[Bug target/84438] New: Another code pattern that breaks PDP11 with -m10: including reproducer code

["etchedpixels at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84438

            Bug ID: 84438
           Summary: Another code pattern that breaks PDP11 with -m10:
                    including reproducer code
           Product: gcc
           Version: 7.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: etchedpixels at gmail dot com
  Target Milestone: ---

Created attachment 43447
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=43447&action=edit
Example showing the bug

The attached function blows up the compiler with -m10

(gcc 7.3.0 pdp11-aout host is linux 64bit)

tmp/5.c: In function ‘div10quickm’:
/tmp/5.c:18:1: error: unrecognizable insn:
 }
 ^
(insn 11 10 12 2 (set (reg:SI 23 [ _2 ])
        (ashift:SI (reg:SI 23 [ _2 ])
            (const_int -1 [0xffffffffffffffff]))) "/tmp/5.c":7 -1
     (expr_list:REG_EQUAL (lshiftrt:SI (reg:SI 37)
            (const_int 2 [0x2]))
        (nil)))
/tmp/5.c:18:1: internal compiler error: in extract_insn, at recog.c:2311
0x8d8b48 _fatal_insn(char const*, rtx_def const*, char const*, int, char
const*)
        ../../gcc-7.3.0/gcc/rtl-error.c:108
0x8d8b79 _fatal_insn_not_found(rtx_def const*, char const*, int, char const*)
        ../../gcc-7.3.0/gcc/rtl-error.c:116
0x8ae40f extract_insn(rtx_insn*)
        ../../gcc-7.3.0/gcc/recog.c:2311
0x6fe3f3 instantiate_virtual_regs_in_insn
        ../../gcc-7.3.0/gcc/function.c:1589
0x6fe3f3 instantiate_virtual_regs
        ../../gcc-7.3.0/gcc/function.c:1957
0x6fe3f3 execute
        ../../gcc-7.3.0/gcc/function.c:2006