From: dlg <dlg@openbsd.org>
Date: Wed, 3 Jan 2018 23:20:10 +0000 (+0000)
Subject: rework __swapXX to avoid the use of __statement.
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=837da382461abe58acb462403e3fe895ffcc9a7e;p=openbsd

rework __swapXX to avoid the use of __statement.

the primary motivation of this was to allow the use of things like
htons() and htole16() as case labels. previously gcc would vomit
with "expression is not an integer constant expression" if you tried
that.

ok guenther@
---

diff --git a/sys/sys/_endian.h b/sys/sys/_endian.h
index e390cce0bb3..c4429bbff1a 100644
--- a/sys/sys/_endian.h
+++ b/sys/sys/_endian.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: _endian.h,v 1.3 2018/01/03 06:27:42 dlg Exp $	*/
+/*	$OpenBSD: _endian.h,v 1.4 2018/01/03 23:20:10 dlg Exp $	*/
 
 /*-
  * Copyright (c) 1997 Niklas Hallqvist.  All rights reserved.
@@ -43,40 +43,8 @@
 #define _BIG_ENDIAN	4321
 #define _PDP_ENDIAN	3412
 
-#ifdef __GNUC__
-
-#define __swap16gen(x) __statement({					\
-	__uint16_t __swap16gen_x = (x);					\
-									\
-	(__uint16_t)((__swap16gen_x & 0xff) << 8 |			\
-	    (__swap16gen_x & 0xff00) >> 8);				\
-})
-
-#define __swap32gen(x) __statement({					\
-	__uint32_t __swap32gen_x = (x);					\
-									\
-	(__uint32_t)((__swap32gen_x & 0xff) << 24 |			\
-	    (__swap32gen_x & 0xff00) << 8 |				\
-	    (__swap32gen_x & 0xff0000) >> 8 |				\
-	    (__swap32gen_x & 0xff000000) >> 24);			\
-})
-
-#define __swap64gen(x) __statement({					\
-	__uint64_t __swap64gen_x = (x);					\
-									\
-	(__uint64_t)((__swap64gen_x & 0xff) << 56 |			\
-	    (__swap64gen_x & 0xff00ULL) << 40 |				\
-	    (__swap64gen_x & 0xff0000ULL) << 24 |			\
-	    (__swap64gen_x & 0xff000000ULL) << 8 |			\
-	    (__swap64gen_x & 0xff00000000ULL) >> 8 |			\
-	    (__swap64gen_x & 0xff0000000000ULL) >> 24 |			\
-	    (__swap64gen_x & 0xff000000000000ULL) >> 40 |		\
-	    (__swap64gen_x & 0xff00000000000000ULL) >> 56);		\
-})
-
-#else /* __GNUC__ */
-
 /* Note that these macros evaluate their arguments several times.  */
+
 #define __swap16gen(x)							\
     (__uint16_t)(((__uint16_t)(x) & 0xffU) << 8 | ((__uint16_t)(x) & 0xff00U) >> 8)
 
@@ -95,53 +63,29 @@
 	    ((__uint64_t)(x) & 0xff000000000000ULL) >> 40 |		\
 	    ((__uint64_t)(x) & 0xff00000000000000ULL) >> 56)
 
-#endif /* __GNUC__ */
+#ifndef __HAVE_MD_SWAP
+static inline __uint16_t
+__swap16md(__uint16_t x)
+{
+	return (__swap16gen(x));
+}
+
+static inline __uint32_t
+__swap32md(__uint32_t x)
+{
+	return (__swap32gen(x));
+}
+
+static inline __uint64_t
+__swap64md(__uint64_t x)
+{
+	return (__swap64gen(x));
+}
+#endif
 
-/*
- * Define __HAVE_MD_SWAP if you provide __swap{16,32}md functions/macros
- * that are optimized for your architecture,  These will be used for
- * __swap{16,32} unless the argument is a constant and we are using GCC,
- * where we can take advantage of the CSE phase much better by using the
- * generic version.
- */
-#ifdef __HAVE_MD_SWAP
-#if __GNUC__
-
-#define __swap16(x) __statement({					\
-	__uint16_t __swap16_x = (x);					\
-									\
-	(__uint16_t)(__builtin_constant_p(x) ? __swap16gen(__swap16_x) :\
-	    __swap16md(__swap16_x));					\
-})
-
-#define __swap32(x) __statement({					\
-	__uint32_t __swap32_x = (x);					\
-									\
-	(__uint32_t)(__builtin_constant_p(x) ? __swap32gen(__swap32_x) :\
-	    __swap32md(__swap32_x));					\
-})
-
-#define __swap64(x) __statement({					\
-	__uint64_t __swap64_x = (x);					\
-									\
-	(__uint64_t)(__builtin_constant_p(x) ? __swap64gen(__swap64_x) :\
-	    __swap64md(__swap64_x));					\
-})
-
-#else
-
-/* have MD macros, but not gcc */
-#define __swap16 __swap16md
-#define __swap32 __swap32md
-#define __swap64 __swap64md
-
-#endif /* __GNUC__  */
-
-#else /* __HAVE_MD_SWAP */
-#define __swap16 __swap16gen
-#define __swap32 __swap32gen
-#define __swap64 __swap64gen
-#endif /* __HAVE_MD_SWAP */
+#define __swap16(x) (__builtin_constant_p(x) ? __swap16gen(x) : __swap16md(x))
+#define __swap32(x) (__builtin_constant_p(x) ? __swap32gen(x) : __swap32md(x))
+#define __swap64(x) (__builtin_constant_p(x) ? __swap64gen(x) : __swap64md(x))
 
 #if _BYTE_ORDER == _LITTLE_ENDIAN