- Try harder to trick gcc into not optimizing away statements

  that are intended to raise underflow and inexact exceptions.
- On systems where long double is the same as double, nextafter
  should be aliased as nexttoward, nexttowardl, and nextafterl.

2 files changed, 19 insertions, 8 deletions

diff --git a/lib/msun/src/s_nextafter.c b/lib/msun/src/s_nextafter.c
index 4fc5b77..a235099 100644
--- a/lib/msun/src/s_nextafter.c
+++ b/lib/msun/src/s_nextafter.c
@@ -21,12 +21,16 @@ static char rcsid[] = "$FreeBSD$";
  *   Special cases:
  */
 
+#include <sys/cdefs.h>
+#include <float.h>
+
 #include "math.h"
 #include "math_private.h"
 
 double
 nextafter(double x, double y)
 {
+	volatile double t;
 	int32_t hx,hy,ix,iy;
 	u_int32_t lx,ly;
 
@@ -41,8 +45,8 @@ nextafter(double x, double y)
 	if(x==y) return y;		/* x=y, return y */
 	if((ix|lx)==0) {			/* x == 0 */
 	    INSERT_WORDS(x,hy&0x80000000,1);	/* return +-minsubnormal */
-	    y = x*x;
-	    if(y==x) return y; else return x;	/* raise underflow flag */
+	    t = x*x;
+	    if(t==x) return t; else return x;	/* raise underflow flag */
 	}
 	if(hx>=0) {				/* x > 0 */
 	    if(hx>hy||((hx==hy)&&(lx>ly))) {	/* x > y, x -= ulp */
@@ -64,8 +68,8 @@ nextafter(double x, double y)
 	hy = hx&0x7ff00000;
 	if(hy>=0x7ff00000) return x+x;	/* overflow  */
 	if(hy<0x00100000) {		/* underflow */
-	    y = x*x;
-	    if(y!=x) {		/* raise underflow flag */
+	    t = x*x;
+	    if(t!=x) {		/* raise underflow flag */
 	        INSERT_WORDS(y,hx,lx);
 		return y;
 	    }
@@ -73,3 +77,9 @@ nextafter(double x, double y)
 	INSERT_WORDS(x,hx,lx);
 	return x;
 }
+
+#if (LDBL_MANT_DIG == 53)
+__strong_reference(nextafter, nexttoward);
+__strong_reference(nextafter, nexttowardl);
+__strong_reference(nextafter, nextafterl);
+#endif
diff --git a/lib/msun/src/s_nextafterf.c b/lib/msun/src/s_nextafterf.c
index c4032e9..b8a1125 100644
--- a/lib/msun/src/s_nextafterf.c
+++ b/lib/msun/src/s_nextafterf.c
@@ -23,6 +23,7 @@ static char rcsid[] = "$FreeBSD$";
 float
 nextafterf(float x, float y)
 {
+	volatile float t;
 	int32_t hx,hy,ix,iy;
 
 	GET_FLOAT_WORD(hx,x);
@@ -36,8 +37,8 @@ nextafterf(float x, float y)
 	if(x==y) return y;		/* x=y, return y */
 	if(ix==0) {				/* x == 0 */
 	    SET_FLOAT_WORD(x,(hy&0x80000000)|1);/* return +-minsubnormal */
-	    y = x*x;
-	    if(y==x) return y; else return x;	/* raise underflow flag */
+	    t = x*x;
+	    if(t==x) return t; else return x;	/* raise underflow flag */
 	}
 	if(hx>=0) {				/* x > 0 */
 	    if(hx>hy) {				/* x > y, x -= ulp */
@@ -55,8 +56,8 @@ nextafterf(float x, float y)
 	hy = hx&0x7f800000;
 	if(hy>=0x7f800000) return x+x;	/* overflow  */
 	if(hy<0x00800000) {		/* underflow */
-	    y = x*x;
-	    if(y!=x) {		/* raise underflow flag */
+	    t = x*x;
+	    if(t!=x) {		/* raise underflow flag */
 	        SET_FLOAT_WORD(y,hx);
 		return y;
 	    }