[Bug bootstrap/83396] [8 Regression] Bootstrap failures with Statement Frontiers

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83396

--- Comment #38 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
So a CODE_LABEL with NULL BLOCK_FOR_INSN?  Ugh, that sounds broken.
In the patch a workaround is of course easy, just replace:
+                 if (BB_HEAD (BLOCK_FOR_INSN (last_label)) == last_label)
+                   BLOCK_FOR_INSN (insn) = NULL;
with
+                 if (BLOCK_FOR_INSN (last_label)
+                     && BB_HEAD (BLOCK_FOR_INSN (last_label)) == last_label)
+                   BLOCK_FOR_INSN (insn) = NULL;