From d8e39bbb847b35d8912db2d13096d588651a72f1 Mon Sep 17 00:00:00 2001
From: Anders Carlsson <andersca@mac.com>
Date: Sat, 11 Apr 2009 01:08:03 +0000
Subject: [PATCH] Add support for generating reference initialization code.

llvm-svn: 68852
---
 clang/lib/CodeGen/CGExprConstant.cpp | 23 +++++++++++++++++++++--
 clang/test/CodeGenCXX/const-init.cpp | 11 +++++++++++
 2 files changed, 32 insertions(+), 2 deletions(-)
 create mode 100644 clang/test/CodeGenCXX/const-init.cpp

diff --git a/clang/lib/CodeGen/CGExprConstant.cpp b/clang/lib/CodeGen/CGExprConstant.cpp
index a3fca20f4fb1..2373ad64e923 100644
--- a/clang/lib/CodeGen/CGExprConstant.cpp
+++ b/clang/lib/CodeGen/CGExprConstant.cpp
@@ -474,7 +474,26 @@ llvm::Constant *CodeGenModule::EmitConstantExpr(const Expr *E,
                                                 CodeGenFunction *CGF) {
   Expr::EvalResult Result;
   
-  if (E->Evaluate(Result, Context)) {
+  bool Success = false;
+  
+  if (DestType->isReferenceType()) {
+    // If the destination type is a reference type, we need to evaluate it
+    // as an lvalue.
+    if (E->EvaluateAsLValue(Result, Context)) {
+      if (const Expr *LVBase = Result.Val.getLValueBase()) {
+        if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(LVBase)) {
+          const ValueDecl *VD = cast<ValueDecl>(DRE->getDecl());
+
+          // We can only initialize a reference with an lvalue if the lvalue
+          // is not a reference itself.
+          Success = !VD->getType()->isReferenceType();
+        }
+      }
+    }
+  } else 
+    Success = E->Evaluate(Result, Context);
+  
+  if (Success) {
     assert(!Result.HasSideEffects && 
            "Constant expr should not have any side effects!");
     switch (Result.Val.getKind()) {
@@ -482,7 +501,7 @@ llvm::Constant *CodeGenModule::EmitConstantExpr(const Expr *E,
       assert(0 && "Constant expressions should be initialized.");
       return 0;
     case APValue::LValue: {
-      const llvm::Type *DestTy = getTypes().ConvertTypeForMem(E->getType());
+      const llvm::Type *DestTy = getTypes().ConvertTypeForMem(DestType);
       llvm::Constant *Offset = 
         llvm::ConstantInt::get(llvm::Type::Int64Ty, 
                                Result.Val.getLValueOffset());
diff --git a/clang/test/CodeGenCXX/const-init.cpp b/clang/test/CodeGenCXX/const-init.cpp
new file mode 100644
index 000000000000..427ba5372992
--- /dev/null
+++ b/clang/test/CodeGenCXX/const-init.cpp
@@ -0,0 +1,11 @@
+// RUN: clang-cc -verify -emit-llvm -o %t %s
+
+int a = 10;
+int &ar = a;
+
+void f();
+void (&fr)() = f;
+
+struct S { int& a; };
+S s = { a };
+