitConstantExpr(Init, Init->getType(), CGF);
817 RewriteType |= (C->getType() != ElemTy);
821 RewriteType |= (fillC->getType() != ElemTy);
822 Elts.resize(NumElements, fillC);
825 // FIXME: Try to avoid packing the array
826 std::vector<llvm::Type*> Types;
827 Types.reserve(NumInitableElts + NumElements);
828 for (unsigned i = 0, e = Elts.size(); i < e; ++i)
829 Types.push_back(Elts[i]->getType());
830 llvm::StructType *SType = llvm::StructType::get(AType->getContext(),
832 return llvm::ConstantStruct::get(SType, Elts);
835 return llvm::ConstantArray::get(AType, Elts);
838 llvm::Constant *EmitRecordInitialization(InitListExpr *ILE) {
839 return ConstStructBuilder::BuildStruct(CGM, CGF, ILE);
842 llvm::Constant *VisitImplicitValueInitExpr(ImplicitValueInitExpr* E) {
843 return CGM.EmitNullConstant(E->getType());
846 llvm::Constant *VisitInitListExpr(InitListExpr *ILE) {
847 if (ILE->isTransparent())
848 return Visit(ILE->getInit(0));
850 if (ILE->getType()->isArrayType())
851 return EmitArrayInitialization(ILE);
853 if (ILE->getType()->isRecordType())
854 return EmitRecordInitialization(ILE);
859 llvm::Constant *EmitDesignatedInitUpdater(llvm::Constant *Base,
860 InitListExpr *Updater) {
861 QualType ExprType = Updater->getType();
863 if (ExprType->isArrayType()) {
864 llvm::ArrayType *AType = cast<llvm::ArrayType>(ConvertType(ExprType));
865 llvm::Type *ElemType = AType->getElementType();
867 unsigned NumInitElements = Updater->getNumInits();
868 unsigned NumElements = AType->getNumElements();
870 std::vector<llvm::Constant *> Elts;
871 Elts.reserve(NumElements);
873 if (llvm::ConstantDataArray *DataArray =
874 dyn_cast<llvm::ConstantDataArray>(Base))
875 for (unsigned i = 0; i != NumElements; ++i)
876 Elts.push_back(DataArray->getElementAsConstant(i));
877 else if (llvm::ConstantArray *Array =
878 dyn_cast<llvm::ConstantArray>(Base))
879 for (unsigned i = 0; i != NumElements; ++i)
880 Elts.push_back(Array->getOperand(i));
882 return nullptr; // FIXME: other array types not implemented
884 llvm::Constant *fillC = nullptr;
885 if (Expr *filler = Updater->getArrayFiller())
886 if (!isa<NoInitExpr>(filler))
887 fillC = CGM.EmitConstantExpr(filler, filler->getType(), CGF);
888 bool RewriteType = (fillC && fillC->getType() != ElemType);
890 for (unsigned i = 0; i != NumElements; ++i) {
891 Expr *Init = nullptr;
892 if (i < NumInitElements)
893 Init = Updater->getInit(i);
897 else if (!Init || isa<NoInitExpr>(Init))
899 else if (InitListExpr *ChildILE = dyn_cast<InitListExpr>(Init))
900 Elts[i] = EmitDesignatedInitUpdater(Elts[i], ChildILE);
902 Elts[i] = CGM.EmitConstantExpr(Init, Init->getType(), CGF);
906 RewriteType |= (Elts[i]->getType() != ElemType);
910 std::vector<llvm::Type *> Types;
911 Types.reserve(NumElements);
912 for (unsigned i = 0; i != NumElements; ++i)
913 Types.push_back(Elts[i]->getType());
914 llvm::StructType *SType = llvm::StructType::get(AType->getContext(),
916 return llvm::ConstantStruct::get(SType, Elts);
919 return llvm::ConstantArray::get(AType, Elts);
922 if (ExprType->isRecordType())
923 return ConstStructBuilder::BuildStruct(CGM, CGF, this,
924 dyn_cast<llvm::ConstantStruct>(Base), Updater);
929 llvm::Constant *VisitDesignatedInitUpdateExpr(DesignatedInitUpdateExpr *E) {
930 return EmitDesignatedInitUpdater(
931 CGM.EmitConstantExpr(E->getBase(), E->getType(), CGF),
935 llvm::Constant *VisitCXXConstructExpr(CXXConstructExpr *E) {
936 if (!E->getConstructor()->isTrivial())
939 QualType Ty = E->getType();
941 // FIXME: We should not have to call getBaseElementType here.
942 const RecordType *RT =
943 CGM.getContext().getBaseElementType(Ty)->getAs<RecordType>();
944 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
946 // If the class doesn't have a trivial destructor, we can't emit it as a
948 if (!RD->hasTrivialDestructor())
951 // Only copy and default constructors can be trivial.
954 if (E->getNumArgs()) {
955 assert(E->getNumArgs() == 1 && "trivial ctor with > 1 argument");
956 assert(E->getConstructor()->isCopyOrMoveConstructor() &&
957 "trivial ctor has argument but isn't a copy/move ctor");
959 Expr *Arg = E->getArg(0);
960 assert(CGM.getContext().hasSameUnqualifiedType(Ty, Arg->getType()) &&
961 "argument to copy ctor is of wrong type");
966 return CGM.EmitNullConstant(Ty);
969 llvm::Constant *VisitStringLiteral(StringLiteral *E) {
970 return CGM.GetConstantArrayFromStringLiteral(E);
973 llvm::Constant *VisitObjCEncodeExpr(ObjCEncodeExpr *E) {
974 // This must be an @encode initializing an array in a static initializer.
975 // Don't emit it as the address of the string, emit the string data itself
976 // as an inline array.
978 CGM.getContext().getObjCEncodingForType(E->getEncodedType(), Str);
979 QualType T = E->getType();
980 if (T->getTypeClass() == Type::TypeOfExpr)
981 T = cast<TypeOfExprType>(T)->getUnderlyingExpr()->getType();
982 const ConstantArrayType *CAT = cast<ConstantArrayType>(T);
984 // Resize the string to the right size, adding zeros at the end, or
985 // truncating as needed.
986 Str.resize(CAT->getSize().getZExtValue(), '\0');
987 return llvm::ConstantDataArray::getString(VMContext, Str, false);
990 llvm::Constant *VisitUnaryExtension(const UnaryOperator *E) {
991 return Visit(E->getSubExpr());
995 llvm::Type *ConvertType(QualType T) {
996 return CGM.getTypes().ConvertType(T);
1000 ConstantAddress EmitLValue(APValue::LValueBase LVBase) {
1001 if (const ValueDecl *Decl = LVBase.dyn_cast<const ValueDecl*>()) {
1002 if (Decl->hasAttr<WeakRefAttr>())
1003 return CGM.GetWeakRefReference(Decl);
1004 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Decl))
1005 return ConstantAddress(CGM.GetAddrOfFunction(FD), CharUnits::One());
1006 if (const VarDecl* VD = dyn_cast<VarDecl>(Decl)) {
1007 // We can never refer to a variable with local storage.
1008 if (!VD->hasLocalStorage()) {
1009 CharUnits Align = CGM.getContext().getDeclAlign(VD);
1010 if (VD->isFileVarDecl() || VD->hasExternalStorage())
1011 return ConstantAddress(CGM.GetAddrOfGlobalVar(VD), Align);
1012 else if (VD->isLocalVarDecl()) {
1013 auto Ptr = CGM.getOrCreateStaticVarDecl(
1014 *VD, CGM.getLLVMLinkageVarDefinition(VD, /*isConstant=*/false));
1015 return ConstantAddress(Ptr, Align);
1019 return ConstantAddress::invalid();
1022 Expr *E = const_cast<Expr*>(LVBase.get<const Expr*>());
1023 switch (E->getStmtClass()) {
1025 case Expr::CompoundLiteralExprClass: {
1026 CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E);
1027 CharUnits Align = CGM.getContext().getTypeAlignInChars(E->getType());
1028 if (llvm::GlobalVariable *Addr =
1029 CGM.getAddrOfConstantCompoundLiteralIfEmitted(CLE))
1030 return ConstantAddress(Addr, Align);
1032 llvm::Constant* C = CGM.EmitConstantExpr(CLE->getInitializer(),
1033 CLE->getType(), CGF);
1034 // FIXME: "Leaked" on failure.
1035 if (!C) return ConstantAddress::invalid();
1037 auto GV = new llvm::GlobalVariable(CGM.getModule(), C->getType(),
1038 E->getType().isConstant(CGM.getContext()),
1039 llvm::GlobalValue::InternalLinkage,
1040 C, ".compoundliteral", nullptr,
1041 llvm::GlobalVariable::NotThreadLocal,
1042 CGM.getContext().getTargetAddressSpace(E->getType()));
1043 GV->setAlignment(Align.getQuantity());
1044 CGM.setAddrOfConstantCompoundLiteral(CLE, GV);
1045 return ConstantAddress(GV, Align);
1047 case Expr::StringLiteralClass:
1048 return CGM.GetAddrOfConstantStringFromLiteral(cast<StringLiteral>(E));
1049 case Expr::ObjCEncodeExprClass:
1050 return CGM.GetAddrOfConstantStringFromObjCEncode(cast<ObjCEncodeExpr>(E));
1051 case Expr::ObjCStringLiteralClass: {
1052 ObjCStringLiteral* SL = cast<ObjCStringLiteral>(E);
1054 CGM.getObjCRuntime().GenerateConstantString(SL->getString());
1055 return C.getElementBitCast(ConvertType(E->getType()));
1057 case Expr::PredefinedExprClass: {
1058 unsigned Type = cast<PredefinedExpr>(E)->getIdentType();
1060 LValue Res = CGF->EmitPredefinedLValue(cast<PredefinedExpr>(E));
1061 return cast<ConstantAddress>(Res.getAddress());
1062 } else if (Type == PredefinedExpr::PrettyFunction) {
1063 return CGM.GetAddrOfConstantCString("top level", ".tmp");
1066 return CGM.GetAddrOfConstantCString("", ".tmp");
1068 case Expr::AddrLabelExprClass: {
1069 assert(CGF && "Invalid address of label expression outside function.");
1070 llvm::Constant *Ptr =
1071 CGF->GetAddrOfLabel(cast<AddrLabelExpr>(E)->getLabel());
1072 Ptr = llvm::ConstantExpr::getBitCast(Ptr, ConvertType(E->getType()));
1073 return ConstantAddress(Ptr, CharUnits::One());
1075 case Expr::CallExprClass: {
1076 CallExpr* CE = cast<CallExpr>(E);
1077 unsigned builtin = CE->getBuiltinCallee();
1079 Builtin::BI__builtin___CFStringMakeConstantString &&
1081 Builtin::BI__builtin___NSStringMakeConstantString)
1083 const Expr *Arg = CE->getArg(0)->IgnoreParenCasts();
1084 const StringLiteral *Literal = cast<StringLiteral>(Arg);
1086 Builtin::BI__builtin___NSStringMakeConstantString) {
1087 return CGM.getObjCRuntime().GenerateConstantString(Literal);
1089 // FIXME: need to deal with UCN conversion issues.
1090 return CGM.GetAddrOfConstantCFString(Literal);
1092 case Expr::BlockExprClass: {
1093 StringRef FunctionName;
1095 FunctionName = CGF->CurFn->getName();
1097 FunctionName = "global";
1099 // This is not really an l-value.
1100 llvm::Constant *Ptr =
1101 CGM.GetAddrOfGlobalBlock(cast<BlockExpr>(E), FunctionName);
1102 return ConstantAddress(Ptr, CGM.getPointerAlign());
1104 case Expr::CXXTypeidExprClass: {
1105 CXXTypeidExpr *Typeid = cast<CXXTypeidExpr>(E);
1107 if (Typeid->isTypeOperand())
1108 T = Typeid->getTypeOperand(CGM.getContext());
1110 T = Typeid->getExprOperand()->getType();
1111 return ConstantAddress(CGM.GetAddrOfRTTIDescriptor(T),
1112 CGM.getPointerAlign());
1114 case Expr::CXXUuidofExprClass: {
1115 return CGM.GetAddrOfUuidDescriptor(cast<CXXUuidofExpr>(E));
1117 case Expr::MaterializeTemporaryExprClass: {
1118 MaterializeTemporaryExpr *MTE = cast<MaterializeTemporaryExpr>(E);
1119 assert(MTE->getStorageDuration() == SD_Static);
1120 SmallVector<const Expr *, 2> CommaLHSs;
1121 SmallVector<SubobjectAdjustment, 2> Adjustments;
1122 const Expr *Inner = MTE->GetTemporaryExpr()
1123 ->skipRValueSubobjectAdjustments(CommaLHSs, Adjustments);
1124 return CGM.GetAddrOfGlobalTemporary(MTE, Inner);
1128 return ConstantAddress::invalid();
1132 } // end anonymous namespace.
1134 bool ConstStructBuilder::Build(ConstExprEmitter *Emitter,
1135 llvm::ConstantStruct *Base,
1136 InitListExpr *Updater) {
1137 assert(Base && "base expression should not be empty");
1139 QualType ExprType = Updater->getType();
1140 RecordDecl *RD = ExprType->getAs<RecordType>()->getDecl();
1141 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
1142 const llvm::StructLayout *BaseLayout = CGM.getDataLayout().getStructLayout(
1144 unsigned FieldNo = -1;
1145 unsigned ElementNo = 0;
1147 // Bail out if we have base classes. We could support these, but they only
1148 // arise in C++1z where we will have already constant folded most interesting
1149 // cases. FIXME: There are still a few more cases we can handle this way.
1150 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD))
1151 if (CXXRD->getNumBases())
1154 for (FieldDecl *Field : RD->fields()) {
1157 if (RD->isUnion() && Updater->getInitializedFieldInUnion() != Field)
1160 // Skip anonymous bitfields.
1161 if (Field->isUnnamedBitfield())
1164 llvm::Constant *EltInit = Base->getOperand(ElementNo);
1166 // Bail out if the type of the ConstantStruct does not have the same layout
1167 // as the type of the InitListExpr.
1168 if (CGM.getTypes().ConvertType(Field->getType()) != EltInit->getType() ||
1169 Layout.getFieldOffset(ElementNo) !=
1170 BaseLayout->getElementOffsetInBits(ElementNo))
1173 // Get the initializer. If we encounter an empty field or a NoInitExpr,
1174 // we use values from the base expression.
1175 Expr *Init = nullptr;
1176 if (ElementNo < Updater->getNumInits())
1177 Init = Updater->getInit(ElementNo);
1179 if (!Init || isa<NoInitExpr>(Init))
1181 else if (InitListExpr *ChildILE = dyn_cast<InitListExpr>(Init))
1182 EltInit = Emitter->EmitDesignatedInitUpdater(EltInit, ChildILE);
1184 EltInit = CGM.EmitConstantExpr(Init, Field->getType(), CGF);
1191 if (!Field->isBitField())
1192 AppendField(Field, Layout.getFieldOffset(FieldNo), EltInit);
1193 else if (llvm::ConstantInt *CI = dyn_cast<llvm::ConstantInt>(EltInit))
1194 AppendBitField(Field, Layout.getFieldOffset(FieldNo), CI);
1196 // Initializing a bitfield with a non-trivial constant?
1203 llvm::Constant *CodeGenModule::EmitConstantInit(const VarDecl &D,
1204 CodeGenFunction *CGF) {
1205 // Make a quick check if variable can be default NULL initialized
1206 // and avoid going through rest of code which may do, for c++11,
1207 // initialization of memory to all NULLs.
1208 if (!D.hasLocalStorage()) {
1209 QualType Ty = D.getType();
1210 if (Ty->isArrayType())
1211 Ty = Context.getBaseElementType(Ty);
1212 if (Ty->isRecordType())
1213 if (const CXXConstructExpr *E =
1214 dyn_cast_or_null<CXXConstructExpr>(D.getInit())) {
1215 const CXXConstructorDecl *CD = E->getConstructor();
1216 if (CD->isTrivial() && CD->isDefaultConstructor())
1217 return EmitNullConstant(D.getType());
1221 if (const APValue *Value = D.evaluateValue())
1222 return EmitConstantValueForMemory(*Value, D.getType(), CGF);
1224 // FIXME: Implement C++11 [basic.start.init]p2: if the initializer of a
1225 // reference is a constant expression, and the reference binds to a temporary,
1226 // then constant initialization is performed. ConstExprEmitter will
1227 // incorrectly emit a prvalue constant in this case, and the calling code
1228 // interprets that as the (pointer) value of the reference, rather than the
1229 // desired value of the referee.
1230 if (D.getType()->isReferenceType())
1233 const Expr *E = D.getInit();
1234 assert(E && "No initializer to emit");
1236 llvm::Constant* C = ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E));
1237 if (C && C->getType()->isIntegerTy(1)) {
1238 llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType());
1239 C = llvm::ConstantExpr::getZExt(C, BoolTy);
1244 llvm::Constant *CodeGenModule::EmitConstantExpr(const Expr *E,
1246 CodeGenFunction *CGF) {
1247 Expr::EvalResult Result;
1249 bool Success = false;
1251 if (DestType->isReferenceType())
1252 Success = E->EvaluateAsLValue(Result, Context);
1254 Success = E->EvaluateAsRValue(Result, Context);
1256 llvm::Constant *C = nullptr;
1257 if (Success && !Result.HasSideEffects)
1258 C = EmitConstantValue(Result.Val, DestType, CGF);
1260 C = ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E));
1262 if (C && C->getType()->isIntegerTy(1)) {
1263 llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType());
1264 C = llvm::ConstantExpr::getZExt(C, BoolTy);
1269 llvm::Constant *CodeGenModule::getNullPointer(llvm::PointerType *T, QualType QT) {
1270 return getTargetCodeGenInfo().getNullPointer(*this, T, QT);
1273 llvm::Constant *CodeGenModule::EmitConstantValue(const APValue &Value,
1275 CodeGenFunction *CGF) {
1276 // For an _Atomic-qualified constant, we may need to add tail padding.
1277 if (auto *AT = DestType->getAs<AtomicType>()) {
1278 QualType InnerType = AT->getValueType();
1279 auto *Inner = EmitConstantValue(Value, InnerType, CGF);
1281 uint64_t InnerSize = Context.getTypeSize(InnerType);
1282 uint64_t OuterSize = Context.getTypeSize(DestType);
1283 if (InnerSize == OuterSize)
1286 assert(InnerSize < OuterSize && "emitted over-large constant for atomic");
1287 llvm::Constant *Elts[] = {
1289 llvm::ConstantAggregateZero::get(
1290 llvm::ArrayType::get(Int8Ty, (OuterSize - InnerSize) / 8))
1292 return llvm::ConstantStruct::getAnon(Elts);
1295 switch (Value.getKind()) {
1296 case APValue::Uninitialized:
1297 llvm_unreachable("Constant expressions should be initialized.");
1298 case APValue::LValue: {
1299 llvm::Type *DestTy = getTypes().ConvertTypeForMem(DestType);
1300 llvm::Constant *Offset =
1301 llvm::ConstantInt::get(Int64Ty, Value.getLValueOffset().getQuantity());
1303 llvm::Constant *C = nullptr;
1305 if (APValue::LValueBase LVBase = Value.getLValueBase()) {
1306 // An array can be represented as an lvalue referring to the base.
1307 if (isa<llvm::ArrayType>(DestTy)) {
1308 assert(Offset->isNullValue() && "offset on array initializer");
1309 return ConstExprEmitter(*this, CGF).Visit(
1310 const_cast<Expr*>(LVBase.get<const Expr*>()));
1313 C = ConstExprEmitter(*this, CGF).EmitLValue(LVBase).getPointer();
1315 // Apply offset if necessary.
1316 if (!Offset->isNullValue()) {
1317 unsigned AS = C->getType()->getPointerAddressSpace();
1318 llvm::Type *CharPtrTy = Int8Ty->getPointerTo(AS);
1319 llvm::Constant *Casted = llvm::ConstantExpr::getBitCast(C, CharPtrTy);
1320 Casted = llvm::ConstantExpr::getGetElementPtr(Int8Ty, Casted, Offset);
1321 C = llvm::ConstantExpr::getPointerCast(Casted, C->getType());
1324 // Convert to the appropriate type; this could be an lvalue for
1326 if (isa<llvm::PointerType>(DestTy))
1327 return llvm::ConstantExpr::getPointerCast(C, DestTy);
1329 return llvm::ConstantExpr::getPtrToInt(C, DestTy);
1333 // Convert to the appropriate type; this could be an lvalue for
1335 if (auto PT = dyn_cast<llvm::PointerType>(DestTy)) {
1336 if (Value.isNullPointer())
1337 return getNullPointer(PT, DestType);
1338 // Convert the integer to a pointer-sized integer before converting it
1340 C = llvm::ConstantExpr::getIntegerCast(
1341 C, getDataLayout().getIntPtrType(DestTy),
1342 /*isSigned=*/false);
1343 return llvm::ConstantExpr::getIntToPtr(C, DestTy);
1346 // If the types don't match this should only be a truncate.
1347 if (C->getType() != DestTy)
1348 return llvm::ConstantExpr::getTrunc(C, DestTy);
1354 return llvm::ConstantInt::get(VMContext, Value.getInt());
1355 case APValue::ComplexInt: {
1356 llvm::Constant *Complex[2];
1358 Complex[0] = llvm::ConstantInt::get(VMContext,
1359 Value.getComplexIntReal());
1360 Complex[1] = llvm::ConstantInt::get(VMContext,
1361 Value.getComplexIntImag());
1363 // FIXME: the target may want to specify that this is packed.
1364 llvm::StructType *STy = llvm::StructType::get(Complex[0]->getType(),
1365 Complex[1]->getType(),
1367 return llvm::ConstantStruct::get(STy, Complex);
1369 case APValue::Float: {
1370 const llvm::APFloat &Init = Value.getFloat();
1371 if (&Init.getSemantics() == &llvm::APFloat::IEEEhalf() &&
1372 !Context.getLangOpts().NativeHalfType &&
1373 !Context.getLangOpts().HalfArgsAndReturns)
1374 return llvm::ConstantInt::get(VMContext, Init.bitcastToAPInt());
1376 return llvm::ConstantFP::get(VMContext, Init);
1378 case APValue::ComplexFloat: {
1379 llvm::Constant *Complex[2];
1381 Complex[0] = llvm::ConstantFP::get(VMContext,
1382 Value.getComplexFloatReal());
1383 Complex[1] = llvm::ConstantFP::get(VMContext,
1384 Value.getComplexFloatImag());
1386 // FIXME: the target may want to specify that this is packed.
1387 llvm::StructType *STy = llvm::StructType::get(Complex[0]->getType(),
1388 Complex[1]->getType(),
1390 return llvm::ConstantStruct::get(STy, Complex);
1392 case APValue::Vector: {
1393 unsigned NumElts = Value.getVectorLength();
1394 SmallVector<llvm::Constant *, 4> Inits(NumElts);
1396 for (unsigned I = 0; I != NumElts; ++I) {
1397 const APValue &Elt = Value.getVectorElt(I);
1399 Inits[I] = llvm::ConstantInt::get(VMContext, Elt.getInt());
1400 else if (Elt.isFloat())
1401 Inits[I] = llvm::ConstantFP::get(VMContext, Elt.getFloat());
1403 llvm_unreachable("unsupported vector element type");
1405 return llvm::ConstantVector::get(Inits);
1407 case APValue::AddrLabelDiff: {
1408 const AddrLabelExpr *LHSExpr = Value.getAddrLabelDiffLHS();
1409 const AddrLabelExpr *RHSExpr = Value.getAddrLabelDiffRHS();
1410 llvm::Constant *LHS = EmitConstantExpr(LHSExpr, LHSExpr->getType(), CGF);
1411 llvm::Constant *RHS = EmitConstantExpr(RHSExpr, RHSExpr->getType(), CGF);
1413 // Compute difference
1414 llvm::Type *ResultType = getTypes().ConvertType(DestType);
1415 LHS = llvm::ConstantExpr::getPtrToInt(LHS, IntPtrTy);
1416 RHS = llvm::ConstantExpr::getPtrToInt(RHS, IntPtrTy);
1417 llvm::Constant *AddrLabelDiff = llvm::ConstantExpr::getSub(LHS, RHS);
1419 // LLVM is a bit sensitive about the exact format of the
1420 // address-of-label difference; make sure to truncate after
1422 return llvm::ConstantExpr::getTruncOrBitCast(AddrLabelDiff, ResultType);
1424 case APValue::Struct:
1425 case APValue::Union:
1426 return ConstStructBuilder::BuildStruct(*this, CGF, Value, DestType);
1427 case APValue::Array: {
1428 const ArrayType *CAT = Context.getAsArrayType(DestType);
1429 unsigned NumElements = Value.getArraySize();
1430 unsigned NumInitElts = Value.getArrayInitializedElts();
1432 // Emit array filler, if there is one.
1433 llvm::Constant *Filler = nullptr;
1434 if (Value.hasArrayFiller())
1435 Filler = EmitConstantValueForMemory(Value.getArrayFiller(),
1436 CAT->getElementType(), CGF);
1438 // Emit initializer elements.
1439 llvm::Type *CommonElementType =
1440 getTypes().ConvertType(CAT->getElementType());
1442 // Try to use a ConstantAggregateZero if we can.
1443 if (Filler && Filler->isNullValue() && !NumInitElts) {
1444 llvm::ArrayType *AType =
1445 llvm::ArrayType::get(CommonElementType, NumElements);
1446 return llvm::ConstantAggregateZero::get(AType);
1449 std::vector<llvm::Constant*> Elts;
1450 Elts.reserve(NumElements);
1451 for (unsigned I = 0; I < NumElements; ++I) {
1452 llvm::Constant *C = Filler;
1453 if (I < NumInitElts)
1454 C = EmitConstantValueForMemory(Value.getArrayInitializedElt(I),
1455 CAT->getElementType(), CGF);
1457 assert(Filler && "Missing filler for implicit elements of initializer");
1459 CommonElementType = C->getType();
1460 else if (C->getType() != CommonElementType)
1461 CommonElementType = nullptr;
1465 if (!CommonElementType) {
1466 // FIXME: Try to avoid packing the array
1467 std::vector<llvm::Type*> Types;
1468 Types.reserve(NumElements);
1469 for (unsigned i = 0, e = Elts.size(); i < e; ++i)
1470 Types.push_back(Elts[i]->getType());
1471 llvm::StructType *SType = llvm::StructType::get(VMContext, Types, true);
1472 return llvm::ConstantStruct::get(SType, Elts);
1475 llvm::ArrayType *AType =
1476 llvm::ArrayType::get(CommonElementType, NumElements);
1477 return llvm::ConstantArray::get(AType, Elts);
1479 case APValue::MemberPointer:
1480 return getCXXABI().EmitMemberPointer(Value, DestType);
1482 llvm_unreachable("Unknown APValue kind");
1486 CodeGenModule::EmitConstantValueForMemory(const APValue &Value,
1488 CodeGenFunction *CGF) {
1489 llvm::Constant *C = EmitConstantValue(Value, DestType, CGF);
1490 if (C->getType()->isIntegerTy(1)) {
1491 llvm::Type *BoolTy = getTypes().ConvertTypeForMem(DestType);
1492 C = llvm::ConstantExpr::getZExt(C, BoolTy);
1497 llvm::GlobalVariable *CodeGenModule::getAddrOfConstantCompoundLiteralIfEmitted(
1498 const CompoundLiteralExpr *E) {
1499 return EmittedCompoundLiterals.lookup(E);
1502 void CodeGenModule::setAddrOfConstantCompoundLiteral(
1503 const CompoundLiteralExpr *CLE, llvm::GlobalVariable *GV) {
1504 bool Ok = EmittedCompoundLiterals.insert(std::make_pair(CLE, GV)).second;
1506 assert(Ok && "CLE has already been emitted!");
1510 CodeGenModule::GetAddrOfConstantCompoundLiteral(const CompoundLiteralExpr *E) {
1511 assert(E->isFileScope() && "not a file-scope compound literal expr");
1512 return ConstExprEmitter(*this, nullptr).EmitLValue(E);
1516 CodeGenModule::getMemberPointerConstant(const UnaryOperator *uo) {
1517 // Member pointer constants always have a very particular form.
1518 const MemberPointerType *type = cast<MemberPointerType>(uo->getType());
1519 const ValueDecl *decl = cast<DeclRefExpr>(uo->getSubExpr())->getDecl();
1521 // A member function pointer.
1522 if (const CXXMethodDecl *method = dyn_cast<CXXMethodDecl>(decl))
1523 return getCXXABI().EmitMemberFunctionPointer(method);
1525 // Otherwise, a member data pointer.
1526 uint64_t fieldOffset = getContext().getFieldOffset(decl);
1527 CharUnits chars = getContext().toCharUnitsFromBits((int64_t) fieldOffset);
1528 return getCXXABI().EmitMemberDataPointer(type, chars);
1531 static llvm::Constant *EmitNullConstantForBase(CodeGenModule &CGM,
1532 llvm::Type *baseType,
1533 const CXXRecordDecl *base);
1535 static llvm::Constant *EmitNullConstant(CodeGenModule &CGM,
1536 const RecordDecl *record,
1537 bool asCompleteObject) {
1538 const CGRecordLayout &layout = CGM.getTypes().getCGRecordLayout(record);
1539 llvm::StructType *structure =
1540 (asCompleteObject ? layout.getLLVMType()
1541 : layout.getBaseSubobjectLLVMType());
1543 unsigned numElements = structure->getNumElements();
1544 std::vector<llvm::Constant *> elements(numElements);
1546 auto CXXR = dyn_cast<CXXRecordDecl>(record);
1547 // Fill in all the bases.
1549 for (const auto &I : CXXR->bases()) {
1550 if (I.isVirtual()) {
1551 // Ignore virtual bases; if we're laying out for a complete
1552 // object, we'll lay these out later.
1556 const CXXRecordDecl *base =
1557 cast<CXXRecordDecl>(I.getType()->castAs<RecordType>()->getDecl());
1559 // Ignore empty bases.
1560 if (base->isEmpty() ||
1561 CGM.getContext().getASTRecordLayout(base).getNonVirtualSize()
1565 unsigned fieldIndex = layout.getNonVirtualBaseLLVMFieldNo(base);
1566 llvm::Type *baseType = structure->getElementType(fieldIndex);
1567 elements[fieldIndex] = EmitNullConstantForBase(CGM, baseType, base);
1571 // Fill in all the fields.
1572 for (const auto *Field : record->fields()) {
1573 // Fill in non-bitfields. (Bitfields always use a zero pattern, which we
1574 // will fill in later.)
1575 if (!Field->isBitField()) {
1576 unsigned fieldIndex = layout.getLLVMFieldNo(Field);
1577 elements[fieldIndex] = CGM.EmitNullConstant(Field->getType());
1580 // For unions, stop after the first named field.
1581 if (record->isUnion()) {
1582 if (Field->getIdentifier())
1584 if (const auto *FieldRD =
1585 dyn_cast_or_null<RecordDecl>(Field->getType()->getAsTagDecl()))
1586 if (FieldRD->findFirstNamedDataMember())
1591 // Fill in the virtual bases, if we're working with the complete object.
1592 if (CXXR && asCompleteObject) {
1593 for (const auto &I : CXXR->vbases()) {
1594 const CXXRecordDecl *base =
1595 cast<CXXRecordDecl>(I.getType()->castAs<RecordType>()->getDecl());
1597 // Ignore empty bases.
1598 if (base->isEmpty())
1601 unsigned fieldIndex = layout.getVirtualBaseIndex(base);
1603 // We might have already laid this field out.
1604 if (elements[fieldIndex]) continue;
1606 llvm::Type *baseType = structure->getElementType(fieldIndex);
1607 elements[fieldIndex] = EmitNullConstantForBase(CGM, baseType, base);
1611 // Now go through all other fields and zero them out.
1612 for (unsigned i = 0; i != numElements; ++i) {
1614 elements[i] = llvm::Constant::getNullValue(structure->getElementType(i));
1617 return llvm::ConstantStruct::get(structure, elements);
1620 /// Emit the null constant for a base subobject.
1621 static llvm::Constant *EmitNullConstantForBase(CodeGenModule &CGM,
1622 llvm::Type *baseType,
1623 const CXXRecordDecl *base) {
1624 const CGRecordLayout &baseLayout = CGM.getTypes().getCGRecordLayout(base);
1626 // Just zero out bases that don't have any pointer to data members.
1627 if (baseLayout.isZeroInitializableAsBase())
1628 return llvm::Constant::getNullValue(baseType);
1630 // Otherwise, we can just use its null constant.
1631 return EmitNullConstant(CGM, base, /*asCompleteObject=*/false);
1634 llvm::Constant *CodeGenModule::EmitNullConstant(QualType T) {
1635 if (T->getAs<PointerType>())
1636 return getNullPointer(
1637 cast<llvm::PointerType>(getTypes().ConvertTypeForMem(T)), T);
1639 if (getTypes().isZeroInitializable(T))
1640 return llvm::Constant::getNullValue(getTypes().ConvertTypeForMem(T));
1642 if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(T)) {
1643 llvm::ArrayType *ATy =
1644 cast<llvm::ArrayType>(getTypes().ConvertTypeForMem(T));
1646 QualType ElementTy = CAT->getElementType();
1648 llvm::Constant *Element = EmitNullConstant(ElementTy);
1649 unsigned NumElements = CAT->getSize().getZExtValue();
1650 SmallVector<llvm::Constant *, 8> Array(NumElements, Element);
1651 return llvm::ConstantArray::get(ATy, Array);
1654 if (const RecordType *RT = T->getAs<RecordType>())
1655 return ::EmitNullConstant(*this, RT->getDecl(), /*complete object*/ true);
1657 assert(T->isMemberDataPointerType() &&
1658 "Should only see pointers to data members here!");
1660 return getCXXABI().EmitNullMemberPointer(T->castAs<MemberPointerType>());
1664 CodeGenModule::EmitNullConstantForBase(const CXXRecordDecl *Record) {
1665 return ::EmitNullConstant(*this, Record, false);