[Bug c/77311] New: bfin: error: unable to find a register to spill in class 'CCREGS'

["wbx at openadk dot org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77311

            Bug ID: 77311
           Summary: bfin: error: unable to find a register to spill in
                    class 'CCREGS'
           Product: gcc
           Version: 6.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: wbx at openadk dot org
  Target Milestone: ---

Created attachment 39480
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=39480&action=edit
ffmpeg preprocessed file

When compiling either ffmpeg or binutils for bfin with gcc 6.1.0 you get
something like
that:

CC      libavcodec/huffyuvencdsp.o
In file included from libavcodec/hevcdsp.c:111:0:
libavcodec/hevcdsp_template.c: In function 'hevc_v_loop_filter_luma_8':
libavcodec/hevcdsp_template.c:1678:1: error: unable to find a register to spill
in class 'CCREGS'
 }
 ^
libavcodec/hevcdsp_template.c:1678:1: error: this is the insn:
(insn 488 474 719 20 (set (reg:BI 15 FP [549])
        (eq:BI (reg/v:SI 15 FP [orig:98 no_p ] [98])
            (const_int 0 [0]))) libavcodec/hevcdsp_template.c:1596 118
{compare_eq}
     (expr_list:REG_DEAD (reg/v:SI 15 FP [orig:98 no_p ] [98])
        (nil)))
libavcodec/hevcdsp_template.c:1678: confused by earlier errors, bailing out
common.mak:57: recipe for target 'libavcodec/hevcdsp.o' failed
make[1]: *** [libavcodec/hevcdsp.o] Error 1
make[1]: *** Waiting for unfinished jobs....

It seems as some kind of gcc optimization bug with Os/O2/O3, as the problematic
code can be compiled with O1 without any problem.

Problem found via Buildroot autobuilders:
http://autobuild.buildroot.net/results/111/1118d568959006b7f973761884fd3f4b63be19b1/

Preprocessed file attached.