[Bug bootstrap/81995] New: [8.0 Regression] gcc/reg-stack.c:2073:1: error: unrecognizable insn:

[gerald at pfeifer dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81995

            Bug ID: 81995
           Summary: [8.0 Regression] gcc/reg-stack.c:2073:1: error:
                    unrecognizable insn:
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gerald at pfeifer dot com
  Target Milestone: ---
            Target: i586-unknown-freebsd10.3

This seems to have been introduced between Aug 20th 16:40 GMT and 
Aug 21th 16:40 GMT on i586-unknown-freebsd10.3:

/scratch/tmp/gerald/GCC-HEAD/gcc/reg-stack.c: In function 'bool
subst_stack_regs
_pat(rtx_insn*, stack_ptr, rtx)':
/scratch/tmp/gerald/GCC-HEAD/gcc/reg-stack.c:2073:1: error: unrecognizable
insn:
 }
 ^
(insn 2014 669 671 94 (parallel [
            (set (reg:SI 588 [ _913 ])
                (ior:SI (ashift:SI (const_int 1 [0x1])
                        (subreg:QI (reg:SI 581 [ pretmp_894 ]) 0))
                    (mem:SI (plus:SI (reg/f:SI 568 [ _856 ])
                            (const_int 4 [0x4])) [0 MEM[(struct stack_def
*)_856
 + 4B]+0 S4 A32])))
            (clobber (reg:CC 17 flags))
        ]) -1
     (nil))
during RTL pass: subreg2
/scratch/tmp/gerald/GCC-HEAD/gcc/reg-stack.c:2073:1: internal compiler error:
in
 extract_insn, at recog.c:2311


My guess is this is specific to i586 (or i386), though I did not find an
immediate candidate commit.