Reinstate the optimization suppressing available_externally functions

at -O0. The only change from the previous patch is that we don't try
to generate virtual method thunks for an available_externally
function.

llvm-svn: 108230

1 files changed, 17 insertions, 8 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index cb83ffde6f0..bf606a61658 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -813,18 +813,27 @@ void CodeGenModule::EmitGlobalDefinition(GlobalDecl GD) {
                                  Context.getSourceManager(),
                                  "Generating code for declaration");
   
-  if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(D))
-    if (Method->isVirtual())
-      getVTables().EmitThunks(GD);
+  if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(D)) {
+    // At -O0, don't generate IR for functions with available_externally 
+    // linkage.
+    if (CodeGenOpts.OptimizationLevel == 0 &&
+        getFunctionLinkage(Function) 
+                                  == llvm::Function::AvailableExternallyLinkage)
+      return;
+
+    if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(D)) {
+      if (Method->isVirtual())
+        getVTables().EmitThunks(GD);
 
-  if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(D))
-    return EmitCXXConstructor(CD, GD.getCtorType());
+      if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(Method))
+        return EmitCXXConstructor(CD, GD.getCtorType());
   
-  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(D))
-    return EmitCXXDestructor(DD, GD.getDtorType());
+      if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(Method))
+        return EmitCXXDestructor(DD, GD.getDtorType());
+    }
 
-  if (isa<FunctionDecl>(D))
     return EmitGlobalFunctionDefinition(GD);
+  }
   
   if (const VarDecl *VD = dyn_cast<VarDecl>(D))
     return EmitGlobalVarDefinition(VD);