Fix two bugs in the signbit() macro, which was implemented last year:

- It was added to libc instead of libm.  Hopefully no programs rely
  on this mistake.

- It didn't work properly on large long doubles because its argument
  was converted to type double, resulting in undefined behavior.

lib/libc/gen/Makefile.inc

@@ -25,8 +25,7 @@ SRCS+=  __xuname.c _pthread_stubs.c _rand48.c _spinlock_stub.c _thread_init.c \
 	raise.c readdir.c readpassphrase.c rewinddir.c \
 	scandir.c seed48.c seekdir.c sem.c semctl.c \
 	setdomainname.c sethostname.c setjmperr.c setmode.c \
-	setproctitle.c setprogname.c \
-	siginterrupt.c siglist.c signal.c signbit.c \
+	setproctitle.c setprogname.c siginterrupt.c siglist.c signal.c \
 	sigsetops.c sleep.c srand48.c statvfs.c stringlist.c strtofflags.c \
 	sysconf.c sysctl.c sysctlbyname.c sysctlnametomib.c \
 	syslog.c telldir.c termios.c time.c times.c timezone.c ttyname.c \
@@ -57,7 +56,7 @@ MAN+=	alarm.3 arc4random.3 \
 	scandir.3 sem_destroy.3 sem_getvalue.3 sem_init.3 \
 	sem_open.3 sem_post.3 sem_wait.3 \
 	setjmp.3 setmode.3 setproctitle.3 shm_open.3 \
-	siginterrupt.3 signal.3 signbit.3 sigsetops.3 sleep.3 \
+	siginterrupt.3 signal.3 sigsetops.3 sleep.3 \
 	statvfs.3 stringlist.3 \
 	strtofflags.3 sysconf.3 sysctl.3 syslog.3 tcgetpgrp.3 \
 	tcsendbreak.3 tcsetattr.3 tcsetpgrp.3 time.3 times.3 timezone.3 \

lib/msun/Makefile

@@ -89,7 +89,7 @@ COMMON_SRCS= b_exp.c b_log.c b_tgamma.c \
 	s_log1pf.c s_logb.c s_logbf.c s_matherr.c s_modff.c \
 	s_nearbyint.c s_nextafter.c s_nextafterf.c \
 	s_rint.c s_rintf.c s_round.c s_roundf.c \
-	s_scalbln.c s_scalbn.c s_scalbnf.c \
+	s_scalbln.c s_scalbn.c s_scalbnf.c s_signbit.c \
 	s_signgam.c s_significand.c s_significandf.c s_sin.c s_sinf.c s_tan.c \
 	s_tanf.c s_tanh.c s_tanhf.c s_trunc.c s_truncf.c \
 	w_acos.c w_acosf.c w_acosh.c w_acoshf.c w_asin.c w_asinf.c w_atan2.c \
@@ -131,8 +131,8 @@ INCS=	fenv.h math.h
 MAN=	acos.3 acosh.3 asin.3 asinh.3 atan.3 atan2.3 atanh.3 ceil.3 \
 	cos.3 cosh.3 erf.3 exp.3 fabs.3 fdim.3 feclearexcept.3 fegetenv.3 \
         fegetround.3 fenv.3 floor.3 fmax.3 fmod.3 hypot.3 ieee.3 \
-	ieee_test.3 j0.3 lgamma.3 math.3 rint.3 round.3 sin.3 sinh.3 sqrt.3 \
-	tan.3 tanh.3 trunc.3
+	ieee_test.3 j0.3 lgamma.3 math.3 rint.3 round.3 \
+	signbit.3 sin.3 sinh.3 sqrt.3 tan.3 tanh.3 trunc.3
 
 MLINKS+=acos.3 acosf.3
 MLINKS+=acosh.3 acoshf.3

lib/msun/man/signbit.3

@@ -24,14 +24,14 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd February 11, 2003
+.Dd July 18, 2004
 .Dt SIGNBIT 3
 .Os
 .Sh NAME
 .Nm signbit
 .Nd "determine whether a floating-point number's sign is negative"
 .Sh LIBRARY
-.Lb libc
+.Lb libm
 .Sh SYNOPSIS
 .In math.h
 .Ft int

lib/msun/src/math.h

@@ -113,7 +113,10 @@ extern const union __nan_un {
 #define	isunordered(x, y)	(isnan(x) || isnan(y))
 #endif /* __MATH_BUILTIN_RELOPS */
 
-#define	signbit(x)	__signbit(x)
+#define	signbit(x)					\
+    ((sizeof (x) == sizeof (float)) ? __signbitf(x)	\
+    : (sizeof (x) == sizeof (double)) ? __signbit(x)	\
+    : __signbitl(x))
 
 typedef	__double_t	double_t;
 typedef	__float_t	float_t;
@@ -215,6 +218,8 @@ int	__isnormalf(float) __pure2;
 int	__isnormal(double) __pure2;
 int	__isnormall(long double) __pure2;
 int	__signbit(double) __pure2;
+int	__signbitf(float) __pure2;
+int	__signbitl(long double) __pure2;
 
 double	acos(double);
 double	asin(double);

lib/msun/src/s_signbit.c

@@ -38,3 +38,21 @@ __signbit(double d)
 	u.d = d;
 	return (u.bits.sign);
 }
+
+int
+__signbitf(float f)
+{
+	union IEEEf2bits u;
+
+	u.f = f;
+	return (u.bits.sign);
+}
+
+int
+__signbitl(long double e)
+{
+	union IEEEl2bits u;
+
+	u.e = e;
+	return (u.bits.sign);
+}