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From: "christophe.leroy at csgroup dot eu" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/97445] Some fonctions marked static inline in Linux kernel are not inlined
Date: Tue, 20 Oct 2020 13:51:18 +0000 [thread overview]
Message-ID: <bug-97445-4-x5WeGMuEsY@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-97445-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97445
--- Comment #40 from Christophe Leroy <christophe.leroy at csgroup dot eu> ---
(In reply to Jakub Jelinek from comment #39)
> (In reply to Christophe Leroy from comment #38)
> > But on powerpc that's already the case and it doesn't solve the issue.
> >
> > static inline int fls(unsigned int x)
> > {
> > return 32 - __builtin_clz(x);
> > }
> >
> > static inline int fls64(__u64 x)
> > {
> > return 64 - __builtin_clzll(x);
> > }
>
> That is clearly a kernel bug (__builtin_clz* is documented undefined for 0,
> while fls* wants to be well defined there), and shouldn't change anything,
> because
> in the if (__builtin_constant_p (size))
> case get_order doesn't use fls*, but ilog2. And it is ilog2 that should be
> changed.
What's the bug ?
int f(int x)
{
return __builtin_clz(x);
}
Compiles into
<f>:
cntlzw r3, r3
blr
Powerpc 32 bits documentation says:
cntlzw : Count Leading Zeros Word
A count of the number of consecutive zero bits starting at bit 0 of rS is
placed into rA. This number ranges from 0 to 32, inclusive.
I can't see a problem when x == 0
next prev parent reply other threads:[~2020-10-20 13:51 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-15 13:41 [Bug c/97445] New: " christophe.leroy at csgroup dot eu
2020-10-15 13:46 ` [Bug c/97445] " jakub at gcc dot gnu.org
2020-10-15 14:27 ` rguenth at gcc dot gnu.org
2020-10-15 14:49 ` segher at gcc dot gnu.org
2020-10-15 14:52 ` jakub at gcc dot gnu.org
2020-10-15 15:08 ` christophe.leroy at csgroup dot eu
2020-10-15 15:13 ` christophe.leroy at csgroup dot eu
2020-10-17 16:23 ` christophe.leroy at csgroup dot eu
2020-10-17 16:31 ` christophe.leroy at csgroup dot eu
2020-10-19 12:33 ` jakub at gcc dot gnu.org
2020-10-19 12:39 ` christophe.leroy at csgroup dot eu
2020-10-19 12:57 ` christophe.leroy at csgroup dot eu
2020-10-19 12:59 ` christophe.leroy at csgroup dot eu
2020-10-19 13:01 ` christophe.leroy at csgroup dot eu
2020-10-19 15:05 ` marxin at gcc dot gnu.org
2020-10-19 15:06 ` marxin at gcc dot gnu.org
2020-10-19 15:11 ` marxin at gcc dot gnu.org
2020-10-19 15:18 ` hubicka at ucw dot cz
2020-10-19 15:33 ` marxin at gcc dot gnu.org
2020-10-19 16:13 ` hubicka at gcc dot gnu.org
2020-10-19 16:20 ` hubicka at ucw dot cz
2020-10-19 16:52 ` jakub at gcc dot gnu.org
2020-10-19 17:13 ` hubicka at ucw dot cz
2020-10-20 5:19 ` christophe.leroy at csgroup dot eu
2020-10-20 6:44 ` Jan Hubicka
2020-10-20 5:21 ` christophe.leroy at csgroup dot eu
2020-10-20 5:21 ` christophe.leroy at csgroup dot eu
2020-10-20 6:17 ` christophe.leroy at csgroup dot eu
2020-10-20 6:44 ` hubicka at ucw dot cz
2020-10-20 7:09 ` christophe.leroy at csgroup dot eu
2020-10-20 7:10 ` christophe.leroy at csgroup dot eu
2020-10-20 7:10 ` christophe.leroy at csgroup dot eu
2020-10-20 9:55 ` segher at gcc dot gnu.org
2020-10-20 10:16 ` Jan Hubicka
2020-10-20 10:16 ` hubicka at ucw dot cz
2020-10-20 10:40 ` jakub at gcc dot gnu.org
2020-10-20 11:12 ` Jan Hubicka
2020-10-20 11:12 ` hubicka at ucw dot cz
2020-10-20 11:17 ` Jan Hubicka
2020-10-20 13:12 ` Jan Hubicka
2020-10-20 11:17 ` hubicka at ucw dot cz
2020-10-20 11:45 ` hubicka at ucw dot cz
2020-10-20 13:12 ` hubicka at ucw dot cz
2020-10-20 13:28 ` christophe.leroy at csgroup dot eu
2020-10-20 13:31 ` jakub at gcc dot gnu.org
2020-10-20 13:51 ` christophe.leroy at csgroup dot eu [this message]
2020-10-20 14:18 ` jakub at gcc dot gnu.org
2020-10-20 14:22 ` christophe.leroy at csgroup dot eu
2020-10-20 14:24 ` christophe.leroy at csgroup dot eu
2020-10-20 14:29 ` jakub at gcc dot gnu.org
2020-10-20 16:58 ` jakub at gcc dot gnu.org
2020-10-20 21:19 ` segher at gcc dot gnu.org
2020-10-21 5:38 ` christophe.leroy at csgroup dot eu
2020-10-21 15:04 ` [Bug ipa/97445] " hubicka at gcc dot gnu.org
2020-10-21 15:16 ` hubicka at gcc dot gnu.org
2020-10-21 18:01 ` cvs-commit at gcc dot gnu.org
2020-10-21 18:21 ` marxin at gcc dot gnu.org
2020-10-21 18:24 ` hubicka at ucw dot cz
2020-10-21 18:25 ` marxin at gcc dot gnu.org
2020-10-21 18:34 ` hubicka at ucw dot cz
2020-10-21 18:38 ` marxin at gcc dot gnu.org
2020-10-21 23:42 ` cvs-commit at gcc dot gnu.org
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