From: Andrew MacLeod <amacleod@redhat.com>
Date: Wed, 15 Feb 2012 16:41:25 +0000 (+0000)
Subject: extend.texi: Reserve upper bits of memory model for future use.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=b1cef2a5429146655e2d9c99e29c6d2422f6255c;p=gcc.git

extend.texi: Reserve upper bits of memory model for future use.


2012-02-15  Andrew MacLeod  <amacleod@redhat.com>

	* extend.texi: Reserve upper bits of memory model for future use.

From-SVN: r184277
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 3cbbf18ecb9..9d860de0124 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,7 @@
+2012-02-15  Andrew MacLeod  <amacleod@redhat.com>
+
+	* extend.texi: Reserve upper bits of memory model for future use.
+
 2012-01-15  Georg-Johann Lay  <avr@gjlay.de>
 	    Anatoly Sokolov <aesok@post.ru>
 	    Eric Weddington <eric.weddington@atmel.com>
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index b666a2ef1c4..e4d17cf48ff 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -7092,6 +7092,11 @@ functions will map any runtime value to @code{__ATOMIC_SEQ_CST} rather
 than invoke a runtime library call or inline a switch statement.  This is
 standard compliant, safe, and the simplest approach for now.
 
+The memory model parameter is a signed int, but only the lower 8 bits are
+reserved for the memory model.  The remainder of the signed int is reserved
+for future use and should be 0.  Use of the predefined atomic values will
+ensure proper usage.
+
 @deftypefn {Built-in Function} @var{type} __atomic_load_n (@var{type} *ptr, int memmodel)
 This built-in function implements an atomic load operation.  It returns the
 contents of @code{*@var{ptr}}.