[Bug target/116715] New: RISC-V: Miscompile at -O2 with -march=rv64id_zbs

[patrick at rivosinc dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116715

            Bug ID: 116715
           Summary: RISC-V: Miscompile at -O2 with -march=rv64id_zbs
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: patrick at rivosinc dot com
  Target Milestone: ---

Testcase:
int a, b;
int d;
long f = 695372830942;
void c(char g) { a = g; }
int main() {
  d = 0;
  for (; d < 1; d = 1)
    --f;
  d |= b = f;
  long h = d;
  c(h >> 40);
  __builtin_printf("%lX\n", a ^ 5UL);
}

Commands:
> /scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/bin/riscv64-unknown-linux-gnu-gcc
>  -march=rv64idzbs -O1 preprocessed.c -o test.out
> /scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/bin/qemu-riscv64 test.out
FA

> /scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/bin/riscv64-unknown-linux-gnu-gcc
>  -march=rv64idzbs -O2 preprocessed.c -o test.out
> /scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/bin/qemu-riscv64 test.out
5

Found via fuzzer.