Author: hiraditya Date: Wed Sep 28 22:32:04 2016 New Revision: 282679 URL: http://llvm.org/viewvc/llvm-project?rev=282679&view=rev Log: [PR30341] Alias must point to a definition
Inlining the destructor caused the compiler to generate bad IR which failed the Verifier in the backend. https://llvm.org/bugs/show_bug.cgi?id=30341 This patch disables alias to available_externally definitions. Reviewers: eugenis, rsmith Differential Revision: https://reviews.llvm.org/D24682 Added: cfe/trunk/test/CodeGenCXX/alias-available-externally.cpp Modified: cfe/trunk/lib/CodeGen/CGCXX.cpp Modified: cfe/trunk/lib/CodeGen/CGCXX.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGCXX.cpp?rev=282679&r1=282678&r2=282679&view=diff ============================================================================== --- cfe/trunk/lib/CodeGen/CGCXX.cpp (original) +++ cfe/trunk/lib/CodeGen/CGCXX.cpp Wed Sep 28 22:32:04 2016 @@ -134,6 +134,11 @@ bool CodeGenModule::TryEmitDefinitionAsA llvm::GlobalValue::LinkageTypes TargetLinkage = getFunctionLinkage(TargetDecl); + // available_externally definitions aren't real definitions, so we cannot + // create an alias to one. + if (TargetLinkage == llvm::GlobalValue::AvailableExternallyLinkage) + return true; + // Check if we have it already. StringRef MangledName = getMangledName(AliasDecl); llvm::GlobalValue *Entry = GetGlobalValue(MangledName); @@ -156,14 +161,7 @@ bool CodeGenModule::TryEmitDefinitionAsA // Instead of creating as alias to a linkonce_odr, replace all of the uses // of the aliasee. - if (llvm::GlobalValue::isDiscardableIfUnused(Linkage) && - (TargetLinkage != llvm::GlobalValue::AvailableExternallyLinkage || - !TargetDecl.getDecl()->hasAttr<AlwaysInlineAttr>())) { - // FIXME: An extern template instantiation 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. + if (llvm::GlobalValue::isDiscardableIfUnused(Linkage)) { addReplacement(MangledName, Aliasee); return false; } Added: cfe/trunk/test/CodeGenCXX/alias-available-externally.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/alias-available-externally.cpp?rev=282679&view=auto ============================================================================== --- cfe/trunk/test/CodeGenCXX/alias-available-externally.cpp (added) +++ cfe/trunk/test/CodeGenCXX/alias-available-externally.cpp Wed Sep 28 22:32:04 2016 @@ -0,0 +1,19 @@ +// RUN: %clang_cc1 -O1 -std=c++11 -emit-llvm -disable-llvm-passes -o - %s | FileCheck %s +// Clang should not generate alias to available_externally definitions. +// Check that the destructor of Foo is defined. +// CHECK: define linkonce_odr void @_ZN3FooD2Ev +template <class CharT> +struct String { + String() {} + ~String(); +}; + +template <class CharT> +inline __attribute__((visibility("hidden"), always_inline)) +String<CharT>::~String() {} + +extern template struct String<char>; + +struct Foo : public String<char> { Foo() { String<char> s; } }; + +Foo f; _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
