Use GCC builtins for nearbyint functions if desired.

This patch is using the corresponding GCC builtin for nearbyintf, nearbyint,
nearbintl and nearbyintf128 if the USE_FUNCTION_BUILTIN macros are defined to one
in math-use-builtins.h.

This is the case for s390 if build with at least --march=z196 --mzarch.
Otherwise the generic implementation is used.  The code of the generic
implementation is not changed.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

4 files changed, 37 insertions, 18 deletions

diff --git a/sysdeps/ieee754/dbl-64/s_nearbyint.c b/sysdeps/ieee754/dbl-64/s_nearbyint.c
index c261885c5a..2deaeb2568 100644
--- a/sysdeps/ieee754/dbl-64/s_nearbyint.c
+++ b/sysdeps/ieee754/dbl-64/s_nearbyint.c
@@ -26,16 +26,20 @@
 #include <math_private.h>
 #include <fenv_private.h>
 #include <libm-alias-double.h>
-
-static const double
-TWO52[2] = {
-	    4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
-	    -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
-};
+#include <math-use-builtins.h>
 
 double
 __nearbyint (double x)
 {
+#if USE_NEARBYINT_BUILTIN
+  return __builtin_nearbyint (x);
+#else
+  /* Use generic implementation.  */
+  static const double
+    TWO52[2] = {
+		4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
+		-4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
+  };
   fenv_t env;
   int64_t i0, sx;
   int32_t j0;
@@ -67,5 +71,6 @@ __nearbyint (double x)
   math_force_eval (t);
   libc_fesetenv (&env);
   return t;
+#endif /* ! USE_NEARBYINT_BUILTIN  */
 }
 libm_alias_double (__nearbyint, nearbyint)
diff --git a/sysdeps/ieee754/float128/float128_private.h b/sysdeps/ieee754/float128/float128_private.h
index 4e31ef365b..e96986a968 100644
--- a/sysdeps/ieee754/float128/float128_private.h
+++ b/sysdeps/ieee754/float128/float128_private.h
@@ -139,6 +139,9 @@
 #undef libm_alias_double_ldouble
 #define libm_alias_double_ldouble(func) libm_alias_float64_float128 (func)
 
+#include <math-use-builtins.h>
+#undef USE_NEARBYINTL_BUILTIN
+#define USE_NEARBYINTL_BUILTIN USE_NEARBYINTF128_BUILTIN
 
 /* IEEE function renames.  */
 #define __ieee754_acoshl __ieee754_acoshf128
@@ -342,6 +345,7 @@
 /* Builtin renames.  */
 #define __builtin_copysignl __builtin_copysignf128
 #define __builtin_signbitl __builtin_signbit
+#define __builtin_nearbyintl __builtin_nearbyintf128
 
 /* Get the constant suffix from bits/floatn-compat.h.  */
 #define L(x) __f128 (x)
diff --git a/sysdeps/ieee754/flt-32/s_nearbyintf.c b/sysdeps/ieee754/flt-32/s_nearbyintf.c
index acedf34c90..b37e003e12 100644
--- a/sysdeps/ieee754/flt-32/s_nearbyintf.c
+++ b/sysdeps/ieee754/flt-32/s_nearbyintf.c
@@ -21,16 +21,20 @@
 #include <math_private.h>
 #include <fenv_private.h>
 #include <libm-alias-float.h>
-
-static const float
-TWO23[2]={
-  8.3886080000e+06, /* 0x4b000000 */
- -8.3886080000e+06, /* 0xcb000000 */
-};
+#include <math-use-builtins.h>
 
 float
 __nearbyintf(float x)
 {
+#if USE_NEARBYINTF_BUILTIN
+  return __builtin_nearbyintf (x);
+#else
+  /* Use generic implementation.  */
+  static const float
+    TWO23[2] = {
+		8.3886080000e+06, /* 0x4b000000 */
+		-8.3886080000e+06, /* 0xcb000000 */
+  };
 	fenv_t env;
 	int32_t i0,j0,sx;
 	float w,t;
@@ -58,5 +62,6 @@ __nearbyintf(float x)
 	math_force_eval (t);
 	libc_fesetenvf (&env);
 	return t;
+#endif /* ! USE_NEARBYINT_BUILTIN  */
 }
 libm_alias_float (__nearbyint, nearbyint)
diff --git a/sysdeps/ieee754/ldbl-128/s_nearbyintl.c b/sysdeps/ieee754/ldbl-128/s_nearbyintl.c
index f044cb4334..a4ad8e82e5 100644
--- a/sysdeps/ieee754/ldbl-128/s_nearbyintl.c
+++ b/sysdeps/ieee754/ldbl-128/s_nearbyintl.c
@@ -28,15 +28,19 @@
 #include <math-barriers.h>
 #include <math_private.h>
 #include <libm-alias-ldouble.h>
-
-static const _Float128
-TWO112[2]={
-  L(5.19229685853482762853049632922009600E+33), /* 0x406F000000000000, 0 */
- L(-5.19229685853482762853049632922009600E+33)  /* 0xC06F000000000000, 0 */
-};
+#include <math-use-builtins.h>
 
 _Float128 __nearbyintl(_Float128 x)
 {
+#if USE_NEARBYINTL_BUILTIN
+  return __builtin_nearbyintl (x);
+#else
+  /* Use generic implementation.  */
+  static const _Float128
+    TWO112[2] = {
+		 L(5.19229685853482762853049632922009600E+33), /* 0x406F000000000000, 0 */
+		 L(-5.19229685853482762853049632922009600E+33)  /* 0xC06F000000000000, 0 */
+  };
 	fenv_t env;
 	int64_t i0,j0,sx;
 	uint64_t i1 __attribute__ ((unused));
@@ -65,5 +69,6 @@ _Float128 __nearbyintl(_Float128 x)
 	math_force_eval (t);
 	fesetenv (&env);
 	return t;
+#endif /* ! USE_NEARBYINTL_BUILTIN  */
 }
 libm_alias_ldouble (__nearbyint, nearbyint)