[Bug rtl-optimization/58679] [4.9 regression] ICE in create_pre_exit, at mode-switching.c:421 with -mavx after r202915

[ubizjak at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58679

--- Comment #2 from Uroš Bizjak <ubizjak at gmail dot com> ---
The compile failure with the testcase from Comment #0 has gone latent, but the
problem looks similar to PR 58792 [1].

On a related note, the allocator introduces extra move for pr30185.c testcase
that results in:

foo:
        movq    %rsi, %rax
        cqto
        idivq   %rcx
        movq    %rax, %rsi         <---- here (*)
        xorl    %eax, %eax
        movq    %rsi, %rdx
        ret

"movq %rax, %rdx" should be emitted at (*).

[1] http://gcc.gnu.org/ml/gcc-patches/2013-10/msg01606.html