target-arm: Implement correct NaN propagation rules
Implement the correct NaN propagation rules for ARM targets by
providing an appropriate pickNaN function.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
diff --git a/fpu/softfloat-specialize.h b/fpu/softfloat-specialize.h
index 8dcf469..f43f2d0a 100644
--- a/fpu/softfloat-specialize.h
+++ b/fpu/softfloat-specialize.h
@@ -168,6 +168,28 @@
| tie-break rule.
*----------------------------------------------------------------------------*/
+#if defined(TARGET_ARM)
+static int pickNaN(flag aIsQNaN, flag aIsSNaN, flag bIsQNaN, flag bIsSNaN,
+ flag aIsLargerSignificand)
+{
+ /* ARM mandated NaN propagation rules: take the first of:
+ * 1. A if it is signaling
+ * 2. B if it is signaling
+ * 3. A (quiet)
+ * 4. B (quiet)
+ * A signaling NaN is always quietened before returning it.
+ */
+ if (aIsSNaN) {
+ return 0;
+ } else if (bIsSNaN) {
+ return 1;
+ } else if (aIsQNaN) {
+ return 0;
+ } else {
+ return 1;
+ }
+}
+#else
static int pickNaN(flag aIsQNaN, flag aIsSNaN, flag bIsQNaN, flag bIsSNaN,
flag aIsLargerSignificand)
{
@@ -197,6 +219,7 @@
return 1;
}
}
+#endif
/*----------------------------------------------------------------------------
| Takes two single-precision floating-point values `a' and `b', one of which
