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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug ipa/99862] [meta-issue] various missed optimizations for dead code elimination
Date: Fri, 09 Apr 2021 11:42:34 +0000 [thread overview]
Message-ID: <bug-99862-4-Lpv2PH5JnA@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-99862-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99862
--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Zhendong Su from comment #2)
> [659] % gcctk -O1 -S -o O1.s small.c
> [660] % gcctk -O3 -S -o O3.s small.c
> [661] %
> [661] % wc O1.s O3.s
> 40 86 599 O1.s
> 68 138 1047 O3.s
> 108 224 1646 total
> [662] %
> [662] % grep foo O1.s
> [663] % grep foo O3.s
> call foo
> [664] %
> [664] % cat small.c
> extern void foo(void);
> int a, b, *c;
> static void d(int f) {
> if (f)
> foo();
> }
> static int e(int f) {
> int g[] = {2, 8, 2, 8, 2, 8, 2, 8, 2, 8, 2};
> int h[60];
> h[0] = g != c;
> if (b)
> while (a) {
> int *i[1] = {&h[6]};
> }
> return f;
> }
> static int *j(int *p) { return 0; }
> int main () {
> int m = e(0);
> d(m);
> int l[8];
> if (j(l))
> while (1)
> ;
> return 0;
> }
This is a case similar to PR99991, we create a IPA CP clone and fail to inline
that at -O3 while we are happy to IPA inline e() at -O1.
next prev parent reply other threads:[~2021-04-09 11:42 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-01 7:59 [Bug ipa/99862] New: " zhendong.su at inf dot ethz.ch
2021-04-01 8:01 ` [Bug ipa/99862] " zhendong.su at inf dot ethz.ch
2021-04-01 8:06 ` zhendong.su at inf dot ethz.ch
2021-04-02 0:28 ` egallager at gcc dot gnu.org
2021-04-02 17:02 ` zhendong.su at inf dot ethz.ch
2021-04-09 11:37 ` rguenth at gcc dot gnu.org
2021-04-09 11:39 ` rguenth at gcc dot gnu.org
2021-04-09 11:42 ` rguenth at gcc dot gnu.org [this message]
2021-04-09 11:53 ` rguenth at gcc dot gnu.org
2021-04-09 11:59 ` zhendong.su at inf dot ethz.ch
2021-04-10 10:12 ` egallager at gcc dot gnu.org
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