From: jamal <hadi-fAAogVwAN2Kw5LPnMra/2Q@public.gmane.org>
To: Arnaldo Carvalho de Melo <acme-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: dwarves-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: Changing the word-size was: Re: eat your own dog food?
Date: Sun, 13 Jan 2008 14:13:02 -0500 [thread overview]
Message-ID: <1200251582.4427.15.camel@localhost> (raw)
In-Reply-To: <20080113182657.GI17675-f8uhVLnGfZaxAyOMLChx1axOck334EZe@public.gmane.org>
On Sun, 2008-13-01 at 16:26 -0200, Arnaldo Carvalho de Melo wrote:
> > > >
> > > > Working on that, implementing type__most_aligned_member(), that will
> > > > recursively find the member that is most aligned, but then how to deal
> > > > with packed structs?
packed structs _always_ have alignment = 1 afaik.
> Looks OK:
I updated tree and recompiled - retested and all looks ok to me ....
> [acme@doppio examples]$ file align
> [acme@doppio examples]$ ../build/pahole align
> struct foo {
> char l; /* 0 1 */
>
> /* XXX 3 bytes hole, try to pack */
>
> struct {
> unsigned int b; /* 4 4 */
> struct {
> long unsigned int c; /* 8 4 */
> }; /* 8 4 */
> }; /* 4 8 */
> char a; /* 12 1 */
>
> /* size: 16, cachelines: 1 */
> /* sum members: 10, holes: 1, sum holes: 3 */
> /* padding: 3 */
> /* last cacheline: 16 bytes */
> };
>
> [acme@doppio examples]$ ../build/pahole -w8 align
> struct foo {
> char l; /* 0 1 */
>
> /* XXX 3 bytes hole, try to pack */
>
> struct {
> unsigned int b; /* 4 4 */
>
> /* XXX 4 bytes hole, try to pack */
>
> struct {
> long unsigned int c; /* 12 8 */
> }; /* 12 8 */
> }; /* 4 16 */
>
> /* Bitfield combined with next fields */
>
> char a; /* 16 1 */
>
> /* size: 24, cachelines: 1 */
> /* sum members: 14, holes: 1, sum holes: 3 */
> /* padding: 7 */
> /* last cacheline: 24 bytes */
> };
>
> But not when going from 32-bit to 64-bit, sigh :-\
> And there is another bug, the bitfield combining code got confused,
> because the offset for 'a' is not at 20 as it should even when not
> correctly aligning the outernmost unnamed struct.
got same results here. Other than that annoyance the results look
correct.
Note: So far what you have seems to work well (sans the little bug
above) for say x86 32<->64. The bizare part imo is the alignment
difference with different archs (eg -w 4 for ppc vs ia32 would result in
different holes/paddings).
Q: Wouldnt it be better to just build arrays/tables of all the rules as
per eabi? i.e you have a sizeof and alignment rows and then you can do
table lookup of arch/type where key could infact be a dwarf tag. What
that would mean is to have cli interface for --arch ppc32 or --arch
mips64 etc. If you do that, then allow users to also add new archs for
you.
> Will fix.
Ok, let me know.
cheers,
jamal
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next prev parent reply other threads:[~2008-01-13 19:13 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-10 12:42 eat your own dog food? jamal
2008-01-10 13:39 ` Arnaldo Carvalho de Melo
[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 [this message]
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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