[Bug debug/81936] ICE in dwarf2out_die_ref_for_decl, at dwarf2out.c:5543

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81936

--- Comment #9 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #8)
> but found it doesn't work because flag_generate_offload is actually false.
> 
> I'm now trying this (code snippet copied from symbol_table::compile), but
> I'm not sure if setting flag_generate_offload is the proper solution, and if
> so, where it should be inserted:
> ...
> diff --git a/gcc/cgraphunit.c b/gcc/cgraphunit.c
> index e8cc765095d..29a1d038b0e 100644
> --- a/gcc/cgraphunit.c
> +++ b/gcc/cgraphunit.c
> @@ -2586,6 +2586,10 @@ symbol_table::finalize_compilation_unit (void)
>    current_function_decl = NULL;
>    set_cfun (NULL);
>  
> +  /* Offloading requires LTO infrastructure.  */
> +  if (!in_lto_p && g->have_offload)
> +    flag_generate_offload = 1;
> +
>    /* Do not skip analyzing the functions if there were errors, we
>       miss diagnostics for following functions otherwise.  */
>  
> ...

That didn't work since g->have_offload is not set yet. Setting it after
analyze_functions does work:
...
diff --git a/gcc/cgraphunit.c b/gcc/cgraphunit.c
index e8cc765095d..080451a44df 100644
--- a/gcc/cgraphunit.c
+++ b/gcc/cgraphunit.c
@@ -2614,6 +2614,10 @@ symbol_table::finalize_compilation_unit (void)
   /* Gimplify and lower thunks.  */
   analyze_functions (/*first_time=*/false);

+  /* Offloading requires LTO infrastructure.  */
+  if (!in_lto_p && g->have_offload)
+    flag_generate_offload = 1;
+
   if (!seen_error ())
     {
       /* Emit early debug for reachable functions, and by consequence,
...

And then we run into the next ICE:
...
libgomp/testsuite/libgomp.c/pr66714.c:17:1: internal compiler error: in
output_loc_operands, at dwarf2out.c:2232
0x86f757 output_loc_operands
        gcc/dwarf2out.c:2232
0x86f757 output_loc_sequence(dw_loc_descr_node*, int)
        gcc/dwarf2out.c:2419
0x86ff61 output_die
        gcc/dwarf2out.c:10038
0x86fa0a output_die
        gcc/dwarf2out.c:10348
0x86fa0a output_die
        gcc/dwarf2out.c:10348
0x871118 output_comp_unit
        gcc/dwarf2out.c:10483
0x898408 dwarf2out_early_finish
        gcc/dwarf2out.c:30597
0x7fe3b8 symbol_table::finalize_compilation_unit()
        gcc/cgraphunit.c:2631
Please submit a full bug report,
...