Start optimizing the use of the fenv interfaces in libm itself

1 files changed, 10 insertions, 18 deletions

diff --git a/sysdeps/ieee754/dbl-64/wordsize-64/s_nearbyint.c b/sysdeps/ieee754/dbl-64/wordsize-64/s_nearbyint.c
index cb49019ddb..861da20b10 100644
--- a/sysdeps/ieee754/dbl-64/wordsize-64/s_nearbyint.c
+++ b/sysdeps/ieee754/dbl-64/wordsize-64/s_nearbyint.c
@@ -24,22 +24,14 @@
 #include "math.h"
 #include "math_private.h"
 
-#ifdef __STDC__
 static const double
-#else
-static double
-#endif
 TWO52[2]={
   4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
  -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
 };
 
-#ifdef __STDC__
-	double __nearbyint(double x)
-#else
-	double __nearbyint(x)
-	double x;
-#endif
+double
+__nearbyint(double x)
 {
 	fenv_t env;
 	int64_t i0,sx;
@@ -47,20 +39,19 @@ TWO52[2]={
 	EXTRACT_WORDS64(i0,x);
 	sx = (i0>>63)&1;
 	j0 = ((i0>>52)&0x7ff)-0x3ff;
-	if(j0<52) {
+	if(__builtin_expect(j0<52, 1)) {
 	    if(j0<0) {
 	      if((i0&UINT64_C(0x7fffffffffffffff))==0) return x;
 		uint64_t i = i0 & UINT64_C(0xfffffffffffff);
 		i0 &= UINT64_C(0xfffe000000000000);
 		i0 |= (((i|-i) >> 12) & UINT64_C(0x8000000000000));
 		INSERT_WORDS64(x,i0);
-		feholdexcept (&env);
+		libc_feholdexcept (&env);
 		double w = TWO52[sx]+x;
 		double t =  w-TWO52[sx];
-		fesetenv (&env);
-		EXTRACT_WORDS64(i0,t);
-		INSERT_WORDS64(t,(i0&UINT64_C(0x7fffffffffffffff))|(sx<<63));
-		return t;
+		math_opt_barrier(t);
+		libc_fesetenv (&env);
+		return copysign(t, x);
 	    } else {
 		uint64_t i = UINT64_C(0x000fffffffffffff)>>j0;
 		if((i0&i)==0) return x; /* x is integral */
@@ -73,10 +64,11 @@ TWO52[2]={
 	    else return x;		/* x is integral */
 	}
 	INSERT_WORDS64(x,i0);
-	feholdexcept (&env);
+	libc_feholdexcept (&env);
 	double w = TWO52[sx]+x;
 	double t = w-TWO52[sx];
-	fesetenv (&env);
+	math_opt_barrier (t);
+	libc_fesetenv (&env);
 	return t;
 }
 weak_alias (__nearbyint, nearbyint)