From 1faa89f9c619e4b2411fab4af7e22ee7a2bd9009 Mon Sep 17 00:00:00 2001
From: Anders Carlsson <andersca@mac.com>
Date: Sat, 5 Feb 2011 04:35:53 +0000
Subject: Re-land r124768, with a fix for PR9130.

We now emit everything except unused implicit virtual member functions when building the vtable.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@124935 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/CodeGenModule.cpp | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

(limited to 'lib/CodeGen/CodeGenModule.cpp')

diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index a086badfa8..82365aab42 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -654,7 +654,8 @@ llvm::Constant *CodeGenModule::GetWeakRefReference(const ValueDecl *VD) {
 
   llvm::Constant *Aliasee;
   if (isa<llvm::FunctionType>(DeclTy))
-    Aliasee = GetOrCreateLLVMFunction(AA->getAliasee(), DeclTy, GlobalDecl());
+    Aliasee = GetOrCreateLLVMFunction(AA->getAliasee(), DeclTy, GlobalDecl(),
+                                      /*ForVTable=*/false);
   else
     Aliasee = GetOrCreateLLVMGlobal(AA->getAliasee(),
                                     llvm::PointerType::getUnqual(DeclTy), 0);
@@ -786,7 +787,7 @@ void CodeGenModule::EmitGlobalDefinition(GlobalDecl GD) {
 llvm::Constant *
 CodeGenModule::GetOrCreateLLVMFunction(llvm::StringRef MangledName,
                                        const llvm::Type *Ty,
-                                       GlobalDecl D) {
+                                       GlobalDecl D, bool ForVTable) {
   // Lookup the entry, lazily creating it if necessary.
   llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
   if (Entry) {
@@ -844,12 +845,15 @@ CodeGenModule::GetOrCreateLLVMFunction(llvm::StringRef MangledName,
   //   - special member functions with implicit definitions
   // If we ever change our AST traversal to walk into class methods,
   // this will be unnecessary.
+  //
+  // We also don't emit a definition for a function if it's going to be an entry
+  // in a vtable, unless it's already marked as used.
   } else if (getLangOptions().CPlusPlus && D.getDecl()) {
     // Look for a declaration that's lexically in a record.
     const FunctionDecl *FD = cast<FunctionDecl>(D.getDecl());
     do {
       if (isa<CXXRecordDecl>(FD->getLexicalDeclContext())) {
-        if (FD->isImplicit()) {
+        if (FD->isImplicit() && !ForVTable) {
           assert(FD->isUsed() && "Sema didn't mark implicit function as used!");
           DeferredDeclsToEmit.push_back(D);
           break;
@@ -876,13 +880,14 @@ CodeGenModule::GetOrCreateLLVMFunction(llvm::StringRef MangledName,
 /// non-null, then this function will use the specified type if it has to
 /// create it (this occurs when we see a definition of the function).
 llvm::Constant *CodeGenModule::GetAddrOfFunction(GlobalDecl GD,
-                                                 const llvm::Type *Ty) {
+                                                 const llvm::Type *Ty,
+                                                 bool ForVTable) {
   // If there was no specific requested type, just convert it now.
   if (!Ty)
     Ty = getTypes().ConvertType(cast<ValueDecl>(GD.getDecl())->getType());
   
   llvm::StringRef MangledName = getMangledName(GD);
-  return GetOrCreateLLVMFunction(MangledName, Ty, GD);
+  return GetOrCreateLLVMFunction(MangledName, Ty, GD, ForVTable);
 }
 
 /// CreateRuntimeFunction - Create a new runtime function with the specified
@@ -890,7 +895,7 @@ llvm::Constant *CodeGenModule::GetAddrOfFunction(GlobalDecl GD,
 llvm::Constant *
 CodeGenModule::CreateRuntimeFunction(const llvm::FunctionType *FTy,
                                      llvm::StringRef Name) {
-  return GetOrCreateLLVMFunction(Name, FTy, GlobalDecl());
+  return GetOrCreateLLVMFunction(Name, FTy, GlobalDecl(), /*ForVTable=*/false);
 }
 
 static bool DeclIsConstantGlobal(ASTContext &Context, const VarDecl *D) {
@@ -1458,7 +1463,8 @@ void CodeGenModule::EmitAliasDefinition(GlobalDecl GD) {
   // if a deferred decl.
   llvm::Constant *Aliasee;
   if (isa<llvm::FunctionType>(DeclTy))
-    Aliasee = GetOrCreateLLVMFunction(AA->getAliasee(), DeclTy, GlobalDecl());
+    Aliasee = GetOrCreateLLVMFunction(AA->getAliasee(), DeclTy, GlobalDecl(),
+                                      /*ForVTable=*/false);
   else
     Aliasee = GetOrCreateLLVMGlobal(AA->getAliasee(),
                                     llvm::PointerType::getUnqual(DeclTy), 0);
@@ -1524,7 +1530,7 @@ llvm::Value *CodeGenModule::getBuiltinLibFunction(const FunctionDecl *FD,
   const llvm::FunctionType *Ty =
     cast<llvm::FunctionType>(getTypes().ConvertType(FD->getType()));
 
-  return GetOrCreateLLVMFunction(Name, Ty, GlobalDecl(FD));
+  return GetOrCreateLLVMFunction(Name, Ty, GlobalDecl(FD), /*ForVTable=*/false);
 }
 
 llvm::Function *CodeGenModule::getIntrinsic(unsigned IID,const llvm::Type **Tys,
-- 
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