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[Bug middle-end/24786] Missing warning on questionable use of parameter to initialize static
- From: "manu at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Fri, 18 Sep 2015 00:40:37 +0000
- Subject: [Bug middle-end/24786] Missing warning on questionable use of parameter to initialize static
- Auto-submitted: auto-generated
- References: <bug-24786-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=24786
Manuel LÃpez-IbÃÃez <manu at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed|2005-11-11 17:59:15 |2015-9-18
CC| |manu at gcc dot gnu.org
Component|c++ |middle-end
Version|4.1.0 |6.0
--- Comment #3 from Manuel LÃpez-IbÃÃez <manu at gcc dot gnu.org> ---
GCC generates code like this:
const char *names[1];
const char *blah2() {
char x = 7;
if (first_time)
names[0] = { &x };
return names[0];
}
and we end up returning:
# .MEM_1 = PHI <.MEM_4(2), .MEM_9(4), .MEM_6(3)>
[test.c:5:17] # VUSE <.MEM_1>
# PT = nonlocal escaped { D.2254 } (escaped)
_10 = [test.c:5:17] _ZZ5blah2vE5namesD.2255[0];
# .MEM_11 = VDEF <.MEM_1>
xD.2254 ={v} {CLOBBER};
[test.c:5:17] # VUSE <.MEM_11>
return _10;
;; succ: EXIT [100.0%]
While in the non-static case we propagate &x:
;; basic block 2, loop depth 0, count 0, freq 10000, maybe hot
;; prev block 0, next block 1, flags: (NEW, REACHABLE)
;; pred: ENTRY [100.0%] (FALLTHRU,EXECUTABLE)
;; starting at line 5
# .MEM_2 = VDEF <.MEM_1(D)>
xD.2254 ={v} {CLOBBER};
[test.c:5:17] # VUSE <.MEM_2>
return &xD.2254;
;; succ: EXIT [100.0%]
This seems like a missed optimization.
Somehow related to PR60517.