https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63671
--- Comment #5 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
There is also code size differnce. I tried to track it down and with
-fno-devirtualize I need to disable all places devirtualization happens:
Index: gimple-fold.c
===================================================================
--- gimple-fold.c (revision 217304)
+++ gimple-fold.c (working copy)
@@ -331,7 +331,7 @@ fold_gimple_assign (gimple_stmt_iterator
tree val = OBJ_TYPE_REF_EXPR (rhs);
if (is_gimple_min_invariant (val))
return val;
- else if (flag_devirtualize && virtual_method_call_p (rhs))
+ else if (flag_devirtualize && virtual_method_call_p (rhs) && 0)
{
bool final;
vec <cgraph_node *>targets
@@ -2633,7 +2633,7 @@ gimple_fold_call (gimple_stmt_iterator *
gimple_call_set_fn (stmt, OBJ_TYPE_REF_EXPR (callee));
changed = true;
}
- else if (flag_devirtualize && !inplace && virtual_method_call_p
(callee))
+ else if (flag_devirtualize && !inplace && virtual_method_call_p (callee)
&& 0)
{
bool final;
vec <cgraph_node *>targets
Index: ipa.c
===================================================================
--- ipa.c (revision 217304)
+++ ipa.c (working copy)
@@ -198,7 +198,7 @@ walk_polymorphic_call_targets (hash_set<
final or anonymous (so we know all its derivation)
and there is only one possible virtual call target,
make the edge direct. */
- if (final)
+ if (final && 0)
{
if (targets.length () <= 1 && dbg_cnt (devirt))
{
Index: tree-ssa-pre.c
===================================================================
--- tree-ssa-pre.c (revision 217304)
+++ tree-ssa-pre.c (working copy)
@@ -4320,7 +4320,7 @@ eliminate_dom_walker::before_dom_childre
{
tree fn = gimple_call_fn (stmt);
if (fn
- && flag_devirtualize
+ && flag_devirtualize && 0
&& virtual_method_call_p (fn))
{
tree otr_type = obj_type_ref_class (fn);
So apparently it is not the unit growth nor reachability code. It is simply
presence of direct calls instead of polymorphic calls that seems to make
inliner to do bad decisions...
