PR23833, DR2140: an lvalue-to-rvalue conversion on a glvalue of type

nullptr_t does not access memory.

We now reuse CK_NullToPointer to represent a conversion from a glvalue
of type nullptr_t to a prvalue of nullptr_t where necessary.

llvm-svn: 345562

2 files changed, 4 insertions, 3 deletions

diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 42481939fa1..0bbf3a6c561 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -1300,7 +1300,8 @@ static bool isSimpleZero(const Expr *E, CodeGenFunction &CGF) {
   // (int*)0 - Null pointer expressions.
   if (const CastExpr *ICE = dyn_cast<CastExpr>(E))
     return ICE->getCastKind() == CK_NullToPointer &&
-        CGF.getTypes().isPointerZeroInitializable(E->getType());
+           CGF.getTypes().isPointerZeroInitializable(E->getType()) &&
+           !E->HasSideEffects(CGF.getContext());
   // '\0'
   if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E))
     return CL->getValue() == 0;
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index c0cb8ad1711..a2b3f99573e 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -1895,14 +1895,14 @@ Value *ScalarExprEmitter::VisitCastExpr(CastExpr *CE) {
 
   case CK_NullToPointer:
     if (MustVisitNullValue(E))
-      (void) Visit(E);
+      CGF.EmitIgnoredExpr(E);
 
     return CGF.CGM.getNullPointer(cast<llvm::PointerType>(ConvertType(DestTy)),
                               DestTy);
 
   case CK_NullToMemberPointer: {
     if (MustVisitNullValue(E))
-      (void) Visit(E);
+      CGF.EmitIgnoredExpr(E);
 
     const MemberPointerType *MPT = CE->getType()->getAs<MemberPointerType>();
     return CGF.CGM.getCXXABI().EmitNullMemberPointer(MPT);