https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63892
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |hubicka at gcc dot gnu.org
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
So, during ICF we don't create alias because
sem_item::target_supports_symbol_aliases_p () tells us not to.
But I really don't see a reason why we couldn't try to redirect_callers in this
case, both original and alias are local functions without address taken.
There is another case that worries me - if the above mentioned function returns
false, we set create_thunk even for stdarg_p functions.
So, I think we should do something like:
--- gcc/ipa-icf.c.jj 2015-02-19 12:52:33.000000000 +0100
+++ gcc/ipa-icf.c 2015-02-20 10:06:04.532637240 +0100
@@ -651,7 +651,9 @@ sem_function::merge (sem_item *alias_ite
section (or we risk link failures when section is discarded). */
if ((original_address_matters
&& alias_address_matters)
- || original_discardable)
+ || original_discardable
+ || DECL_COMDAT_GROUP (alias->decl)
+ || !sem_item::target_supports_symbol_aliases_p ())
{
create_thunk = !stdarg_p (TREE_TYPE (alias->decl));
create_alias = false;
@@ -659,6 +661,7 @@ sem_function::merge (sem_item *alias_ite
the extra thunk wrapper for direct calls. */
redirect_callers
= (!original_discardable
+ && !DECL_COMDAT_GROUP (alias->decl)
&& alias->get_availability () > AVAIL_INTERPOSABLE
&& original->get_availability () > AVAIL_INTERPOSABLE
&& !alias->instrumented_version);
@@ -670,13 +673,6 @@ sem_function::merge (sem_item *alias_ite
redirect_callers = false;
}
- if (create_alias && (DECL_COMDAT_GROUP (alias->decl)
- || !sem_item::target_supports_symbol_aliases_p ()))
- {
- create_alias = false;
- create_thunk = true;
- }
-
/* We want thunk to always jump to the local function body
unless the body is comdat and may be optimized out. */
if ((create_thunk || redirect_callers)
Unfortunately this ICEs on the testcase in question, when we reach:
725 /* The alias function is removed if symbol address
726 does not matter. */
727 if (!alias_address_matters)
728 alias->remove ();
because in
1645 void
1646 sem_item_optimizer::remove_symtab_node (symtab_node *node)
1647 {
1648 gcc_assert (!m_classes.elements());
1649
1650 m_removed_items_set.add (node);
1651 }
called during the alias->remove ()
m_classes.elements() is 3. I'm not familiar with that code, Martin/Honza, can
you please have a look?
And, another thing, not analyzed fully, is that when we create a thunk to the
local calling convention function and the thunk isn't visible either, the
question is why it doesn't use the same calling convention (i.e. local again).
Last thing, I believe we should change the testcase anyway, either use
-fno-ipa-icf or add say some volatile int v; v++;
into one of the functions, so that sibcall-3.c tests what it originally meant
to test. With ICF it can be turned into a tail recursion test, while clearly
originally it was meant to be a tail call test.
We can certainly copy the current testcase into a new one...
