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

[Stefan Liebler <stli at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=6c1b6a5e8cd91e0e1965509ad91e627e60eb00a3

commit 6c1b6a5e8cd91e0e1965509ad91e627e60eb00a3
Author: Stefan Liebler <stli@linux.ibm.com>
Date:   Wed Dec 11 15:09:20 2019 +0100

    Use GCC builtins for floor functions if desired.
    
    This patch is using the corresponding GCC builtin for floorf, floor,
    floorl and floorf128 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>

Diff:
---
 sysdeps/generic/math-use-builtins.h         |  5 +++++
 sysdeps/ieee754/dbl-64/s_floor.c            |  6 ++++++
 sysdeps/ieee754/float128/float128_private.h |  3 +++
 sysdeps/ieee754/flt-32/s_floorf.c           |  6 ++++++
 sysdeps/ieee754/ldbl-128/s_floorl.c         |  6 ++++++
 sysdeps/s390/fpu/math-use-builtins.h        | 11 +++++++++++
 6 files changed, 37 insertions(+)

diff --git a/sysdeps/generic/math-use-builtins.h b/sysdeps/generic/math-use-builtins.h
index 64b4a4b..e1c5df6 100644
--- a/sysdeps/generic/math-use-builtins.h
+++ b/sysdeps/generic/math-use-builtins.h
@@ -31,4 +31,9 @@
 #define USE_RINTL_BUILTIN 0
 #define USE_RINTF128_BUILTIN 0
 
+#define USE_FLOOR_BUILTIN 0
+#define USE_FLOORF_BUILTIN 0
+#define USE_FLOORL_BUILTIN 0
+#define USE_FLOORF128_BUILTIN 0
+
 #endif /* math-use-builtins.h */
diff --git a/sysdeps/ieee754/dbl-64/s_floor.c b/sysdeps/ieee754/dbl-64/s_floor.c
index ce0c42b..7832521 100644
--- a/sysdeps/ieee754/dbl-64/s_floor.c
+++ b/sysdeps/ieee754/dbl-64/s_floor.c
@@ -35,6 +35,7 @@
 #include <math_private.h>
 #include <stdint.h>
 #include <libm-alias-double.h>
+#include <math-use-builtins.h>
 
 /*
  * floor(x)
@@ -47,6 +48,10 @@
 double
 __floor (double x)
 {
+#if USE_FLOOR_BUILTIN
+  return __builtin_floor (x);
+#else
+  /* Use generic implementation.  */
   int64_t i0;
   EXTRACT_WORDS64 (i0, x);
   int32_t j0 = ((i0 >> 52) & 0x7ff) - 0x3ff;
@@ -74,6 +79,7 @@ __floor (double x)
   else if (j0 == 0x400)
     return x + x;			/* inf or NaN */
   return x;
+#endif /* ! USE_FLOOR_BUILTIN  */
 }
 #ifndef __floor
 libm_alias_double (__floor, floor)
diff --git a/sysdeps/ieee754/float128/float128_private.h b/sysdeps/ieee754/float128/float128_private.h
index f458e7b..8c8a74a 100644
--- a/sysdeps/ieee754/float128/float128_private.h
+++ b/sysdeps/ieee754/float128/float128_private.h
@@ -144,6 +144,8 @@
 #define USE_NEARBYINTL_BUILTIN USE_NEARBYINTF128_BUILTIN
 #undef USE_RINTL_BUILTIN
 #define USE_RINTL_BUILTIN USE_RINTF128_BUILTIN
+#undef USE_FLOORL_BUILTIN
+#define USE_FLOORL_BUILTIN USE_FLOORF128_BUILTIN
 
 /* IEEE function renames.  */
 #define __ieee754_acoshl __ieee754_acoshf128
@@ -349,6 +351,7 @@
 #define __builtin_signbitl __builtin_signbit
 #define __builtin_nearbyintl __builtin_nearbyintf128
 #define __builtin_rintl __builtin_rintf128
+#define __builtin_floorl __builtin_floorf128
 
 /* Get the constant suffix from bits/floatn-compat.h.  */
 #define L(x) __f128 (x)
diff --git a/sysdeps/ieee754/flt-32/s_floorf.c b/sysdeps/ieee754/flt-32/s_floorf.c
index b34d967..afe02a1 100644
--- a/sysdeps/ieee754/flt-32/s_floorf.c
+++ b/sysdeps/ieee754/flt-32/s_floorf.c
@@ -24,10 +24,15 @@
 #include <math.h>
 #include <math_private.h>
 #include <libm-alias-float.h>
+#include <math-use-builtins.h>
 
 float
 __floorf(float x)
 {
+#if USE_FLOORF_BUILTIN
+  return __builtin_floorf (x);
+#else
+  /* Use generic implementation.  */
 	int32_t i0,j0;
 	uint32_t i;
 	GET_FLOAT_WORD(i0,x);
@@ -50,6 +55,7 @@ __floorf(float x)
 	}
 	SET_FLOAT_WORD(x,i0);
 	return x;
+#endif /* ! USE_FLOORF_BUILTIN  */
 }
 #ifndef __floorf
 libm_alias_float (__floor, floor)
diff --git a/sysdeps/ieee754/ldbl-128/s_floorl.c b/sysdeps/ieee754/ldbl-128/s_floorl.c
index f340a3f..cfe0083 100644
--- a/sysdeps/ieee754/ldbl-128/s_floorl.c
+++ b/sysdeps/ieee754/ldbl-128/s_floorl.c
@@ -28,9 +28,14 @@ static char rcsid[] = "$NetBSD: $";
 #include <math.h>
 #include <math_private.h>
 #include <libm-alias-ldouble.h>
+#include <math-use-builtins.h>
 
 _Float128 __floorl(_Float128 x)
 {
+#if USE_FLOORL_BUILTIN
+  return __builtin_floorl (x);
+#else
+  /* Use generic implementation.  */
 	int64_t i0,i1,j0;
 	uint64_t i,j;
 	GET_LDOUBLE_WORDS64(i0,i1,x);
@@ -65,5 +70,6 @@ _Float128 __floorl(_Float128 x)
 	}
 	SET_LDOUBLE_WORDS64(x,i0,i1);
 	return x;
+#endif /* ! USE_FLOORL_BUILTIN  */
 }
 libm_alias_ldouble (__floor, floor)
diff --git a/sysdeps/s390/fpu/math-use-builtins.h b/sysdeps/s390/fpu/math-use-builtins.h
index 8b702a6..c213c16 100644
--- a/sysdeps/s390/fpu/math-use-builtins.h
+++ b/sysdeps/s390/fpu/math-use-builtins.h
@@ -34,12 +34,18 @@
 # define USE_RINTF_BUILTIN 1
 # define USE_RINTL_BUILTIN 1
 
+# define USE_FLOOR_BUILTIN 1
+# define USE_FLOORF_BUILTIN 1
+# define USE_FLOORL_BUILTIN 1
+
 # if __GNUC_PREREQ (8, 0)
 #  define USE_NEARBYINTF128_BUILTIN 1
 #  define USE_RINTF128_BUILTIN 1
+#  define USE_FLOORF128_BUILTIN 1
 # else
 #  define USE_NEARBYINTF128_BUILTIN 0
 #  define USE_RINTF128_BUILTIN 0
+#  define USE_FLOORF128_BUILTIN 0
 # endif
 
 #else
@@ -55,6 +61,11 @@
 # define USE_RINTL_BUILTIN 0
 # define USE_RINTF128_BUILTIN 0
 
+# define USE_FLOOR_BUILTIN 0
+# define USE_FLOORF_BUILTIN 0
+# define USE_FLOORL_BUILTIN 0
+# define USE_FLOORF128_BUILTIN 0
+
 #endif /* ! HAVE_S390_MIN_Z196_ZARCH_ASM_SUPPORT  */
 
 #endif /* math-use-builtins.h */