Re: [EXT] Re: Questions about initialization data during LTO

[Gary Oblock <goblock@marvell.com>]

On 9/14/19 8:39 AM, Martin Liška wrote:

On 9/13/19 3:01 PM, Gary Oblock wrote:


So, back to my questions, any ideas about how to get initialization
information? This
is going to be a very powerful optimization for code with structures of
arrays and
I just need a little help getting around a few obstacles in my path.



Sure. So I would point you to the IPA ICF pass, which makes merging
of variables in WPA phase of LTO. Let's take a look at:

ipa-icf.c:1839 (sem_variable::equals) where
we do:
   if (DECL_INITIAL (decl) == error_mark_node && in_lto_p)
     dyn_cast <varpool_node *>(node)->get_constructor ();

That's the way how load DECL_INITIAL of variables.
Does it help you?

Martin



So Martin, let me get this straight, all of the initialization information
can be fetched here? I ask this because I was under the impression that
some of it was deleted and could not be recovered. The worst case scenario
for my optimization (making it illegal) is if the user specified an initialization
and the initialization disappeared without leaving a trace in the IR that it ever
existed.

Many thanks,

Gary