On 02-Mar-2017 8:07 AM, "Richard Henderson" <r...@twiddle.net> wrote:
On 03/02/2017 02:24 AM, Nikunj A Dadhania wrote:
> +static void float64_madd_set_vxisi(CPUPPCState *env, float64 a, float64
> b,
> + float64 c, unsigned int flags)
> {
> + float64 f = float64_mul(a, b, &env->fp_status);
>
What is the point of this multiply?
Only to compute vxisi as stated in the thread
"If the product of x and y is an Infinity and z is an Infinity of the
opposite sign, vxisi_flag is set to 1."
Let me know if I there is an alternative way to achieve this.
> + /* a*b = ∞ and c = ∞, find ∞ - ∞ case and set VXISI */
> + if (float64_is_infinity(f) && float64_is_infinity(c)) {
> + if ((f ^ c) == 0) {
> + /* Both negative/positive inifinity and substraction*/
> + if (flags & MSUB_FLGS) {
>
I would really prefer you use the float_muladd_* names.
Sure.
+uint64_t helper_##op(CPUPPCState *env, uint64_t arg1, \
> + uint64_t arg2, uint64_t arg3) \
> +{ \
> + if (unlikely((float64_is_infinity(arg1) && float64_is_zero(arg2)) ||
> \
> + (float64_is_zero(arg1) && float64_is_infinity(arg2)))) {
> \
> + /* Multiplication of zero by infinity */ \
> + arg1 = float_invalid_op_excp(env, POWERPC_EXCP_FP_VXIMZ, 1); \
> + } else { \
> + if (unlikely(float64_is_signaling_nan(arg1, &env->fp_status) || \
> + float64_is_signaling_nan(arg2, &env->fp_status) || \
> + float64_is_signaling_nan(arg3, &env->fp_status))) {
> \
> + /* sNaN operation */ \
> + float_invalid_op_excp(env, POWERPC_EXCP_FP_VXSNAN, 1); \
> + } \
> + \
> + float64_madd_set_vxisi(env, arg1, arg2, arg3, madd_flags); \
> + arg1 = float64_muladd(arg1, arg2, arg3, madd_flags, \
> + &env->fp_status); \
> + float_check_status(env); \
>
I know this is the layout of the bulk of the ppc target, but it's
inefficient. Let's do this one correctly, akin to target/tricore:
result = float64_muladd(args...);
flags = get_float_exception_flags(&env->fp_status);
if (flags) {
if (flags & float_flag_invalid) {
// examine inputs to see why we return NaN
}
float_check_status(env);
}
Sure.
Nikunj
