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From: "rguenth at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/20408] Unnecessary code generated for empty structs
Date: Tue, 27 Nov 2007 09:40:00 -0000 [thread overview]
Message-ID: <20071127094015.16499.qmail@sourceware.org> (raw)
In-Reply-To: <bug-20408-9525@http.gcc.gnu.org/bugzilla/>
------- Comment #20 from rguenth at gcc dot gnu dot org 2007-11-27 09:40 -------
For the testcase in comment #13 we now generate two(!) temporaries:
void barc() ()
{
struct Foo D.2027;
struct Foo D.2028;
D.2027 = {};
D.2028 = {};
bar (D.2028);
}
via gimplification of
;; Function void barc() (_Z4barcv)
;; enabled by -tree-original
<<cleanup_point <<< Unknown tree: expr_stmt
bar (TARGET_EXPR <D.2027, {}>;, <<< Unknown tree: empty_class_expr >>>
;) >>>
>>;
though the generated assembler looks like we cannot do better:
_Z4barcv:
.LFB3:
subq $8, %rsp
.LCFI0:
movb $0, (%rsp)
call _Z3bar3Foo
addq $8, %rsp
ret
_Z4foocv:
.LFB2:
subq $24, %rsp
.LCFI1:
leaq 23(%rsp), %rdi
call _Z3fooRK3Foo
addq $24, %rsp
ret
On the tree level the first simple DSE pass gets rid of the extra temporary
and its initialization.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|WAITING |NEW
Last reconfirmed|2005-12-09 04:25:06 |2007-11-27 09:40:15
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20408
next prev parent reply other threads:[~2007-11-27 9:40 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-20408-9525@http.gcc.gnu.org/bugzilla/>
2007-11-26 14:17 ` steven at gcc dot gnu dot org
2007-11-27 9:40 ` rguenth at gcc dot gnu dot org [this message]
[not found] <bug-20408-4@http.gcc.gnu.org/bugzilla/>
2020-12-09 13:53 ` jason at gcc dot gnu.org
2021-02-09 1:52 ` cvs-commit at gcc dot gnu.org
2021-02-12 2:30 ` cvs-commit at gcc dot gnu.org
2005-03-10 15:48 [Bug middle-end/20408] New: Unnessasary " chris at bubblescope dot net
2005-03-10 17:31 ` [Bug middle-end/20408] Unnecessary " pinskia at gcc dot gnu dot org
2005-03-10 17:35 ` pinskia at gcc dot gnu dot org
2005-09-04 16:26 ` rguenth at gcc dot gnu dot org
2005-09-04 16:37 ` rguenth at gcc dot gnu dot org
2005-09-04 17:12 ` rguenth at gcc dot gnu dot org
2005-09-05 10:36 ` rguenth at gcc dot gnu dot org
2005-09-05 10:48 ` rguenth at gcc dot gnu dot org
2005-09-05 12:38 ` rguenth at gcc dot gnu dot org
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