[c++17] P0135R1: Guaranteed copy elision.

When an object of class type is initialized from a prvalue of the same type
(ignoring cv qualifications), use the prvalue to initialize the object directly
instead of inserting a redundant elidable call to a copy constructor.

llvm-svn: 288866

1 files changed, 3 insertions, 13 deletions

diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index f51330c8b19..98f476efe93 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -1145,15 +1145,15 @@ void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
   if (E->hadArrayRangeDesignator())
     CGF.ErrorUnsupported(E, "GNU array range designator extension");
 
+  if (E->isTransparent())
+    return Visit(E->getInit(0));
+
   AggValueSlot Dest = EnsureSlot(E->getType());
 
   LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType());
 
   // Handle initialization of an array.
   if (E->getType()->isArrayType()) {
-    if (E->isStringLiteralInit())
-      return Visit(E->getInit(0));
-
     QualType elementType =
         CGF.getContext().getAsArrayType(E->getType())->getElementType();
 
@@ -1162,16 +1162,6 @@ void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
     return;
   }
 
-  if (E->getType()->isAtomicType()) {
-    // An _Atomic(T) object can be list-initialized from an expression
-    // of the same type.
-    assert(E->getNumInits() == 1 &&
-           CGF.getContext().hasSameUnqualifiedType(E->getInit(0)->getType(),
-                                                   E->getType()) &&
-           "unexpected list initialization for atomic object");
-    return Visit(E->getInit(0));
-  }
-
   assert(E->getType()->isRecordType() && "Only support structs/unions here!");
 
   // Do struct initialization; this code just sets each individual member