[Bug debug/110308] New: [14 Regression] ICE on audiofile-0.3.6: RTL: vartrack: Segmentation fault in mode_to_precision(machine_mode)

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110308

            Bug ID: 110308
           Summary: [14 Regression] ICE on audiofile-0.3.6: RTL: vartrack:
                    Segmentation fault in mode_to_precision(machine_mode)
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: slyfox at gcc dot gnu.org
  Target Milestone: ---

Initially observed ICE on audiofile-0.3.6 when building with
r14-1921-g7360cba833cd92.

Reduced example:

// $ cat bug.cpp.cpp
int channelCount, decodeBlock_outputLength;
struct BlockCodec {
  virtual int decodeBlock(const unsigned char *, short *);
};
struct ms_adpcm_state {
  char predictorIndex;
  int sample1;
  ms_adpcm_state();
};
bool decodeBlock_ok;
void encodeBlock() { ms_adpcm_state(); }
struct MSADPCM : BlockCodec {
  int decodeBlock(const unsigned char *, short *);
};
void decodeSample(ms_adpcm_state, bool *);
int MSADPCM::decodeBlock(const unsigned char *, short *) {
  ms_adpcm_state decoderState[2];
  ms_adpcm_state *state[2];
  state[0] = &decoderState[0];
  if (channelCount == 2)
    state[1] = &decoderState[0];
  short m_coefficients[state[1]->predictorIndex];
  for (int i = 0; i < channelCount; i++)
    ++state[i]->sample1;
  decodeSample(*state[1], &decodeBlock_ok);
  return decodeBlock_outputLength;
}

$ g++ -fvisibility=hidden -g2 -O2 -c bug.cpp.cpp -o bug.o
during RTL pass: vartrack
bug.cpp.cpp: In function 'void encodeBlock()':
bug.cpp.cpp:11:40: internal compiler error: Segmentation fault
   11 | void encodeBlock() { ms_adpcm_state(); }
      |                                        ^
0xe9ac7f crash_signal
        ../../source/gcc/toplev.cc:314
0x1155ea0 mode_to_precision(machine_mode)
        ../../source/gcc/machmode.h:585
0x1155ea0 GET_MODE_PRECISION(machine_mode)
        ../../source/gcc/machmode.h:702
0x1155ea0 paradoxical_subreg_p(machine_mode, machine_mode)
        ../../source/gcc/rtl.h:3211
0x1155ea0 track_loc_p
        ../../source/gcc/var-tracking.cc:5341
0x1157121 use_type
        ../../source/gcc/var-tracking.cc:5555
0x11574a1 add_stores
        ../../source/gcc/var-tracking.cc:5966
0xe3ef65 note_pattern_stores(rtx_def const*, void (*)(rtx_def*, rtx_def const*,
void*), void*)
        ../../source/gcc/rtlanal.cc:1979
0x11567c0 add_with_sets
        ../../source/gcc/var-tracking.cc:6638
0xa666a8 cselib_record_sets
        ../../source/gcc/cselib.cc:3012
0xa67d5e cselib_process_insn(rtx_insn*)
        ../../source/gcc/cselib.cc:3174
0x1162fef vt_initialize
        ../../source/gcc/var-tracking.cc:10282
0x1167ca3 variable_tracking_main_1
        ../../source/gcc/var-tracking.cc:10510
0x1167e6b variable_tracking_main()
        ../../source/gcc/var-tracking.cc:10563
0x1167e6b execute
        ../../source/gcc/var-tracking.cc:10600

$ g++ -v
Using built-in specs.
COLLECT_GCC=/<<NIX>>/gcc-14.0.0/bin/g++
COLLECT_LTO_WRAPPER=/<<NIX>>/gcc-14.0.0/libexec/gcc/x86_64-unknown-linux-gnu/14.0.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with:
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 14.0.0 99999999 (experimental) (GCC)