Hi,
PR 55264 is caused by cgraph machinery thinking it knows all calls to
a virtual method when that is actually not true. As discussed with
Honza, prior to inlining, we should not assume some virtual functions
(namely those that are neither DECL_COMDAT nor DECL_EXTERNAL) are not
reachable.
DECL_EXTERNAL however still affects the cgraph_node->local.local flag
and so in order to avoid some LTO failures, I had to adjust IPA-CP to
consider such virtual functions non-local so that verification of
lattice propagation does not complain. I'm a bit puzzled by the value
of the flag in this situation but at least it does not seem to cause
any other problems.
Below is a trunk patch to do all this. It does not apply to released
versions which also suffer from the same problem so I'll prepare a
special version(s) for them once this gets approved. Bootstrapped and
tested on x86_64-linux. OK for trunk?
Thanks,
Martin
2013-01-15 Martin Jambor <mjam...@suse.cz>
PR tree-optimizations/55264
* ipa-inline-transform.c (can_remove_node_now_p_1): Never return true
for virtual methods.
* ipa.c (symtab_remove_unreachable_nodes): Never return true for
virtual methods before inlining is over.
* ipa-cp.c (initialize_node_lattices): Also consider all virtual
methods non-local.
testsuite/
* g++.dg/ipa/pr55264.C: New test.
Index: src/gcc/ipa-inline-transform.c
===================================================================
--- src.orig/gcc/ipa-inline-transform.c
+++ src/gcc/ipa-inline-transform.c
@@ -92,9 +92,7 @@ can_remove_node_now_p_1 (struct cgraph_n
those only after all devirtualizable virtual calls are processed.
Lacking may edges in callgraph we just preserve them post
inlining. */
- && (!DECL_VIRTUAL_P (node->symbol.decl)
- || (!DECL_COMDAT (node->symbol.decl)
- && !DECL_EXTERNAL (node->symbol.decl)))
+ && !DECL_VIRTUAL_P (node->symbol.decl)
/* During early inlining some unanalyzed cgraph nodes might be in the
callgraph and they might reffer the function in question. */
&& !cgraph_new_nodes);
Index: src/gcc/ipa.c
===================================================================
--- src.orig/gcc/ipa.c
+++ src/gcc/ipa.c
@@ -241,8 +241,7 @@ symtab_remove_unreachable_nodes (bool be
&& (!cgraph_can_remove_if_no_direct_calls_and_refs_p (node)
/* Keep around virtual functions for possible devirtualization. */
|| (before_inlining_p
- && DECL_VIRTUAL_P (node->symbol.decl)
- && (DECL_COMDAT (node->symbol.decl) || DECL_EXTERNAL
(node->symbol.decl)))))
+ && DECL_VIRTUAL_P (node->symbol.decl))))
{
gcc_assert (!node->global.inlined_to);
pointer_set_insert (reachable, node);
Index: src/gcc/testsuite/g++.dg/ipa/pr55264.C
===================================================================
--- /dev/null
+++ src/gcc/testsuite/g++.dg/ipa/pr55264.C
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-early-inlining -fno-weak" } */
+
+struct S
+{
+ S();
+ virtual inline void foo ()
+ {
+ foo();
+ }
+};
+
+void
+B ()
+{
+ S().foo ();
+}
Index: src/gcc/ipa-cp.c
===================================================================
--- src.orig/gcc/ipa-cp.c
+++ src/gcc/ipa-cp.c
@@ -699,7 +699,8 @@ initialize_node_lattices (struct cgraph_
int i;
gcc_checking_assert (cgraph_function_with_gimple_body_p (node));
- if (!node->local.local)
+ if (!node->local.local
+ || DECL_VIRTUAL_P (node->symbol.decl))
{
/* When cloning is allowed, we can assume that externally visible
functions are not called. We will compensate this by cloning
