diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h index 9d49bac26a86..b15c9d3f1ee8 100644 --- a/clang/include/clang/AST/Decl.h +++ b/clang/include/clang/AST/Decl.h @@ -1656,6 +1656,7 @@ private: unsigned HasImplicitReturnZero : 1; unsigned IsLateTemplateParsed : 1; unsigned IsConstexpr : 1; + unsigned InstantiationIsPending:1; /// \brief Indicates if the function uses __try. unsigned UsesSEHTry : 1; @@ -1751,6 +1752,7 @@ protected: IsDeleted(false), IsTrivial(false), IsDefaulted(false), IsExplicitlyDefaulted(false), HasImplicitReturnZero(false), IsLateTemplateParsed(false), IsConstexpr(isConstexprSpecified), + InstantiationIsPending(false), UsesSEHTry(false), HasSkippedBody(false), WillHaveBody(false), EndRangeLoc(NameInfo.getEndLoc()), TemplateOrSpecialization(), DNLoc(NameInfo.getInfo()) {} @@ -1943,6 +1945,15 @@ public: bool isConstexpr() const { return IsConstexpr; } void setConstexpr(bool IC) { IsConstexpr = IC; } + /// \brief Whether the instantiation of this function is pending. + /// This bit is set when the decision to instantiate this function is made + /// and unset if and when the function body is created. That leaves out + /// cases where instantiation did not happen because the template definition + /// was not seen in this TU. This bit remains set in those cases, under the + /// assumption that the instantiation will happen in some other TU. + bool instantiationIsPending() const { return InstantiationIsPending; } + void setInstantiationIsPending(bool IC) { InstantiationIsPending = IC; } + /// \brief Indicates the function uses __try. bool usesSEHTry() const { return UsesSEHTry; } void setUsesSEHTry(bool UST) { UsesSEHTry = UST; } diff --git a/clang/lib/CodeGen/CGClass.cpp b/clang/lib/CodeGen/CGClass.cpp index 5b4dc5ff0ab3..127d7df348ee 100644 --- a/clang/lib/CodeGen/CGClass.cpp +++ b/clang/lib/CodeGen/CGClass.cpp @@ -2770,10 +2770,19 @@ CodeGenFunction::CanDevirtualizeMemberFunctionCall(const Expr *Base, // We can devirtualize calls on an object accessed by a class member access // expression, since by C++11 [basic.life]p6 we know that it can't refer to - // a derived class object constructed in the same location. + // a derived class object constructed in the same location. However, we avoid + // devirtualizing a call to a template function that we could instantiate + // implicitly, but have not decided to do so. This is needed because if this + // function does not get instantiated, the devirtualization will create a + // direct call to a function whose body may not exist. In contrast, calls to + // template functions that are not defined in this TU are allowed to be + // devirtualized under assumption that it is user responsibility to + // instantiate them in some other TU. if (const MemberExpr *ME = dyn_cast(Base)) if (const ValueDecl *VD = dyn_cast(ME->getMemberDecl())) - return VD->getType()->isRecordType(); + return VD->getType()->isRecordType() && + (MD->instantiationIsPending() || MD->isDefined() || + !MD->isImplicitlyInstantiable()); // Likewise for calls on an object accessed by a (non-reference) pointer to // member access. diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp index e7b0914641ff..007a5e483e6c 100644 --- a/clang/lib/Sema/Sema.cpp +++ b/clang/lib/Sema/Sema.cpp @@ -740,6 +740,9 @@ void Sema::ActOnEndOfTranslationUnit() { // Load pending instantiations from the external source. SmallVector Pending; ExternalSource->ReadPendingInstantiations(Pending); + for (auto PII : Pending) + if (auto Func = dyn_cast(PII.first)) + Func->setInstantiationIsPending(true); PendingInstantiations.insert(PendingInstantiations.begin(), Pending.begin(), Pending.end()); } diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp index 75a6903392ea..f49df6b3216d 100644 --- a/clang/lib/Sema/SemaExpr.cpp +++ b/clang/lib/Sema/SemaExpr.cpp @@ -13732,6 +13732,7 @@ void Sema::MarkFunctionReferenced(SourceLocation Loc, FunctionDecl *Func, // call to such a function. InstantiateFunctionDefinition(PointOfInstantiation, Func); else { + Func->setInstantiationIsPending(true); PendingInstantiations.push_back(std::make_pair(Func, PointOfInstantiation)); // Notify the consumer that a function was implicitly instantiated. diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp index 148ce24293a0..c58122cd271b 100644 --- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp +++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp @@ -3782,6 +3782,7 @@ void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation, // Try again at the end of the translation unit (at which point a // definition will be required). assert(!Recursive); + Function->setInstantiationIsPending(true); PendingInstantiations.push_back( std::make_pair(Function, PointOfInstantiation)); } else if (TSK == TSK_ImplicitInstantiation) { @@ -3801,6 +3802,7 @@ void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation, // Postpone late parsed template instantiations. if (PatternDecl->isLateTemplateParsed() && !LateTemplateParser) { + Function->setInstantiationIsPending(true); PendingInstantiations.push_back( std::make_pair(Function, PointOfInstantiation)); return; @@ -5146,6 +5148,8 @@ void Sema::PerformPendingInstantiations(bool LocalOnly) { TSK_ExplicitInstantiationDefinition; InstantiateFunctionDefinition(/*FIXME:*/Inst.second, Function, true, DefinitionRequired, true); + if (Function->isDefined()) + Function->setInstantiationIsPending(false); continue; } diff --git a/clang/test/CodeGen/no-devirt.cpp b/clang/test/CodeGen/no-devirt.cpp new file mode 100644 index 000000000000..4333b7cde7c6 --- /dev/null +++ b/clang/test/CodeGen/no-devirt.cpp @@ -0,0 +1,59 @@ +// RUN: %clang_cc1 %s -DUSEIT -triple %itanium_abi_triple -emit-llvm -o - | FileCheck %s + +// Test with decls and template defs in pch, and just use in .cpp +// RUN: %clang_cc1 %s -DTMPL_DEF_IN_HEADER -triple %itanium_abi_triple -emit-pch -o %t +// RUN: %clang_cc1 %s -DTMPL_DEF_IN_HEADER -DUSEIT -triple %itanium_abi_triple -include-pch %t -emit-llvm -o - | FileCheck %s + +// Test with A in pch, and B and C in main +// Test with just decls in pch, and template defs and use in .cpp +// RUN: %clang_cc1 %s -triple %itanium_abi_triple -emit-pch -o %t +// RUN: %clang_cc1 %s -DUSEIT -triple %itanium_abi_triple -include-pch %t -emit-llvm -o - | FileCheck %s + +#ifndef HEADER +#define HEADER +template < typename T, int N = 0 > class TmplWithArray { +public: + virtual T& operator [] (int idx); + virtual T& func1 (int idx); + virtual T& func2 (int idx); + T ar[N+1]; +}; +struct Wrapper { + TmplWithArray data; + bool indexIt(int a) { + if (a > 6) return data[a] ; // Should not devirtualize + if (a > 4) return data.func1(a); // Should devirtualize + return data.func2(a); // Should devirtualize + } +}; + +#ifdef TMPL_DEF_IN_HEADER +template T& TmplWithArray::operator[](int idx) { + return ar[idx]; +} +template T& TmplWithArray::func1(int idx) { + return ar[idx]; +} +#endif // TMPL_DEF_IN_HEADER +#endif // HEADER + +#ifdef USEIT +#ifndef TMPL_DEF_IN_HEADER +template T& TmplWithArray::operator[](int idx) { + return ar[idx]; +} +template T& TmplWithArray::func1(int idx) { + return ar[idx]; +} +#endif // !TMPL_DEF_IN_HEADER +extern Wrapper ew; +bool stuff(int p) +{ + return ew.indexIt(p); +} +#endif + +// CHECK-NOT: call {{.*}} @_ZN13TmplWithArrayIbLi10EEixEi +// CHECK-DAG: call {{.*}} @_ZN13TmplWithArrayIbLi10EE5func1Ei +// CHECK-DAG: call {{.*}} @_ZN13TmplWithArrayIbLi10EE5func2Ei +