On 11/02/2015 06:11 PM, Alexandre Oliva wrote:
On Oct 14, 2015, Richard Biener <richard.guent...@gmail.com> wrote:
On Wed, Oct 14, 2015 at 5:25 AM, Alexandre Oliva <aol...@redhat.com> wrote:
On Oct 12, 2015, Richard Biener <richard.guent...@gmail.com> wrote:
On Sat, Oct 10, 2015 at 3:16 PM, Alexandre Oliva <aol...@redhat.com> wrote:
On Oct 9, 2015, Richard Biener <richard.guent...@gmail.com> wrote:
Ok. Note that I think emit_block_move shouldn't mess with the addressable flag.
I have successfully tested a patch that stops it from doing so,
reverting https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49429#c11 but
according to bugs 49429 and 49454, it looks like removing it would mess
with escape analysis introduced in r175063 for bug 44194. The thread
that introduces the mark_addressable calls suggests some discomfort with
this solution, and even a suggestion that the markings should be
deferred past the end of expand, but in the end there was agreement to
go with it. https://gcc.gnu.org/ml/gcc-patches/2011-06/msg01746.html
Aww, indeed. Of course the issue is that we don't track pointers to the
stack introduced during RTL properly.
Thanks for checking. Might want to add a comment before that
addressable setting now that you've done the archeology.
I decided to give the following approach a try instead. The following
patch was regstrapped on x86_64-linux-gnu and i686-linux-gnu.
Ok to install?
It looks ok to me but lacks a comment in mark_addressable_1 why we
do this queueing when currently expanding to RTL.
+/* Mark X as addressable or queue it up if called during expand. */
+
+static void
+mark_addressable_1 (tree x)
How about this:
/* Mark X as addressable or queue it up if called during expand. We
don't want to apply it immediately during expand because decls are
made addressable at that point due to RTL-only concerns, such as
uses of memcpy for block moves, and TREE_ADDRESSABLE changes
is_gimple_reg, which might make it seem like a variable that used
to be a gimple_reg shouldn't have been an SSA name. So we queue up
this flag setting and only apply it when we're done with GIMPLE and
only RTL issues matter. */
Sounds good.
jeff
