1 //===------- ItaniumCXXABI.cpp - Emit LLVM Code from ASTs for a Module ----===//
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 provides C++ code generation targeting the Itanium C++ ABI. The class
11 // in this file generates structures that follow the Itanium C++ ABI, which is
13 // http://www.codesourcery.com/public/cxx-abi/abi.html
14 // http://www.codesourcery.com/public/cxx-abi/abi-eh.html
16 // It also supports the closely-related ARM ABI, documented at:
17 // http://infocenter.arm.com/help/topic/com.arm.doc.ihi0041c/IHI0041C_cppabi.pdf
19 //===----------------------------------------------------------------------===//
22 #include "CGRecordLayout.h"
23 #include "CodeGenFunction.h"
24 #include "CodeGenModule.h"
25 #include <clang/AST/Mangle.h>
26 #include <clang/AST/Type.h>
27 #include <llvm/Intrinsics.h>
28 #include <llvm/Target/TargetData.h>
29 #include <llvm/Value.h>
31 using namespace clang;
32 using namespace CodeGen;
35 class ItaniumCXXABI : public CodeGen::CGCXXABI {
37 llvm::IntegerType *PtrDiffTy;
41 // It's a little silly for us to cache this.
42 llvm::IntegerType *getPtrDiffTy() {
44 QualType T = getContext().getPointerDiffType();
45 llvm::Type *Ty = CGM.getTypes().ConvertType(T);
46 PtrDiffTy = cast<llvm::IntegerType>(Ty);
51 bool NeedsArrayCookie(const CXXNewExpr *expr);
52 bool NeedsArrayCookie(const CXXDeleteExpr *expr,
53 QualType elementType);
56 ItaniumCXXABI(CodeGen::CodeGenModule &CGM, bool IsARM = false) :
57 CGCXXABI(CGM), PtrDiffTy(0), IsARM(IsARM) { }
59 bool isZeroInitializable(const MemberPointerType *MPT);
61 llvm::Type *ConvertMemberPointerType(const MemberPointerType *MPT);
63 llvm::Value *EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF,
65 llvm::Value *MemFnPtr,
66 const MemberPointerType *MPT);
68 llvm::Value *EmitMemberDataPointerAddress(CodeGenFunction &CGF,
71 const MemberPointerType *MPT);
73 llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,
77 llvm::Constant *EmitMemberPointerConversion(llvm::Constant *C,
80 llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT);
82 llvm::Constant *EmitMemberPointer(const CXXMethodDecl *MD);
83 llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,
86 llvm::Value *EmitMemberPointerComparison(CodeGenFunction &CGF,
89 const MemberPointerType *MPT,
92 llvm::Value *EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
94 const MemberPointerType *MPT);
96 void BuildConstructorSignature(const CXXConstructorDecl *Ctor,
99 SmallVectorImpl<CanQualType> &ArgTys);
101 void BuildDestructorSignature(const CXXDestructorDecl *Dtor,
104 SmallVectorImpl<CanQualType> &ArgTys);
106 void BuildInstanceFunctionParams(CodeGenFunction &CGF,
108 FunctionArgList &Params);
110 void EmitInstanceFunctionProlog(CodeGenFunction &CGF);
112 CharUnits GetArrayCookieSize(const CXXNewExpr *expr);
113 llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF,
115 llvm::Value *NumElements,
116 const CXXNewExpr *expr,
117 QualType ElementType);
118 void ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr,
119 const CXXDeleteExpr *expr,
120 QualType ElementType, llvm::Value *&NumElements,
121 llvm::Value *&AllocPtr, CharUnits &CookieSize);
123 void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
124 llvm::GlobalVariable *DeclPtr);
127 class ARMCXXABI : public ItaniumCXXABI {
129 ARMCXXABI(CodeGen::CodeGenModule &CGM) : ItaniumCXXABI(CGM, /*ARM*/ true) {}
131 void BuildConstructorSignature(const CXXConstructorDecl *Ctor,
134 SmallVectorImpl<CanQualType> &ArgTys);
136 void BuildDestructorSignature(const CXXDestructorDecl *Dtor,
139 SmallVectorImpl<CanQualType> &ArgTys);
141 void BuildInstanceFunctionParams(CodeGenFunction &CGF,
143 FunctionArgList &Params);
145 void EmitInstanceFunctionProlog(CodeGenFunction &CGF);
147 void EmitReturnFromThunk(CodeGenFunction &CGF, RValue RV, QualType ResTy);
149 CharUnits GetArrayCookieSize(const CXXNewExpr *expr);
150 llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF,
152 llvm::Value *NumElements,
153 const CXXNewExpr *expr,
154 QualType ElementType);
155 void ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr,
156 const CXXDeleteExpr *expr,
157 QualType ElementType, llvm::Value *&NumElements,
158 llvm::Value *&AllocPtr, CharUnits &CookieSize);
161 /// \brief Returns true if the given instance method is one of the
162 /// kinds that the ARM ABI says returns 'this'.
163 static bool HasThisReturn(GlobalDecl GD) {
164 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
165 return ((isa<CXXDestructorDecl>(MD) && GD.getDtorType() != Dtor_Deleting) ||
166 (isa<CXXConstructorDecl>(MD)));
171 CodeGen::CGCXXABI *CodeGen::CreateItaniumCXXABI(CodeGenModule &CGM) {
172 return new ItaniumCXXABI(CGM);
175 CodeGen::CGCXXABI *CodeGen::CreateARMCXXABI(CodeGenModule &CGM) {
176 return new ARMCXXABI(CGM);
180 ItaniumCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) {
181 if (MPT->isMemberDataPointer())
182 return getPtrDiffTy();
183 return llvm::StructType::get(getPtrDiffTy(), getPtrDiffTy(), NULL);
186 /// In the Itanium and ARM ABIs, method pointers have the form:
187 /// struct { ptrdiff_t ptr; ptrdiff_t adj; } memptr;
189 /// In the Itanium ABI:
190 /// - method pointers are virtual if (memptr.ptr & 1) is nonzero
191 /// - the this-adjustment is (memptr.adj)
192 /// - the virtual offset is (memptr.ptr - 1)
195 /// - method pointers are virtual if (memptr.adj & 1) is nonzero
196 /// - the this-adjustment is (memptr.adj >> 1)
197 /// - the virtual offset is (memptr.ptr)
198 /// ARM uses 'adj' for the virtual flag because Thumb functions
199 /// may be only single-byte aligned.
201 /// If the member is virtual, the adjusted 'this' pointer points
202 /// to a vtable pointer from which the virtual offset is applied.
204 /// If the member is non-virtual, memptr.ptr is the address of
205 /// the function to call.
207 ItaniumCXXABI::EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF,
209 llvm::Value *MemFnPtr,
210 const MemberPointerType *MPT) {
211 CGBuilderTy &Builder = CGF.Builder;
213 const FunctionProtoType *FPT =
214 MPT->getPointeeType()->getAs<FunctionProtoType>();
215 const CXXRecordDecl *RD =
216 cast<CXXRecordDecl>(MPT->getClass()->getAs<RecordType>()->getDecl());
218 llvm::FunctionType *FTy =
219 CGM.getTypes().GetFunctionType(CGM.getTypes().getFunctionInfo(RD, FPT),
222 llvm::IntegerType *ptrdiff = getPtrDiffTy();
223 llvm::Constant *ptrdiff_1 = llvm::ConstantInt::get(ptrdiff, 1);
225 llvm::BasicBlock *FnVirtual = CGF.createBasicBlock("memptr.virtual");
226 llvm::BasicBlock *FnNonVirtual = CGF.createBasicBlock("memptr.nonvirtual");
227 llvm::BasicBlock *FnEnd = CGF.createBasicBlock("memptr.end");
229 // Extract memptr.adj, which is in the second field.
230 llvm::Value *RawAdj = Builder.CreateExtractValue(MemFnPtr, 1, "memptr.adj");
232 // Compute the true adjustment.
233 llvm::Value *Adj = RawAdj;
235 Adj = Builder.CreateAShr(Adj, ptrdiff_1, "memptr.adj.shifted");
237 // Apply the adjustment and cast back to the original struct type
239 llvm::Value *Ptr = Builder.CreateBitCast(This, Builder.getInt8PtrTy());
240 Ptr = Builder.CreateInBoundsGEP(Ptr, Adj);
241 This = Builder.CreateBitCast(Ptr, This->getType(), "this.adjusted");
243 // Load the function pointer.
244 llvm::Value *FnAsInt = Builder.CreateExtractValue(MemFnPtr, 0, "memptr.ptr");
246 // If the LSB in the function pointer is 1, the function pointer points to
247 // a virtual function.
248 llvm::Value *IsVirtual;
250 IsVirtual = Builder.CreateAnd(RawAdj, ptrdiff_1);
252 IsVirtual = Builder.CreateAnd(FnAsInt, ptrdiff_1);
253 IsVirtual = Builder.CreateIsNotNull(IsVirtual, "memptr.isvirtual");
254 Builder.CreateCondBr(IsVirtual, FnVirtual, FnNonVirtual);
256 // In the virtual path, the adjustment left 'This' pointing to the
257 // vtable of the correct base subobject. The "function pointer" is an
258 // offset within the vtable (+1 for the virtual flag on non-ARM).
259 CGF.EmitBlock(FnVirtual);
261 // Cast the adjusted this to a pointer to vtable pointer and load.
262 llvm::Type *VTableTy = Builder.getInt8PtrTy();
263 llvm::Value *VTable = Builder.CreateBitCast(This, VTableTy->getPointerTo());
264 VTable = Builder.CreateLoad(VTable, "memptr.vtable");
267 llvm::Value *VTableOffset = FnAsInt;
268 if (!IsARM) VTableOffset = Builder.CreateSub(VTableOffset, ptrdiff_1);
269 VTable = Builder.CreateGEP(VTable, VTableOffset);
271 // Load the virtual function to call.
272 VTable = Builder.CreateBitCast(VTable, FTy->getPointerTo()->getPointerTo());
273 llvm::Value *VirtualFn = Builder.CreateLoad(VTable, "memptr.virtualfn");
274 CGF.EmitBranch(FnEnd);
276 // In the non-virtual path, the function pointer is actually a
278 CGF.EmitBlock(FnNonVirtual);
279 llvm::Value *NonVirtualFn =
280 Builder.CreateIntToPtr(FnAsInt, FTy->getPointerTo(), "memptr.nonvirtualfn");
283 CGF.EmitBlock(FnEnd);
284 llvm::PHINode *Callee = Builder.CreatePHI(FTy->getPointerTo(), 2);
285 Callee->addIncoming(VirtualFn, FnVirtual);
286 Callee->addIncoming(NonVirtualFn, FnNonVirtual);
290 /// Compute an l-value by applying the given pointer-to-member to a
292 llvm::Value *ItaniumCXXABI::EmitMemberDataPointerAddress(CodeGenFunction &CGF,
295 const MemberPointerType *MPT) {
296 assert(MemPtr->getType() == getPtrDiffTy());
298 CGBuilderTy &Builder = CGF.Builder;
300 unsigned AS = cast<llvm::PointerType>(Base->getType())->getAddressSpace();
303 Base = Builder.CreateBitCast(Base, Builder.getInt8Ty()->getPointerTo(AS));
305 // Apply the offset, which we assume is non-null.
306 llvm::Value *Addr = Builder.CreateInBoundsGEP(Base, MemPtr, "memptr.offset");
308 // Cast the address to the appropriate pointer type, adopting the
309 // address space of the base pointer.
311 = CGF.ConvertTypeForMem(MPT->getPointeeType())->getPointerTo(AS);
312 return Builder.CreateBitCast(Addr, PType);
315 /// Perform a derived-to-base or base-to-derived member pointer conversion.
317 /// Obligatory offset/adjustment diagram:
318 /// <-- offset --> <-- adjustment -->
319 /// |--------------------------|----------------------|--------------------|
320 /// ^Derived address point ^Base address point ^Member address point
322 /// So when converting a base member pointer to a derived member pointer,
323 /// we add the offset to the adjustment because the address point has
324 /// decreased; and conversely, when converting a derived MP to a base MP
325 /// we subtract the offset from the adjustment because the address point
328 /// The standard forbids (at compile time) conversion to and from
329 /// virtual bases, which is why we don't have to consider them here.
331 /// The standard forbids (at run time) casting a derived MP to a base
332 /// MP when the derived MP does not point to a member of the base.
333 /// This is why -1 is a reasonable choice for null data member
336 ItaniumCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF,
339 assert(E->getCastKind() == CK_DerivedToBaseMemberPointer ||
340 E->getCastKind() == CK_BaseToDerivedMemberPointer);
342 if (isa<llvm::Constant>(Src))
343 return EmitMemberPointerConversion(cast<llvm::Constant>(Src), E);
345 CGBuilderTy &Builder = CGF.Builder;
347 const MemberPointerType *SrcTy =
348 E->getSubExpr()->getType()->getAs<MemberPointerType>();
349 const MemberPointerType *DestTy = E->getType()->getAs<MemberPointerType>();
351 const CXXRecordDecl *SrcDecl = SrcTy->getClass()->getAsCXXRecordDecl();
352 const CXXRecordDecl *DestDecl = DestTy->getClass()->getAsCXXRecordDecl();
355 E->getCastKind() == CK_DerivedToBaseMemberPointer;
357 const CXXRecordDecl *DerivedDecl;
359 DerivedDecl = SrcDecl;
361 DerivedDecl = DestDecl;
363 llvm::Constant *Adj =
364 CGF.CGM.GetNonVirtualBaseClassOffset(DerivedDecl,
367 if (!Adj) return Src;
369 // For member data pointers, this is just a matter of adding the
370 // offset if the source is non-null.
371 if (SrcTy->isMemberDataPointer()) {
374 Dst = Builder.CreateNSWSub(Src, Adj, "adj");
376 Dst = Builder.CreateNSWAdd(Src, Adj, "adj");
379 llvm::Value *Null = llvm::Constant::getAllOnesValue(Src->getType());
380 llvm::Value *IsNull = Builder.CreateICmpEQ(Src, Null, "memptr.isnull");
381 return Builder.CreateSelect(IsNull, Src, Dst);
384 // The this-adjustment is left-shifted by 1 on ARM.
386 uint64_t Offset = cast<llvm::ConstantInt>(Adj)->getZExtValue();
388 Adj = llvm::ConstantInt::get(Adj->getType(), Offset);
391 llvm::Value *SrcAdj = Builder.CreateExtractValue(Src, 1, "src.adj");
394 DstAdj = Builder.CreateNSWSub(SrcAdj, Adj, "adj");
396 DstAdj = Builder.CreateNSWAdd(SrcAdj, Adj, "adj");
398 return Builder.CreateInsertValue(Src, DstAdj, 1);
402 ItaniumCXXABI::EmitMemberPointerConversion(llvm::Constant *C,
404 const MemberPointerType *SrcTy =
405 E->getSubExpr()->getType()->getAs<MemberPointerType>();
406 const MemberPointerType *DestTy =
407 E->getType()->getAs<MemberPointerType>();
410 E->getCastKind() == CK_DerivedToBaseMemberPointer;
412 const CXXRecordDecl *DerivedDecl;
414 DerivedDecl = SrcTy->getClass()->getAsCXXRecordDecl();
416 DerivedDecl = DestTy->getClass()->getAsCXXRecordDecl();
418 // Calculate the offset to the base class.
419 llvm::Constant *Offset =
420 CGM.GetNonVirtualBaseClassOffset(DerivedDecl,
423 // If there's no offset, we're done.
424 if (!Offset) return C;
426 // If the source is a member data pointer, we have to do a null
427 // check and then add the offset. In the common case, we can fold
429 if (SrcTy->isMemberDataPointer()) {
430 assert(C->getType() == getPtrDiffTy());
432 // If it's a constant int, just create a new constant int.
433 if (llvm::ConstantInt *CI = dyn_cast<llvm::ConstantInt>(C)) {
434 int64_t Src = CI->getSExtValue();
436 // Null converts to null.
437 if (Src == -1) return CI;
439 // Otherwise, just add the offset.
440 int64_t OffsetV = cast<llvm::ConstantInt>(Offset)->getSExtValue();
441 int64_t Dst = (DerivedToBase ? Src - OffsetV : Src + OffsetV);
442 return llvm::ConstantInt::get(CI->getType(), Dst, /*signed*/ true);
445 // Otherwise, we have to form a constant select expression.
446 llvm::Constant *Null = llvm::Constant::getAllOnesValue(C->getType());
448 llvm::Constant *IsNull =
449 llvm::ConstantExpr::getICmp(llvm::ICmpInst::ICMP_EQ, C, Null);
453 Dst = llvm::ConstantExpr::getNSWSub(C, Offset);
455 Dst = llvm::ConstantExpr::getNSWAdd(C, Offset);
457 return llvm::ConstantExpr::getSelect(IsNull, Null, Dst);
460 // The this-adjustment is left-shifted by 1 on ARM.
462 int64_t OffsetV = cast<llvm::ConstantInt>(Offset)->getSExtValue();
464 Offset = llvm::ConstantInt::get(Offset->getType(), OffsetV);
467 llvm::ConstantStruct *CS = cast<llvm::ConstantStruct>(C);
469 llvm::Constant *Values[2] = { CS->getOperand(0), 0 };
471 Values[1] = llvm::ConstantExpr::getSub(CS->getOperand(1), Offset);
473 Values[1] = llvm::ConstantExpr::getAdd(CS->getOperand(1), Offset);
475 return llvm::ConstantStruct::get(CS->getType(), Values);
480 ItaniumCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) {
481 llvm::Type *ptrdiff_t = getPtrDiffTy();
483 // Itanium C++ ABI 2.3:
484 // A NULL pointer is represented as -1.
485 if (MPT->isMemberDataPointer())
486 return llvm::ConstantInt::get(ptrdiff_t, -1ULL, /*isSigned=*/true);
488 llvm::Constant *Zero = llvm::ConstantInt::get(ptrdiff_t, 0);
489 llvm::Constant *Values[2] = { Zero, Zero };
490 return llvm::ConstantStruct::getAnon(Values);
494 ItaniumCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT,
496 // Itanium C++ ABI 2.3:
497 // A pointer to data member is an offset from the base address of
498 // the class object containing it, represented as a ptrdiff_t
499 return llvm::ConstantInt::get(getPtrDiffTy(), offset.getQuantity());
502 llvm::Constant *ItaniumCXXABI::EmitMemberPointer(const CXXMethodDecl *MD) {
503 assert(MD->isInstance() && "Member function must not be static!");
504 MD = MD->getCanonicalDecl();
506 CodeGenTypes &Types = CGM.getTypes();
507 llvm::Type *ptrdiff_t = getPtrDiffTy();
509 // Get the function pointer (or index if this is a virtual function).
510 llvm::Constant *MemPtr[2];
511 if (MD->isVirtual()) {
512 uint64_t Index = CGM.getVTableContext().getMethodVTableIndex(MD);
514 const ASTContext &Context = getContext();
515 CharUnits PointerWidth =
516 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
517 uint64_t VTableOffset = (Index * PointerWidth.getQuantity());
520 // ARM C++ ABI 3.2.1:
521 // This ABI specifies that adj contains twice the this
522 // adjustment, plus 1 if the member function is virtual. The
523 // least significant bit of adj then makes exactly the same
524 // discrimination as the least significant bit of ptr does for
526 MemPtr[0] = llvm::ConstantInt::get(ptrdiff_t, VTableOffset);
527 MemPtr[1] = llvm::ConstantInt::get(ptrdiff_t, 1);
529 // Itanium C++ ABI 2.3:
530 // For a virtual function, [the pointer field] is 1 plus the
531 // virtual table offset (in bytes) of the function,
532 // represented as a ptrdiff_t.
533 MemPtr[0] = llvm::ConstantInt::get(ptrdiff_t, VTableOffset + 1);
534 MemPtr[1] = llvm::ConstantInt::get(ptrdiff_t, 0);
537 const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>();
539 // Check whether the function has a computable LLVM signature.
540 if (Types.isFuncTypeConvertible(FPT)) {
541 // The function has a computable LLVM signature; use the correct type.
542 Ty = Types.GetFunctionType(Types.getFunctionInfo(MD),
545 // Use an arbitrary non-function type to tell GetAddrOfFunction that the
546 // function type is incomplete.
549 llvm::Constant *addr = CGM.GetAddrOfFunction(MD, Ty);
551 MemPtr[0] = llvm::ConstantExpr::getPtrToInt(addr, ptrdiff_t);
552 MemPtr[1] = llvm::ConstantInt::get(ptrdiff_t, 0);
555 return llvm::ConstantStruct::getAnon(MemPtr);
558 /// The comparison algorithm is pretty easy: the member pointers are
559 /// the same if they're either bitwise identical *or* both null.
561 /// ARM is different here only because null-ness is more complicated.
563 ItaniumCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF,
566 const MemberPointerType *MPT,
568 CGBuilderTy &Builder = CGF.Builder;
570 llvm::ICmpInst::Predicate Eq;
571 llvm::Instruction::BinaryOps And, Or;
573 Eq = llvm::ICmpInst::ICMP_NE;
574 And = llvm::Instruction::Or;
575 Or = llvm::Instruction::And;
577 Eq = llvm::ICmpInst::ICMP_EQ;
578 And = llvm::Instruction::And;
579 Or = llvm::Instruction::Or;
582 // Member data pointers are easy because there's a unique null
583 // value, so it just comes down to bitwise equality.
584 if (MPT->isMemberDataPointer())
585 return Builder.CreateICmp(Eq, L, R);
587 // For member function pointers, the tautologies are more complex.
588 // The Itanium tautology is:
589 // (L == R) <==> (L.ptr == R.ptr && (L.ptr == 0 || L.adj == R.adj))
590 // The ARM tautology is:
591 // (L == R) <==> (L.ptr == R.ptr &&
592 // (L.adj == R.adj ||
593 // (L.ptr == 0 && ((L.adj|R.adj) & 1) == 0)))
594 // The inequality tautologies have exactly the same structure, except
595 // applying De Morgan's laws.
597 llvm::Value *LPtr = Builder.CreateExtractValue(L, 0, "lhs.memptr.ptr");
598 llvm::Value *RPtr = Builder.CreateExtractValue(R, 0, "rhs.memptr.ptr");
600 // This condition tests whether L.ptr == R.ptr. This must always be
601 // true for equality to hold.
602 llvm::Value *PtrEq = Builder.CreateICmp(Eq, LPtr, RPtr, "cmp.ptr");
604 // This condition, together with the assumption that L.ptr == R.ptr,
605 // tests whether the pointers are both null. ARM imposes an extra
607 llvm::Value *Zero = llvm::Constant::getNullValue(LPtr->getType());
608 llvm::Value *EqZero = Builder.CreateICmp(Eq, LPtr, Zero, "cmp.ptr.null");
610 // This condition tests whether L.adj == R.adj. If this isn't
611 // true, the pointers are unequal unless they're both null.
612 llvm::Value *LAdj = Builder.CreateExtractValue(L, 1, "lhs.memptr.adj");
613 llvm::Value *RAdj = Builder.CreateExtractValue(R, 1, "rhs.memptr.adj");
614 llvm::Value *AdjEq = Builder.CreateICmp(Eq, LAdj, RAdj, "cmp.adj");
616 // Null member function pointers on ARM clear the low bit of Adj,
617 // so the zero condition has to check that neither low bit is set.
619 llvm::Value *One = llvm::ConstantInt::get(LPtr->getType(), 1);
621 // Compute (l.adj | r.adj) & 1 and test it against zero.
622 llvm::Value *OrAdj = Builder.CreateOr(LAdj, RAdj, "or.adj");
623 llvm::Value *OrAdjAnd1 = Builder.CreateAnd(OrAdj, One);
624 llvm::Value *OrAdjAnd1EqZero = Builder.CreateICmp(Eq, OrAdjAnd1, Zero,
626 EqZero = Builder.CreateBinOp(And, EqZero, OrAdjAnd1EqZero);
629 // Tie together all our conditions.
630 llvm::Value *Result = Builder.CreateBinOp(Or, EqZero, AdjEq);
631 Result = Builder.CreateBinOp(And, PtrEq, Result,
632 Inequality ? "memptr.ne" : "memptr.eq");
637 ItaniumCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
639 const MemberPointerType *MPT) {
640 CGBuilderTy &Builder = CGF.Builder;
642 /// For member data pointers, this is just a check against -1.
643 if (MPT->isMemberDataPointer()) {
644 assert(MemPtr->getType() == getPtrDiffTy());
645 llvm::Value *NegativeOne =
646 llvm::Constant::getAllOnesValue(MemPtr->getType());
647 return Builder.CreateICmpNE(MemPtr, NegativeOne, "memptr.tobool");
650 // In Itanium, a member function pointer is not null if 'ptr' is not null.
651 llvm::Value *Ptr = Builder.CreateExtractValue(MemPtr, 0, "memptr.ptr");
653 llvm::Constant *Zero = llvm::ConstantInt::get(Ptr->getType(), 0);
654 llvm::Value *Result = Builder.CreateICmpNE(Ptr, Zero, "memptr.tobool");
656 // On ARM, a member function pointer is also non-null if the low bit of 'adj'
657 // (the virtual bit) is set.
659 llvm::Constant *One = llvm::ConstantInt::get(Ptr->getType(), 1);
660 llvm::Value *Adj = Builder.CreateExtractValue(MemPtr, 1, "memptr.adj");
661 llvm::Value *VirtualBit = Builder.CreateAnd(Adj, One, "memptr.virtualbit");
662 llvm::Value *IsVirtual = Builder.CreateICmpNE(VirtualBit, Zero,
664 Result = Builder.CreateOr(Result, IsVirtual);
670 /// The Itanium ABI requires non-zero initialization only for data
671 /// member pointers, for which '0' is a valid offset.
672 bool ItaniumCXXABI::isZeroInitializable(const MemberPointerType *MPT) {
673 return MPT->getPointeeType()->isFunctionType();
676 /// The generic ABI passes 'this', plus a VTT if it's initializing a
678 void ItaniumCXXABI::BuildConstructorSignature(const CXXConstructorDecl *Ctor,
681 SmallVectorImpl<CanQualType> &ArgTys) {
682 ASTContext &Context = getContext();
684 // 'this' is already there.
686 // Check if we need to add a VTT parameter (which has type void **).
687 if (Type == Ctor_Base && Ctor->getParent()->getNumVBases() != 0)
688 ArgTys.push_back(Context.getPointerType(Context.VoidPtrTy));
691 /// The ARM ABI does the same as the Itanium ABI, but returns 'this'.
692 void ARMCXXABI::BuildConstructorSignature(const CXXConstructorDecl *Ctor,
695 SmallVectorImpl<CanQualType> &ArgTys) {
696 ItaniumCXXABI::BuildConstructorSignature(Ctor, Type, ResTy, ArgTys);
700 /// The generic ABI passes 'this', plus a VTT if it's destroying a
702 void ItaniumCXXABI::BuildDestructorSignature(const CXXDestructorDecl *Dtor,
705 SmallVectorImpl<CanQualType> &ArgTys) {
706 ASTContext &Context = getContext();
708 // 'this' is already there.
710 // Check if we need to add a VTT parameter (which has type void **).
711 if (Type == Dtor_Base && Dtor->getParent()->getNumVBases() != 0)
712 ArgTys.push_back(Context.getPointerType(Context.VoidPtrTy));
715 /// The ARM ABI does the same as the Itanium ABI, but returns 'this'
716 /// for non-deleting destructors.
717 void ARMCXXABI::BuildDestructorSignature(const CXXDestructorDecl *Dtor,
720 SmallVectorImpl<CanQualType> &ArgTys) {
721 ItaniumCXXABI::BuildDestructorSignature(Dtor, Type, ResTy, ArgTys);
723 if (Type != Dtor_Deleting)
727 void ItaniumCXXABI::BuildInstanceFunctionParams(CodeGenFunction &CGF,
729 FunctionArgList &Params) {
730 /// Create the 'this' variable.
731 BuildThisParam(CGF, Params);
733 const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
734 assert(MD->isInstance());
736 // Check if we need a VTT parameter as well.
737 if (CodeGenVTables::needsVTTParameter(CGF.CurGD)) {
738 ASTContext &Context = getContext();
740 // FIXME: avoid the fake decl
741 QualType T = Context.getPointerType(Context.VoidPtrTy);
742 ImplicitParamDecl *VTTDecl
743 = ImplicitParamDecl::Create(Context, 0, MD->getLocation(),
744 &Context.Idents.get("vtt"), T);
745 Params.push_back(VTTDecl);
746 getVTTDecl(CGF) = VTTDecl;
750 void ARMCXXABI::BuildInstanceFunctionParams(CodeGenFunction &CGF,
752 FunctionArgList &Params) {
753 ItaniumCXXABI::BuildInstanceFunctionParams(CGF, ResTy, Params);
755 // Return 'this' from certain constructors and destructors.
756 if (HasThisReturn(CGF.CurGD))
757 ResTy = Params[0]->getType();
760 void ItaniumCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) {
761 /// Initialize the 'this' slot.
764 /// Initialize the 'vtt' slot if needed.
765 if (getVTTDecl(CGF)) {
767 = CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(getVTTDecl(CGF)),
772 void ARMCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) {
773 ItaniumCXXABI::EmitInstanceFunctionProlog(CGF);
775 /// Initialize the return slot to 'this' at the start of the
777 if (HasThisReturn(CGF.CurGD))
778 CGF.Builder.CreateStore(CGF.LoadCXXThis(), CGF.ReturnValue);
781 void ARMCXXABI::EmitReturnFromThunk(CodeGenFunction &CGF,
782 RValue RV, QualType ResultType) {
783 if (!isa<CXXDestructorDecl>(CGF.CurGD.getDecl()))
784 return ItaniumCXXABI::EmitReturnFromThunk(CGF, RV, ResultType);
786 // Destructor thunks in the ARM ABI have indeterminate results.
788 cast<llvm::PointerType>(CGF.ReturnValue->getType())->getElementType();
789 RValue Undef = RValue::get(llvm::UndefValue::get(T));
790 return ItaniumCXXABI::EmitReturnFromThunk(CGF, Undef, ResultType);
793 /************************** Array allocation cookies **************************/
795 bool ItaniumCXXABI::NeedsArrayCookie(const CXXNewExpr *expr) {
796 // If the class's usual deallocation function takes two arguments,
797 // it needs a cookie.
798 if (expr->doesUsualArrayDeleteWantSize())
801 // Automatic Reference Counting:
802 // We need an array cookie for pointers with strong or weak lifetime.
803 QualType AllocatedType = expr->getAllocatedType();
804 if (getContext().getLangOptions().ObjCAutoRefCount &&
805 AllocatedType->isObjCLifetimeType()) {
806 switch (AllocatedType.getObjCLifetime()) {
807 case Qualifiers::OCL_None:
808 case Qualifiers::OCL_ExplicitNone:
809 case Qualifiers::OCL_Autoreleasing:
812 case Qualifiers::OCL_Strong:
813 case Qualifiers::OCL_Weak:
818 // Otherwise, if the class has a non-trivial destructor, it always
820 const CXXRecordDecl *record =
821 AllocatedType->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
822 return (record && !record->hasTrivialDestructor());
825 bool ItaniumCXXABI::NeedsArrayCookie(const CXXDeleteExpr *expr,
826 QualType elementType) {
827 // If the class's usual deallocation function takes two arguments,
828 // it needs a cookie.
829 if (expr->doesUsualArrayDeleteWantSize())
832 return elementType.isDestructedType();
835 CharUnits ItaniumCXXABI::GetArrayCookieSize(const CXXNewExpr *expr) {
836 if (!NeedsArrayCookie(expr))
837 return CharUnits::Zero();
839 // Padding is the maximum of sizeof(size_t) and alignof(elementType)
840 ASTContext &Ctx = getContext();
841 return std::max(Ctx.getTypeSizeInChars(Ctx.getSizeType()),
842 Ctx.getTypeAlignInChars(expr->getAllocatedType()));
845 llvm::Value *ItaniumCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,
847 llvm::Value *NumElements,
848 const CXXNewExpr *expr,
849 QualType ElementType) {
850 assert(NeedsArrayCookie(expr));
852 unsigned AS = cast<llvm::PointerType>(NewPtr->getType())->getAddressSpace();
854 ASTContext &Ctx = getContext();
855 QualType SizeTy = Ctx.getSizeType();
856 CharUnits SizeSize = Ctx.getTypeSizeInChars(SizeTy);
858 // The size of the cookie.
859 CharUnits CookieSize =
860 std::max(SizeSize, Ctx.getTypeAlignInChars(ElementType));
862 // Compute an offset to the cookie.
863 llvm::Value *CookiePtr = NewPtr;
864 CharUnits CookieOffset = CookieSize - SizeSize;
865 if (!CookieOffset.isZero())
866 CookiePtr = CGF.Builder.CreateConstInBoundsGEP1_64(CookiePtr,
867 CookieOffset.getQuantity());
869 // Write the number of elements into the appropriate slot.
870 llvm::Value *NumElementsPtr
871 = CGF.Builder.CreateBitCast(CookiePtr,
872 CGF.ConvertType(SizeTy)->getPointerTo(AS));
873 CGF.Builder.CreateStore(NumElements, NumElementsPtr);
875 // Finally, compute a pointer to the actual data buffer by skipping
876 // over the cookie completely.
877 return CGF.Builder.CreateConstInBoundsGEP1_64(NewPtr,
878 CookieSize.getQuantity());
881 void ItaniumCXXABI::ReadArrayCookie(CodeGenFunction &CGF,
883 const CXXDeleteExpr *expr,
884 QualType ElementType,
885 llvm::Value *&NumElements,
886 llvm::Value *&AllocPtr,
887 CharUnits &CookieSize) {
888 // Derive a char* in the same address space as the pointer.
889 unsigned AS = cast<llvm::PointerType>(Ptr->getType())->getAddressSpace();
890 llvm::Type *CharPtrTy = CGF.Builder.getInt8Ty()->getPointerTo(AS);
892 // If we don't need an array cookie, bail out early.
893 if (!NeedsArrayCookie(expr, ElementType)) {
894 AllocPtr = CGF.Builder.CreateBitCast(Ptr, CharPtrTy);
896 CookieSize = CharUnits::Zero();
900 QualType SizeTy = getContext().getSizeType();
901 CharUnits SizeSize = getContext().getTypeSizeInChars(SizeTy);
902 llvm::Type *SizeLTy = CGF.ConvertType(SizeTy);
905 = std::max(SizeSize, getContext().getTypeAlignInChars(ElementType));
907 CharUnits NumElementsOffset = CookieSize - SizeSize;
909 // Compute the allocated pointer.
910 AllocPtr = CGF.Builder.CreateBitCast(Ptr, CharPtrTy);
911 AllocPtr = CGF.Builder.CreateConstInBoundsGEP1_64(AllocPtr,
912 -CookieSize.getQuantity());
914 llvm::Value *NumElementsPtr = AllocPtr;
915 if (!NumElementsOffset.isZero())
917 CGF.Builder.CreateConstInBoundsGEP1_64(NumElementsPtr,
918 NumElementsOffset.getQuantity());
920 CGF.Builder.CreateBitCast(NumElementsPtr, SizeLTy->getPointerTo(AS));
921 NumElements = CGF.Builder.CreateLoad(NumElementsPtr);
924 CharUnits ARMCXXABI::GetArrayCookieSize(const CXXNewExpr *expr) {
925 if (!NeedsArrayCookie(expr))
926 return CharUnits::Zero();
928 // On ARM, the cookie is always:
929 // struct array_cookie {
930 // std::size_t element_size; // element_size != 0
931 // std::size_t element_count;
933 // TODO: what should we do if the allocated type actually wants
934 // greater alignment?
935 return getContext().getTypeSizeInChars(getContext().getSizeType()) * 2;
938 llvm::Value *ARMCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,
940 llvm::Value *NumElements,
941 const CXXNewExpr *expr,
942 QualType ElementType) {
943 assert(NeedsArrayCookie(expr));
945 // NewPtr is a char*.
947 unsigned AS = cast<llvm::PointerType>(NewPtr->getType())->getAddressSpace();
949 ASTContext &Ctx = getContext();
950 CharUnits SizeSize = Ctx.getTypeSizeInChars(Ctx.getSizeType());
951 llvm::IntegerType *SizeTy =
952 cast<llvm::IntegerType>(CGF.ConvertType(Ctx.getSizeType()));
954 // The cookie is always at the start of the buffer.
955 llvm::Value *CookiePtr = NewPtr;
957 // The first element is the element size.
958 CookiePtr = CGF.Builder.CreateBitCast(CookiePtr, SizeTy->getPointerTo(AS));
959 llvm::Value *ElementSize = llvm::ConstantInt::get(SizeTy,
960 Ctx.getTypeSizeInChars(ElementType).getQuantity());
961 CGF.Builder.CreateStore(ElementSize, CookiePtr);
963 // The second element is the element count.
964 CookiePtr = CGF.Builder.CreateConstInBoundsGEP1_32(CookiePtr, 1);
965 CGF.Builder.CreateStore(NumElements, CookiePtr);
967 // Finally, compute a pointer to the actual data buffer by skipping
968 // over the cookie completely.
969 CharUnits CookieSize = 2 * SizeSize;
970 return CGF.Builder.CreateConstInBoundsGEP1_64(NewPtr,
971 CookieSize.getQuantity());
974 void ARMCXXABI::ReadArrayCookie(CodeGenFunction &CGF,
976 const CXXDeleteExpr *expr,
977 QualType ElementType,
978 llvm::Value *&NumElements,
979 llvm::Value *&AllocPtr,
980 CharUnits &CookieSize) {
981 // Derive a char* in the same address space as the pointer.
982 unsigned AS = cast<llvm::PointerType>(Ptr->getType())->getAddressSpace();
983 llvm::Type *CharPtrTy = CGF.Builder.getInt8Ty()->getPointerTo(AS);
985 // If we don't need an array cookie, bail out early.
986 if (!NeedsArrayCookie(expr, ElementType)) {
987 AllocPtr = CGF.Builder.CreateBitCast(Ptr, CharPtrTy);
989 CookieSize = CharUnits::Zero();
993 QualType SizeTy = getContext().getSizeType();
994 CharUnits SizeSize = getContext().getTypeSizeInChars(SizeTy);
995 llvm::Type *SizeLTy = CGF.ConvertType(SizeTy);
997 // The cookie size is always 2 * sizeof(size_t).
998 CookieSize = 2 * SizeSize;
1000 // The allocated pointer is the input ptr, minus that amount.
1001 AllocPtr = CGF.Builder.CreateBitCast(Ptr, CharPtrTy);
1002 AllocPtr = CGF.Builder.CreateConstInBoundsGEP1_64(AllocPtr,
1003 -CookieSize.getQuantity());
1005 // The number of elements is at offset sizeof(size_t) relative to that.
1006 llvm::Value *NumElementsPtr
1007 = CGF.Builder.CreateConstInBoundsGEP1_64(AllocPtr,
1008 SizeSize.getQuantity());
1010 CGF.Builder.CreateBitCast(NumElementsPtr, SizeLTy->getPointerTo(AS));
1011 NumElements = CGF.Builder.CreateLoad(NumElementsPtr);
1014 /*********************** Static local initialization **************************/
1016 static llvm::Constant *getGuardAcquireFn(CodeGenModule &CGM,
1017 llvm::PointerType *GuardPtrTy) {
1018 // int __cxa_guard_acquire(__guard *guard_object);
1019 llvm::FunctionType *FTy =
1020 llvm::FunctionType::get(CGM.getTypes().ConvertType(CGM.getContext().IntTy),
1021 GuardPtrTy, /*isVarArg=*/false);
1023 return CGM.CreateRuntimeFunction(FTy, "__cxa_guard_acquire");
1026 static llvm::Constant *getGuardReleaseFn(CodeGenModule &CGM,
1027 llvm::PointerType *GuardPtrTy) {
1028 // void __cxa_guard_release(__guard *guard_object);
1029 llvm::FunctionType *FTy =
1030 llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),
1031 GuardPtrTy, /*isVarArg=*/false);
1033 return CGM.CreateRuntimeFunction(FTy, "__cxa_guard_release");
1036 static llvm::Constant *getGuardAbortFn(CodeGenModule &CGM,
1037 llvm::PointerType *GuardPtrTy) {
1038 // void __cxa_guard_abort(__guard *guard_object);
1039 llvm::FunctionType *FTy =
1040 llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()),
1041 GuardPtrTy, /*isVarArg=*/false);
1043 return CGM.CreateRuntimeFunction(FTy, "__cxa_guard_abort");
1047 struct CallGuardAbort : EHScopeStack::Cleanup {
1048 llvm::GlobalVariable *Guard;
1049 CallGuardAbort(llvm::GlobalVariable *Guard) : Guard(Guard) {}
1051 void Emit(CodeGenFunction &CGF, Flags flags) {
1052 CGF.Builder.CreateCall(getGuardAbortFn(CGF.CGM, Guard->getType()), Guard)
1053 ->setDoesNotThrow();
1058 /// The ARM code here follows the Itanium code closely enough that we
1059 /// just special-case it at particular places.
1060 void ItaniumCXXABI::EmitGuardedInit(CodeGenFunction &CGF,
1062 llvm::GlobalVariable *GV) {
1063 CGBuilderTy &Builder = CGF.Builder;
1065 // We only need to use thread-safe statics for local variables;
1066 // global initialization is always single-threaded.
1068 (getContext().getLangOptions().ThreadsafeStatics && D.isLocalVarDecl());
1070 llvm::IntegerType *GuardTy;
1072 // If we have a global variable with internal linkage and thread-safe statics
1073 // are disabled, we can just let the guard variable be of type i8.
1074 bool useInt8GuardVariable = !threadsafe && GV->hasInternalLinkage();
1075 if (useInt8GuardVariable) {
1076 GuardTy = CGF.Int8Ty;
1078 // Guard variables are 64 bits in the generic ABI and 32 bits on ARM.
1079 GuardTy = (IsARM ? CGF.Int32Ty : CGF.Int64Ty);
1081 llvm::PointerType *GuardPtrTy = GuardTy->getPointerTo();
1083 // Create the guard variable.
1084 llvm::SmallString<256> GuardVName;
1085 llvm::raw_svector_ostream Out(GuardVName);
1086 getMangleContext().mangleItaniumGuardVariable(&D, Out);
1089 // Just absorb linkage and visibility from the variable.
1090 llvm::GlobalVariable *GuardVariable =
1091 new llvm::GlobalVariable(CGM.getModule(), GuardTy,
1092 false, GV->getLinkage(),
1093 llvm::ConstantInt::get(GuardTy, 0),
1095 GuardVariable->setVisibility(GV->getVisibility());
1097 // Test whether the variable has completed initialization.
1098 llvm::Value *IsInitialized;
1100 // ARM C++ ABI 3.2.3.1:
1101 // To support the potential use of initialization guard variables
1102 // as semaphores that are the target of ARM SWP and LDREX/STREX
1103 // synchronizing instructions we define a static initialization
1104 // guard variable to be a 4-byte aligned, 4- byte word with the
1105 // following inline access protocol.
1106 // #define INITIALIZED 1
1107 // if ((obj_guard & INITIALIZED) != INITIALIZED) {
1108 // if (__cxa_guard_acquire(&obj_guard))
1111 if (IsARM && !useInt8GuardVariable) {
1112 llvm::Value *V = Builder.CreateLoad(GuardVariable);
1113 V = Builder.CreateAnd(V, Builder.getInt32(1));
1114 IsInitialized = Builder.CreateIsNull(V, "guard.uninitialized");
1116 // Itanium C++ ABI 3.3.2:
1117 // The following is pseudo-code showing how these functions can be used:
1118 // if (obj_guard.first_byte == 0) {
1119 // if ( __cxa_guard_acquire (&obj_guard) ) {
1121 // ... initialize the object ...;
1123 // __cxa_guard_abort (&obj_guard);
1126 // ... queue object destructor with __cxa_atexit() ...;
1127 // __cxa_guard_release (&obj_guard);
1131 // Load the first byte of the guard variable.
1132 llvm::Type *PtrTy = Builder.getInt8PtrTy();
1133 llvm::LoadInst *LI =
1134 Builder.CreateLoad(Builder.CreateBitCast(GuardVariable, PtrTy));
1135 LI->setAlignment(1);
1138 // An implementation supporting thread-safety on multiprocessor
1139 // systems must also guarantee that references to the initialized
1140 // object do not occur before the load of the initialization flag.
1142 // In LLVM, we do this by marking the load Acquire.
1144 LI->setAtomic(llvm::Acquire);
1146 IsInitialized = Builder.CreateIsNull(LI, "guard.uninitialized");
1149 llvm::BasicBlock *InitCheckBlock = CGF.createBasicBlock("init.check");
1150 llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end");
1152 // Check if the first byte of the guard variable is zero.
1153 Builder.CreateCondBr(IsInitialized, InitCheckBlock, EndBlock);
1155 CGF.EmitBlock(InitCheckBlock);
1157 // Variables used when coping with thread-safe statics and exceptions.
1159 // Call __cxa_guard_acquire.
1161 = Builder.CreateCall(getGuardAcquireFn(CGM, GuardPtrTy), GuardVariable);
1163 llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init");
1165 Builder.CreateCondBr(Builder.CreateIsNotNull(V, "tobool"),
1166 InitBlock, EndBlock);
1168 // Call __cxa_guard_abort along the exceptional edge.
1169 CGF.EHStack.pushCleanup<CallGuardAbort>(EHCleanup, GuardVariable);
1171 CGF.EmitBlock(InitBlock);
1174 // Emit the initializer and add a global destructor if appropriate.
1175 CGF.EmitCXXGlobalVarDeclInit(D, GV);
1178 // Pop the guard-abort cleanup if we pushed one.
1179 CGF.PopCleanupBlock();
1181 // Call __cxa_guard_release. This cannot throw.
1182 Builder.CreateCall(getGuardReleaseFn(CGM, GuardPtrTy), GuardVariable);
1184 Builder.CreateStore(llvm::ConstantInt::get(GuardTy, 1), GuardVariable);
1187 CGF.EmitBlock(EndBlock);