[Bug tree-optimization/118805] New: wrong code at -O1 with "-fno-tree-ccp -fno-tree-copy-prop -fno-tree-forwprop -fno-tree-fre" on x86_64-linux-gnu

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118805

            Bug ID: 118805
           Summary: wrong code at -O1 with "-fno-tree-ccp
                    -fno-tree-copy-prop -fno-tree-forwprop -fno-tree-fre"
                    on x86_64-linux-gnu
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhendong.su at inf dot ethz.ch
  Target Milestone: ---

It appears to be a recent regression as it doesn't reproduce with 14.2 and
earlier.

Compiler Explorer: https://godbolt.org/z/P91rdM1Px

[585] % 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/15.0.1/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 15.0.1 20250209 (experimental) (GCC) 
[586] % 
[586] % gcctk -O1 small.c; ./a.out
[587] % 
[587] % gcctk -O1 -fno-tree-ccp -fno-tree-copy-prop -fno-tree-forwprop
-fno-tree-fre small.c
[588] % ./a.out
Aborted
[589] % 
[589] % cat small.c
unsigned char a = 255;
int b;
int main() {
  int c = 0;
  if (c > a && a >= 255)
    __builtin_abort();
  return 0;
}