[Bug target/79951] New: ICE in extract_insn, at recog.c:2311 on ppc64le with -mno-cmpb

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79951

            Bug ID: 79951
           Summary: ICE in extract_insn, at recog.c:2311 on ppc64le with
                    -mno-cmpb
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: marxin at gcc dot gnu.org
  Target Milestone: ---
              Host: x86_64-linux-gnu
            Target: ppc64le-linux-gnu

Following test-case ICE with cross compiler (on x86_64-linux-gnu):

$ ppc64le-linux-gnu-gcc
/home/marxin/Programming/gcc/gcc/testsuite/gcc.dg/tree-ssa/backprop-5.c
-mno-cmpb

/home/marxin/Programming/gcc/gcc/testsuite/gcc.dg/tree-ssa/backprop-5.c: In
function ‘testf’:
/home/marxin/Programming/gcc/gcc/testsuite/gcc.dg/tree-ssa/backprop-5.c:16:1:
error: unrecognizable insn:
 TEST_FUNCTION (float, f)
 ^~~~~~~~~~~~~
(insn 13 12 14 2 (set (reg:SF 164)
        (unspec:SF [
                (reg:SF 165)
                (reg:SF 166)
            ] UNSPEC_COPYSIGN))
"/home/marxin/Programming/gcc/gcc/testsuite/gcc.dg/tree-ssa/backprop-5.c":16 -1
     (nil))
/home/marxin/Programming/gcc/gcc/testsuite/gcc.dg/tree-ssa/backprop-5.c:16:1:
internal compiler error: in extract_insn, at recog.c:2311
0xb08718 _fatal_insn(char const*, rtx_def const*, char const*, int, char
const*)
        .././../gcc/rtl-error.c:108
0xb08749 _fatal_insn_not_found(rtx_def const*, char const*, int, char const*)
        .././../gcc/rtl-error.c:116
0xada041 extract_insn(rtx_insn*)
        .././../gcc/recog.c:2311
0x89dad3 instantiate_virtual_regs_in_insn
        .././../gcc/function.c:1589
0x89dad3 instantiate_virtual_regs
        .././../gcc/function.c:1957
0x89dad3 execute
        .././../gcc/function.c:2006