Bug#184684: target/10073: [3.2/3.3 regression]: powerpc cannot split insn while building rscheme

[Matthias Klose]

Alan Modra writes:
> This should fix it.
> 
>       * combine.c (force_to_mode <NOT>): Use gen_int_mode.

checked with 3.3 branch, no additional failures in testsuite.

        Matthias