1 //===--- CGExprConstant.cpp - Emit LLVM Code from Constant Expressions ----===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This contains code to emit Constant Expr nodes as LLVM code.
12 //===----------------------------------------------------------------------===//
14 #include "CodeGenFunction.h"
15 #include "CodeGenModule.h"
17 #include "CGObjCRuntime.h"
18 #include "CGRecordLayout.h"
19 #include "clang/AST/APValue.h"
20 #include "clang/AST/ASTContext.h"
21 #include "clang/AST/RecordLayout.h"
22 #include "clang/AST/StmtVisitor.h"
23 #include "clang/Basic/Builtins.h"
24 #include "llvm/Constants.h"
25 #include "llvm/Function.h"
26 #include "llvm/GlobalVariable.h"
27 #include "llvm/Target/TargetData.h"
28 using namespace clang;
29 using namespace CodeGen;
31 //===----------------------------------------------------------------------===//
33 //===----------------------------------------------------------------------===//
36 class ConstStructBuilder {
41 CharUnits NextFieldOffsetInChars;
42 CharUnits LLVMStructAlignment;
43 std::vector<llvm::Constant *> Elements;
45 static llvm::Constant *BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF,
49 ConstStructBuilder(CodeGenModule &CGM, CodeGenFunction *CGF)
50 : CGM(CGM), CGF(CGF), Packed(false),
51 NextFieldOffsetInChars(CharUnits::Zero()),
52 LLVMStructAlignment(CharUnits::One()) { }
54 bool AppendField(const FieldDecl *Field, uint64_t FieldOffset,
55 llvm::Constant *InitExpr);
57 void AppendBitField(const FieldDecl *Field, uint64_t FieldOffset,
58 llvm::ConstantInt *InitExpr);
60 void AppendPadding(CharUnits PadSize);
62 void AppendTailPadding(CharUnits RecordSize);
64 void ConvertStructToPacked();
66 bool Build(InitListExpr *ILE);
68 CharUnits getAlignment(const llvm::Constant *C) const {
69 if (Packed) return CharUnits::One();
70 return CharUnits::fromQuantity(
71 CGM.getTargetData().getABITypeAlignment(C->getType()));
74 CharUnits getSizeInChars(const llvm::Constant *C) const {
75 return CharUnits::fromQuantity(
76 CGM.getTargetData().getTypeAllocSize(C->getType()));
80 bool ConstStructBuilder::
81 AppendField(const FieldDecl *Field, uint64_t FieldOffset,
82 llvm::Constant *InitCst) {
84 const ASTContext &Context = CGM.getContext();
86 CharUnits FieldOffsetInChars = Context.toCharUnitsFromBits(FieldOffset);
88 assert(NextFieldOffsetInChars <= FieldOffsetInChars
89 && "Field offset mismatch!");
91 CharUnits FieldAlignment = getAlignment(InitCst);
93 // Round up the field offset to the alignment of the field type.
94 CharUnits AlignedNextFieldOffsetInChars =
95 NextFieldOffsetInChars.RoundUpToAlignment(FieldAlignment);
97 if (AlignedNextFieldOffsetInChars > FieldOffsetInChars) {
98 assert(!Packed && "Alignment is wrong even with a packed struct!");
100 // Convert the struct to a packed struct.
101 ConvertStructToPacked();
103 AlignedNextFieldOffsetInChars = NextFieldOffsetInChars;
106 if (AlignedNextFieldOffsetInChars < FieldOffsetInChars) {
107 // We need to append padding.
109 FieldOffsetInChars - NextFieldOffsetInChars);
111 assert(NextFieldOffsetInChars == FieldOffsetInChars &&
112 "Did not add enough padding!");
114 AlignedNextFieldOffsetInChars = NextFieldOffsetInChars;
118 Elements.push_back(InitCst);
119 NextFieldOffsetInChars = AlignedNextFieldOffsetInChars +
120 getSizeInChars(InitCst);
123 assert(LLVMStructAlignment == CharUnits::One() &&
124 "Packed struct not byte-aligned!");
126 LLVMStructAlignment = std::max(LLVMStructAlignment, FieldAlignment);
131 void ConstStructBuilder::AppendBitField(const FieldDecl *Field,
132 uint64_t FieldOffset,
133 llvm::ConstantInt *CI) {
134 const ASTContext &Context = CGM.getContext();
135 const uint64_t CharWidth = Context.getCharWidth();
136 uint64_t NextFieldOffsetInBits = Context.toBits(NextFieldOffsetInChars);
137 if (FieldOffset > NextFieldOffsetInBits) {
138 // We need to add padding.
139 CharUnits PadSize = Context.toCharUnitsFromBits(
140 llvm::RoundUpToAlignment(FieldOffset - NextFieldOffsetInBits,
141 Context.Target.getCharAlign()));
143 AppendPadding(PadSize);
147 Field->getBitWidth()->EvaluateAsInt(Context).getZExtValue();
149 llvm::APInt FieldValue = CI->getValue();
151 // Promote the size of FieldValue if necessary
152 // FIXME: This should never occur, but currently it can because initializer
153 // constants are cast to bool, and because clang is not enforcing bitfield
155 if (FieldSize > FieldValue.getBitWidth())
156 FieldValue = FieldValue.zext(FieldSize);
158 // Truncate the size of FieldValue to the bit field size.
159 if (FieldSize < FieldValue.getBitWidth())
160 FieldValue = FieldValue.trunc(FieldSize);
162 NextFieldOffsetInBits = Context.toBits(NextFieldOffsetInChars);
163 if (FieldOffset < NextFieldOffsetInBits) {
164 // Either part of the field or the entire field can go into the previous
166 assert(!Elements.empty() && "Elements can't be empty!");
168 unsigned BitsInPreviousByte = NextFieldOffsetInBits - FieldOffset;
170 bool FitsCompletelyInPreviousByte =
171 BitsInPreviousByte >= FieldValue.getBitWidth();
173 llvm::APInt Tmp = FieldValue;
175 if (!FitsCompletelyInPreviousByte) {
176 unsigned NewFieldWidth = FieldSize - BitsInPreviousByte;
178 if (CGM.getTargetData().isBigEndian()) {
179 Tmp = Tmp.lshr(NewFieldWidth);
180 Tmp = Tmp.trunc(BitsInPreviousByte);
182 // We want the remaining high bits.
183 FieldValue = FieldValue.trunc(NewFieldWidth);
185 Tmp = Tmp.trunc(BitsInPreviousByte);
187 // We want the remaining low bits.
188 FieldValue = FieldValue.lshr(BitsInPreviousByte);
189 FieldValue = FieldValue.trunc(NewFieldWidth);
193 Tmp = Tmp.zext(CharWidth);
194 if (CGM.getTargetData().isBigEndian()) {
195 if (FitsCompletelyInPreviousByte)
196 Tmp = Tmp.shl(BitsInPreviousByte - FieldValue.getBitWidth());
198 Tmp = Tmp.shl(CharWidth - BitsInPreviousByte);
201 // 'or' in the bits that go into the previous byte.
202 llvm::Value *LastElt = Elements.back();
203 if (llvm::ConstantInt *Val = dyn_cast<llvm::ConstantInt>(LastElt))
204 Tmp |= Val->getValue();
206 assert(isa<llvm::UndefValue>(LastElt));
207 // If there is an undef field that we're adding to, it can either be a
208 // scalar undef (in which case, we just replace it with our field) or it
209 // is an array. If it is an array, we have to pull one byte off the
210 // array so that the other undef bytes stay around.
211 if (!isa<llvm::IntegerType>(LastElt->getType())) {
212 // The undef padding will be a multibyte array, create a new smaller
213 // padding and then an hole for our i8 to get plopped into.
214 assert(isa<llvm::ArrayType>(LastElt->getType()) &&
215 "Expected array padding of undefs");
216 const llvm::ArrayType *AT = cast<llvm::ArrayType>(LastElt->getType());
217 assert(AT->getElementType()->isIntegerTy(CharWidth) &&
218 AT->getNumElements() != 0 &&
219 "Expected non-empty array padding of undefs");
221 // Remove the padding array.
222 NextFieldOffsetInChars -= CharUnits::fromQuantity(AT->getNumElements());
225 // Add the padding back in two chunks.
226 AppendPadding(CharUnits::fromQuantity(AT->getNumElements()-1));
227 AppendPadding(CharUnits::One());
228 assert(isa<llvm::UndefValue>(Elements.back()) &&
229 Elements.back()->getType()->isIntegerTy(CharWidth) &&
230 "Padding addition didn't work right");
234 Elements.back() = llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp);
236 if (FitsCompletelyInPreviousByte)
240 while (FieldValue.getBitWidth() > CharWidth) {
243 if (CGM.getTargetData().isBigEndian()) {
244 // We want the high bits.
246 FieldValue.lshr(FieldValue.getBitWidth() - CharWidth).trunc(CharWidth);
248 // We want the low bits.
249 Tmp = FieldValue.trunc(CharWidth);
251 FieldValue = FieldValue.lshr(CharWidth);
254 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp));
255 ++NextFieldOffsetInChars;
257 FieldValue = FieldValue.trunc(FieldValue.getBitWidth() - CharWidth);
260 assert(FieldValue.getBitWidth() > 0 &&
261 "Should have at least one bit left!");
262 assert(FieldValue.getBitWidth() <= CharWidth &&
263 "Should not have more than a byte left!");
265 if (FieldValue.getBitWidth() < CharWidth) {
266 if (CGM.getTargetData().isBigEndian()) {
267 unsigned BitWidth = FieldValue.getBitWidth();
269 FieldValue = FieldValue.zext(CharWidth) << (CharWidth - BitWidth);
271 FieldValue = FieldValue.zext(CharWidth);
274 // Append the last element.
275 Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(),
277 ++NextFieldOffsetInChars;
280 void ConstStructBuilder::AppendPadding(CharUnits PadSize) {
281 if (PadSize.isZero())
284 const llvm::Type *Ty = llvm::Type::getInt8Ty(CGM.getLLVMContext());
285 if (PadSize > CharUnits::One())
286 Ty = llvm::ArrayType::get(Ty, PadSize.getQuantity());
288 llvm::Constant *C = llvm::UndefValue::get(Ty);
289 Elements.push_back(C);
290 assert(getAlignment(C) == CharUnits::One() &&
291 "Padding must have 1 byte alignment!");
293 NextFieldOffsetInChars += getSizeInChars(C);
296 void ConstStructBuilder::AppendTailPadding(CharUnits RecordSize) {
297 assert(NextFieldOffsetInChars <= RecordSize &&
300 AppendPadding(RecordSize - NextFieldOffsetInChars);
303 void ConstStructBuilder::ConvertStructToPacked() {
304 std::vector<llvm::Constant *> PackedElements;
305 CharUnits ElementOffsetInChars = CharUnits::Zero();
307 for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
308 llvm::Constant *C = Elements[i];
310 CharUnits ElementAlign = CharUnits::fromQuantity(
311 CGM.getTargetData().getABITypeAlignment(C->getType()));
312 CharUnits AlignedElementOffsetInChars =
313 ElementOffsetInChars.RoundUpToAlignment(ElementAlign);
315 if (AlignedElementOffsetInChars > ElementOffsetInChars) {
316 // We need some padding.
318 AlignedElementOffsetInChars - ElementOffsetInChars;
320 const llvm::Type *Ty = llvm::Type::getInt8Ty(CGM.getLLVMContext());
321 if (NumChars > CharUnits::One())
322 Ty = llvm::ArrayType::get(Ty, NumChars.getQuantity());
324 llvm::Constant *Padding = llvm::UndefValue::get(Ty);
325 PackedElements.push_back(Padding);
326 ElementOffsetInChars += getSizeInChars(Padding);
329 PackedElements.push_back(C);
330 ElementOffsetInChars += getSizeInChars(C);
333 assert(ElementOffsetInChars == NextFieldOffsetInChars &&
334 "Packing the struct changed its size!");
336 Elements = PackedElements;
337 LLVMStructAlignment = CharUnits::One();
341 bool ConstStructBuilder::Build(InitListExpr *ILE) {
342 RecordDecl *RD = ILE->getType()->getAs<RecordType>()->getDecl();
343 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
345 unsigned FieldNo = 0;
346 unsigned ElementNo = 0;
347 const FieldDecl *LastFD = 0;
348 bool IsMsStruct = RD->hasAttr<MsStructAttr>();
350 for (RecordDecl::field_iterator Field = RD->field_begin(),
351 FieldEnd = RD->field_end(); Field != FieldEnd; ++Field, ++FieldNo) {
353 // Zero-length bitfields following non-bitfield members are
355 if (CGM.getContext().ZeroBitfieldFollowsNonBitfield((*Field), LastFD) ||
356 CGM.getContext().ZeroBitfieldFollowsBitfield((*Field), LastFD)) {
363 // If this is a union, skip all the fields that aren't being initialized.
364 if (RD->isUnion() && ILE->getInitializedFieldInUnion() != *Field)
367 // Don't emit anonymous bitfields, they just affect layout.
368 if (Field->isBitField() && !Field->getIdentifier()) {
373 // Get the initializer. A struct can include fields without initializers,
374 // we just use explicit null values for them.
375 llvm::Constant *EltInit;
376 if (ElementNo < ILE->getNumInits())
377 EltInit = CGM.EmitConstantExpr(ILE->getInit(ElementNo++),
378 Field->getType(), CGF);
380 EltInit = CGM.EmitNullConstant(Field->getType());
385 if (!Field->isBitField()) {
386 // Handle non-bitfield members.
387 if (!AppendField(*Field, Layout.getFieldOffset(FieldNo), EltInit))
390 // Otherwise we have a bitfield.
391 AppendBitField(*Field, Layout.getFieldOffset(FieldNo),
392 cast<llvm::ConstantInt>(EltInit));
396 CharUnits LayoutSizeInChars = Layout.getSize();
398 if (NextFieldOffsetInChars > LayoutSizeInChars) {
399 // If the struct is bigger than the size of the record type,
400 // we must have a flexible array member at the end.
401 assert(RD->hasFlexibleArrayMember() &&
402 "Must have flexible array member if struct is bigger than type!");
404 // No tail padding is necessary.
408 CharUnits LLVMSizeInChars =
409 NextFieldOffsetInChars.RoundUpToAlignment(LLVMStructAlignment);
411 // Check if we need to convert the struct to a packed struct.
412 if (NextFieldOffsetInChars <= LayoutSizeInChars &&
413 LLVMSizeInChars > LayoutSizeInChars) {
414 assert(!Packed && "Size mismatch!");
416 ConvertStructToPacked();
417 assert(NextFieldOffsetInChars <= LayoutSizeInChars &&
418 "Converting to packed did not help!");
421 // Append tail padding if necessary.
422 AppendTailPadding(LayoutSizeInChars);
424 assert(LayoutSizeInChars == NextFieldOffsetInChars &&
425 "Tail padding mismatch!");
430 llvm::Constant *ConstStructBuilder::
431 BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF, InitListExpr *ILE) {
432 ConstStructBuilder Builder(CGM, CGF);
434 if (!Builder.Build(ILE))
437 llvm::Constant *Result =
438 llvm::ConstantStruct::get(CGM.getLLVMContext(),
439 Builder.Elements, Builder.Packed);
441 assert(Builder.NextFieldOffsetInChars.RoundUpToAlignment(
442 Builder.getAlignment(Result)) ==
443 Builder.getSizeInChars(Result) && "Size mismatch!");
449 //===----------------------------------------------------------------------===//
451 //===----------------------------------------------------------------------===//
453 class ConstExprEmitter :
454 public StmtVisitor<ConstExprEmitter, llvm::Constant*> {
456 CodeGenFunction *CGF;
457 llvm::LLVMContext &VMContext;
459 ConstExprEmitter(CodeGenModule &cgm, CodeGenFunction *cgf)
460 : CGM(cgm), CGF(cgf), VMContext(cgm.getLLVMContext()) {
463 //===--------------------------------------------------------------------===//
465 //===--------------------------------------------------------------------===//
467 llvm::Constant *VisitStmt(Stmt *S) {
471 llvm::Constant *VisitParenExpr(ParenExpr *PE) {
472 return Visit(PE->getSubExpr());
475 llvm::Constant *VisitGenericSelectionExpr(GenericSelectionExpr *GE) {
476 return Visit(GE->getResultExpr());
479 llvm::Constant *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
480 return Visit(E->getInitializer());
483 llvm::Constant *VisitUnaryAddrOf(UnaryOperator *E) {
484 if (E->getType()->isMemberPointerType())
485 return CGM.getMemberPointerConstant(E);
490 llvm::Constant *VisitBinSub(BinaryOperator *E) {
491 // This must be a pointer/pointer subtraction. This only happens for
493 if (!isa<AddrLabelExpr>(E->getLHS()->IgnoreParenNoopCasts(CGM.getContext())) ||
494 !isa<AddrLabelExpr>(E->getRHS()->IgnoreParenNoopCasts(CGM.getContext())))
497 llvm::Constant *LHS = CGM.EmitConstantExpr(E->getLHS(),
498 E->getLHS()->getType(), CGF);
499 llvm::Constant *RHS = CGM.EmitConstantExpr(E->getRHS(),
500 E->getRHS()->getType(), CGF);
502 const llvm::Type *ResultType = ConvertType(E->getType());
503 LHS = llvm::ConstantExpr::getPtrToInt(LHS, ResultType);
504 RHS = llvm::ConstantExpr::getPtrToInt(RHS, ResultType);
506 // No need to divide by element size, since addr of label is always void*,
507 // which has size 1 in GNUish.
508 return llvm::ConstantExpr::getSub(LHS, RHS);
511 llvm::Constant *VisitCastExpr(CastExpr* E) {
512 Expr *subExpr = E->getSubExpr();
513 llvm::Constant *C = CGM.EmitConstantExpr(subExpr, subExpr->getType(), CGF);
516 const llvm::Type *destType = ConvertType(E->getType());
518 switch (E->getCastKind()) {
520 // GCC cast to union extension
521 assert(E->getType()->isUnionType() &&
522 "Destination type is not union type!");
524 // Build a struct with the union sub-element as the first member,
525 // and padded to the appropriate size
526 std::vector<llvm::Constant*> Elts;
527 std::vector<const llvm::Type*> Types;
529 Types.push_back(C->getType());
530 unsigned CurSize = CGM.getTargetData().getTypeAllocSize(C->getType());
531 unsigned TotalSize = CGM.getTargetData().getTypeAllocSize(destType);
533 assert(CurSize <= TotalSize && "Union size mismatch!");
534 if (unsigned NumPadBytes = TotalSize - CurSize) {
535 const llvm::Type *Ty = llvm::Type::getInt8Ty(VMContext);
537 Ty = llvm::ArrayType::get(Ty, NumPadBytes);
539 Elts.push_back(llvm::UndefValue::get(Ty));
543 llvm::StructType* STy =
544 llvm::StructType::get(C->getType()->getContext(), Types, false);
545 return llvm::ConstantStruct::get(STy, Elts);
547 case CK_NullToMemberPointer: {
548 const MemberPointerType *MPT = E->getType()->getAs<MemberPointerType>();
549 return CGM.getCXXABI().EmitNullMemberPointer(MPT);
552 case CK_DerivedToBaseMemberPointer:
553 case CK_BaseToDerivedMemberPointer:
554 return CGM.getCXXABI().EmitMemberPointerConversion(C, E);
556 case CK_LValueToRValue:
560 case CK_AnyPointerToObjCPointerCast:
561 case CK_AnyPointerToBlockPointerCast:
562 case CK_LValueBitCast:
564 if (C->getType() == destType) return C;
565 return llvm::ConstantExpr::getBitCast(C, destType);
567 case CK_Dependent: llvm_unreachable("saw dependent cast!");
569 // These will never be supported.
570 case CK_ObjCObjectLValueCast:
571 case CK_GetObjCProperty:
576 // These might need to be supported for constexpr.
577 case CK_UserDefinedConversion:
578 case CK_ConstructorConversion:
581 // These should eventually be supported.
582 case CK_ArrayToPointerDecay:
583 case CK_FunctionToPointerDecay:
584 case CK_BaseToDerived:
585 case CK_DerivedToBase:
586 case CK_UncheckedDerivedToBase:
587 case CK_MemberPointerToBoolean:
589 case CK_FloatingRealToComplex:
590 case CK_FloatingComplexToReal:
591 case CK_FloatingComplexToBoolean:
592 case CK_FloatingComplexCast:
593 case CK_FloatingComplexToIntegralComplex:
594 case CK_IntegralRealToComplex:
595 case CK_IntegralComplexToReal:
596 case CK_IntegralComplexToBoolean:
597 case CK_IntegralComplexCast:
598 case CK_IntegralComplexToFloatingComplex:
601 case CK_PointerToIntegral:
602 if (!E->getType()->isBooleanType())
603 return llvm::ConstantExpr::getPtrToInt(C, destType);
606 case CK_PointerToBoolean:
607 return llvm::ConstantExpr::getICmp(llvm::CmpInst::ICMP_EQ, C,
608 llvm::ConstantPointerNull::get(cast<llvm::PointerType>(C->getType())));
610 case CK_NullToPointer:
611 return llvm::ConstantPointerNull::get(cast<llvm::PointerType>(destType));
613 case CK_IntegralCast: {
614 bool isSigned = subExpr->getType()->isSignedIntegerType();
615 return llvm::ConstantExpr::getIntegerCast(C, destType, isSigned);
618 case CK_IntegralToPointer: {
619 bool isSigned = subExpr->getType()->isSignedIntegerType();
620 C = llvm::ConstantExpr::getIntegerCast(C, CGM.IntPtrTy, isSigned);
621 return llvm::ConstantExpr::getIntToPtr(C, destType);
624 case CK_IntegralToBoolean:
625 return llvm::ConstantExpr::getICmp(llvm::CmpInst::ICMP_EQ, C,
626 llvm::Constant::getNullValue(C->getType()));
628 case CK_IntegralToFloating:
629 if (subExpr->getType()->isSignedIntegerType())
630 return llvm::ConstantExpr::getSIToFP(C, destType);
632 return llvm::ConstantExpr::getUIToFP(C, destType);
634 case CK_FloatingToIntegral:
635 if (E->getType()->isSignedIntegerType())
636 return llvm::ConstantExpr::getFPToSI(C, destType);
638 return llvm::ConstantExpr::getFPToUI(C, destType);
640 case CK_FloatingToBoolean:
641 return llvm::ConstantExpr::getFCmp(llvm::CmpInst::FCMP_UNE, C,
642 llvm::Constant::getNullValue(C->getType()));
644 case CK_FloatingCast:
645 return llvm::ConstantExpr::getFPCast(C, destType);
647 llvm_unreachable("Invalid CastKind");
650 llvm::Constant *VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
651 return Visit(DAE->getExpr());
654 llvm::Constant *EmitArrayInitialization(InitListExpr *ILE) {
655 unsigned NumInitElements = ILE->getNumInits();
656 if (NumInitElements == 1 && ILE->getType() == ILE->getInit(0)->getType() &&
657 (isa<StringLiteral>(ILE->getInit(0)) ||
658 isa<ObjCEncodeExpr>(ILE->getInit(0))))
659 return Visit(ILE->getInit(0));
661 std::vector<llvm::Constant*> Elts;
662 const llvm::ArrayType *AType =
663 cast<llvm::ArrayType>(ConvertType(ILE->getType()));
664 const llvm::Type *ElemTy = AType->getElementType();
665 unsigned NumElements = AType->getNumElements();
667 // Initialising an array requires us to automatically
668 // initialise any elements that have not been initialised explicitly
669 unsigned NumInitableElts = std::min(NumInitElements, NumElements);
671 // Copy initializer elements.
673 bool RewriteType = false;
674 for (; i < NumInitableElts; ++i) {
675 Expr *Init = ILE->getInit(i);
676 llvm::Constant *C = CGM.EmitConstantExpr(Init, Init->getType(), CGF);
679 RewriteType |= (C->getType() != ElemTy);
683 // Initialize remaining array elements.
684 // FIXME: This doesn't handle member pointers correctly!
685 llvm::Constant *fillC;
686 if (Expr *filler = ILE->getArrayFiller())
687 fillC = CGM.EmitConstantExpr(filler, filler->getType(), CGF);
689 fillC = llvm::Constant::getNullValue(ElemTy);
692 RewriteType |= (fillC->getType() != ElemTy);
693 for (; i < NumElements; ++i)
694 Elts.push_back(fillC);
697 // FIXME: Try to avoid packing the array
698 std::vector<const llvm::Type*> Types;
699 for (unsigned i = 0; i < Elts.size(); ++i)
700 Types.push_back(Elts[i]->getType());
701 const llvm::StructType *SType = llvm::StructType::get(AType->getContext(),
703 return llvm::ConstantStruct::get(SType, Elts);
706 return llvm::ConstantArray::get(AType, Elts);
709 llvm::Constant *EmitStructInitialization(InitListExpr *ILE) {
710 return ConstStructBuilder::BuildStruct(CGM, CGF, ILE);
713 llvm::Constant *EmitUnionInitialization(InitListExpr *ILE) {
714 return ConstStructBuilder::BuildStruct(CGM, CGF, ILE);
717 llvm::Constant *VisitImplicitValueInitExpr(ImplicitValueInitExpr* E) {
718 return CGM.EmitNullConstant(E->getType());
721 llvm::Constant *VisitInitListExpr(InitListExpr *ILE) {
722 if (ILE->getType()->isScalarType()) {
723 // We have a scalar in braces. Just use the first element.
724 if (ILE->getNumInits() > 0) {
725 Expr *Init = ILE->getInit(0);
726 return CGM.EmitConstantExpr(Init, Init->getType(), CGF);
728 return CGM.EmitNullConstant(ILE->getType());
731 if (ILE->getType()->isArrayType())
732 return EmitArrayInitialization(ILE);
734 if (ILE->getType()->isRecordType())
735 return EmitStructInitialization(ILE);
737 if (ILE->getType()->isUnionType())
738 return EmitUnionInitialization(ILE);
740 // If ILE was a constant vector, we would have handled it already.
741 if (ILE->getType()->isVectorType())
744 assert(0 && "Unable to handle InitListExpr");
745 // Get rid of control reaches end of void function warning.
750 llvm::Constant *VisitCXXConstructExpr(CXXConstructExpr *E) {
751 if (!E->getConstructor()->isTrivial())
754 QualType Ty = E->getType();
756 // FIXME: We should not have to call getBaseElementType here.
757 const RecordType *RT =
758 CGM.getContext().getBaseElementType(Ty)->getAs<RecordType>();
759 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
761 // If the class doesn't have a trivial destructor, we can't emit it as a
763 if (!RD->hasTrivialDestructor())
766 // Only copy and default constructors can be trivial.
769 if (E->getNumArgs()) {
770 assert(E->getNumArgs() == 1 && "trivial ctor with > 1 argument");
771 assert(E->getConstructor()->isCopyConstructor() &&
772 "trivial ctor has argument but isn't a copy ctor");
774 Expr *Arg = E->getArg(0);
775 assert(CGM.getContext().hasSameUnqualifiedType(Ty, Arg->getType()) &&
776 "argument to copy ctor is of wrong type");
781 return CGM.EmitNullConstant(Ty);
784 llvm::Constant *VisitStringLiteral(StringLiteral *E) {
785 assert(!E->getType()->isPointerType() && "Strings are always arrays");
787 // This must be a string initializing an array in a static initializer.
788 // Don't emit it as the address of the string, emit the string data itself
789 // as an inline array.
790 return llvm::ConstantArray::get(VMContext,
791 CGM.GetStringForStringLiteral(E), false);
794 llvm::Constant *VisitObjCEncodeExpr(ObjCEncodeExpr *E) {
795 // This must be an @encode initializing an array in a static initializer.
796 // Don't emit it as the address of the string, emit the string data itself
797 // as an inline array.
799 CGM.getContext().getObjCEncodingForType(E->getEncodedType(), Str);
800 const ConstantArrayType *CAT = cast<ConstantArrayType>(E->getType());
802 // Resize the string to the right size, adding zeros at the end, or
803 // truncating as needed.
804 Str.resize(CAT->getSize().getZExtValue(), '\0');
805 return llvm::ConstantArray::get(VMContext, Str, false);
808 llvm::Constant *VisitUnaryExtension(const UnaryOperator *E) {
809 return Visit(E->getSubExpr());
813 const llvm::Type *ConvertType(QualType T) {
814 return CGM.getTypes().ConvertType(T);
818 llvm::Constant *EmitLValue(Expr *E) {
819 switch (E->getStmtClass()) {
821 case Expr::CompoundLiteralExprClass: {
822 // Note that due to the nature of compound literals, this is guaranteed
823 // to be the only use of the variable, so we just generate it here.
824 CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E);
825 llvm::Constant* C = Visit(CLE->getInitializer());
826 // FIXME: "Leaked" on failure.
828 C = new llvm::GlobalVariable(CGM.getModule(), C->getType(),
829 E->getType().isConstant(CGM.getContext()),
830 llvm::GlobalValue::InternalLinkage,
831 C, ".compoundliteral", 0, false,
832 CGM.getContext().getTargetAddressSpace(E->getType()));
835 case Expr::DeclRefExprClass: {
836 ValueDecl *Decl = cast<DeclRefExpr>(E)->getDecl();
837 if (Decl->hasAttr<WeakRefAttr>())
838 return CGM.GetWeakRefReference(Decl);
839 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Decl))
840 return CGM.GetAddrOfFunction(FD);
841 if (const VarDecl* VD = dyn_cast<VarDecl>(Decl)) {
842 // We can never refer to a variable with local storage.
843 if (!VD->hasLocalStorage()) {
844 if (VD->isFileVarDecl() || VD->hasExternalStorage())
845 return CGM.GetAddrOfGlobalVar(VD);
846 else if (VD->isLocalVarDecl()) {
847 assert(CGF && "Can't access static local vars without CGF");
848 return CGF->GetAddrOfStaticLocalVar(VD);
854 case Expr::StringLiteralClass:
855 return CGM.GetAddrOfConstantStringFromLiteral(cast<StringLiteral>(E));
856 case Expr::ObjCEncodeExprClass:
857 return CGM.GetAddrOfConstantStringFromObjCEncode(cast<ObjCEncodeExpr>(E));
858 case Expr::ObjCStringLiteralClass: {
859 ObjCStringLiteral* SL = cast<ObjCStringLiteral>(E);
861 CGM.getObjCRuntime().GenerateConstantString(SL->getString());
862 return llvm::ConstantExpr::getBitCast(C, ConvertType(E->getType()));
864 case Expr::PredefinedExprClass: {
865 unsigned Type = cast<PredefinedExpr>(E)->getIdentType();
867 LValue Res = CGF->EmitPredefinedLValue(cast<PredefinedExpr>(E));
868 return cast<llvm::Constant>(Res.getAddress());
869 } else if (Type == PredefinedExpr::PrettyFunction) {
870 return CGM.GetAddrOfConstantCString("top level", ".tmp");
873 return CGM.GetAddrOfConstantCString("", ".tmp");
875 case Expr::AddrLabelExprClass: {
876 assert(CGF && "Invalid address of label expression outside function.");
877 llvm::Constant *Ptr =
878 CGF->GetAddrOfLabel(cast<AddrLabelExpr>(E)->getLabel());
879 return llvm::ConstantExpr::getBitCast(Ptr, ConvertType(E->getType()));
881 case Expr::CallExprClass: {
882 CallExpr* CE = cast<CallExpr>(E);
883 unsigned builtin = CE->isBuiltinCall(CGM.getContext());
885 Builtin::BI__builtin___CFStringMakeConstantString &&
887 Builtin::BI__builtin___NSStringMakeConstantString)
889 const Expr *Arg = CE->getArg(0)->IgnoreParenCasts();
890 const StringLiteral *Literal = cast<StringLiteral>(Arg);
892 Builtin::BI__builtin___NSStringMakeConstantString) {
893 return CGM.getObjCRuntime().GenerateConstantString(Literal);
895 // FIXME: need to deal with UCN conversion issues.
896 return CGM.GetAddrOfConstantCFString(Literal);
898 case Expr::BlockExprClass: {
899 std::string FunctionName;
901 FunctionName = CGF->CurFn->getName();
903 FunctionName = "global";
905 return CGM.GetAddrOfGlobalBlock(cast<BlockExpr>(E), FunctionName.c_str());
913 } // end anonymous namespace.
915 llvm::Constant *CodeGenModule::EmitConstantExpr(const Expr *E,
917 CodeGenFunction *CGF) {
918 Expr::EvalResult Result;
920 bool Success = false;
922 if (DestType->isReferenceType())
923 Success = E->EvaluateAsLValue(Result, Context);
925 Success = E->Evaluate(Result, Context);
927 if (Success && !Result.HasSideEffects) {
928 switch (Result.Val.getKind()) {
929 case APValue::Uninitialized:
930 assert(0 && "Constant expressions should be initialized.");
932 case APValue::LValue: {
933 const llvm::Type *DestTy = getTypes().ConvertTypeForMem(DestType);
934 llvm::Constant *Offset =
935 llvm::ConstantInt::get(llvm::Type::getInt64Ty(VMContext),
936 Result.Val.getLValueOffset().getQuantity());
939 if (const Expr *LVBase = Result.Val.getLValueBase()) {
940 C = ConstExprEmitter(*this, CGF).EmitLValue(const_cast<Expr*>(LVBase));
942 // Apply offset if necessary.
943 if (!Offset->isNullValue()) {
944 const llvm::Type *Type = llvm::Type::getInt8PtrTy(VMContext);
945 llvm::Constant *Casted = llvm::ConstantExpr::getBitCast(C, Type);
946 Casted = llvm::ConstantExpr::getGetElementPtr(Casted, &Offset, 1);
947 C = llvm::ConstantExpr::getBitCast(Casted, C->getType());
950 // Convert to the appropriate type; this could be an lvalue for
952 if (isa<llvm::PointerType>(DestTy))
953 return llvm::ConstantExpr::getBitCast(C, DestTy);
955 return llvm::ConstantExpr::getPtrToInt(C, DestTy);
959 // Convert to the appropriate type; this could be an lvalue for
961 if (isa<llvm::PointerType>(DestTy))
962 return llvm::ConstantExpr::getIntToPtr(C, DestTy);
964 // If the types don't match this should only be a truncate.
965 if (C->getType() != DestTy)
966 return llvm::ConstantExpr::getTrunc(C, DestTy);
972 llvm::Constant *C = llvm::ConstantInt::get(VMContext,
973 Result.Val.getInt());
975 if (C->getType()->isIntegerTy(1)) {
976 const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType());
977 C = llvm::ConstantExpr::getZExt(C, BoolTy);
981 case APValue::ComplexInt: {
982 llvm::Constant *Complex[2];
984 Complex[0] = llvm::ConstantInt::get(VMContext,
985 Result.Val.getComplexIntReal());
986 Complex[1] = llvm::ConstantInt::get(VMContext,
987 Result.Val.getComplexIntImag());
989 // FIXME: the target may want to specify that this is packed.
990 return llvm::ConstantStruct::get(VMContext, Complex, 2, false);
993 return llvm::ConstantFP::get(VMContext, Result.Val.getFloat());
994 case APValue::ComplexFloat: {
995 llvm::Constant *Complex[2];
997 Complex[0] = llvm::ConstantFP::get(VMContext,
998 Result.Val.getComplexFloatReal());
999 Complex[1] = llvm::ConstantFP::get(VMContext,
1000 Result.Val.getComplexFloatImag());
1002 // FIXME: the target may want to specify that this is packed.
1003 return llvm::ConstantStruct::get(VMContext, Complex, 2, false);
1005 case APValue::Vector: {
1006 llvm::SmallVector<llvm::Constant *, 4> Inits;
1007 unsigned NumElts = Result.Val.getVectorLength();
1009 if (Context.getLangOptions().AltiVec &&
1011 cast<CastExpr>(E)->getCastKind() == CK_VectorSplat) {
1012 // AltiVec vector initialization with a single literal
1013 APValue &Elt = Result.Val.getVectorElt(0);
1015 llvm::Constant* InitValue = Elt.isInt()
1016 ? cast<llvm::Constant>
1017 (llvm::ConstantInt::get(VMContext, Elt.getInt()))
1018 : cast<llvm::Constant>
1019 (llvm::ConstantFP::get(VMContext, Elt.getFloat()));
1021 for (unsigned i = 0; i != NumElts; ++i)
1022 Inits.push_back(InitValue);
1025 for (unsigned i = 0; i != NumElts; ++i) {
1026 APValue &Elt = Result.Val.getVectorElt(i);
1028 Inits.push_back(llvm::ConstantInt::get(VMContext, Elt.getInt()));
1030 Inits.push_back(llvm::ConstantFP::get(VMContext, Elt.getFloat()));
1033 return llvm::ConstantVector::get(Inits);
1038 llvm::Constant* C = ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E));
1039 if (C && C->getType()->isIntegerTy(1)) {
1040 const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType());
1041 C = llvm::ConstantExpr::getZExt(C, BoolTy);
1046 static uint64_t getFieldOffset(ASTContext &C, const FieldDecl *field) {
1047 const ASTRecordLayout &layout = C.getASTRecordLayout(field->getParent());
1048 return layout.getFieldOffset(field->getFieldIndex());
1052 CodeGenModule::getMemberPointerConstant(const UnaryOperator *uo) {
1053 // Member pointer constants always have a very particular form.
1054 const MemberPointerType *type = cast<MemberPointerType>(uo->getType());
1055 const ValueDecl *decl = cast<DeclRefExpr>(uo->getSubExpr())->getDecl();
1057 // A member function pointer.
1058 if (const CXXMethodDecl *method = dyn_cast<CXXMethodDecl>(decl))
1059 return getCXXABI().EmitMemberPointer(method);
1061 // Otherwise, a member data pointer.
1062 uint64_t fieldOffset;
1063 if (const FieldDecl *field = dyn_cast<FieldDecl>(decl))
1064 fieldOffset = getFieldOffset(getContext(), field);
1066 const IndirectFieldDecl *ifield = cast<IndirectFieldDecl>(decl);
1069 for (IndirectFieldDecl::chain_iterator ci = ifield->chain_begin(),
1070 ce = ifield->chain_end(); ci != ce; ++ci)
1071 fieldOffset += getFieldOffset(getContext(), cast<FieldDecl>(*ci));
1074 CharUnits chars = getContext().toCharUnitsFromBits((int64_t) fieldOffset);
1075 return getCXXABI().EmitMemberDataPointer(type, chars);
1079 FillInNullDataMemberPointers(CodeGenModule &CGM, QualType T,
1080 std::vector<llvm::Constant *> &Elements,
1081 uint64_t StartOffset) {
1082 assert(StartOffset % CGM.getContext().getCharWidth() == 0 &&
1083 "StartOffset not byte aligned!");
1085 if (CGM.getTypes().isZeroInitializable(T))
1088 if (const ConstantArrayType *CAT =
1089 CGM.getContext().getAsConstantArrayType(T)) {
1090 QualType ElementTy = CAT->getElementType();
1091 uint64_t ElementSize = CGM.getContext().getTypeSize(ElementTy);
1093 for (uint64_t I = 0, E = CAT->getSize().getZExtValue(); I != E; ++I) {
1094 FillInNullDataMemberPointers(CGM, ElementTy, Elements,
1095 StartOffset + I * ElementSize);
1097 } else if (const RecordType *RT = T->getAs<RecordType>()) {
1098 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
1099 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD);
1101 // Go through all bases and fill in any null pointer to data members.
1102 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
1103 E = RD->bases_end(); I != E; ++I) {
1104 if (I->isVirtual()) {
1105 // Ignore virtual bases.
1109 const CXXRecordDecl *BaseDecl =
1110 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
1112 // Ignore empty bases.
1113 if (BaseDecl->isEmpty())
1116 // Ignore bases that don't have any pointer to data members.
1117 if (CGM.getTypes().isZeroInitializable(BaseDecl))
1120 uint64_t BaseOffset = Layout.getBaseClassOffsetInBits(BaseDecl);
1121 FillInNullDataMemberPointers(CGM, I->getType(),
1122 Elements, StartOffset + BaseOffset);
1125 // Visit all fields.
1126 unsigned FieldNo = 0;
1127 for (RecordDecl::field_iterator I = RD->field_begin(),
1128 E = RD->field_end(); I != E; ++I, ++FieldNo) {
1129 QualType FieldType = I->getType();
1131 if (CGM.getTypes().isZeroInitializable(FieldType))
1134 uint64_t FieldOffset = StartOffset + Layout.getFieldOffset(FieldNo);
1135 FillInNullDataMemberPointers(CGM, FieldType, Elements, FieldOffset);
1138 assert(T->isMemberPointerType() && "Should only see member pointers here!");
1139 assert(!T->getAs<MemberPointerType>()->getPointeeType()->isFunctionType() &&
1140 "Should only see pointers to data members here!");
1142 CharUnits StartIndex = CGM.getContext().toCharUnitsFromBits(StartOffset);
1143 CharUnits EndIndex = StartIndex + CGM.getContext().getTypeSizeInChars(T);
1145 // FIXME: hardcodes Itanium member pointer representation!
1146 llvm::Constant *NegativeOne =
1147 llvm::ConstantInt::get(llvm::Type::getInt8Ty(CGM.getLLVMContext()),
1148 -1ULL, /*isSigned*/true);
1150 // Fill in the null data member pointer.
1151 for (CharUnits I = StartIndex; I != EndIndex; ++I)
1152 Elements[I.getQuantity()] = NegativeOne;
1156 static llvm::Constant *EmitNullConstantForBase(CodeGenModule &CGM,
1157 const llvm::Type *baseType,
1158 const CXXRecordDecl *base);
1160 static llvm::Constant *EmitNullConstant(CodeGenModule &CGM,
1161 const CXXRecordDecl *record,
1162 bool asCompleteObject) {
1163 const CGRecordLayout &layout = CGM.getTypes().getCGRecordLayout(record);
1164 const llvm::StructType *structure =
1165 (asCompleteObject ? layout.getLLVMType()
1166 : layout.getBaseSubobjectLLVMType());
1168 unsigned numElements = structure->getNumElements();
1169 std::vector<llvm::Constant *> elements(numElements);
1171 // Fill in all the bases.
1172 for (CXXRecordDecl::base_class_const_iterator
1173 I = record->bases_begin(), E = record->bases_end(); I != E; ++I) {
1174 if (I->isVirtual()) {
1175 // Ignore virtual bases; if we're laying out for a complete
1176 // object, we'll lay these out later.
1180 const CXXRecordDecl *base =
1181 cast<CXXRecordDecl>(I->getType()->castAs<RecordType>()->getDecl());
1183 // Ignore empty bases.
1184 if (base->isEmpty())
1187 unsigned fieldIndex = layout.getNonVirtualBaseLLVMFieldNo(base);
1188 const llvm::Type *baseType = structure->getElementType(fieldIndex);
1189 elements[fieldIndex] = EmitNullConstantForBase(CGM, baseType, base);
1192 // Fill in all the fields.
1193 for (RecordDecl::field_iterator I = record->field_begin(),
1194 E = record->field_end(); I != E; ++I) {
1195 const FieldDecl *field = *I;
1197 // Ignore bit fields.
1198 if (field->isBitField())
1201 unsigned fieldIndex = layout.getLLVMFieldNo(field);
1202 elements[fieldIndex] = CGM.EmitNullConstant(field->getType());
1205 // Fill in the virtual bases, if we're working with the complete object.
1206 if (asCompleteObject) {
1207 for (CXXRecordDecl::base_class_const_iterator
1208 I = record->vbases_begin(), E = record->vbases_end(); I != E; ++I) {
1209 const CXXRecordDecl *base =
1210 cast<CXXRecordDecl>(I->getType()->castAs<RecordType>()->getDecl());
1212 // Ignore empty bases.
1213 if (base->isEmpty())
1216 unsigned fieldIndex = layout.getVirtualBaseIndex(base);
1218 // We might have already laid this field out.
1219 if (elements[fieldIndex]) continue;
1221 const llvm::Type *baseType = structure->getElementType(fieldIndex);
1222 elements[fieldIndex] = EmitNullConstantForBase(CGM, baseType, base);
1226 // Now go through all other fields and zero them out.
1227 for (unsigned i = 0; i != numElements; ++i) {
1229 elements[i] = llvm::Constant::getNullValue(structure->getElementType(i));
1232 return llvm::ConstantStruct::get(structure, elements);
1235 /// Emit the null constant for a base subobject.
1236 static llvm::Constant *EmitNullConstantForBase(CodeGenModule &CGM,
1237 const llvm::Type *baseType,
1238 const CXXRecordDecl *base) {
1239 const CGRecordLayout &baseLayout = CGM.getTypes().getCGRecordLayout(base);
1241 // Just zero out bases that don't have any pointer to data members.
1242 if (baseLayout.isZeroInitializableAsBase())
1243 return llvm::Constant::getNullValue(baseType);
1245 // If the base type is a struct, we can just use its null constant.
1246 if (isa<llvm::StructType>(baseType)) {
1247 return EmitNullConstant(CGM, base, /*complete*/ false);
1250 // Otherwise, some bases are represented as arrays of i8 if the size
1251 // of the base is smaller than its corresponding LLVM type. Figure
1252 // out how many elements this base array has.
1253 const llvm::ArrayType *baseArrayType = cast<llvm::ArrayType>(baseType);
1254 unsigned numBaseElements = baseArrayType->getNumElements();
1256 // Fill in null data member pointers.
1257 std::vector<llvm::Constant *> baseElements(numBaseElements);
1258 FillInNullDataMemberPointers(CGM, CGM.getContext().getTypeDeclType(base),
1261 // Now go through all other elements and zero them out.
1262 if (numBaseElements) {
1263 const llvm::Type *i8 = llvm::Type::getInt8Ty(CGM.getLLVMContext());
1264 llvm::Constant *i8_zero = llvm::Constant::getNullValue(i8);
1265 for (unsigned i = 0; i != numBaseElements; ++i) {
1266 if (!baseElements[i])
1267 baseElements[i] = i8_zero;
1271 return llvm::ConstantArray::get(baseArrayType, baseElements);
1274 llvm::Constant *CodeGenModule::EmitNullConstant(QualType T) {
1275 if (getTypes().isZeroInitializable(T))
1276 return llvm::Constant::getNullValue(getTypes().ConvertTypeForMem(T));
1278 if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(T)) {
1280 QualType ElementTy = CAT->getElementType();
1282 llvm::Constant *Element = EmitNullConstant(ElementTy);
1283 unsigned NumElements = CAT->getSize().getZExtValue();
1284 std::vector<llvm::Constant *> Array(NumElements);
1285 for (unsigned i = 0; i != NumElements; ++i)
1288 const llvm::ArrayType *ATy =
1289 cast<llvm::ArrayType>(getTypes().ConvertTypeForMem(T));
1290 return llvm::ConstantArray::get(ATy, Array);
1293 if (const RecordType *RT = T->getAs<RecordType>()) {
1294 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
1295 return ::EmitNullConstant(*this, RD, /*complete object*/ true);
1298 assert(T->isMemberPointerType() && "Should only see member pointers here!");
1299 assert(!T->getAs<MemberPointerType>()->getPointeeType()->isFunctionType() &&
1300 "Should only see pointers to data members here!");
1302 // Itanium C++ ABI 2.3:
1303 // A NULL pointer is represented as -1.
1304 return getCXXABI().EmitNullMemberPointer(T->castAs<MemberPointerType>());