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* Re: [PATCH v2 8/9] bfs: remove multiple assignments [not found] ` <Pine.LNX.4.61.0801261833270.1966@ginsburg.homenet> @ 2008-01-26 23:48 ` Dmitri Vorobiev 2008-01-28 7:02 ` Joel Schopp 0 siblings, 1 reply; 4+ messages in thread From: Dmitri Vorobiev @ 2008-01-26 23:48 UTC (permalink / raw) To: Tigran Aivazian Cc: trivial, linux-fsdevel, apw, rdunlap, jschopp, Linux-kernel Tigran Aivazian wrote: > On Sat, 26 Jan 2008, Dmitri Vorobiev wrote: >> - inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC; >> + inode->i_mtime = CURRENT_TIME_SEC; >> + inode->i_atime = CURRENT_TIME_SEC; >> + inode->i_ctime = CURRENT_TIME_SEC; > > multiple assignments like "x = y = z = value;" can potentially > (depending on the compiler and arch) be faster than "x = value; y = > value; z=value;" > > I am surprized that this script complains about them as it is a > perfectly valid thing to do in C. I think it seems wise to ask the maintainers of checkpatch.pl to comment on that. I'm Cc:ing them now. Thanks, Dmitri ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2 8/9] bfs: remove multiple assignments 2008-01-26 23:48 ` [PATCH v2 8/9] bfs: remove multiple assignments Dmitri Vorobiev @ 2008-01-28 7:02 ` Joel Schopp 2008-01-30 13:06 ` Al Viro 0 siblings, 1 reply; 4+ messages in thread From: Joel Schopp @ 2008-01-28 7:02 UTC (permalink / raw) To: Dmitri Vorobiev Cc: Tigran Aivazian, trivial, linux-fsdevel, apw, rdunlap, Linux-kernel >>> - inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC; >>> + inode->i_mtime = CURRENT_TIME_SEC; >>> + inode->i_atime = CURRENT_TIME_SEC; >>> + inode->i_ctime = CURRENT_TIME_SEC; >> multiple assignments like "x = y = z = value;" can potentially >> (depending on the compiler and arch) be faster than "x = value; y = >> value; z=value;" >> >> I am surprized that this script complains about them as it is a >> perfectly valid thing to do in C. > > I think it seems wise to ask the maintainers of checkpatch.pl to > comment on that. I'm Cc:ing them now. > There are plenty of things that are valid to do in C that don't make for maintainable code. These scripts are designed to make your code easier for real people to review and maintain. As for if this can be faster we don't deal in the realm of "can". Please show a concrete example of gcc making Linux kernel code faster with multiple assignments per line. If you can do that I'm willing to change my mind and I'll lead the charge for mutliple assignments per line. ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2 8/9] bfs: remove multiple assignments 2008-01-28 7:02 ` Joel Schopp @ 2008-01-30 13:06 ` Al Viro 2008-01-30 13:36 ` Dmitri Vorobiev 0 siblings, 1 reply; 4+ messages in thread From: Al Viro @ 2008-01-30 13:06 UTC (permalink / raw) To: Joel Schopp Cc: Dmitri Vorobiev, Tigran Aivazian, trivial, linux-fsdevel, apw, rdunlap, Linux-kernel On Mon, Jan 28, 2008 at 01:02:03AM -0600, Joel Schopp wrote: > >>>- inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC; > >>>+ inode->i_mtime = CURRENT_TIME_SEC; > >>>+ inode->i_atime = CURRENT_TIME_SEC; > >>>+ inode->i_ctime = CURRENT_TIME_SEC; > >>multiple assignments like "x = y = z = value;" can potentially > >>(depending on the compiler and arch) be faster than "x = value; y = > >>value; z=value;" > >> > >>I am surprized that this script complains about them as it is a > >>perfectly valid thing to do in C. > > > >I think it seems wise to ask the maintainers of checkpatch.pl to > >comment on that. I'm Cc:ing them now. > > > > There are plenty of things that are valid to do in C that don't make for > maintainable code. These scripts are designed to make your code easier for > real people to review and maintain. Except that in this case the new variant is not equivalent to the old one... ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2 8/9] bfs: remove multiple assignments 2008-01-30 13:06 ` Al Viro @ 2008-01-30 13:36 ` Dmitri Vorobiev 0 siblings, 0 replies; 4+ messages in thread From: Dmitri Vorobiev @ 2008-01-30 13:36 UTC (permalink / raw) To: Al Viro Cc: Joel Schopp, Dmitri Vorobiev, Tigran Aivazian, trivial, linux-fsdevel, apw, rdunlap, Linux-kernel Al Viro wrote: > On Mon, Jan 28, 2008 at 01:02:03AM -0600, Joel Schopp wrote: >>>>> - inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC; >>>>> + inode->i_mtime = CURRENT_TIME_SEC; >>>>> + inode->i_atime = CURRENT_TIME_SEC; >>>>> + inode->i_ctime = CURRENT_TIME_SEC; >>>> multiple assignments like "x = y = z = value;" can potentially >>>> (depending on the compiler and arch) be faster than "x = value; y = >>>> value; z=value;" >>>> >>>> I am surprized that this script complains about them as it is a >>>> perfectly valid thing to do in C. >>> I think it seems wise to ask the maintainers of checkpatch.pl to >>> comment on that. I'm Cc:ing them now. >>> >> There are plenty of things that are valid to do in C that don't make for >> maintainable code. These scripts are designed to make your code easier for >> real people to review and maintain. > > Except that in this case the new variant is not equivalent to the old one... Yes, you're right. In fact, I felt like sending yet another version of these patches, but this gets preempted all the time by "the other things". Dmitri ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2008-01-30 13:37 UTC | newest]
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2008-01-26 23:48 ` [PATCH v2 8/9] bfs: remove multiple assignments Dmitri Vorobiev
2008-01-28 7:02 ` Joel Schopp
2008-01-30 13:06 ` Al Viro
2008-01-30 13:36 ` Dmitri Vorobiev
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