[Bug target/113209] New: [14] RISC-V rv64gcv_zvl256b vector: Runtime mismatch with rv64gc

["patrick at rivosinc dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113209

            Bug ID: 113209
           Summary: [14] RISC-V rv64gcv_zvl256b vector: Runtime mismatch
                    with rv64gc
           Product: gcc
           Version: 14.0
            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 b, c, d, f, i, a;
int e[1] = {0};
int *g = e;
int *k = e;
int *z;
long h;
int j[5] = {0,0,0,0,0};
void n() {
  if (c) {
    int **l = &z;
    *l = e;
    while (d)
      ;
  }
}
void o() {
  for (; b < 5; b += a) {
    n();
    for (h = 0; h < 5; h++)
      j[h] = 1;
    int m = *e != *g;
    a |= i <= m;
    f = -12;
    for (; f; f++)
      if (*k)
        break;
  }
}
int main() {
  o();
  if (a == 1)
    return 0;
  else
    return 1;
}

Commands:
> /scratch/tc-testing/tc-jan-1-trunk/build-rv64gcv/bin/riscv64-unknown-linux-gnu-gcc -march=rv64gcv_zvl256b -O3 red.c -o user-config.out
> QEMU_CPU=rv64,vlen=256,v=true,vext_spec=v1.0,Zve32f=true,Zve64f=true timeout --verbose -k 0.1 1 /scratch/tc-testing/tc-dec-22-trunk/build-rv64gcv/bin/qemu-riscv64 user-config.out
> echo $?
1

> /scratch/tc-testing/tc-jan-1-trunk/build-rv64gcv/bin/riscv64-unknown-linux-gnu-gcc -march=rv64gc -O3 red.c -o user-config.out
> QEMU_CPU=rv64,vlen=256,v=true,vext_spec=v1.0,Zve32f=true,Zve64f=true timeout --verbose -k 0.1 1 /scratch/tc-testing/tc-dec-22-trunk/build-rv64gcv/bin/qemu-riscv64 user-config.out
> echo $?
0

With a printf:
gcv_zvl256b
a = 9

gc
a = 1

Analysis:
Working backwards from a
a |= i <= m
Since true/false only evaluate to 1/0, 'a' should never be 9