[CHKP] Never expand instrumentation thunks

[Ilya Enkovich]

Hi,

This patch disables attempts to expand instrumentation thunks which appear when we create specialized function versions.  Problem was found during SPEC2006 insatrumentation with '-Ofast -flto'.  Unfortunately I couldn't make a small reproducer.  Bootstrapped and tested on x86_64-unknown-linux-gnu.  OK for trunk?

Thanks,
Ilya
--
2015-03-18  Ilya Enkovich  <ilya.enkovich@intel.com>

	* cgraphunit.c (cgraph_node::expand_thunk): Don't expand
	instrumentation thunks.


diff --git a/gcc/cgraphunit.c b/gcc/cgraphunit.c
index e640907..abc9cfe 100644
--- a/gcc/cgraphunit.c
+++ b/gcc/cgraphunit.c
@@ -1508,6 +1508,10 @@ cgraph_node::expand_thunk (bool output_asm_thunks, bool force_gimple_thunk)
   tree thunk_fndecl = decl;
   tree a;
 
+  /* Instrumentation thunk is the same function with
+     a different signature.  Never need to expand it.  */
+  if (thunk.add_pointer_bounds_args)
+    return false;
 
   if (!force_gimple_thunk && this_adjusting
       && targetm.asm_out.can_output_mi_thunk (thunk_fndecl, fixed_offset,