[Bug rtl-optimization/117239] New: wrong code at -O{s,2} with "-fno-inline -fschedule-insns" on x86_64-linux-gnu

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117239

            Bug ID: 117239
           Summary: wrong code at -O{s,2} with "-fno-inline
                    -fschedule-insns" on x86_64-linux-gnu
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhendong.su at inf dot ethz.ch
  Target Milestone: ---

It appears to be a regression from 11.*, and affects 12.* and later.


Compiler Explorer: https://godbolt.org/z/b86d6z9bf


[526] % 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/15.0.0/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 15.0.0 20241020 (experimental) (GCC) 
[527] % 
[527] % gcctk -O2 small.c; ./a.out
[528] % gcctk -O2 -fno-inline -fschedule-insns small.c
[529] % ./a.out
Aborted
[530] % cat small.c
int a, b, j = 1, k;
int l() { return a; }
struct c {
  int d;
  int e;
  int f;
  int g;
  short h;
  int i;
};
void m(int n, struct c o) {
  if (o.i)
    j = 0;
}
int r(struct c n) { return b; }
int main() {
  struct c q = {0, 0, 0, 0, 0, 1};
  k = r(q);
  m(l(), q);
  if (j != 0)
    __builtin_abort();
  return 0;
}