[Bug target/92791] New: [10 Regression] ICE in extract_insn, at recog.c:2311 since r278645

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92791

            Bug ID: 92791
           Summary: [10 Regression] ICE in extract_insn, at recog.c:2311
                    since r278645
           Product: gcc
           Version: 10.0
            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: i586-linux-gnu
            Target: i586-linux-gnu

Created attachment 47414
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=47414&action=edit
Source files

It's an ugly bug for which I spent 2 days with a reduction. Still I ended up
with ~7MB of source files. It's reduced from boost package:

$ g++ -fPIC -O2 -flto=auto -march=i686 -fno-strict-aliasing -c *.ii
...
$ g++ -flto=16 -shared 1.o 2.o 3.o 4.o 5.o 6.o 7.o 8.o 9.o 10.o 11.o 12.o 13.o
...
(insn 63 62 64 4 (set (strict_low_part (subreg:QI (reg/v:DI 128 [ sbuf_it ])
4))
        (reg:QI 145)) "6.ii":2362:116 -1
     (nil))
during RTL pass: vregs
6.ii:7056:1562: internal compiler error: in extract_insn, at recog.c:2311
0x827c17f _fatal_insn(char const*, rtx_def const*, char const*, int, char
const*)
        ../../gcc/rtl-error.c:108
0x827c1aa _fatal_insn_not_found(rtx_def const*, char const*, int, char const*)
        ../../gcc/rtl-error.c:116
0x827a264 extract_insn(rtx_insn*)
        ../../gcc/recog.c:2311
0x85c3a91 instantiate_virtual_regs_in_insn
        ../../gcc/function.c:1607
0x85c3a91 instantiate_virtual_regs
        ../../gcc/function.c:1977
0x85c3a91 execute
        ../../gcc/function.c:2026