[Bug ipa/106124] [11/12/13 Regression] ICE in dwarf2out_abstract_function, at dwarf2out.cc:23254

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106124

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org
   Last reconfirmed|                            |2023-03-27
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |ASSIGNED

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
We have

(gdb) p debug_tree (type)
 <record_type 0x7ffff64452a0 ._anon_1 asm_written cxx-odr-p type_5 QI
    size <integer_cst 0x7ffff628b0c0 type <integer_type 0x7ffff62890a8
bitsizetype> constant 8>
...

with TREE_ASM_WRITTEN but not a DIE recorded.  For this reason
gen_type_die_with_usage does nothing.

Earlier we created a DIE for the type but we pruned it as unused later via

#0  mark_removed (
    die=<dw_die_ref 0x7ffff645c4b0 DW_TAG_structure_type <parent=0x7ffff6296000
DW_TAG_compile_unit>>) at /home/rguenther/src/trunk/gcc/dwarf2out.cc:30245
#1  0x00000000013c291a in prune_unused_types_prune (
    die=<dw_die_ref 0x7ffff6296000 DW_TAG_compile_unit>)
    at /home/rguenther/src/trunk/gcc/dwarf2out.cc:30278
#2  0x00000000013c2c21 in prune_unused_types ()
    at /home/rguenther/src/trunk/gcc/dwarf2out.cc:30363
#3  0x00000000013c8cdb in dwarf2out_early_finish (filename=0x45b83a0 "t.ii")
    at /home/rguenther/src/trunk/gcc/dwarf2out.cc:32997

we can possibly "fix" that failure to re-create the DIE late by making
sure to also clear TREE_ASM_WRITTEN on it.

Of course the question is why we have no early DIE for the function

 <function_decl 0x7ffff6444b00 _FUN
    type <function_type 0x7ffff629e0a8
...
    full-name "static constexpr int A::omp declare reduction
x~i(T&)::<lambda()>::_FUN()"

I suppose that's the OMP reduction function and that's always(?) inlined?

The following fixes the ICE, but as said I wonder why nothing creates a
DIE for the function early?

I'm going to test this and propose it still.

diff --git a/gcc/dwarf2out.cc b/gcc/dwarf2out.cc
index 1711ad2c2da..1a0015ce00f 100644
--- a/gcc/dwarf2out.cc
+++ b/gcc/dwarf2out.cc
@@ -5894,6 +5894,7 @@ lookup_type_die (tree type)
   if (die && die->removed)
     {
       TYPE_SYMTAB_DIE (type) = NULL;
+      TREE_ASM_WRITTEN (type) = 0;
       return NULL;
     }
   return die;