Gentoo Archives: gentoo-dev

From: "C. Bergström" <cbergstrom@×××××××××.com>
To: gentoo-dev@l.g.o
Cc: Alex Xu <alex_y_xu@×××××.ca>
Subject: Re: [gentoo-dev] Re: LTO use in the tree
Date: Sun, 27 Apr 2014 02:38:34
Message-Id: 535C6D64.3030200@pathscale.com
In Reply to: Re: [gentoo-dev] Re: LTO use in the tree by Alex Xu
1 On 04/27/14 09:14 AM, Alex Xu wrote:
2 > On 26/04/14 08:34 PM, "C. Bergström" wrote:
3 >> Pragmatically nobody gives a f* if grep has been optimized to the max
4 >> since it's usually not the bottleneck.
5 > http://lists.freebsd.org/pipermail/freebsd-current/2010-August/019310.html
6 My point about grep + LTO still stands
7
8 #1 This isn't gentoo FreeBSD so it's probably irrelevant from the start
9 - (the comparison is gnu vs bsd grep. Further - LTO won't save your butt
10 from poor programming practices or magically turn things into efficient
11 syscalls)
12
13 #2 The only reference to anything which the compiler could impact is
14 "Use Boyer-Moore (and unroll its inner loop a few times)." Finding out
15 which flag controls that for ${CC} would have some importance. It's
16 almost certainly combined with -O3 and or some standalone loop related
17 optimization. (Nothing depending on LTO). If they were really clever or
18 determined - there's probably a few GCC or other pragma which could
19 give a hint about unrolling.
20 -----------
21 The color of my bikeshed is __________________

Replies

Subject Author
Re: [gentoo-dev] Re: LTO use in the tree Rich Freeman <rich0@g.o>