[Bug tree-optimization/127764] New: Wrong code at -O2/3/s on x86_64-pc-linux-gnu

[xintong.zhou1 at uwaterloo dot ca via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127764

            Bug ID: 127764
           Summary: Wrong code at -O2/3/s on x86_64-pc-linux-gnu
           Product: gcc
           Version: 17.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: xintong.zhou1 at uwaterloo dot ca
  Target Milestone: ---

Compiler Explorer: https://godbolt.org/z/T3TP36fdP

Note:
- fail: trunk, 10 - 16
- work: 9 or earlier

$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=/data/x27zhou/compiler-nightly/install/gcc/bin/gcc
COLLECT_LTO_WRAPPER=/data/x27zhou/compiler-nightly/install/gcc/libexec/gcc/x86_64-pc-linux-gnu/17.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /data/x27zhou/compiler-nightly/src/gcc/configure CC='ccache
clang' CXX='ccache clang++' --enable-checking=yes --disable-bootstrap
--disable-multilib --enable-languages=c,c++
--prefix=/data/x27zhou/compiler-nightly/install/gcc
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 17.0.0 20261007 (experimental) (GCC)
$
$ gcc-trunk -O0 small.c && ./a.out
$ gcc-trunk -O2 small.c && ./a.out
[1]    2274086 illegal hardware instruction (core dumped)  ./a.out
$
$ cat small.c
int b, c;
int d(int *p1) {
  switch ((unsigned char)*p1)
  case 1:
  case 3:
  case 255:
    return 1 + b % 60;
  return 0;
}
int main() {
  int e[] = {255};
  c = d(e);
}