[Bug middle-end/112560] New: ICE in try_combine on pr112494.c

["jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112560

            Bug ID: 112560
           Summary: ICE in try_combine on pr112494.c
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
                CC: 141242068 at smail dot nju.edu.cn, ubizjak at gmail dot com
        Depends on: 112494
  Target Milestone: ---
            Target: x86_64-linux-gnu

+++ This bug was initially created as a clone of Bug #112494 +++

As written in
https://gcc.gnu.org/pipermail/gcc-patches/2023-November/636503.html
I see with --enable-checking=yes,rtl,extra on x86_64-linux:

Executing on host: /home/jakub/src/gcc/obj48/gcc/xgcc
-B/home/jakub/src/gcc/obj48/gcc/ 
/home/jakub/src/gcc/gcc/testsuite/gcc.target/i386/pr112494.c   
-fdiagnostics-plain-output   -Og -fno-tree-copy-prop -fno-tree-fre
-fno-tree-ccp -fno-tree-forwprop -S -o pr112494.s    (timeout = 300)
spawn -ignore SIGHUP /home/jakub/src/gcc/obj48/gcc/xgcc
-B/home/jakub/src/gcc/obj48/gcc/
/home/jakub/src/gcc/gcc/testsuite/gcc.target/i386/pr112494.c
-fdiagnostics-plain-output -Og -fno-tree-copy-prop -fno-tree-fre -fno-tree-ccp
-fno-tree-forwprop -S -o pr112494.s
during RTL pass: combine
/home/jakub/src/gcc/gcc/testsuite/gcc.target/i386/pr112494.c: In function
'main':
/home/jakub/src/gcc/gcc/testsuite/gcc.target/i386/pr112494.c:17:1: internal
compiler error: RTL check: expected elt 0 type 'e' or 'u', have 'E' (rtx
unspec) in try_combine, at combine.cc:3237
0x834954 rtl_check_failed_type2(rtx_def const*, int, int, int, char const*,
int, char const*)
        ../../gcc/rtl.cc:761
0xd8a46e try_combine
        ../../gcc/combine.cc:3237
0x25d65ff combine_instructions
        ../../gcc/combine.cc:1264
0x25d65ff rest_of_handle_combine
        ../../gcc/combine.cc:15080
0x25d65ff execute
        ../../gcc/combine.cc:15124
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
compiler exited with status 1

This is on
3236                      /* Just replace the CC reg with a new mode.  */
3237                      SUBST (XEXP (*cc_use_loc, 0), newpat_dest);
3238                      undobuf.other_insn = cc_use_insn;
in combine.cc, where *cc_use_loc is
(unspec:DI [
        (reg:CC 17 flags)
    ] UNSPEC_PUSHFL)
on which XEXP (guess combine assumes CC must be used inside of a
comparison).


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112494
[Bug 112494] ICE in ix86_cc_mode, at config/i386/i386.cc:16477