[PING][PATCH] Mark symbols in offload tables with force_output in read_offload_tables

[Ilya Verbin]

Hi!

On Tue, Jan 05, 2016 at 15:56:15 +0100, Tom de Vries wrote:
> >diff --git a/gcc/lto-cgraph.c b/gcc/lto-cgraph.c
> >index 62e5454..cdaee41 100644
> >--- a/gcc/lto-cgraph.c
> >+++ b/gcc/lto-cgraph.c
> >@@ -1911,6 +1911,11 @@ input_offload_tables (void)
> >  	      tree fn_decl
> >  		= lto_file_decl_data_get_fn_decl (file_data, decl_index);
> >  	      vec_safe_push (offload_funcs, fn_decl);
> >+
> >+	      /* Prevent IPA from removing fn_decl as unreachable, since there
> >+		 may be no refs from the parent function to child_fn in offload
> >+		 LTO mode.  */
> >+	      cgraph_node::get (fn_decl)->mark_force_output ();
> >  	    }
> >  	  else if (tag == LTO_symtab_variable)
> >  	    {
> >@@ -1918,6 +1923,10 @@ input_offload_tables (void)
> >  	      tree var_decl
> >  		= lto_file_decl_data_get_var_decl (file_data, decl_index);
> >  	      vec_safe_push (offload_vars, var_decl);
> >+
> >+	      /* Prevent IPA from removing var_decl as unused, since there
> >+		 may be no refs to var_decl in offload LTO mode.  */
> >+	      varpool_node::get (var_decl)->force_output = 1;
> >  	    }

This doesn't work when there is more than one LTO partition, because only first
partition contains full offload table to maintain correct order, but cgraph and
varpool nodes aren't necessarily created for the first partition.  To reproduce:

$ make check-target-libgomp RUNTESTFLAGS="c.exp=for-* --target_board=unix/-flto"
FAIL: libgomp.c/for-3.c (internal compiler error)
FAIL: libgomp.c/for-5.c (internal compiler error)
FAIL: libgomp.c/for-6.c (internal compiler error)
$ make check-target-libgomp RUNTESTFLAGS="c++.exp=for-* --target_board=unix/-flto"
FAIL: libgomp.c++/for-11.C (internal compiler error)
FAIL: libgomp.c++/for-13.C (internal compiler error)
FAIL: libgomp.c++/for-14.C (internal compiler error)

  -- Ilya