[U-Boot] analyze/change assembly code
Albert ARIBAUD
albert.u.boot at aribaud.net
Sat Nov 10 12:25:22 CET 2012
Hi Gerlando,
On Tue, 30 Oct 2012 12:08:01 +0100, Gerlando Falauto
<gerlando.falauto at keymile.com> wrote:
> Hi all,
>
> we recently to had face some nasty issues, where for some reason two
> (functionally identical) versions of some code behave very differently.
> Namely, one version works and the other doesn't always work.
> It was clear from the beginning this was because of HW- (or compiler-)
> related issues.
> I thought it would then be useful to have a peek at what the compiler is
> doing behind the scenes, and possibly make some simple changes to the
> code. For instance, inserting some nops here and there, or reordering
> some instructions, may help in tracking down these different behaviors.
>
> I know the easiest way to LOOK at the file is simply to use objdump to
> disassemble an .o file. In the end I somehow managed to tamper with the
> makefiles so to get what I wanted for a given file, by adding a fake new
> ".s" target with the recipe to build it, and having the .o file depend
> on a ".S" file (which would be a manual/changed copy of the generated
> ".s" file) instead of the original ".c" file.
> This is however not linear and nice at all. So I was wondering whether
> there already is a well-established way of having the make process
> create (and keep) assembly files which can be then manually changed.
>
> Does my question make any sense at all? Any ideas?
Add -save-temps to the gcc arguments? Watch out for parallel build
issues, though.
Amicalement,
--
Albert.
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