------- Comment #12 from rguenth at gcc dot gnu dot org 2010-08-07 21:16
-------
Ok, I see when gimplifying the call that we mark it for NRV because while
x doesn't have it's address taken it's value-expr has and we didn't replace
it at that point but we check
4262 else if (!is_gimple_non_addressable (*to_p))
4271 use_target = true;
so I think this is a bug that it doesn't mark the original parameter
decl as address-taken which happens here (function.c:gimplify_parameters):
/* If PARM was addressable, move that flag over
to the local copy, as its address will be taken,
not the PARMs. */
if (TREE_ADDRESSABLE (parm))
{
TREE_ADDRESSABLE (parm) = 0;
TREE_ADDRESSABLE (local) = 1;
}
We should defer clearing the param addressable flag to update_address_taken.
So the following should fix this. Can you bootstrap/test this?
Index: gcc/function.c
===================================================================
--- gcc/function.c (revision 162781)
+++ gcc/function.c (working copy)
@@ -3423,12 +3423,10 @@ gimplify_parameters (void)
DECL_IGNORED_P (local) = 0;
/* If PARM was addressable, move that flag over
to the local copy, as its address will be taken,
- not the PARMs. */
+ not the PARMs. Keep the parms address taken
+ as we'll query that flag during gimplification. */
if (TREE_ADDRESSABLE (parm))
- {
- TREE_ADDRESSABLE (parm) = 0;
- TREE_ADDRESSABLE (local) = 1;
- }
+ TREE_ADDRESSABLE (local) = 1;
}
else
{
(patch to the 4.5 branch, but should apply to the trunk as well).
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44632
