4 files changed, 43 insertions, 7 deletions

diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 20fe39d0af5..6c620713f76 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -89,6 +89,15 @@ QualType ParmVarDecl::getOriginalType() const {
   return getType();
 }
 
+void VarDecl::setInit(ASTContext &C, Expr *I) { 
+    if (EvaluatedStmt *Eval = Init.dyn_cast<EvaluatedStmt *>()) {
+      Eval->~EvaluatedStmt();
+      C.Deallocate(Eval);
+    }
+
+    Init = I;
+  }
+
 bool VarDecl::isExternC(ASTContext &Context) const {
   if (!Context.getLangOptions().CPlusPlus)
     return (getDeclContext()->isTranslationUnit() && 
@@ -287,8 +296,13 @@ VarDecl *VarDecl::Create(ASTContext &C, DeclContext *DC, SourceLocation L,
 
 void VarDecl::Destroy(ASTContext& C) {
   Expr *Init = getInit();
-  if (Init)
+  if (Init) {
     Init->Destroy(C);
+    if (EvaluatedStmt *Eval = this->Init.dyn_cast<EvaluatedStmt *>()) {
+      Eval->~EvaluatedStmt();
+      C.Deallocate(Eval);
+    }
+  }
   this->~VarDecl();
   C.Deallocate((void *)this);
 }
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index 6711faffe74..aca5efeb163 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -1210,8 +1210,21 @@ static ICEDiag CheckICE(const Expr* E, ASTContext &Ctx) {
       //   type initialized by an ICE can be used in ICEs.
       if (const VarDecl *Dcl =
               dyn_cast<VarDecl>(cast<DeclRefExpr>(E)->getDecl())) {
-        if (const Expr *Init = Dcl->getInit())
-          return CheckICE(Init, Ctx);
+        if (Dcl->isInitKnownICE()) {
+          // We have already checked whether this subexpression is an
+          // integral constant expression.
+          if (Dcl->isInitICE())
+            return NoDiag();
+          else
+            return ICEDiag(2, E->getLocStart());
+        }
+
+        if (const Expr *Init = Dcl->getInit()) {
+          ICEDiag Result = CheckICE(Init, Ctx);
+          // Cache the result of the ICE test.
+          Dcl->setInitKnownICE(Ctx, Result.Val == 0);
+          return Result;
+        }
       }
     }
     return ICEDiag(2, E->getLocStart());
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 34b01879708..7651884aa60 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -700,8 +700,17 @@ bool IntExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) {
   // In C, they can also be folded, although they are not ICEs.
   if (E->getType().getCVRQualifiers() == QualType::Const) {
     if (const VarDecl *D = dyn_cast<VarDecl>(E->getDecl())) {
-      if (const Expr *Init = D->getInit())
-        return Visit(const_cast<Expr*>(Init));
+      if (APValue *V = D->getEvaluatedValue())
+        return Success(V->getInt(), E);
+      if (const Expr *Init = D->getInit()) {
+        if (Visit(const_cast<Expr*>(Init))) {
+          // Cache the evaluated value in the variable declaration.
+          D->setEvaluatedValue(Info.Ctx, Result);
+          return true;
+        }
+
+        return false;
+      }
     }
   }
 
diff --git a/clang/lib/AST/StmtIterator.cpp b/clang/lib/AST/StmtIterator.cpp
index 20024f513ff..5c22e28894f 100644
--- a/clang/lib/AST/StmtIterator.cpp
+++ b/clang/lib/AST/StmtIterator.cpp
@@ -140,14 +140,14 @@ Stmt*& StmtIteratorBase::GetDeclExpr() const {
   
   if (inDeclGroup()) {
     VarDecl* VD = cast<VarDecl>(*DGI);
-    return VD->Init;
+    return *VD->getInitAddress();
   }
   
   assert (inDecl());
 
   if (VarDecl* VD = dyn_cast<VarDecl>(decl)) {
     assert (VD->Init);
-    return VD->Init;
+    return *VD->getInitAddress();
   }
 
   EnumConstantDecl* ECD = cast<EnumConstantDecl>(decl);