[Bug target/116278] New: [15] RISC-V: Miscompile at -O2 -fwrapv -fno-strict-aliasing

[patrick at rivosinc dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116278

            Bug ID: 116278
           Summary: [15] RISC-V: Miscompile at -O2 -fwrapv
                    -fno-strict-aliasing
           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:
signed char b[1];
int c;
signed char *d = b;
int main() {
  b[0] = -40;
  c = ({ (unsigned short)d[0] < 0xFFF6 ? (unsigned short)d[0] : 0xFFF6; }) + 9;
  __builtin_printf("%d\n", c);
}

Commands:
> /scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/bin/riscv64-unknown-linux-gnu-gcc
>  -O2 -fwrapv -fno-strict-aliasing red.c -o red.out
> /scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/bin/qemu-riscv64 red.out
65535
> /scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/bin/riscv64-unknown-linux-gnu-gcc
>  -O1 -fwrapv -fno-strict-aliasing red.c -o red.out
> /scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/bin/qemu-riscv64 red.out
65505

Found via fuzzer