Re: Fix partitioning of aliases
On Mon, Apr 9, 2012 at 12:18 PM, Jan Hubicka hubi...@ucw.cz wrote: Hi, this patch fixes several different ICEs related to handling aliases in WHOPR partitioning. It took me over week debug this, but when variable alias is added to a boundary and its destination is not added, we get queue of unforutnate events where the destinatoin gets analyzed and added at ltrans time resulting in interesting miscompilation seen at Mozilla with some vtables. The problem is that constructor won't get streamed when the declaration is not in varpool at partitioning time and thus once the variable is re-added it has zero constructor. Of course the problem manifests itself in various weird ways depending on ordering of linker command maing it very difficult to reduce anything. While working on this I also noticed that PR 52634 is about related problem where aliases are incorectly partitioned into multiple partitions. The patch also fixes the varpool ICEs mentioned in the other two PRs. I failed to produce testcase version of PR52722 testcase, since it does not link now either, but it won't ICE. I will commit the patch and wait for some time, but I would like to backport it to 4.7, since it solves quite nasty misoptimization problem. At mainline after this patch i would like to follow with series of cleanups and API changes I have in queue for symtab work. Honza PR lto/52722 PR lto/51765 PR lto/52634 * lto-cgraph.c (compute_ltrans_boundary): When alias is in the boundary, add its target too. * lto.c (add_references_to_partition): Add also aliased nodes. (add_cgraph_node_to_partition, add_varpool_node_to_partition): Work on nodes, not functions/variables; when adding alias, add also the aliased object. * gcc.dg/lto/pr52634_1.c: New testcase. * gcc.dg/lto/pr52634_0.c: New testcase. Hi Jan, Can you backport it to 4.7? It also fixes: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53768 Thanks. -- H.J.
Re: Fix partitioning of aliases
On Mon, 9 Apr 2012, Jan Hubicka wrote:
Hi,
this patch fixes several different ICEs related to handling aliases in WHOPR
partitioning. It took me over week debug this, but when variable alias
is added to a boundary and its destination is not added, we get queue of
unforutnate events where the destinatoin gets analyzed and added at ltrans
time
resulting in interesting miscompilation seen at Mozilla with some vtables.
The problem is that constructor won't get streamed when the declaration is
not in varpool at partitioning time and thus once the variable is re-added
it has zero constructor.
Of course the problem manifests itself in various weird ways depending
on ordering of linker command maing it very difficult to reduce anything.
While working on this I also noticed that PR 52634 is about related problem
where aliases are incorectly partitioned into multiple partitions.
The patch also fixes the varpool ICEs mentioned in the other two PRs.
I failed to produce testcase version of PR52722 testcase, since it does not
link now either, but it won't ICE.
I will commit the patch and wait for some time, but I would like to backport
it to 4.7, since it solves quite nasty misoptimization problem.
Yeah, it looks fine to me.
At mainline after this patch i would like to follow with series of cleanups
and API changes I have in queue for symtab work.
Thanks,
Richard.
Honza
PR lto/52722
PR lto/51765
PR lto/52634
* lto-cgraph.c (compute_ltrans_boundary): When alias is in the boundary,
add its target too.
* lto.c (add_references_to_partition): Add also aliased nodes.
(add_cgraph_node_to_partition,
add_varpool_node_to_partition): Work on nodes, not functions/variables;
when adding alias, add also the aliased object.
* gcc.dg/lto/pr52634_1.c: New testcase.
* gcc.dg/lto/pr52634_0.c: New testcase.
Index: lto-cgraph.c
===
*** lto-cgraph.c (revision 185767)
--- lto-cgraph.c (working copy)
*** compute_ltrans_boundary (struct lto_out_
*** 799,804
--- 799,806
lto_set_varpool_encoder_encode_initializer (varpool_encoder, vnode);
add_references (encoder, varpool_encoder, vnode-ref_list);
}
+ else if (vnode-alias || vnode-alias_of)
+ add_references (encoder, varpool_encoder, vnode-ref_list);
}
/* Go over all the nodes again to include callees that are not in
Index: lto/lto.c
===
*** lto/lto.c (revision 185767)
--- lto/lto.c (working copy)
*** free_ltrans_partitions (void)
*** 1444,1450
VEC_free (ltrans_partition, heap, ltrans_partitions);
}
! /* See all references that go to comdat objects and bring them into
partition too. */
static void
add_references_to_partition (ltrans_partition part, struct ipa_ref_list
*refs)
{
--- 1444,1451
VEC_free (ltrans_partition, heap, ltrans_partitions);
}
! /* See all references that go to comdat objects and bring them into
partition too.
!Also see all aliases of the newly added entry and bring them, too. */
static void
add_references_to_partition (ltrans_partition part, struct ipa_ref_list
*refs)
{
*** add_references_to_partition (ltrans_part
*** 1453,1467
for (i = 0; ipa_ref_list_reference_iterate (refs, i, ref); i++)
{
if (ref-refered_type == IPA_REF_CGRAPH
!DECL_COMDAT (cgraph_function_node (ipa_ref_node (ref), NULL)-decl)
!cgraph_node_in_set_p (ipa_ref_node (ref), part-cgraph_set))
add_cgraph_node_to_partition (part, ipa_ref_node (ref));
else
if (ref-refered_type == IPA_REF_VARPOOL
! DECL_COMDAT (ipa_ref_varpool_node (ref)-decl)
! !varpool_node_in_set_p (ipa_ref_varpool_node (ref),
part-varpool_set))
add_varpool_node_to_partition (part, ipa_ref_varpool_node (ref));
}
}
/* Worker for add_cgraph_node_to_partition. */
--- 1454,1498
for (i = 0; ipa_ref_list_reference_iterate (refs, i, ref); i++)
{
if (ref-refered_type == IPA_REF_CGRAPH
!(DECL_COMDAT (cgraph_function_node (ipa_ref_node (ref),
!NULL)-decl)
! || (ref-use == IPA_REF_ALIAS
!lookup_attribute
!(weakref, DECL_ATTRIBUTES (ipa_ref_node (ref)-decl
!cgraph_node_in_set_p (ipa_ref_node (ref), part-cgraph_set))
add_cgraph_node_to_partition (part, ipa_ref_node (ref));
else
if (ref-refered_type == IPA_REF_VARPOOL
! (DECL_COMDAT (ipa_ref_varpool_node (ref)-decl)
! || (ref-use == IPA_REF_ALIAS
! lookup_attribute
! (weakref,
! DECL_ATTRIBUTES (ipa_ref_varpool_node (ref)-decl
!
Fix partitioning of aliases
Hi,
this patch fixes several different ICEs related to handling aliases in WHOPR
partitioning. It took me over week debug this, but when variable alias
is added to a boundary and its destination is not added, we get queue of
unforutnate events where the destinatoin gets analyzed and added at ltrans time
resulting in interesting miscompilation seen at Mozilla with some vtables.
The problem is that constructor won't get streamed when the declaration is
not in varpool at partitioning time and thus once the variable is re-added
it has zero constructor.
Of course the problem manifests itself in various weird ways depending
on ordering of linker command maing it very difficult to reduce anything.
While working on this I also noticed that PR 52634 is about related problem
where aliases are incorectly partitioned into multiple partitions.
The patch also fixes the varpool ICEs mentioned in the other two PRs.
I failed to produce testcase version of PR52722 testcase, since it does not
link now either, but it won't ICE.
I will commit the patch and wait for some time, but I would like to backport
it to 4.7, since it solves quite nasty misoptimization problem.
At mainline after this patch i would like to follow with series of cleanups
and API changes I have in queue for symtab work.
Honza
PR lto/52722
PR lto/51765
PR lto/52634
* lto-cgraph.c (compute_ltrans_boundary): When alias is in the boundary,
add its target too.
* lto.c (add_references_to_partition): Add also aliased nodes.
(add_cgraph_node_to_partition,
add_varpool_node_to_partition): Work on nodes, not functions/variables;
when adding alias, add also the aliased object.
* gcc.dg/lto/pr52634_1.c: New testcase.
* gcc.dg/lto/pr52634_0.c: New testcase.
Index: lto-cgraph.c
===
*** lto-cgraph.c(revision 185767)
--- lto-cgraph.c(working copy)
*** compute_ltrans_boundary (struct lto_out_
*** 799,804
--- 799,806
lto_set_varpool_encoder_encode_initializer (varpool_encoder, vnode);
add_references (encoder, varpool_encoder, vnode-ref_list);
}
+ else if (vnode-alias || vnode-alias_of)
+ add_references (encoder, varpool_encoder, vnode-ref_list);
}
/* Go over all the nodes again to include callees that are not in
Index: lto/lto.c
===
*** lto/lto.c (revision 185767)
--- lto/lto.c (working copy)
*** free_ltrans_partitions (void)
*** 1444,1450
VEC_free (ltrans_partition, heap, ltrans_partitions);
}
! /* See all references that go to comdat objects and bring them into partition
too. */
static void
add_references_to_partition (ltrans_partition part, struct ipa_ref_list *refs)
{
--- 1444,1451
VEC_free (ltrans_partition, heap, ltrans_partitions);
}
! /* See all references that go to comdat objects and bring them into partition
too.
!Also see all aliases of the newly added entry and bring them, too. */
static void
add_references_to_partition (ltrans_partition part, struct ipa_ref_list *refs)
{
*** add_references_to_partition (ltrans_part
*** 1453,1467
for (i = 0; ipa_ref_list_reference_iterate (refs, i, ref); i++)
{
if (ref-refered_type == IPA_REF_CGRAPH
! DECL_COMDAT (cgraph_function_node (ipa_ref_node (ref), NULL)-decl)
!cgraph_node_in_set_p (ipa_ref_node (ref), part-cgraph_set))
add_cgraph_node_to_partition (part, ipa_ref_node (ref));
else
if (ref-refered_type == IPA_REF_VARPOOL
!DECL_COMDAT (ipa_ref_varpool_node (ref)-decl)
!!varpool_node_in_set_p (ipa_ref_varpool_node (ref),
part-varpool_set))
add_varpool_node_to_partition (part, ipa_ref_varpool_node (ref));
}
}
/* Worker for add_cgraph_node_to_partition. */
--- 1454,1498
for (i = 0; ipa_ref_list_reference_iterate (refs, i, ref); i++)
{
if (ref-refered_type == IPA_REF_CGRAPH
! (DECL_COMDAT (cgraph_function_node (ipa_ref_node (ref),
! NULL)-decl)
! || (ref-use == IPA_REF_ALIAS
! lookup_attribute
! (weakref, DECL_ATTRIBUTES (ipa_ref_node (ref)-decl
!cgraph_node_in_set_p (ipa_ref_node (ref), part-cgraph_set))
add_cgraph_node_to_partition (part, ipa_ref_node (ref));
else
if (ref-refered_type == IPA_REF_VARPOOL
!(DECL_COMDAT (ipa_ref_varpool_node (ref)-decl)
! || (ref-use == IPA_REF_ALIAS
!lookup_attribute
!(weakref,
! DECL_ATTRIBUTES (ipa_ref_varpool_node (ref)-decl
!!varpool_node_in_set_p (ipa_ref_varpool_node (ref),
! part-varpool_set))
