diff options
| author | David Majnemer <david.majnemer@gmail.com> | 2016-02-10 17:40:47 +0000 |
|---|---|---|
| committer | David Majnemer <david.majnemer@gmail.com> | 2016-02-10 17:40:47 +0000 |
| commit | f813c829dd9e628b456e9df9826bba69f7224a92 (patch) | |
| tree | 28c2f40f6c164563b24eb33fa1379e9ab6c2f731 /lib/CodeGen/MicrosoftCXXABI.cpp | |
| parent | 222af3db18686a08f455b6a5132de5a98d0273f4 (diff) | |
[MS ABI] Never reference dllimport'd vtables
Referencing a dllimported vtable is impossible in a constexpr
constructor. It would be friendlier to C++ programmers if we
synthesized a copy of the vftable which referenced imported virtual
functions. This would let us initialize the object in a way which
preserves both the intent to import functionality from another DLL while
also making constexpr work.
Differential Revision: http://reviews.llvm.org/D17061
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@260388 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen/MicrosoftCXXABI.cpp')
| -rw-r--r-- | lib/CodeGen/MicrosoftCXXABI.cpp | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/lib/CodeGen/MicrosoftCXXABI.cpp b/lib/CodeGen/MicrosoftCXXABI.cpp index 0664381b44..f47b120a90 100644 --- a/lib/CodeGen/MicrosoftCXXABI.cpp +++ b/lib/CodeGen/MicrosoftCXXABI.cpp @@ -1673,7 +1673,16 @@ llvm::GlobalVariable *MicrosoftCXXABI::getAddrOfVTable(const CXXRecordDecl *RD, SmallString<256> VFTableName; mangleVFTableName(getMangleContext(), RD, VFPtr, VFTableName); - llvm::GlobalValue::LinkageTypes VFTableLinkage = CGM.getVTableLinkage(RD); + // Classes marked __declspec(dllimport) need vftables generated on the + // import-side in order to support features like constexpr. No other + // translation unit relies on the emission of the local vftable, translation + // units are expected to generate them as needed. + // + // Because of this unique behavior, we maintain this logic here instead of + // getVTableLinkage. + llvm::GlobalValue::LinkageTypes VFTableLinkage = + RD->hasAttr<DLLImportAttr>() ? llvm::GlobalValue::LinkOnceODRLinkage + : CGM.getVTableLinkage(RD); bool VFTableComesFromAnotherTU = llvm::GlobalValue::isAvailableExternallyLinkage(VFTableLinkage) || llvm::GlobalValue::isExternalLinkage(VFTableLinkage); @@ -1746,9 +1755,7 @@ llvm::GlobalVariable *MicrosoftCXXABI::getAddrOfVTable(const CXXRecordDecl *RD, if (C) VTable->setComdat(C); - if (RD->hasAttr<DLLImportAttr>()) - VFTable->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass); - else if (RD->hasAttr<DLLExportAttr>()) + if (RD->hasAttr<DLLExportAttr>()) VFTable->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass); VFTablesMap[ID] = VFTable; |