[Bug target/118510] New: [15 Regression][x86] ICE in extract_insn, at recog.cc:2869 with -mapxf since r15-5635-g1ff69000b50e8a

[mjires at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118510

            Bug ID: 118510
           Summary: [15 Regression][x86] ICE in extract_insn, at
                    recog.cc:2869 with -mapxf since
                    r15-5635-g1ff69000b50e8a
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mjires at gcc dot gnu.org
                CC: ubizjak at gmail dot com
  Target Milestone: ---
            Target: x86_64

Compiling reduced testcase gcc.dg/ipa/20040703-wpa.c results in ICE since
r15-5635-g1ff69000b50e8a.

$ cat 20040703-wpa.c
typedef struct cpp_num cpp_num;
struct cpp_num {
  int high;
  unsigned low;
  int overflow;
};
int num_rshift_n;
cpp_num num_lshift(cpp_num num) {
  num.low = num.low >> num_rshift_n | num.high << (32 - num_rshift_n);
  return num;
}


$ gcc 20040703-wpa.c -mapxf -O2
20040703-wpa.c: In function ‘num_lshift’:
20040703-wpa.c:11:1: error: unrecognizable insn:
   11 | }
      | ^
(insn 39 38 16 2 (parallel [
            (set (reg:SI 124)
                (ior:SI (lshiftrt:SI (reg:SI 120)
                        (and:QI (subreg:QI (reg:SI 98 [ num_rshift_n.0_1 ]) 0)
                            (const_int 31 [0x1f])))
                    (subreg:SI (ashift:DI (zero_extend:DI (subreg:SI (reg:DI
122 [ num ]) 0))
                            (minus:QI (const_int 32 [0x20])
                                (and:QI (subreg:QI (reg:SI 98 [
num_rshift_n.0_1 ]) 0)
                                    (const_int 31 [0x1f])))) 0)))
            (clobber (reg:CC 17 flags))
            (set (mem/c:SI (plus:DI (reg/f:DI 19 frame)
                        (const_int -28 [0xffffffffffffffe4])) [1 num.low+0 S4
A32])
                (reg:SI 124))
        ]) "20040703-wpa.c":9:37 -1
     (nil))
during RTL pass: subreg3
20040703-wpa.c:11:1: internal compiler error: in extract_insn, at recog.cc:2882
0x370010f internal_error(char const*, ...)
        /home/mjires/git/GCC/master/gcc/diagnostic-global-context.cc:517
0x36cfabb fancy_abort(char const*, int, char const*)
        /home/mjires/git/GCC/master/gcc/diagnostic.cc:1722
0x17e96a0 _fatal_insn(char const*, rtx_def const*, char const*, int, char
const*)
        /home/mjires/git/GCC/master/gcc/rtl-error.cc:108
0x17e96e1 _fatal_insn_not_found(rtx_def const*, char const*, int, char const*)
        /home/mjires/git/GCC/master/gcc/rtl-error.cc:116
0x1792f12 extract_insn(rtx_insn*)
        /home/mjires/git/GCC/master/gcc/recog.cc:2882
0x34fe2be decompose_multiword_subregs
        /home/mjires/git/GCC/master/gcc/lower-subreg.cc:1587
0x34fec65 execute
        /home/mjires/git/GCC/master/gcc/lower-subreg.cc:1894
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.


$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/home/mjires/built/master/libexec/gcc/x86_64-pc-linux-gnu/15.0.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /home/mjires/git/GCC/master/configure
--prefix=/home/mjires/built/master --disable-bootstrap
--enable-languages=c,c++,fortran,lto --disable-multilib --disable-libsanitizer
--enable-checking
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 15.0.1 20250116 (experimental) (GCC)