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[Bug target/70232] [6 regression] excessive stack usage with -O2
- From: "rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 16 Mar 2016 14:28:52 +0000
- Subject: [Bug target/70232] [6 regression] excessive stack usage with -O2
- Auto-submitted: auto-generated
- References: <bug-70232-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70232
--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
But not sure how this became a regression - does GCC 5 really do better here?
With -fno-tree-dominator-opts the warning no longer triggers and we get
sub sp, sp, #428
so it may be another jump-threading related regression. With additional
-fno-tree-vrp we get to
sub sp, sp, #140
> grep '<< 56' t.c.211t.optimized
_68 = _38 << 56;
_98 = _97 << 56;
for both and with VRP and DOM
> grep '<< 56' t.c.211t.optimized
_68 = _38 << 56;
_98 = _97 << 56;
_137 = _138 << 56;
_375 = _376 << 56;
_342 = _343 << 56;
_170 = _169 << 56;
_603 = _602 << 56;
_636 = _635 << 56;
_209 = _208 << 56;
_683 = _682 << 56;
_716 = _715 << 56;
_239 = _238 << 56;
_523 = _522 << 56;
_556 = _555 << 56;
_300 = _301 << 56;
_37 = _76 << 56;
_443 = _442 << 56;
_476 = _475 << 56;
so we get nine(!) copies of it.