[Pan-users] Re: Debugging Pan with gdb

[Duncan]

"Charles Kerr" <address@hidden> posted
address@hidden, excerpted
below, on  Tue, 22 Aug 2006 19:22:02 -0500:

> Duncan is absolutely right about -g, though I'd go further and recommend
> adding -ggdb3 to your CFLAGS before compiling glib/atk/pango/gtk/gmime.

Only to be fair it wasn't me but "walt" that suggested the -g.  I simply
addressed the -fomit-frame-pointer arch specific debugging thing, with the
consequent implications for -O optimization.  The -g stuff seemed a good
point which I agree with, but as I said, I don't claim to be either a
C/C++ coder or a debugging expert, so while I know enough to follow the
thread and comment about a particular option (-g or -fomit-frame-pointer)
after it is brought up, the -g suggestion didn't spontaneously occur to
me, and it was walt that mentioned it.

> Likewise I'd add -ggdb3 to your CXXFLAGS before compiling Pan. For Pan +
> gcc 4.x I use: % CXXFLAGS="-ggdb3 -Os -Wall" ./configure, and replace
> "-Os" with "-O" for older gcc's or when using valgrind.

Likewise, that looks entirely logical after I see it posted, but I don't
know enough about it to suggest it on my own. =8^(

The thing I find most interesting there however is the choice of -Os.  I
use that myself, over the more common -O2 or -O3, because it is my opinion
(after a bit of study) that modern CPUs tend to be cache size and memory
bandwidth limited more than clock cycle limited, so reducing size (-Os) to
better fit in cache is more efficient than optimizing for CPU cycles (-O3,
to a lessor extent -O2) at the expense of size.  It would seem you are of
a similar opinion. =8^)

Of course, as any good Gentooist, I could debate the merits of various
CFLAGS, and whether they are "ricer" choices or logical optimization
choices, until the cows come home. =8^)  

Case in point (warning, pretty hard core Gentoo-speak in the first couple
pages <g>), here's a 29KB pdf blubb, aka Simon Stelling, Gentoo/amd64
project op-lead, made of a multi-page post of mine. (FWIW I became aware
of it after someone pointed it out as a case of belaboring the obvious,
and I don't know exactly why blubb chose to PDF it but knowing him it
could well be a bit of fun at my expense, but I posted it and stand by
what I posted, in any case.  If I can't take a bit of fun at my expense, I
shouldn't be posting in a public forum, and despite all, I'm a bit proud
of it, or I'd certainly not be posting the link. =8^)

http://dev.gentoo.org/~blubb/duncan.pdf

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman