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Re: [PATCH] Use __glibc_(un)likely instead __builtin_expect.
- From: OndÅej BÃlka <neleai at seznam dot cz>
- To: Namhyung Kim <namhyung at gmail dot com>
- Cc: Siddhesh Poyarekar <siddhesh at redhat dot com>, libc-alpha at sourceware dot org
- Date: Wed, 30 Oct 2013 14:12:45 +0100
- Subject: Re: [PATCH] Use __glibc_(un)likely instead __builtin_expect.
- Authentication-results: sourceware.org; auth=none
- References: <20131022220131 dot GA30971 at domone dot podge> <20131028071843 dot GH1633 at spoyarek dot pnq dot redhat dot com> <87vc0g7uvh dot fsf at sejong dot aot dot lge dot com>
On Tue, Oct 29, 2013 at 10:01:38AM +0900, Namhyung Kim wrote:
> Hello,
>
> On Mon, 28 Oct 2013 12:48:43 +0530, Siddhesh Poyarekar wrote:
> > On Wed, Oct 23, 2013 at 12:01:31AM +0200, OndÅej BÃlka wrote:
> >>
> >> Hi,
> >>
> >> Now I return to one of todo-list issues which is using glibc-likely/unlikely.
> >>
> >> First comes a easy case which can be expressed as following script.
> >>
> >> cat $1 | sed -e "s/if (__builtin_expect (\(.*\), 0))/if (__glibc_unlikely (\1))/" | sed -e "s/if (__builtin_expect (\(.*\), 1))/if (__glibc_likely (\1))/"
> >>
> >
> > Based on Roland's comment, I did some automated verification of the
> > patch. I found the following problems:
> >
> > 1. Changes in whitespace in macro definitions
> > 2. Changes in whitespace in malloc routines
> >
> > Could you fix these and repost?
>
> I can see following cases also:
>
> 1. if (__builtin_expect (XXX, 0) == 0)
>
> Shouldn't it look like below?
>
> if (__glibc_likely (XXX == 0))
>
>
> 2. if (__builtin_expect (YYY, 1) == 0)
>
> Likewise
>
> if (__glibc_unlikely (YYY == 0))
>
Could but it would come as separate patch.