Re: [PATCH v4 8/9] fpu: Add conversion routines for OCP FP8 E4M3

[Max Chou <max.chou@sifive.com>]

On 2026-02-16 15:30, Richard Henderson wrote:
> It doesn't feel right doing this here, because true overflow is handled
> elsewhere.  This is re-packing a FloatParts for a given FloatFmt.
> 
> Perhaps parts64_float_to_float() would be the proper place for this, as
> that's the conversion operation, and recognizing this overflow feels like
> part of a conversion.

Hmm, I agree with you. Maybe we could add a new float_to_e5m2 similar to
float_to_ahp and replacing the parts_float_to_float calls in
float32_to_float8_e5m2/bfloat16_to_float8_e5m2.

+static void parts_float_to_e5m2(FloatParts64 *a, float_status *s,
+                                bool saturate)
+{
+    switch (a->cls) {
+    case float_class_snan:
+    case float_class_qnan:
+        parts_return_nan(a, s);
+        break;
+    case float_class_inf:
+        if (saturate) {
+            float_raise(float_flag_invalid, s);
+            a->cls = float_class_normal;
+            a->exp = float8_e5m2_params.exp_max - 1;
+            a->frac = MAKE_64BIT_MASK(float8_e5m2_params.frac_shift,
+                                      float8_e5m2_params.frac_size + 1);
+        }
+        break;
+    case float_class_denormal:
+        float_raise(float_flag_input_denormal_used, s);
+        break;
+    case float_class_normal:
+    case float_class_zero:
+        break;
+    default:
+        g_assert_not_reached();
+    }
+}

Thanks for the feedbacks,
rnax