S390: Implement roundtoint and converttoint and define TOINT_INTRINSICS.

This patch implements roundtoint and convertoint for s390
by using the load-fp-integer and convert-to-fixed instructions.
Both functions are using "round to nearest with ties away from zero"
rounding mode and do not raise inexact exceptions.

1 files changed, 53 insertions, 0 deletions

diff --git a/sysdeps/s390/fpu/math_private.h b/sysdeps/s390/fpu/math_private.h
new file mode 100644
index 0000000..a1ae91a
--- /dev/null
+++ b/sysdeps/s390/fpu/math_private.h
@@ -0,0 +1,53 @@
+/* Configure optimized libm functions.  S390 version.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef S390_MATH_PRIVATE_H
+#define S390_MATH_PRIVATE_H 1
+
+#include <stdint.h>
+#include <math.h>
+
+#ifdef HAVE_S390_MIN_Z196_ZARCH_ASM_SUPPORT
+# define TOINT_INTRINSICS 1
+
+static inline double_t
+roundtoint (double_t x)
+{
+  double_t y;
+  /* The z196 zarch "load fp integer" (fidbra) instruction is rounding
+     x to the nearest integer with ties away from zero (M3-field: 1)
+     where inexact exceptions are suppressed (M4-field: 4).  */
+  __asm__ ("fidbra %0,1,%1,4" : "=f" (y) : "f" (x));
+  return y;
+}
+
+static inline int32_t
+converttoint (double_t x)
+{
+  int32_t y;
+  /* The z196 zarch "convert to fixed" (cfdbra) instruction is rounding
+     x to the nearest integer with ties away from zero (M3-field: 1)
+     where inexact exceptions are suppressed (M4-field: 4).  */
+  __asm__ ("cfdbra %0,1,%1,4" : "=d" (y) : "f" (x) : "cc");
+  return y;
+}
+#endif
+
+#include_next <math_private.h>
+
+#endif