[PATCH v1 2/2] x86_64: Add {u}int_fast defs ideal for x86_64

[Noah Goldstein <goldstein.w.n@gmail.com>]

{u}int_fast{16|32} should never use 64-bit types. 64-bit instructions
often use more code size (REX prefix) and a variety of instructions are
slower on many implementations (div, bswap, etc...).

Full xcheck passes on x86_64.
---
 sysdeps/x86_64/int-fast.h | 50 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 sysdeps/x86_64/int-fast.h

diff --git a/sysdeps/x86_64/int-fast.h b/sysdeps/x86_64/int-fast.h
new file mode 100644
index 0000000000..8f341de646
--- /dev/null
+++ b/sysdeps/x86_64/int-fast.h
@@ -0,0 +1,50 @@
+/* Copyright (C) 2022 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 _INT_FAST_X86_64_H
+#define _INT_FAST_X86_64_H	1
+
+#define __HAS_INT_FAST_DEFS	1
+
+/* Signed.  */
+typedef signed char		int_fast8_t;
+/* On x86_64 32-bit instructions are almost always fastest.  */
+typedef int			int_fast16_t;
+typedef int			int_fast32_t;
+typedef long int		int_fast64_t;
+
+/* Unsigned.  */
+typedef unsigned char		uint_fast8_t;
+/* On x86_64 32-bit instructions are almost always fastest.  */
+typedef unsigned int		uint_fast16_t;
+typedef unsigned int		uint_fast32_t;
+typedef unsigned long int	uint_fast64_t;
+
+
+# define __INT_FAST8_BASE		INT8
+# define __INT_FAST16_BASE		INT32
+# define __INT_FAST32_BASE		INT32
+# define __INT_FAST64_BASE		INT64
+
+# define __UINT_FAST8_BASE		UINT8
+# define __UINT_FAST16_BASE		UINT32
+# define __UINT_FAST32_BASE		UINT32
+# define __UINT_FAST64_BASE		UINT64
+
+# include <sysdeps/generic/int-fast.h>
+
+#endif
-- 
2.25.1