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Re: [PATCH] Combine location with block using block_locations
- From: Jan Hubicka <hubicka at ucw dot cz>
- To: Michael Matz <matz at suse dot de>, Richard Guenther <richard dot guenther at gmail dot com>, Dehao Chen <dehao at google dot com>, Diego Novillo <dnovillo at google dot com>, Dodji Seketeli <dodji at redhat dot com>, gcc-patches at gcc dot gnu dot org, Jakub Jelinek <jakub at redhat dot com>, Jan Hubicka <hubicka at ucw dot cz>, David Li <davidxl at google dot com>, Tom Tromey <tromey at redhat dot com>, Jason Merrill <jason at redhat dot com>, Richard Henderson <rth at redhat dot com>
- Date: Thu, 13 Sep 2012 12:04:46 +0200
- Subject: Re: [PATCH] Combine location with block using block_locations
- References: <alpine.LNX.2.00.1209111500200.9940@wotan.suse.de> <CAFiYyc0vM+LZJ_6MRFud9c1LhyFsu2jf-E38FuDryoMo5G7iYw@mail.gmail.com> <CAO2gOZV8SP-sOVEJBEsvF+M3yiKwtw7yWarfhZ1xeCVYjE_7KA@mail.gmail.com> <alpine.LNX.2.00.1209111728160.9940@wotan.suse.de> <CAFiYyc2zQZwnGKtSxq5VGgQkN1TpSobwq9wt8GiwtwHKoWuOyA@mail.gmail.com> <alpine.LNX.2.00.1209121411120.9940@wotan.suse.de> <CAFiYyc0gqxhKPC_n+sT2U6GY-_uCFiRduvmsuJnp+JTjVip-tQ@mail.gmail.com> <alpine.LNX.2.00.1209121523200.9940@wotan.suse.de> <alpine.LNX.2.00.1209121612000.9940@wotan.suse.de> <20120912143737.GA8585@virgil.arch.suse.de>
> Hi,
>
> On Wed, Sep 12, 2012 at 04:17:45PM +0200, Michael Matz wrote:
> > Hi,
> >
> > On Wed, 12 Sep 2012, Michael Matz wrote:
> >
> > > > Hm, but we shouldn't end up streaming any BLOCKs at this point (nor
> > > > local TYPE_DECLs). Those are supposed to be in the local function
> > > > sections only where no fixup for prevailing decls happens.
> > >
> > > That's true, something is fishy with the patch, will try to investigate.
> >
> > ipa-prop creates the problem. Its tree mapping can contain expressions,
> > expressions can have locations, locations now have blocks. The tree maps
> > are stored as part of jump functions, and hence as part of node summaries.
> > Node summaries are global, hence blocks, and therefore block vars can be
> > placed in the global blob.
> >
> > That's not supposed to happen. The patch below fixes this instance of the
> > problem and makes the testcase work with Dehaos patch with the
> > LTO_NO_PREVAIL call added back in.
> >
> >
> > Ciao,
> > Michael.
> > ------------
> > Index: lto-cgraph.c
> > ===================================================================
> > --- lto-cgraph.c (revision 190803)
> > +++ lto-cgraph.c (working copy)
> > @@ -1373,6 +1373,7 @@ output_node_opt_summary (struct output_b
> > mechanism to store function local declarations into summaries. */
> > gcc_assert (parm);
> > streamer_write_uhwi (ob, parm_num);
> > + gcc_assert (IS_UNKNOWN_LOCATION (EXPR_LOCATION (map->new_tree)));
> > stream_write_tree (ob, map->new_tree, true);
> > bp = bitpack_create (ob->main_stream);
> > bp_pack_value (&bp, map->replace_p, 1);
> > Index: ipa-prop.c
> > ===================================================================
> > --- ipa-prop.c (revision 190803)
> > +++ ipa-prop.c (working copy)
> > @@ -1378,7 +1378,11 @@ ipa_compute_jump_functions_for_edge (str
> > tree arg = gimple_call_arg (call, n);
> >
> > if (is_gimple_ip_invariant (arg))
> > - ipa_set_jf_constant (jfunc, arg);
> > + {
> > + arg = unshare_expr (arg);
> > + SET_EXPR_LOCATION (arg, UNKNOWN_LOCATION);
> > + ipa_set_jf_constant (jfunc, arg);
> > + }
> > else if (!is_gimple_reg_type (TREE_TYPE (arg))
> > && TREE_CODE (arg) == PARM_DECL)
>
> Perhaps it would be better if ipa_set_jf_constant did that, just in
> case we ever add another caller? Note that arithmetic functions also
> have their second operand tree stored in them and so perhaps
> ipa_set_jf_arith_pass_through should do the same.
>
> And I it is also necessary to do the same thing at the end of
> determine_known_aggregate_parts, i.e. before assignment to
> item->value. I can post a separate patch if necessary.
Yes, this seem resonable thing to do. Patchees for this are preapproved.
>
> I wasn't following this thread but I hope that streaming types does
> not cause this problem. If they do, there are quite a few in various
> jump functions and indirect call graph edges.
We probably ought to ban streaming in BLOCK_DECL and other beasts that are
not expected at WPA stage.
Concerning Richi's suggestion to move jump functions completely away from
trees, I am really not 100% sure how good idea it is in long term. As IPA
analysis are getting more accurate we will stream more and more expressions. I
am not convinced it makes sense to reinvent way of representing them rather
than fixing what we have.
Honza