[glibc] Use GCC builtins for copysign functions if desired.

[Stefan Liebler <stli@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=f818afdd3b29d7eef2010448457c9f5c16e684cd

commit f818afdd3b29d7eef2010448457c9f5c16e684cd
Author: Stefan Liebler <stli@linux.ibm.com>
Date:   Wed Dec 11 15:09:24 2019 +0100

    Use GCC builtins for copysign functions if desired.
    
    This patch is always using the corresponding GCC builtin for copysignf, copysign,
    and is using the builtin for copysignl, copysignf128 if the USE_FUNCTION_BUILTIN
    macros are defined to one in math-use-builtins.h.
    
    Altough the long double version is enabled by default we still need
    the macro and the alternative implementation as the _Float128 version
    of the builtin is not available with all supported GCC versions.
    
    Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

Diff:
---
 sysdeps/generic/math-use-builtins.h         |  9 +++++++++
 sysdeps/ieee754/dbl-64/s_copysign.c         |  9 ++-------
 sysdeps/ieee754/float128/float128_private.h |  3 +++
 sysdeps/ieee754/flt-32/s_copysignf.c        | 12 ++++--------
 sysdeps/ieee754/ldbl-128/s_copysignl.c      |  6 ++++++
 sysdeps/s390/fpu/math-use-builtins.h        |  7 +++++++
 6 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/sysdeps/generic/math-use-builtins.h b/sysdeps/generic/math-use-builtins.h
index 34ca438..770b54c 100644
--- a/sysdeps/generic/math-use-builtins.h
+++ b/sysdeps/generic/math-use-builtins.h
@@ -19,6 +19,8 @@
 #ifndef MATH_USE_BUILTINS_H
 #define MATH_USE_BUILTINS_H	1
 
+#include <features.h> /* For __GNUC_PREREQ.  */
+
 /* Define these macros to 1 to use __builtin_xyz instead of the
    generic implementation.  */
 #define USE_NEARBYINT_BUILTIN 0
@@ -51,4 +53,11 @@
 #define USE_ROUNDL_BUILTIN 0
 #define USE_ROUNDF128_BUILTIN 0
 
+#define USE_COPYSIGNL_BUILTIN 1
+#if __GNUC_PREREQ (7, 0)
+# define USE_COPYSIGNF128_BUILTIN 1
+#else
+# define USE_COPYSIGNF128_BUILTIN 0
+#endif
+
 #endif /* math-use-builtins.h */
diff --git a/sysdeps/ieee754/dbl-64/s_copysign.c b/sysdeps/ieee754/dbl-64/s_copysign.c
index 589b088..94025b7 100644
--- a/sysdeps/ieee754/dbl-64/s_copysign.c
+++ b/sysdeps/ieee754/dbl-64/s_copysign.c
@@ -10,7 +10,7 @@
  * ====================================================
  */
 
-#if defined(LIBM_SCCS) && !defined(lint)
+#if defined (LIBM_SCCS) && ! defined (lint)
 static char rcsid[] = "$NetBSD: s_copysign.c,v 1.8 1995/05/10 20:46:57 jtc Exp $";
 #endif
 
@@ -22,16 +22,11 @@ static char rcsid[] = "$NetBSD: s_copysign.c,v 1.8 1995/05/10 20:46:57 jtc Exp $
 
 #define NO_MATH_REDIRECT
 #include <math.h>
-#include <math_private.h>
 #include <libm-alias-double.h>
 
 double
 __copysign (double x, double y)
 {
-  uint32_t hx, hy;
-  GET_HIGH_WORD (hx, x);
-  GET_HIGH_WORD (hy, y);
-  SET_HIGH_WORD (x, (hx & 0x7fffffff) | (hy & 0x80000000));
-  return x;
+  return __builtin_copysign (x, y);
 }
 libm_alias_double (__copysign, copysign)
diff --git a/sysdeps/ieee754/float128/float128_private.h b/sysdeps/ieee754/float128/float128_private.h
index a6c76ce..7f7f904 100644
--- a/sysdeps/ieee754/float128/float128_private.h
+++ b/sysdeps/ieee754/float128/float128_private.h
@@ -152,6 +152,8 @@
 #define USE_TRUNCL_BUILTIN USE_TRUNCF128_BUILTIN
 #undef USE_ROUNDL_BUILTIN
 #define USE_ROUNDL_BUILTIN USE_ROUNDF128_BUILTIN
+#undef USE_COPYSIGNL_BUILTIN
+#define USE_COPYSIGNL_BUILTIN USE_COPYSIGNF128_BUILTIN
 
 /* IEEE function renames.  */
 #define __ieee754_acoshl __ieee754_acoshf128
@@ -361,6 +363,7 @@
 #define __builtin_ceill __builtin_ceilf128
 #define __builtin_truncl __builtin_truncf128
 #define __builtin_roundl __builtin_roundf128
+#define __builtin_copysignl __builtin_copysignf128
 
 /* Get the constant suffix from bits/floatn-compat.h.  */
 #define L(x) __f128 (x)
diff --git a/sysdeps/ieee754/flt-32/s_copysignf.c b/sysdeps/ieee754/flt-32/s_copysignf.c
index 77d1d90..1c097d3 100644
--- a/sysdeps/ieee754/flt-32/s_copysignf.c
+++ b/sysdeps/ieee754/flt-32/s_copysignf.c
@@ -13,7 +13,7 @@
  * ====================================================
  */
 
-#if defined(LIBM_SCCS) && !defined(lint)
+#if defined (LIBM_SCCS) && ! defined (lint)
 static char rcsid[] = "$NetBSD: s_copysignf.c,v 1.4 1995/05/10 20:46:59 jtc Exp $";
 #endif
 
@@ -25,15 +25,11 @@ static char rcsid[] = "$NetBSD: s_copysignf.c,v 1.4 1995/05/10 20:46:59 jtc Exp
 
 #define NO_MATH_REDIRECT
 #include <math.h>
-#include <math_private.h>
 #include <libm-alias-float.h>
 
-float __copysignf(float x, float y)
+float
+__copysignf (float x, float y)
 {
-	uint32_t ix,iy;
-	GET_FLOAT_WORD(ix,x);
-	GET_FLOAT_WORD(iy,y);
-	SET_FLOAT_WORD(x,(ix&0x7fffffff)|(iy&0x80000000));
-        return x;
+  return __builtin_copysignf (x, y);
 }
 libm_alias_float (__copysign, copysign)
diff --git a/sysdeps/ieee754/ldbl-128/s_copysignl.c b/sysdeps/ieee754/ldbl-128/s_copysignl.c
index a501139..848a184 100644
--- a/sysdeps/ieee754/ldbl-128/s_copysignl.c
+++ b/sysdeps/ieee754/ldbl-128/s_copysignl.c
@@ -27,14 +27,20 @@ static char rcsid[] = "$NetBSD: $";
 #include <math.h>
 #include <math_private.h>
 #include <libm-alias-ldouble.h>
+#include <math-use-builtins.h>
 
 _Float128 __copysignl(_Float128 x, _Float128 y)
 {
+#if USE_COPYSIGNL_BUILTIN
+  return __builtin_copysignl (x, y);
+#else
+  /* Use generic implementation.  */
 	uint64_t hx,hy;
 	GET_LDOUBLE_MSW64(hx,x);
 	GET_LDOUBLE_MSW64(hy,y);
 	SET_LDOUBLE_MSW64(x,(hx&0x7fffffffffffffffULL)
 			    |(hy&0x8000000000000000ULL));
         return x;
+#endif /* ! USE_COPYSIGNL_BUILTIN  */
 }
 libm_alias_ldouble (__copysign, copysign)
diff --git a/sysdeps/s390/fpu/math-use-builtins.h b/sysdeps/s390/fpu/math-use-builtins.h
index 51cb9f9..4c4aad2 100644
--- a/sysdeps/s390/fpu/math-use-builtins.h
+++ b/sysdeps/s390/fpu/math-use-builtins.h
@@ -101,4 +101,11 @@
 
 #endif /* ! HAVE_S390_MIN_Z196_ZARCH_ASM_SUPPORT  */
 
+#define USE_COPYSIGNL_BUILTIN 1
+#if __GNUC_PREREQ (7, 0)
+# define USE_COPYSIGNF128_BUILTIN 1
+#else
+# define USE_COPYSIGNF128_BUILTIN 0
+#endif
+
 #endif /* math-use-builtins.h */