Introduce a new AST node describing reference binding to temporaries.
MaterializeTemporaryExpr captures a reference binding to a temporary
value, making explicit that the temporary value (a prvalue) needs to
be materialized into memory so that its address can be used. The
intended AST invariant here is that a reference will always bind to a
glvalue, and MaterializeTemporaryExpr will be used to convert prvalues
into glvalues for that binding to happen. For example, given
const int& r = 1.0;
The initializer of "r" will be a MaterializeTemporaryExpr whose
subexpression is an implicit conversion from the double literal "1.0"
to an integer value.
IR generation benefits most from this new node, since it was
previously guessing (badly) when to materialize temporaries for the
purposes of reference binding. There are likely more refactoring and
cleanups we could perform there, but the introduction of
MaterializeTemporaryExpr fixes PR9565, a case where IR generation
would effectively bind a const reference directly to a bitfield in a
struct. Addresses <rdar://problem/9552231>.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@133521 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 54900e0..1b9fd77 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -2205,6 +2205,14 @@
return NULL;
}
+ case Stmt::MaterializeTemporaryExprClass:
+ if (Expr *Result = EvalAddr(
+ cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
+ refVars))
+ return Result;
+
+ return E;
+
// Everything else: we simply don't reason about them.
default:
return NULL;
@@ -2306,6 +2314,14 @@
return EvalVal(M->getBase(), refVars);
}
+ case Stmt::MaterializeTemporaryExprClass:
+ if (Expr *Result = EvalVal(
+ cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
+ refVars))
+ return Result;
+
+ return E;
+
default:
// Check that we don't return or take the address of a reference to a
// temporary. This is only useful in C++.