[Bug bootstrap/63573] [5 Regression] libgo: ICE building libgo on powerpc-linux-gnu

["hubicka at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63573

--- Comment #18 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
OK, in the new testcase we produce thunk that is subsetquently inlined. 
Inlining does not drop from_thunk_p flag and thus the call is expanded as
in-thunk call, but after inlining of course the parameters no longer correspond
to the parameters of outer function - and this is what from_thunk_p flag
promises.

I think correct fix is to clear the flag:
Index: tree-inline.c
===================================================================
--- tree-inline.c       (revision 217307)
+++ tree-inline.c       (working copy)
@@ -1567,9 +1567,13 @@ remap_gimple_stmt (gimple stmt, copy_bod
       copy = gimple_copy (stmt);

       /* Clear flags that need revisiting.  */
-      if (is_gimple_call (copy)
-         && gimple_call_tail_p (copy))
-       gimple_call_set_tail (copy, false);
+      if (is_gimple_call (copy))
+       {
+         if (gimple_call_tail_p (copy))
+           gimple_call_set_tail (copy, false);
+         if (gimple_call_from_thunk_p (copy))
+           gimple_call_set_from_thunk (copy, false);
+       }

       /* Remap the region numbers for __builtin_eh_{pointer,filter},
         RESX and EH_DISPATCH.  */

Now however we have extra copies born in the inlined sequences. I wonder if
this is harmful (i.e. can it trigger for non-PODs that require copy
constructors?) and if we can avoid them (since they consume memory).

I think when inlining *into* the thunk call, the inliner should avoid producing
extra copies in setup_one_parameter, but it does not solve problem in question
where we are inlining the thunk.

I am testing the above patch.