message: Guard against integer division by zero
  * The SPIR-V spec doesn't state what will happen, only that it's undefined. For
  the sake of something sensible (and because it has a good chance of matching
  at least some hardware) we use D3D's behaviour and set the value to 0xFFFFFFFF
diff: @@ -783,13 +783,23 @@ void ThreadState::StepNext(ShaderDebugState *state,
  else if(opdata.op == Op::SDiv)
  {
  for(uint8_t c = 0; c < var.columns; c++)
  + {
  + if(b.value.uv[c] == 0)
  + var.value.uv[c] = ~0U;
  + else
  var.value.iv[c] /= b.value.iv[c];
  }
  + }
  else if(opdata.op == Op::UDiv)
  {
  for(uint8_t c = 0; c < var.columns; c++)
  + {
  + if(b.value.uv[c] == 0)
  + var.value.uv[c] = ~0U;
  + else
  var.value.uv[c] /= b.value.uv[c];
  }
  + }
  else if(opdata.op == Op::IAdd)
  {
  for(uint8_t c = 0; c < var.columns; c++)
  