Re: [patch] Optimize empty class copies within a C++ return statement

[Jason Merrill]

On 03/06/2015 11:19 AM, Aldy Hernandez wrote:

We are hitting the MODIFY_EXPR case.  Indeed, _because_ we hit the
MODIFY_EXPR is that we return the uninitialized temporary.

For example, we start with:

     return retval = TARGET_EXPR <D.2347, ...>

which becomes:

     <stuff with &D.2347>
     return D.2349 = D.2347;

which the aforementioned MODIFY_EXPR case turns into:

     <stuff with &D.2347>
     return D.2349;

But doesn't this still involve a MODIFY_EXPR, i.e. return retval = D.2349?

Jason