Use a trivial comdat for C++ tables.

This produces comdats for vtables, typeinfo, typeinfo names, and vtts.

When combined with llvm not producing implicit comdats, not doing this would
cause code bloat on ELF and link errors on COFF.

llvm-svn: 226227

3 files changed, 16 insertions, 3 deletions

diff --git a/clang/lib/CodeGen/CGVTT.cpp b/clang/lib/CodeGen/CGVTT.cpp
index bd280ea14e8..81bd65179b7 100644
--- a/clang/lib/CodeGen/CGVTT.cpp
+++ b/clang/lib/CodeGen/CGVTT.cpp
@@ -94,6 +94,9 @@ CodeGenVTables::EmitVTTDefinition(llvm::GlobalVariable *VTT,
   // Set the correct linkage.
   VTT->setLinkage(Linkage);
 
+  if (CGM.supportsCOMDAT() && VTT->isWeakForLinker())
+    VTT->setComdat(CGM.getModule().getOrInsertComdat(VTT->getName()));
+
   // Set the right visibility.
   CGM.setGlobalVisibility(VTT, RD);
 }
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 7a97aa64ea9..72d7a6cd8e0 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1828,7 +1828,10 @@ CodeGenModule::CreateOrReplaceCXXRuntimeVariable(StringRef Name,
     
     OldGV->eraseFromParent();
   }
-  
+
+  if (supportsCOMDAT() && GV->isWeakForLinker())
+    GV->setComdat(TheModule.getOrInsertComdat(GV->getName()));
+
   return GV;
 }
 
diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index 7d8ad465bf3..29d922c68e3 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -1256,6 +1256,9 @@ void ItaniumCXXABI::emitVTableDefinitions(CodeGenVTables &CGVT,
   // Set the correct linkage.
   VTable->setLinkage(Linkage);
 
+  if (CGM.supportsCOMDAT() && VTable->isWeakForLinker())
+    VTable->setComdat(CGM.getModule().getOrInsertComdat(VTable->getName()));
+
   // Set the right visibility.
   CGM.setGlobalVisibility(VTable, RD);
 
@@ -2716,9 +2719,13 @@ llvm::Constant *ItaniumRTTIBuilder::BuildTypeInfo(QualType Ty, bool Force) {
 
   llvm::Constant *Init = llvm::ConstantStruct::getAnon(Fields);
 
+  llvm::Module &M = CGM.getModule();
   llvm::GlobalVariable *GV =
-    new llvm::GlobalVariable(CGM.getModule(), Init->getType(),
-                             /*Constant=*/true, Linkage, Init, Name);
+      new llvm::GlobalVariable(M, Init->getType(),
+                               /*Constant=*/true, Linkage, Init, Name);
+
+  if (CGM.supportsCOMDAT() && GV->isWeakForLinker())
+    GV->setComdat(M.getOrInsertComdat(GV->getName()));
 
   // If there's already an old global variable, replace it with the new one.
   if (OldGV) {