softfloat: Sink frac_cmp in parts_pick_nan until needed

Move the fractional comparison to the end of the
float_2nan_prop_x87 case.  This is not required for
any other 2nan propagation rule.  Reorganize the
x87 case itself to break out of the switch when the
fractional comparison is not required.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20241203203949.483774-11-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/fpu/softfloat-parts.c.inc b/fpu/softfloat-parts.c.inc
index 3c77dcbb15439eb0d3f0258fe1d6a109aedd2690..abe24aeaa00e4d8bf5a05d87485d5082e47ae667 100644 (file)
--- a/fpu/softfloat-parts.c.inc
+++ b/fpu/softfloat-parts.c.inc
@@ -52,11 +52,6 @@ static FloatPartsN *partsN(pick_nan)(FloatPartsN *a, FloatPartsN *b,
         return a;
     }
 
-    cmp = frac_cmp(a, b);
-    if (cmp == 0) {
-        cmp = a->sign < b->sign;
-    }
-
     switch (s->float_2nan_prop_rule) {
     case float_2nan_prop_s_ab:
         if (have_snan) {
@@ -89,20 +84,24 @@ static FloatPartsN *partsN(pick_nan)(FloatPartsN *a, FloatPartsN *b,
          * return the NaN with the positive sign bit (if any).
          */
         if (is_snan(a->cls)) {
-            if (is_snan(b->cls)) {
-                which = cmp > 0 ? 0 : 1;
-            } else {
+            if (!is_snan(b->cls)) {
                 which = is_qnan(b->cls) ? 1 : 0;
+                break;
             }
         } else if (is_qnan(a->cls)) {
             if (is_snan(b->cls) || !is_qnan(b->cls)) {
                 which = 0;
-            } else {
-                which = cmp > 0 ? 0 : 1;
+                break;
             }
         } else {
             which = 1;
+            break;
+        }
+        cmp = frac_cmp(a, b);
+        if (cmp == 0) {
+            cmp = a->sign < b->sign;
         }
+        which = cmp > 0 ? 0 : 1;
         break;
     default:
         g_assert_not_reached();