From aec244516102246dc471dfd7bad3e5188a304cf9 Mon Sep 17 00:00:00 2001
From: Leo Yuriev <leo@yuriev.ru>
Date: Sun, 29 Oct 2017 00:57:14 +0300
Subject: [PATCH] mdbx: rework '_noop' and related macros.

Change-Id: Ic9ff3662a6abeb64aa0816e448007dd524794b1e
---
 src/defs.h   | 54 ++++++++++++++++++++++++++++++++++++++++------------
 test/utils.h | 10 ----------
 2 files changed, 42 insertions(+), 22 deletions(-)

diff --git a/src/defs.h b/src/defs.h
index 06886880..5190fa3a 100644
--- a/src/defs.h
+++ b/src/defs.h
@@ -139,14 +139,51 @@
 #   endif
 #endif /* __deprecated */
 
+#if !defined(__noop) && !defined(_MSC_VER)
+#	ifdef __cplusplus
+		static inline void __noop_consume_args() {}
+		template <typename First, typename... Rest>
+		static inline void
+		__noop_consume_args(const First &first, const Rest &... rest) {
+			(void) first; __noop_consume_args(rest...);
+		}
+#		define __noop(...) __noop_consume_args(__VA_ARGS__)
+#	elif defined(__GNUC__) && (!defined(__STRICT_ANSI__) || !__STRICT_ANSI__)
+		static __inline void __noop_consume_args(void* anchor, ...) {
+			(void) anchor;
+		}
+#		define __noop(...) __noop_consume_args(0, ##__VA_ARGS__)
+#	else
+#		define __noop(...) do {} while(0)
+#	endif
+#endif /* __noop */
+
 #ifndef __fallthrough
-#   if __GNUC_PREREQ(7, 0) || __has_attribute(fallthrough)
-#       define __fallthrough __attribute__((fallthrough))
-#   else
-#       define __fallthrough do {} while(0)
-#   endif
+#	if __GNUC_PREREQ(7, 0) || __has_attribute(fallthrough)
+#		define __fallthrough __attribute__((fallthrough))
+#	else
+#		define __fallthrough __noop()
+#	endif
 #endif /* __fallthrough */
 
+#ifndef __unreachable
+#	if __GNUC_PREREQ(4,5)
+#		define __unreachable() __builtin_unreachable()
+#	elif defined(_MSC_VER)
+#		define __unreachable() __assume(0)
+#	else
+#		define __unreachable() __noop()
+#	endif
+#endif /* __unreachable */
+
+#ifndef __prefetch
+#	if defined(__GNUC__) || defined(__clang__)
+#		define __prefetch(ptr) __builtin_prefetch(ptr)
+#	else
+#		define __prefetch(ptr) __noop(ptr)
+#	endif
+#endif /* __prefetch */
+
 #ifndef __aligned
 #   if defined(__GNUC__) || __has_attribute(aligned)
 #       define __aligned(N) __attribute__((aligned(N)))
@@ -283,13 +320,6 @@
 #   endif
 #endif /* unlikely */
 
-#if !defined(__noop) && !defined(_MSC_VER)
-    static __inline int __do_noop(void* crutch, ...) {
-      (void) crutch; return 0;
-    }
-#   define __noop(...) __do_noop(0, __VA_ARGS__)
-#endif /* __noop */
-
 /* Wrapper around __func__, which is a C99 feature */
 #if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L
 #   define mdbx_func_ __func__
diff --git a/test/utils.h b/test/utils.h
index 726f676a..b7fd62eb 100644
--- a/test/utils.h
+++ b/test/utils.h
@@ -51,9 +51,6 @@
 #endif
 
 #if __GNUC_PREREQ(4, 4) || defined(__clang__)
-#if __GNUC_PREREQ(4, 5) || defined(__clang__)
-#define unreachable() __builtin_unreachable()
-#endif
 #define bswap64(v) __builtin_bswap64(v)
 #define bswap32(v) __builtin_bswap32(v)
 #if __GNUC_PREREQ(4, 8) || __has_builtin(__builtin_bswap16)
@@ -67,7 +64,6 @@
     "It is recommended to use Visual Studio 2015 (MSC 19.0) or newer.")
 #endif
 
-#define unreachable() __assume(0)
 #define bswap64(v) _byteswap_uint64(v)
 #define bswap32(v) _byteswap_ulong(v)
 #define bswap16(v) _byteswap_ushort(v)
@@ -90,12 +86,6 @@
 
 #endif /* compiler */
 
-#ifndef unreachable
-#define unreachable()                                                          \
-  do {                                                                         \
-  } while (1)
-#endif
-
 #ifndef bswap64
 #ifdef __bswap_64
 #define bswap64(v) __bswap_64(v)