On 06/26/2012 04:28 AM, Richard Guenther wrote:
No - the fact that the flag is C++ specific but in common.opt is odd enough and -ftemp-reuse-stack sounds very very generic - which in fact it is not, it's a no-op in C. Is there a more formal phrase for the temporary kind that is affected?
Not that I'm aware of. This is a temporary introduced by TARGET_EXPR, which lives until the end of the enclosing CLEANUP_POINT_EXPR.
So - a little kludgy but probably more to what I'd like it to be would be to move the option to c-family/c.opt enabled only for C++ and Obj-C++ and export it to the middle-end via a new langhook
Hmm, that does seem rather kludgy for something that affects the behavior of middle-end code working on GENERIC.
(the gimplifier code should be in Frontend code that lowers to GENERIC really and the WITH_CLEANUP_EXPR code should be C++ frontend specific ...).
TARGET_EXPR has been a back-end code since the dawn of GCC version control; if it's still only used by the C++ front end I guess it could move to cp-tree.def, but we can't really lower it until gimplification time because we need to strip away enclosing COMPOUND_EXPRs and such so we can see that it's on the RHS of an initialization and optimize away the temporary in that case. And now that GIMPLE isn't a subset of GENERIC, we can't just use the gimplifier at genericization time. And I'd rather not duplicate the entire gimplifier in the front end.
Jason
