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From: Arnaldo Carvalho de Melo <acme-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: jamal <hadi-fAAogVwAN2Kw5LPnMra/2Q@public.gmane.org>
Cc: dwarves-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: eat your own dog food?
Date: Thu, 10 Jan 2008 11:39:26 -0200
Message-ID: <20080110133926.GF22437@ghostprotocols.net> (raw)
In-Reply-To: <1199968968.4438.49.camel@localhost>

Em Thu, Jan 10, 2008 at 07:42:48AM -0500, jamal escreveu:
> 
> Hey Arnaldo,
> 
> You ever tasted what you are cooking?;->
> 
> ---
> hadi@lilsol:~/git-trees/arnaldo/jamal/build$ pahole ./pahole| grep XXX
>         /* XXX last struct has 1 byte of padding */
>         /* XXX 1 bit hole, try to pack */
>         /* XXX 1 byte hole, try to pack */
>         /* XXX 2 bytes hole, try to pack */
>         /* XXX 2 bits hole, try to pack */
>         /* XXX 1 byte hole, try to pack */
>         /* XXX last struct has 2 bytes of padding */
>         /* XXX 1 byte hole, try to pack */
> hadi@lilsol:~/git-trees/arnaldo/jamal/build$
> ---

:-) I'll check that later :-P But some holes are inevitable, the best
thing is to try:

[acme@doppio pahole]$ pahole --packable build/pahole
argp_child      32      24      8
argp_option     48      40      8
_IO_FILE        216     208     8
[acme@doppio pahole]$

Which is kinda interesting, huh? Only glibc stuff :-)

--packable means: run --reorganize in all structs and compare the result
with the original struct, if we have savings, tell us (original size,
reorganized size, savings).

> On a serious note, feature request:
> 
> I am trying to put words to what i am looking for and it's a little hard
> without providing a lot of boring context. For brevity, lets say i have
> an inherited 500K lines of code. Assume i compiled a program for 32-bit
> target and now i have to move it to a 128-bit playstation 3 with
> whatever strange alignment rules. 
> I want to do achieve 2 and a half things:
> 
> a) 
> i) check the structure for holes for X-bit access alignment where X is
> 16 (old 680xx), 64, 128. I want to do this without compiling the program
> for any of those targets i.e i want to do this on my x86 32-bit
> laptop ;-> i.e call this cross-pahole
> 
> ii) If i can do the above; i should then be able to say "optimize" (what
> you call --reorganize) for X-bit
> 
> b) I want to do a multiple of these example "optimize for 32-bit and
> 64-bit" or "check if it is safe for 128-bit and 16-bit alignemnt"
> 
> Note, clearly if i can make it read config files with rules for
> something like the MIPS EABI in the first part of this email:
>  http://sourceware.org/ml/binutils/2003-06/msg00436.html
> then i can say "check if it safe for mips 32 bit and x86_64" ;->
> And i can make sure my apps will run on that new cpu i dont have access
> to.
> 
> I could ask for more, but let me start/stop here incase you are going to
> lynch me;->

No need for lynching this time. What we have to do is:

. make the addr_size configurable and when the user specifies an
addr_size that is different than the one in the DWARF info being
processed, fixup it in all the data structures. The --reorganize code
already does many kinds of fixups, it would be one more.

. moreover, specify alignment rules, that way the reorganization code
would process all the structs, applying this rule.

IOW: its possible, should be fairly easy to implement the addr_size and
from that the alignment rules.

I'll try to work on the addr_size first, perhaps this weekend as I've
been promising to do way too many things in many fronts :-\

- Arnaldo
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Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-10 12:42 jamal
2008-01-10 13:39 ` Arnaldo Carvalho de Melo [this message]
     [not found]   ` <20080110133926.GF22437-f8uhVLnGfZaxAyOMLChx1axOck334EZe@public.gmane.org>
2008-01-10 13:55     ` jamal
2008-01-10 14:06       ` Arnaldo Carvalho de Melo
     [not found]         ` <20080110140635.GG22437-f8uhVLnGfZaxAyOMLChx1axOck334EZe@public.gmane.org>
2008-01-10 16:39           ` Arnaldo Carvalho de Melo
     [not found]             ` <20080110163959.GJ22437-f8uhVLnGfZaxAyOMLChx1axOck334EZe@public.gmane.org>
2008-01-10 21:37               ` jamal
2008-01-10 21:44                 ` Arnaldo Carvalho de Melo
     [not found]                   ` <20080110214438.GT22437-f8uhVLnGfZaxAyOMLChx1axOck334EZe@public.gmane.org>
2008-01-11  0:45                     ` jamal
2008-01-11  1:04                       ` jamal
2008-01-10 21:39               ` Arnaldo Carvalho de Melo
     [not found]                 ` <20080110213909.GS22437-f8uhVLnGfZaxAyOMLChx1axOck334EZe@public.gmane.org>
2008-01-10 21:41                   ` jamal
2008-01-12 15:21                     ` Arnaldo Carvalho de Melo
     [not found]                       ` <20080112152109.GA23567-f8uhVLnGfZaxAyOMLChx1axOck334EZe@public.gmane.org>
2008-01-12 15:54                         ` Changing the word-size was: " Arnaldo Carvalho de Melo
     [not found]                           ` <20080112155404.GB23567-f8uhVLnGfZaxAyOMLChx1axOck334EZe@public.gmane.org>
2008-01-12 16:28                             ` Arnaldo Carvalho de Melo
     [not found]                               ` <20080112162808.GC23567-f8uhVLnGfZaxAyOMLChx1axOck334EZe@public.gmane.org>
2008-01-12 17:28                                 ` Arnaldo Carvalho de Melo
     [not found]                                   ` <20080112172856.GD23567-f8uhVLnGfZaxAyOMLChx1axOck334EZe@public.gmane.org>
2008-01-12 18:08                                     ` jamal
2008-01-12 18:42                                       ` Arnaldo Carvalho de Melo
     [not found]                                         ` <20080112184211.GA17675-f8uhVLnGfZaxAyOMLChx1axOck334EZe@public.gmane.org>
2008-01-13  0:42                                           ` jamal
2008-01-13  1:15                                             ` jamal
     [not found]                                               ` <20080113163106.GE17675@ghostprotocols.net>
     [not found]                                                 ` <20080113163106.GE17675-f8uhVLnGfZaxAyOMLChx1axOck334EZe@public.gmane.org>
2008-01-13 18:07                                                   ` Arnaldo Carvalho de Melo
     [not found]                                                     ` <20080113180730.GG17675-f8uhVLnGfZaxAyOMLChx1axOck334EZe@public.gmane.org>
2008-01-13 18:19                                                       ` Arnaldo Carvalho de Melo
     [not found]                                                         ` <20080113181901.GH17675-f8uhVLnGfZaxAyOMLChx1axOck334EZe@public.gmane.org>
2008-01-13 18:26                                                           ` Arnaldo Carvalho de Melo
     [not found]                                                             ` <20080113182657.GI17675-f8uhVLnGfZaxAyOMLChx1axOck334EZe@public.gmane.org>
2008-01-13 19:13                                                               ` jamal
2008-01-12 21:36                                     ` Arnaldo Carvalho de Melo
     [not found]                                       ` <20080112213635.GC17675-f8uhVLnGfZaxAyOMLChx1axOck334EZe@public.gmane.org>
2008-01-12 22:08                                         ` Arnaldo Carvalho de Melo

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