Use GCC builtins for trunc functions if desired.

This patch is using the corresponding GCC builtin for truncf, trunc,
truncl and truncf128 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>

1 files changed, 6 insertions, 0 deletions

diff --git a/sysdeps/ieee754/flt-32/s_truncf.c b/sysdeps/ieee754/flt-32/s_truncf.c
index e587706b5b..274638820e 100644
--- a/sysdeps/ieee754/flt-32/s_truncf.c
+++ b/sysdeps/ieee754/flt-32/s_truncf.c
@@ -22,11 +22,16 @@
 
 #include <math_private.h>
 #include <libm-alias-float.h>
+#include <math-use-builtins.h>
 
 
 float
 __truncf (float x)
 {
+#if USE_TRUNCF_BUILTIN
+  return __builtin_truncf (x);
+#else
+  /* Use generic implementation.  */
   int32_t i0, j0;
   int sx;
 
@@ -49,6 +54,7 @@ __truncf (float x)
     }
 
   return x;
+#endif /* ! USE_TRUNCF_BUILTIN  */
 }
 #ifndef __truncf
 libm_alias_float (__trunc, trunc)