[Bug target/106303] [13 Regression] ICE on valid code at -O3 with -fno-inline-small-functions on x86_64-linux-gnu: in extract_insn, at recog.cc:2791 since r13-1607-gc3ed9e0d6e96d869

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106303

--- Comment #4 from Zhendong Su <zhendong.su at inf dot ethz.ch> ---
Here is another repro that ICEs at -O2 (without -fno-inline-small-functions).

[570] % gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/local/suz-local/software/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/13.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--prefix=/local/suz-local/software/local/gcc-trunk --enable-sanitizers
--enable-languages=c,c++ --disable-werror --enable-multilib --with-system-zlib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 13.0.0 20220717 (experimental) [master r13-1722-g7bcd7f47359] (GCC)
[571] %
[571] % gcctk -O2 small.c
small.c: In function ‘n’:
small.c:18:1: error: unrecognizable insn:
   18 | }
      | ^
(insn 41 25 32 8 (set (reg:TI 85 [ D.2008 ])
        (reg:V1TI 90 [ D.2008 ])) "small.c":16:12 -1
     (expr_list:REG_DEAD (reg:V1TI 90 [ D.2008 ])
        (expr_list:REG_EQUAL (mem/c:TI (symbol_ref:DI ("k") [flags 0x2]
<var_decl 0x7f279eb4acf0 k>) [2 k+0 S16 A128])  
            (nil))))
during RTL pass: subreg3
small.c:18:1: internal compiler error: in extract_insn, at recog.cc:2791
0x722ccc _fatal_insn(char const*, rtx_def const*, char const*, int, char
const*)
        ../../gcc-trunk/gcc/rtl-error.cc:108
0x722ce8 _fatal_insn_not_found(rtx_def const*, char const*, int, char const*)
        ../../gcc-trunk/gcc/rtl-error.cc:116
0x72121b extract_insn(rtx_insn*)
        ../../gcc-trunk/gcc/recog.cc:2791
0x1d4e697 decompose_multiword_subregs
        ../../gcc-trunk/gcc/lower-subreg.cc:1555
0x1d4f51d execute
        ../../gcc-trunk/gcc/lower-subreg.cc:1820
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.
[572] %
[572] % cat small.c
struct a {
  int b;
  int c;
  int d;
  int e;
} i, j, k, l;
int f, g, h;
static struct a n() {
  if (f)
    while (1)
      i = k;
  j = k;
  for (; g; g++)
    ;
  if (h)
    return k;
  return j;
}
void o() { l = n(); }
int main() {
  o();
  return 0;
}