[Bug c++/113347] [13 Regression] ICE during gimplification building TVM since r13-8079-gd237e7b291ff52

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113347

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2024-01-12
             Status|UNCONFIRMED                 |NEW
            Summary|[13 Regression] ICE during  |[13 Regression] ICE during
                   |gimplification building TVM |gimplification building TVM
                   |                            |since
                   |                            |r13-8079-gd237e7b291ff52
                 CC|                            |jason at gcc dot gnu.org

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
(gdb) p debug_tree (*expr_p)
 <modify_expr 0x7ffff6bd35c8
    type <boolean_type 0x7ffff6a2eb28 bool public unsigned type_6 QI
        size <integer_cst 0x7ffff6a300c0 constant 8>
        unit-size <integer_cst 0x7ffff6a300d8 constant 1>
        align:8 warn_if_not_align:0 symtab:0 alias-set -1 canonical-type
0x7ffff6a2eb28 precision:1 min <integer_cst 0x7ffff6a30318 0> max <integer_cst
0x7ffff6a30348 1>>
    side-effects readonly
    arg:1 <integer_cst 0x7ffff6a30318 type <boolean_type 0x7ffff6a2eb28 bool>
constant 0>>

so the LHS of the MODIFY_EXPR is NULL.  This is built by finalize_nrv_r:

      /* If a cleanup might throw, we need to clear current_retval_sentinel on
         the exception path so an outer cleanup added by
         maybe_splice_retval_cleanup doesn't run.  */
      if (cp_function_chain->throwing_cleanup) 
        {
          tree clear = build2 (MODIFY_EXPR, boolean_type_node,
                               current_retval_sentinel,
                               boolean_false_node);

          /* We're already only on the EH path, just prepend it.  */
          tree &exp = CLEANUP_EXPR (*tp);
          exp = build2 (COMPOUND_EXPR, void_type_node, clear, exp);

and current_retval_sentinel is NULL here.

Caused by the backport of PR112301, r13-8079-gd237e7b291ff52.