[glibc/azanella/mips-hw-fp-round] mips: Implement trunc with hardware floating-point rounding instruction

[Adhemerval Zanella <azanella@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=b046c66f0874fa75d1bc859851f7d2e28481905f

commit b046c66f0874fa75d1bc859851f7d2e28481905f
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Tue Dec 26 16:52:19 2023 -0300

    mips: Implement trunc with hardware floating-point rounding instruction

Diff:
---
 sysdeps/mips/fpu/round_to_integer.h |  4 ++++
 sysdeps/mips/fpu/s_trunc.c          | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/sysdeps/mips/fpu/round_to_integer.h b/sysdeps/mips/fpu/round_to_integer.h
index a2146e4a71..78975ce3eb 100644
--- a/sysdeps/mips/fpu/round_to_integer.h
+++ b/sysdeps/mips/fpu/round_to_integer.h
@@ -26,6 +26,7 @@ enum round_mode
 {
   CEIL,
   FLOOR,
+  TRUNC,
 };
 
 static inline double
@@ -46,6 +47,9 @@ round_to_integer_double (enum round_mode mode, double x)
   case FLOOR:
     asm ("floor.l.d %0, %0" : "+f" (r));
     break;
+  case TRUNC:
+    asm ("trunc.l.d %0, %0" : "+f" (r));
+    break;
   }
   libc_fesetenv (&fe);
 
diff --git a/sysdeps/mips/fpu/s_trunc.c b/sysdeps/mips/fpu/s_trunc.c
new file mode 100644
index 0000000000..fcc9a8f008
--- /dev/null
+++ b/sysdeps/mips/fpu/s_trunc.c
@@ -0,0 +1,36 @@
+/* Round to integer, toward zero.  MIPS version.
+   Copyright (C) 2023 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/>.  */
+
+#if ((__mips_fpr == 64) \
+      && (__mips_hard_float == 1) \
+      && ((__mips == 32 && __mips_isa_rev > 1) || __mips == 64))
+
+#define NO_MATH_REDIRECT
+#include <math.h>
+#include <round_to_integer.h>
+#include <libm-alias-double.h>
+
+double
+__trunc (double x)
+{
+  return round_to_integer_double (TRUNC, x);
+}
+libm_alias_double (__trunc, trunc)
+#else
+# include <sysdeps/ieee754/dbl-64/s_trunc.c>
+#endif