[Bug target/52933] SH Target: Use div0s for integer sign comparisons

[olegendo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52933

--- Comment #5 from Oleg Endo <olegendo at gcc dot gnu.org> ---
Some of the original test cases are still not working.  In particular cases
where bit positions != 31 are compared/xor'ed:

bool cmp_signs_24 (int a, int b)
{
  return (a & 0x8000) ^ (b & 0x8000);
}

bool cmp_signs_25 (int a, int b)
{
  return (a & 0x8000) != (b & 0x8000);
}

bool cmp_signs_26 (short a, short b)
{
  return (a < 0) == (b < 0);
}

bool cmp_signs_27 (short a, short b)
{
  return (a < 0) != (b < 0);
}

int cmp_signs_28 (short a, short b)
{
  return (a < 0) != (b < 0) ? 40 : -10;
}

Such cases can be improved by shifting the tested bit into MSB position and
using div0s.