From 0b974dba2d6b5581ce422ed883209de46f313fb6 Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Wed, 11 Oct 2017 16:01:52 -0700
Subject: Add configure infrastructure to detect support for C99's restrict.

Will be used in later commits improving performance for a few key
routines where information about aliasing allows for significantly
better code generation.

This allows to use the C99 'restrict' keyword without breaking C89, or
for that matter C++, compilers. If not supported it's defined to be
empty.

Author: Andres Freund
Discussion: https://postgr.es/m/20170914063418.sckdzgjfrsbekae4@alap3.anarazel.de
---
 src/include/pg_config.h.in    | 14 ++++++++++++++
 src/include/pg_config.h.win32 | 11 +++++++++++
 2 files changed, 25 insertions(+)

(limited to 'src')

diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index b0298cca19c..80ee37dd622 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -923,6 +923,20 @@
    if such a type exists, and if the system does not define it. */
 #undef intptr_t
 
+/* Define to the equivalent of the C99 'restrict' keyword, or to
+   nothing if this is not supported.  Do not define if restrict is
+   supported directly.  */
+#undef restrict
+/* Work around a bug in Sun C++: it does not support _Restrict or
+   __restrict__, even though the corresponding Sun C compiler ends up with
+   "#define restrict _Restrict" or "#define restrict __restrict__" in the
+   previous line.  Perhaps some future version of Sun C++ will work with
+   restrict; if so, hopefully it defines __RESTRICT like Sun C does.  */
+#if defined __SUNPRO_CC && !defined __RESTRICT
+# define _Restrict
+# define __restrict__
+#endif
+
 /* Define to empty if the C compiler does not understand signed types. */
 #undef signed
 
diff --git a/src/include/pg_config.h.win32 b/src/include/pg_config.h.win32
index b76aad02676..3be1c235aaa 100644
--- a/src/include/pg_config.h.win32
+++ b/src/include/pg_config.h.win32
@@ -681,6 +681,17 @@
 #define inline __inline
 #endif
 
+/* Define to the equivalent of the C99 'restrict' keyword, or to
+   nothing if this is not supported.  Do not define if restrict is
+   supported directly.  */
+/* Visual Studio 2008 and upwards */
+#if (_MSC_VER >= 1500)
+/* works for C and C++ in msvc */
+#define restrict __restrict
+#else
+#define restrict
+#endif
+
 /* Define to empty if the C compiler does not understand signed types. */
 /* #undef signed */
 
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