[Bug rtl-optimization/121497] New: ICE at -O{2,3} on x86_64-linux-gnu: in extract_insn, at recog.cc:2884

[zhendong.su at inf dot ethz.ch via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121497

            Bug ID: 121497
           Summary: ICE at -O{2,3} on x86_64-linux-gnu: in extract_insn,
                    at recog.cc:2884
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhendong.su at inf dot ethz.ch
  Target Milestone: ---

Compiler Explorer: https://godbolt.org/z/sfjrrjfov

It appears to be a recent regression as it doesn't reproduce with 15.1 and
earlier.

[628] % gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/local/home/suz/suz-local/software/local/gcc-trunk/bin/../libexec/gcc/x86_64-pc-linux-gnu/16.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--enable-checking=yes --prefix=/local/suz-local/software/local/gcc-trunk
--enable-sanitizers --enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 16.0.0 20250810 (experimental) (GCC)
[629] %
[629] % gcctk -O3 -w -c small.c
small.c: In function ‘main’:
small.c:15:1: error: unrecognizable insn:
   15 | }
      | ^
(insn 75 10 74 3 (set (reg:SI 125)
        (const_int 3000000000 [0xb2d05e00])) -1
     (expr_list:REG_EQUIV (const_int 3000000000 [0xb2d05e00])
        (nil)))
during RTL pass: ira
small.c:15:1: internal compiler error: in extract_insn, at recog.cc:2884
0x2547bc6 internal_error(char const*, ...)
        ../../gcc-trunk/gcc/diagnostic-global-context.cc:534
0xa05b9c fancy_abort(char const*, int, char const*)
        ../../gcc-trunk/gcc/diagnostics/context.cc:1687
0x891e3b _fatal_insn(char const*, rtx_def const*, char const*, int, char
const*)
        ../../gcc-trunk/gcc/rtl-error.cc:108
0x891e5d _fatal_insn_not_found(rtx_def const*, char const*, int, char const*)
        ../../gcc-trunk/gcc/rtl-error.cc:116
0x8902e7 extract_insn(rtx_insn*)
        ../../gcc-trunk/gcc/recog.cc:2884
0xf52343 ira_remove_insn_scratches(rtx_insn*, bool, _IO_FILE*, rtx_def*
(*)(rtx_def*))
        ../../gcc-trunk/gcc/ira.cc:5452
0xf54c0d remove_scratches
        ../../gcc-trunk/gcc/ira.cc:5496
0xf54c0d ira
        ../../gcc-trunk/gcc/ira.cc:5852
0xf54c0d execute
        ../../gcc-trunk/gcc/ira.cc:6212
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.
[630] %
[630] % cat small.c
extern void a(int *);
int q;
void b(int c, int d, int e, int f, int g, int h) {
  int t[] = {c, d, e, f, g, h};
  a(t);
}
int main() {
  int k[2], i = 0, *p();
  if (q) {
    for (; (int)p + i < 2; i++)
      k[i] = -1294967296;
    b(k[0] + 7, k[0] + 9, k[0] + 6, k[0] + 9, k[0] + 9, k[0] + 6);
  }
  return 0;
}