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Re: debugging info considered harmful to lto.
- From: Daniel Jacobowitz <dan at debian dot org>
- To: Jan Hubicka <jh at suse dot cz>
- Cc: Kenneth Zadeck <zadeck at naturalbridge dot com>, gcc <gcc at gcc dot gnu dot org>, Ian Lance Taylor <iant at google dot com>, "Park, Seongbae" <seongbae dot park at gmail dot com>, Mark Mitchell <mark at codesourcery dot com>, jason at redhat dot com, "Berlin, Daniel" <dberlin at dberlin dot org>
- Date: Mon, 23 Jul 2007 13:50:50 -0400
- Subject: Re: debugging info considered harmful to lto.
- References: <46A3EA47.firstname.lastname@example.org> <20070723173346.GR1758@kam.mff.cuni.cz>
On Mon, Jul 23, 2007 at 07:33:46PM +0200, Jan Hubicka wrote:
> The particular problem here is that the abstract origin pointers points
> to the blocks within functions they was constructed from. These are used
> by dwarf2out to output abstract copy of the function and then use it
> as a destination of origin pointers from every copy of the function.
> (I am not sure what the block origins are neede for by GDB, explanation
> would be welcome)
It's mostly supposed to be a space optimization. We get e.g. the
names and (sometimes) types of local variables from the origin copy,
and only need a location at each inlining site. I'm sure there are
other things we could do with this information, that rely on knowing
what variables are the same from the user's point of view.