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Re: [CHKP] Never expand instrumentation thunks


> 2015-04-03 0:13 GMT+03:00 Jan Hubicka <hubicka@ucw.cz>:
> >> On 04/02/2015 02:11 PM, Jan Hubicka wrote:
> >> >>>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;
> >> >
> >> >Yeah, this is another case where we hit problem with transparent alias pretending
> >> >to be thunk :)
> >> >I guess the patch is OK for GCC-5 and for next stage1 we can clean this up.
> >> I was actually building a compiler so I could take a look at this
> >> one under a debugger ;-)
> >
> > I think it is really the transparent alias issue.  The comment seems pretty clear about it.
> > What is confusing is that instrumentation thunks are called thunks when they are
> > really not - thunk is a small hunk of code, while instrumentation thunk is a transparent
> > alias.
> >
> > Too bad I did not notice we introduced transparent aliases, i would push out my
> > code for that. I will compare Ilya's changes with mine and hopefully we can
> > catch more bugs and unify the code next stage1.
> 
> Thunk was the best I could find to represent the same function but
> with different signature. It would be great to have a more specialized
> way for that.

Yeah, that is also what we need for https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61886
I just did not notice you are independently solving the same issue :(

Honza


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