CC Hans. This is not a regression (AFAICT), but this is a quality improvement, so may be worth considering in the 4.0 branch?
— Mehdi > On Jan 27, 2017, at 2:04 PM, David Blaikie via Phabricator > <revi...@reviews.llvm.org> wrote: > > dblaikie created this revision. > > As Mehdi put it, entities should either be > available_externally+weak_odr, or linkonce_odr+linkonce_odr. While some > functions are emitted a_e/weak, their local variables were emitted > a_e/linkonce_odr. > > While it might be nice to emit them a_e/weak, the Itanium ABI (& best > guess at MSVC's behavior as well) requires the local to be > linkonce/linkonce. > > > https://reviews.llvm.org/D29233 > > Files: > lib/AST/ASTContext.cpp > test/CodeGenCXX/explicit-instantiation.cpp > > > Index: test/CodeGenCXX/explicit-instantiation.cpp > =================================================================== > --- test/CodeGenCXX/explicit-instantiation.cpp > +++ test/CodeGenCXX/explicit-instantiation.cpp > @@ -5,6 +5,9 @@ > // This check logically is attached to 'template int S<int>::i;' below. > // CHECK: @_ZN1SIiE1iE = weak_odr global i32 > > +// This check is logically attached to 'template int > ExportedStaticLocal::f<int>()' below. > +// CHECK-OPT: @_ZZN19ExportedStaticLocal1fIiEEvvE1i = linkonce_odr global > + > template<typename T, typename U, typename Result> > struct plus { > Result operator()(const T& t, const U& u) const; > @@ -153,3 +156,17 @@ > template <typename T> void S<T>::g() {} > template <typename T> int S<T>::i; > template <typename T> void S<T>::S2::h() {} > + > +namespace ExportedStaticLocal { > +void sink(int&); > +template <typename T> > +inline void f() { > + static int i; > + sink(i); > +} > +// See the check line at the top of the file. > +extern template void f<int>(); > +void use() { > + f<int>(); > +} > +} > Index: lib/AST/ASTContext.cpp > =================================================================== > --- lib/AST/ASTContext.cpp > +++ lib/AST/ASTContext.cpp > @@ -8892,22 +8892,27 @@ > return GVA_Internal; > > if (VD->isStaticLocal()) { > - GVALinkage StaticLocalLinkage = GVA_DiscardableODR; > const DeclContext *LexicalContext = VD->getParentFunctionOrMethod(); > while (LexicalContext && !isa<FunctionDecl>(LexicalContext)) > LexicalContext = LexicalContext->getLexicalParent(); > > - // Let the static local variable inherit its linkage from the nearest > - // enclosing function. > - if (LexicalContext) > - StaticLocalLinkage = > - > Context.GetGVALinkageForFunction(cast<FunctionDecl>(LexicalContext)); > - > - // GVA_StrongODR function linkage is stronger than what we need, > - // downgrade to GVA_DiscardableODR. > - // This allows us to discard the variable if we never end up needing it. > - return StaticLocalLinkage == GVA_StrongODR ? GVA_DiscardableODR > - : StaticLocalLinkage; > + // ObjC Blocks can create local variables that don't have a FunctionDecl > + // LexicalContext. > + if (!LexicalContext) > + return GVA_DiscardableODR; > + > + // Otherwise, let the static local variable inherit its linkage from the > + // nearest enclosing function. > + auto StaticLocalLinkage = > + Context.GetGVALinkageForFunction(cast<FunctionDecl>(LexicalContext)); > + > + // Itanium ABI (& MSVC seems to do similarly) requires static locals in > + // inline functions to be emitted anywhere they're needed, even if the > + // function they are local to is emitted StrongODR/AvailableExternally. > + if (StaticLocalLinkage == GVA_StrongODR || > + StaticLocalLinkage == GVA_AvailableExternally) > + return GVA_DiscardableODR; > + return StaticLocalLinkage; > } > > // MSVC treats in-class initialized static data members as definitions. > > > <D29233.86118.patch> _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
