From: Chen Gang <chengang@emindsoft.com.cn>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Vineet Gupta <Vineet.Gupta1@synopsys.com>,
Arnd Bergmann <arnd@arndb.de>,
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"David S. Miller" <davem@davemloft.net>
Subject: Re: cmsg newgroup alt.sex.fetish.bool (was Re: [PATCH] arch: all: include: asm: bitops: Use bool instead of int for all bit test functions)
Date: Wed, 07 Sep 2016 23:58:20 +0800 [thread overview]
Message-ID: <57D0391C.90305@emindsoft.com.cn> (raw)
In-Reply-To: <20160904010144.GD2356@ZenIV.linux.org.uk>
On 9/4/16 09:01, Al Viro wrote:
> On Sun, Sep 04, 2016 at 06:36:56AM +0800, Chen Gang wrote:
>
>> And for all: shall I provide the proof for another archs?
>>
>> For me, Boolean gives additional chance to compiler to improve the code.
>
> Whereas for compiler it gives nothing. Not in those cases.
>
>> If the compiler can not improve the code, it can treat it as int simply.
>> So theoretically, at least, Boolean should not be worse than int.
>
> Except for pointless code churn and pandering to irrational beliefs, that is...
> Please, RTFISO9899 and learn the semantics of _Bool; it's not that complicated.
> Start with 6.2.5[2,6] and 6.3.1.2, then look through 6.8.4 and 6.8.5 to
> figure out the semantics of conditions in if/while/for. Note also 6.5.8,
> 6.5.9, 6.5.13 and 6.5.14 and observe that type of (x > 5 && y < 1) is *NOT*
> _Bool; it's int.
>
> If you can show any improvement or loss in code generation in this case
> (static inline int converted to static inline bool), I would really like to
> see the details. As in .config/file/function/gcc version/target architecture.
> Optimizer bugs happens, but they should be reported when found, and I would
> expect _Bool handling to be _less_ exercised than that of normal logical
> expressions, so loss is probably more likely. And yes, it also should be
> reported.
>
Sorry for replying late, and excuse me, I did not read the details more.
During these days I have no enough time on it (working, buying house,
and catching a cold, but lucky enough that my father's health is OK).
I shall try to read the details and analyze it within next weekend (I
guess I can not finish within this week end, sorry again for I really
have no time during these days).
But all together, for me, I guess our discussion can not 'prevent' that
bool return value instead of int return value for pure bool function in
our kernel. :-)
Thanks.
--
Chen Gang (陈刚)
Managing Natural Environments is the Duty of Human Beings.
next prev parent reply other threads:[~2016-09-07 15:57 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-28 5:39 [PATCH] arch: all: include: asm: bitops: Use bool instead of int for all bit test functions chengang
2016-08-28 7:02 ` kbuild test robot
2016-08-28 7:10 ` kbuild test robot
2016-08-28 7:10 ` kbuild test robot
2016-08-28 14:54 ` Chen Gang
2016-08-29 8:45 ` Michal Hocko
2016-08-29 13:03 ` Arnd Bergmann
2016-08-29 13:46 ` Peter Zijlstra
2016-08-29 13:54 ` Geert Uytterhoeven
2016-08-29 16:48 ` Vineet Gupta
2016-08-29 21:49 ` Chen Gang
2016-09-01 20:43 ` cmsg newgroup alt.sex.fetish.bool (was Re: [PATCH] arch: all: include: asm: bitops: Use bool instead of int for all bit test functions) Al Viro
2016-09-02 23:33 ` Chen Gang
2016-09-03 0:07 ` Vineet Gupta
2016-09-03 22:36 ` Chen Gang
2016-09-04 1:01 ` Al Viro
2016-09-07 15:58 ` Chen Gang [this message]
2016-09-11 12:27 ` Chen Gang
2016-08-29 22:01 ` [PATCH] arch: all: include: asm: bitops: Use bool instead of int for all bit test functions Chen Gang
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