On 19-06-14 05:53, Richard Henderson wrote:
Do we in fact make sure this isn't an ifunc resolver? I don't immediately see
how those get wired up in the cgraph...
Richard,
using the patch below I changed the
gcc/testsuite/gcc.target/i386/fuse-caller-save.c testcase to use an ifunc
resolver, and observed that the fuse-caller-save optimization didn't work.
The reason the optimization doesn't work in this case is that
default_binds_local_p_1 checks the ifunc attribute:
...
/* Weakrefs may not bind locally, even though the weakref itself is always
static and therefore local. Similarly, the resolver for ifunc functions
might resolve to a non-local function.
FIXME: We can resolve the weakref case more curefuly by looking at the
weakref alias. */
else if (lookup_attribute ("weakref", DECL_ATTRIBUTES (exp))
|| (TREE_CODE (exp) == FUNCTION_DECL
&& lookup_attribute ("ifunc", DECL_ATTRIBUTES (exp))))
local_p = false;
...
The default_binds_local_p_1 function is used via this path in the optimization:
get_call_reg_set_usage -> get_call_cgraph_rtl_info ->
decl_binds_to_current_def_p -> default_binds_local_p -> default_binds_local_p_1 .
Thanks,
- Tom
diff --git a/gcc/testsuite/gcc.target/i386/fuse-caller-save.c b/gcc/testsuite/gcc.target/i386/fuse-caller-save.c
index 4ec4995..012dc12 100644
--- a/gcc/testsuite/gcc.target/i386/fuse-caller-save.c
+++ b/gcc/testsuite/gcc.target/i386/fuse-caller-save.c
@@ -5,11 +5,18 @@
/* Testing -fuse-caller-save optimization option. */
static int __attribute__((noinline))
-bar (int x)
+my_bar (int x)
{
return x + 3;
}
+static void (*resolve_bar (void)) (void)
+{
+ return (void*) my_bar;
+}
+
+static int __attribute__((noinline)) __attribute__((ifunc ("resolve_bar"))) bar (int x);
+
int __attribute__((noinline))
foo (int y)
{
--
1.9.1
