Gentoo Archives: gentoo-amd64

From: Frank Peters <frank.peters@×××××××.net>
To: gentoo-amd64@l.g.o
Subject: Re: [gentoo-amd64] Ghostscript Problem - Need Verification [SOLVED]
Date: Tue, 14 Dec 2010 03:02:50
In Reply to: Re: [gentoo-amd64] Ghostscript Problem - Need Verification by malc
1 Well, the problem is solved and the solution may be of interest
2 to some Gentoo users.
4 At first I thought that I was in for some heavy debugging, but the
5 fault was a simple matter (simple at least superficially).
7 I have been using the latest gcc-4.5.1 for some time now and
8 I try to compile my system with all the newest optimizations, namely
9 the "-flto," "-floop-interchange," "-floop-strip-mine," and
10 "-floop-block" compiler flags which enables Graphite and LTO.
11 Usually I have no problems during an emerge but when I do the
12 temporary removal of the "-flto" option allows the emerge to finish.
13 So far there have been no issues with these flags.
15 Now, whenever a problem with software is encountered the first question
16 to ask is what has been changed on the system. In my case it most
17 likely was the use of these compiler flags. So, on a lark, I decided
18 to re-emerge ghostscript with a basic set of CFLAGS = -O2 -march=native.
19 It worked. The problem I was having with all black images has
20 disappeared and ghostscript functions normally.
22 However, I really cannot consider this to be normal behavior. Compiler
23 optimization should not degrade the function of a program. Something
24 subtle must be at fault with the gcc compiler. But being quite uninformed
25 about compiler design I cannot say much more.
27 Anyway, thanks again for all those who did the test. This confirmed
28 that the problem was not ghostscript per se but rather a strange effect
29 on the ghostscript code caused by the compiler optimization.
31 I can now see why the Gentoo deveolpers are being so cautious by considering
32 these latest GCC options as being experimental.
34 Frank Peters


Subject Author
Re: [gentoo-amd64] Ghostscript Problem - Need Verification [SOLVED] Barry Schwartz <chemoelectric@×××××××××××××.org>