Update NRVO logic to support early return (Attempt 2)
Summary:
This is the second attempt of r333500 (Update NRVO logic to support early return).
The previous one was reverted for a miscompilation for an incorrect NRVO set up on templates such as:
```
struct Foo {};
template <typename T>
T bar() {
T t;
if (false)
return T();
return t;
}
```
Where, `t` is marked as non-NRVO variable before its instantiation. However, while its instantiation, it's left an NRVO candidate, turned into an NRVO variable later.
Reviewers: rsmith
Reviewed By: rsmith
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D47586
llvm-svn: 335019
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 68857d9..7e38dcc 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -740,12 +740,13 @@
SemaRef.BuildVariableInstantiation(Var, D, TemplateArgs, LateAttrs, Owner,
StartingScope, InstantiatingVarTemplate);
+ bool NRVO = false;
if (D->isNRVOVariable()) {
QualType ReturnType = cast<FunctionDecl>(DC)->getReturnType();
if (SemaRef.isCopyElisionCandidate(ReturnType, Var, Sema::CES_Strict))
- Var->setNRVOVariable(true);
+ NRVO = true;
}
-
+ Var->setNRVOVariable(NRVO);
Var->setImplicit(D->isImplicit());
return Var;