[PATCH] Fix PR66705

Jan Hubicka hubicka@ucw.cz
Wed Sep 2 14:23:00 GMT 2015


> On Wed, 2 Sep 2015, Richard Biener wrote:
> 
> > On Wed, 2 Sep 2015, Jan Hubicka wrote:
> > 
> > > > 
> > > > I was naiively using ->get_constructor in IPA PTA without proper
> > > > checking on wheter that succeeds.  Now I tried to use ctor_for_folding
> > > > but that isn't good as we want to analyze non-const globals in IPA
> > > > PTA and we need to analyze their initialiers as well.
> > > > 
> > > > Thus I'm trying below with ctor_for_analysis, but I really "just"
> > > > need the initializer or a "not available" for conservative handling.
> > > > 
> > > > Bootstrapped and tested on x86_64-unknown-linux-gnu.
> > > > 
> > > > Honza - I suppose you should doble-check this and suggest sth
> > > > different (or implement sth more generic in the IPA infrastructure).
> > > 
> > > Yep, you are correct that we don't currently have way to look into ctor
> > > without actually loading. But do you need something more than just walking
> > > references that you already have in ipa-ref lists?
> > 
> > Hmm, no, ipa-ref list should be enough (unless we start field-sensitive
> > analysis or need NULL inits for correctness).  Still have to figure out
> > how to walk the list and how the reference would look like (what
> > is ref->use?  IPA_REF_ADDR?  can those be speculative?)
> 
> Sth like the following seems to work.

Yep, it looks good to me. Do you conservatively handle constructors that are in other units?
Those won't have ipa-ref lists streamed to ltrans stage.  I suppose you do not care because
all references in them can be supplied by foreign code, so you need to be conservative anyway.

Honza



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