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Diffstat (limited to 'contrib/llvm/tools/clang/lib/CodeGen/CGCXX.cpp')
| -rw-r--r-- | contrib/llvm/tools/clang/lib/CodeGen/CGCXX.cpp | 355 |
1 files changed, 355 insertions, 0 deletions
diff --git a/contrib/llvm/tools/clang/lib/CodeGen/CGCXX.cpp b/contrib/llvm/tools/clang/lib/CodeGen/CGCXX.cpp new file mode 100644 index 0000000..cfb2d62 --- /dev/null +++ b/contrib/llvm/tools/clang/lib/CodeGen/CGCXX.cpp @@ -0,0 +1,355 @@ +//===--- CGCXX.cpp - Emit LLVM Code for declarations ----------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This contains code dealing with C++ code generation. +// +//===----------------------------------------------------------------------===// + +// We might split this into multiple files if it gets too unwieldy + +#include "CodeGenModule.h" +#include "CGCXXABI.h" +#include "CodeGenFunction.h" +#include "clang/AST/ASTContext.h" +#include "clang/AST/Decl.h" +#include "clang/AST/DeclCXX.h" +#include "clang/AST/DeclObjC.h" +#include "clang/AST/Mangle.h" +#include "clang/AST/RecordLayout.h" +#include "clang/AST/StmtCXX.h" +#include "clang/Frontend/CodeGenOptions.h" +#include "llvm/ADT/StringExtras.h" +using namespace clang; +using namespace CodeGen; + +/// Try to emit a base destructor as an alias to its primary +/// base-class destructor. +bool CodeGenModule::TryEmitBaseDestructorAsAlias(const CXXDestructorDecl *D) { + if (!getCodeGenOpts().CXXCtorDtorAliases) + return true; + + // Producing an alias to a base class ctor/dtor can degrade debug quality + // as the debugger cannot tell them appart. + if (getCodeGenOpts().OptimizationLevel == 0) + return true; + + // If the destructor doesn't have a trivial body, we have to emit it + // separately. + if (!D->hasTrivialBody()) + return true; + + const CXXRecordDecl *Class = D->getParent(); + + // If we need to manipulate a VTT parameter, give up. + if (Class->getNumVBases()) { + // Extra Credit: passing extra parameters is perfectly safe + // in many calling conventions, so only bail out if the ctor's + // calling convention is nonstandard. + return true; + } + + // If any field has a non-trivial destructor, we have to emit the + // destructor separately. + for (CXXRecordDecl::field_iterator I = Class->field_begin(), + E = Class->field_end(); I != E; ++I) + if (I->getType().isDestructedType()) + return true; + + // Try to find a unique base class with a non-trivial destructor. + const CXXRecordDecl *UniqueBase = 0; + for (CXXRecordDecl::base_class_const_iterator I = Class->bases_begin(), + E = Class->bases_end(); I != E; ++I) { + + // We're in the base destructor, so skip virtual bases. + if (I->isVirtual()) continue; + + // Skip base classes with trivial destructors. + const CXXRecordDecl *Base + = cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); + if (Base->hasTrivialDestructor()) continue; + + // If we've already found a base class with a non-trivial + // destructor, give up. + if (UniqueBase) return true; + UniqueBase = Base; + } + + // If we didn't find any bases with a non-trivial destructor, then + // the base destructor is actually effectively trivial, which can + // happen if it was needlessly user-defined or if there are virtual + // bases with non-trivial destructors. + if (!UniqueBase) + return true; + + // If the base is at a non-zero offset, give up. + const ASTRecordLayout &ClassLayout = Context.getASTRecordLayout(Class); + if (!ClassLayout.getBaseClassOffset(UniqueBase).isZero()) + return true; + + const CXXDestructorDecl *BaseD = UniqueBase->getDestructor(); + return TryEmitDefinitionAsAlias(GlobalDecl(D, Dtor_Base), + GlobalDecl(BaseD, Dtor_Base), + false); +} + +/// Try to emit a definition as a global alias for another definition. +/// If \p InEveryTU is true, we know that an equivalent alias can be produced +/// in every translation unit. +bool CodeGenModule::TryEmitDefinitionAsAlias(GlobalDecl AliasDecl, + GlobalDecl TargetDecl, + bool InEveryTU) { + if (!getCodeGenOpts().CXXCtorDtorAliases) + return true; + + // The alias will use the linkage of the referrent. If we can't + // support aliases with that linkage, fail. + llvm::GlobalValue::LinkageTypes Linkage = getFunctionLinkage(AliasDecl); + + // We can't use an alias if the linkage is not valid for one. + if (!llvm::GlobalAlias::isValidLinkage(Linkage)) + return true; + + llvm::GlobalValue::LinkageTypes TargetLinkage = + getFunctionLinkage(TargetDecl); + + // Check if we have it already. + StringRef MangledName = getMangledName(AliasDecl); + llvm::GlobalValue *Entry = GetGlobalValue(MangledName); + if (Entry && !Entry->isDeclaration()) + return false; + if (Replacements.count(MangledName)) + return false; + + // Derive the type for the alias. + llvm::PointerType *AliasType + = getTypes().GetFunctionType(AliasDecl)->getPointerTo(); + + // Find the referrent. Some aliases might require a bitcast, in + // which case the caller is responsible for ensuring the soundness + // of these semantics. + llvm::GlobalValue *Ref = cast<llvm::GlobalValue>(GetAddrOfGlobal(TargetDecl)); + llvm::Constant *Aliasee = Ref; + if (Ref->getType() != AliasType) + Aliasee = llvm::ConstantExpr::getBitCast(Ref, AliasType); + + // Instead of creating as alias to a linkonce_odr, replace all of the uses + // of the aliassee. + if (llvm::GlobalValue::isDiscardableIfUnused(Linkage) && + (TargetLinkage != llvm::GlobalValue::AvailableExternallyLinkage || + !TargetDecl.getDecl()->hasAttr<AlwaysInlineAttr>())) { + // FIXME: An extern template instanciation will create functions with + // linkage "AvailableExternally". In libc++, some classes also define + // members with attribute "AlwaysInline" and expect no reference to + // be generated. It is desirable to reenable this optimisation after + // corresponding LLVM changes. + Replacements[MangledName] = Aliasee; + return false; + } + + if (!InEveryTU) { + /// If we don't have a definition for the destructor yet, don't + /// emit. We can't emit aliases to declarations; that's just not + /// how aliases work. + if (Ref->isDeclaration()) + return true; + } + + // Don't create an alias to a linker weak symbol. This avoids producing + // different COMDATs in different TUs. Another option would be to + // output the alias both for weak_odr and linkonce_odr, but that + // requires explicit comdat support in the IL. + if (llvm::GlobalValue::isWeakForLinker(TargetLinkage)) + return true; + + // Create the alias with no name. + llvm::GlobalAlias *Alias = + new llvm::GlobalAlias(AliasType, Linkage, "", Aliasee, &getModule()); + + // Switch any previous uses to the alias. + if (Entry) { + assert(Entry->getType() == AliasType && + "declaration exists with different type"); + Alias->takeName(Entry); + Entry->replaceAllUsesWith(Alias); + Entry->eraseFromParent(); + } else { + Alias->setName(MangledName); + } + + // Finally, set up the alias with its proper name and attributes. + SetCommonAttributes(cast<NamedDecl>(AliasDecl.getDecl()), Alias); + + return false; +} + +void CodeGenModule::EmitCXXConstructor(const CXXConstructorDecl *ctor, + CXXCtorType ctorType) { + // The complete constructor is equivalent to the base constructor + // for classes with no virtual bases. Try to emit it as an alias. + if (getTarget().getCXXABI().hasConstructorVariants() && + !ctor->getParent()->getNumVBases() && + (ctorType == Ctor_Complete || ctorType == Ctor_Base)) { + bool ProducedAlias = + !TryEmitDefinitionAsAlias(GlobalDecl(ctor, Ctor_Complete), + GlobalDecl(ctor, Ctor_Base), true); + if (ctorType == Ctor_Complete && ProducedAlias) + return; + } + + const CGFunctionInfo &fnInfo = + getTypes().arrangeCXXConstructorDeclaration(ctor, ctorType); + + llvm::Function *fn = + cast<llvm::Function>(GetAddrOfCXXConstructor(ctor, ctorType, &fnInfo)); + setFunctionLinkage(GlobalDecl(ctor, ctorType), fn); + + CodeGenFunction(*this).GenerateCode(GlobalDecl(ctor, ctorType), fn, fnInfo); + + SetFunctionDefinitionAttributes(ctor, fn); + SetLLVMFunctionAttributesForDefinition(ctor, fn); +} + +llvm::GlobalValue * +CodeGenModule::GetAddrOfCXXConstructor(const CXXConstructorDecl *ctor, + CXXCtorType ctorType, + const CGFunctionInfo *fnInfo) { + GlobalDecl GD(ctor, ctorType); + + StringRef name = getMangledName(GD); + if (llvm::GlobalValue *existing = GetGlobalValue(name)) + return existing; + + if (!fnInfo) + fnInfo = &getTypes().arrangeCXXConstructorDeclaration(ctor, ctorType); + + llvm::FunctionType *fnType = getTypes().GetFunctionType(*fnInfo); + return cast<llvm::Function>(GetOrCreateLLVMFunction(name, fnType, GD, + /*ForVTable=*/false)); +} + +void CodeGenModule::EmitCXXDestructor(const CXXDestructorDecl *dtor, + CXXDtorType dtorType) { + // The complete destructor is equivalent to the base destructor for + // classes with no virtual bases, so try to emit it as an alias. + if (!dtor->getParent()->getNumVBases() && + (dtorType == Dtor_Complete || dtorType == Dtor_Base)) { + bool ProducedAlias = + !TryEmitDefinitionAsAlias(GlobalDecl(dtor, Dtor_Complete), + GlobalDecl(dtor, Dtor_Base), true); + if (ProducedAlias) { + if (dtorType == Dtor_Complete) + return; + if (dtor->isVirtual()) + getVTables().EmitThunks(GlobalDecl(dtor, Dtor_Complete)); + } + } + + // The base destructor is equivalent to the base destructor of its + // base class if there is exactly one non-virtual base class with a + // non-trivial destructor, there are no fields with a non-trivial + // destructor, and the body of the destructor is trivial. + if (dtorType == Dtor_Base && !TryEmitBaseDestructorAsAlias(dtor)) + return; + + const CGFunctionInfo &fnInfo = + getTypes().arrangeCXXDestructor(dtor, dtorType); + + llvm::Function *fn = + cast<llvm::Function>(GetAddrOfCXXDestructor(dtor, dtorType, &fnInfo)); + setFunctionLinkage(GlobalDecl(dtor, dtorType), fn); + + CodeGenFunction(*this).GenerateCode(GlobalDecl(dtor, dtorType), fn, fnInfo); + + SetFunctionDefinitionAttributes(dtor, fn); + SetLLVMFunctionAttributesForDefinition(dtor, fn); +} + +llvm::GlobalValue * +CodeGenModule::GetAddrOfCXXDestructor(const CXXDestructorDecl *dtor, + CXXDtorType dtorType, + const CGFunctionInfo *fnInfo, + llvm::FunctionType *fnType) { + GlobalDecl GD(dtor, dtorType); + + StringRef name = getMangledName(GD); + if (llvm::GlobalValue *existing = GetGlobalValue(name)) + return existing; + + if (!fnType) { + if (!fnInfo) fnInfo = &getTypes().arrangeCXXDestructor(dtor, dtorType); + fnType = getTypes().GetFunctionType(*fnInfo); + } + return cast<llvm::Function>(GetOrCreateLLVMFunction(name, fnType, GD, + /*ForVTable=*/false)); +} + +static llvm::Value *BuildAppleKextVirtualCall(CodeGenFunction &CGF, + GlobalDecl GD, + llvm::Type *Ty, + const CXXRecordDecl *RD) { + assert(!CGF.CGM.getTarget().getCXXABI().isMicrosoft() && + "No kext in Microsoft ABI"); + GD = GD.getCanonicalDecl(); + CodeGenModule &CGM = CGF.CGM; + llvm::Value *VTable = CGM.getCXXABI().getAddrOfVTable(RD, CharUnits()); + Ty = Ty->getPointerTo()->getPointerTo(); + VTable = CGF.Builder.CreateBitCast(VTable, Ty); + assert(VTable && "BuildVirtualCall = kext vtbl pointer is null"); + uint64_t VTableIndex = CGM.getItaniumVTableContext().getMethodVTableIndex(GD); + uint64_t AddressPoint = + CGM.getItaniumVTableContext().getVTableLayout(RD) + .getAddressPoint(BaseSubobject(RD, CharUnits::Zero())); + VTableIndex += AddressPoint; + llvm::Value *VFuncPtr = + CGF.Builder.CreateConstInBoundsGEP1_64(VTable, VTableIndex, "vfnkxt"); + return CGF.Builder.CreateLoad(VFuncPtr); +} + +/// BuildAppleKextVirtualCall - This routine is to support gcc's kext ABI making +/// indirect call to virtual functions. It makes the call through indexing +/// into the vtable. +llvm::Value * +CodeGenFunction::BuildAppleKextVirtualCall(const CXXMethodDecl *MD, + NestedNameSpecifier *Qual, + llvm::Type *Ty) { + assert((Qual->getKind() == NestedNameSpecifier::TypeSpec) && + "BuildAppleKextVirtualCall - bad Qual kind"); + + const Type *QTy = Qual->getAsType(); + QualType T = QualType(QTy, 0); + const RecordType *RT = T->getAs<RecordType>(); + assert(RT && "BuildAppleKextVirtualCall - Qual type must be record"); + const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); + + if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) + return BuildAppleKextVirtualDestructorCall(DD, Dtor_Complete, RD); + + return ::BuildAppleKextVirtualCall(*this, MD, Ty, RD); +} + +/// BuildVirtualCall - This routine makes indirect vtable call for +/// call to virtual destructors. It returns 0 if it could not do it. +llvm::Value * +CodeGenFunction::BuildAppleKextVirtualDestructorCall( + const CXXDestructorDecl *DD, + CXXDtorType Type, + const CXXRecordDecl *RD) { + const CXXMethodDecl *MD = cast<CXXMethodDecl>(DD); + // FIXME. Dtor_Base dtor is always direct!! + // It need be somehow inline expanded into the caller. + // -O does that. But need to support -O0 as well. + if (MD->isVirtual() && Type != Dtor_Base) { + // Compute the function type we're calling. + const CGFunctionInfo &FInfo = + CGM.getTypes().arrangeCXXDestructor(DD, Dtor_Complete); + llvm::Type *Ty = CGM.getTypes().GetFunctionType(FInfo); + return ::BuildAppleKextVirtualCall(*this, GlobalDecl(DD, Type), Ty, RD); + } + return 0; +} |
