| Message ID | 53A2A1B7.1060209@mentor.com |
|---|---|
| State | New |
| Headers | show |
On 06/19/2014 01:39 AM, Tom de Vries wrote: > 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 . Excellent. Thanks for doing the digging I was too lazy to finish last night. r~
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