[PULL,69/72] softfloat: Sink frac_cmp in parts_pick_nan until needed

Commit Message

Peter Maydell Dec. 11, 2024, 4:20 p.m. UTC

From: Richard Henderson <[e-mail]>

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 <[e-mail]>
Reviewed-by: Peter Maydell <[e-mail]>
Message-id: [e-mail]
Signed-off-by: Peter Maydell <[e-mail]>
---
 fpu/softfloat-parts.c.inc | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

Patch

diff --git a/fpu/softfloat-parts.c.inc b/fpu/softfloat-parts.c.inc
index 3c77dcbb154..abe24aeaa00 100644
--- 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();