nearbyint optimization (only clear inexact when necessary)

[musl] / src / math / nearbyint.c

diff --git a/src/math/nearbyint.c b/src/math/nearbyint.c
index 714c55c..7a4c58c 100644 (file)
--- a/src/math/nearbyint.c
+++ b/src/math/nearbyint.c
@@ -1,20 +1,19 @@
 #include <fenv.h>
 #include <math.h>
 
-/*
-rint may raise inexact (and it should not alter the fenv otherwise)
-nearbyint must not raise inexact
+/* nearbyint is the same as rint, but it must not raise the inexact exception */
 
-(according to ieee754r section 7.9 both functions should raise invalid
-when the input is signaling nan, but c99 does not define snan so saving
-and restoring the entire fenv should be fine)
-*/
+double nearbyint(double x)
+{
+#ifdef FE_INEXACT
+       int e;
 
-double nearbyint(double x) {
-       fenv_t e;
-
-       fegetenv(&e);
+       e = fetestexcept(FE_INEXACT);
+#endif
        x = rint(x);
-       fesetenv(&e);
+#ifdef FE_INEXACT
+       if (!e)
+               feclearexcept(FE_INEXACT);
+#endif
        return x;
 }