Module Name: src
Committed By: jruoho
Date: Sun Dec 19 08:10:09 UTC 2010
Modified Files:
src/distrib/sets/lists/comp: mi
src/share/man/man3: Makefile attribute.3 offsetof.3 typeof.3
Added Files:
src/share/man/man3: __alignof__.3
Log Message:
Document the __alignof__ GNU extension.
To generate a diff of this commit:
cvs rdiff -u -r1.1554 -r1.1555 src/distrib/sets/lists/comp/mi
cvs rdiff -u -r1.64 -r1.65 src/share/man/man3/Makefile
cvs rdiff -u -r0 -r1.1 src/share/man/man3/__alignof__.3
cvs rdiff -u -r1.8 -r1.9 src/share/man/man3/attribute.3
cvs rdiff -u -r1.2 -r1.3 src/share/man/man3/offsetof.3
cvs rdiff -u -r1.1 -r1.2 src/share/man/man3/typeof.3
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/distrib/sets/lists/comp/mi
diff -u src/distrib/sets/lists/comp/mi:1.1554 src/distrib/sets/lists/comp/mi:1.1555
--- src/distrib/sets/lists/comp/mi:1.1554 Fri Dec 17 12:14:03 2010
+++ src/distrib/sets/lists/comp/mi Sun Dec 19 08:10:07 2010
@@ -1,4 +1,4 @@
-# $NetBSD: mi,v 1.1554 2010/12/17 12:14:03 jruoho Exp $
+# $NetBSD: mi,v 1.1555 2010/12/19 08:10:07 jruoho Exp $
#
# Note: don't delete entries from here - mark them as "obsolete" instead.
#
@@ -4906,6 +4906,7 @@
./usr/share/man/cat3/__UNCONST.0 comp-c-catman .cat
./usr/share/man/cat3/__UNVOLATILE.0 comp-c-catman .cat
./usr/share/man/cat3/__aligned.0 comp-c-catman .cat
+./usr/share/man/cat3/__alignof__.0 comp-c-catman .cat
./usr/share/man/cat3/__arraycount.0 comp-c-catman .cat
./usr/share/man/cat3/__builtin_object_size.0 comp-c-catman .cat
./usr/share/man/cat3/__cacheline_aligned.0 comp-c-catman .cat
@@ -10994,6 +10995,7 @@
./usr/share/man/html3/__UNCONST.html comp-c-htmlman html
./usr/share/man/html3/__UNVOLATILE.html comp-c-htmlman html
./usr/share/man/html3/__aligned.html comp-c-htmlman html
+./usr/share/man/html3/__alignof__.html comp-c-htmlman html
./usr/share/man/html3/__arraycount.html comp-c-htmlman html
./usr/share/man/html3/__builtin_object_size.html comp-c-htmlman html
./usr/share/man/html3/__cacheline_aligned.html comp-c-htmlman html
@@ -16882,6 +16884,7 @@
./usr/share/man/man3/__UNCONST.3 comp-c-man .man
./usr/share/man/man3/__UNVOLATILE.3 comp-c-man .man
./usr/share/man/man3/__aligned.3 comp-c-man .man
+./usr/share/man/man3/__alignof__.3 comp-c-man .man
./usr/share/man/man3/__arraycount.3 comp-c-man .man
./usr/share/man/man3/__builtin_object_size.3 comp-c-man .man
./usr/share/man/man3/__cacheline_aligned.3 comp-c-man .man
Index: src/share/man/man3/Makefile
diff -u src/share/man/man3/Makefile:1.64 src/share/man/man3/Makefile:1.65
--- src/share/man/man3/Makefile:1.64 Fri Dec 17 12:14:04 2010
+++ src/share/man/man3/Makefile Sun Dec 19 08:10:08 2010
@@ -1,8 +1,8 @@
-# $NetBSD: Makefile,v 1.64 2010/12/17 12:14:04 jruoho Exp $
+# $NetBSD: Makefile,v 1.65 2010/12/19 08:10:08 jruoho Exp $
# @(#)Makefile 8.2 (Berkeley) 12/13/93
MAN= _DIAGASSERT.3 __CONCAT.3 __UNCONST.3 CMSG_DATA.3 \
- __arraycount.3 __insn_barrier.3 \
+ __alignof__.3 __arraycount.3 __insn_barrier.3 \
assert.3 attribute.3 bits.3 bitstring.3 \
cdefs.3 dirent.3 dlfcn.3 dl_iterate_phdr.3 end.3 \
fast_divide32.3 ffs32.3 gcq.3 \
Index: src/share/man/man3/attribute.3
diff -u src/share/man/man3/attribute.3:1.8 src/share/man/man3/attribute.3:1.9
--- src/share/man/man3/attribute.3:1.8 Fri Dec 17 08:23:04 2010
+++ src/share/man/man3/attribute.3 Sun Dec 19 08:10:09 2010
@@ -1,4 +1,4 @@
-.\" $NetBSD: attribute.3,v 1.8 2010/12/17 08:23:04 jruoho Exp $
+.\" $NetBSD: attribute.3,v 1.9 2010/12/19 08:10:09 jruoho Exp $
.\"
.\" Copyright (c) 2010 The NetBSD Foundation, Inc.
.\" All rights reserved.
@@ -27,7 +27,7 @@
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.Dd December 16, 2010
+.Dd December 19, 2010
.Dt ATTRIBUTE 3
.Os
.Sh NAME
@@ -208,6 +208,9 @@
The effectiveness of
.Fn __aligned
is largely dependent on the linker.
+The
+.Xr __alignof__ 3
+operator can be used to examine the alignment.
.It Fn __section "section"
The
.Fn __section
Index: src/share/man/man3/offsetof.3
diff -u src/share/man/man3/offsetof.3:1.2 src/share/man/man3/offsetof.3:1.3
--- src/share/man/man3/offsetof.3:1.2 Sun Mar 21 12:36:21 2010
+++ src/share/man/man3/offsetof.3 Sun Dec 19 08:10:09 2010
@@ -1,4 +1,4 @@
-.\" $NetBSD: offsetof.3,v 1.2 2010/03/21 12:36:21 jruoho Exp $
+.\" $NetBSD: offsetof.3,v 1.3 2010/12/19 08:10:09 jruoho Exp $
.\"
.\" $OpenBSD: offsetof.3,v 1.2 2010/02/18 18:30:19 jmc Exp $
.\"
@@ -17,7 +17,7 @@
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.\"
-.Dd February 18, 2010
+.Dd December 19, 2010
.Dt OFFSETOF 3
.Os
.Sh NAME
@@ -42,7 +42,9 @@
.Ar member
is not aligned to a byte boundary (i.e. it is a bit-field).
.Sh SEE ALSO
-.Xr stddef 3
+.Xr __alignof__ 3 ,
+.Xr stddef 3 ,
+.Xr typeof 3
.Sh STANDARDS
The
.Fn offsetof
Index: src/share/man/man3/typeof.3
diff -u src/share/man/man3/typeof.3:1.1 src/share/man/man3/typeof.3:1.2
--- src/share/man/man3/typeof.3:1.1 Fri Dec 17 12:14:04 2010
+++ src/share/man/man3/typeof.3 Sun Dec 19 08:10:09 2010
@@ -1,4 +1,4 @@
-.\" $NetBSD: typeof.3,v 1.1 2010/12/17 12:14:04 jruoho Exp $
+.\" $NetBSD: typeof.3,v 1.2 2010/12/19 08:10:09 jruoho Exp $
.\"
.\" Copyright (c) 2010 Jukka Ruohonen <[email protected]>
.\" All rights reserved.
@@ -24,7 +24,7 @@
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.Dd December 17, 2010
+.Dd December 19, 2010
.Dt TYPEOF 3
.Os
.Sh NAME
@@ -54,6 +54,7 @@
.Ed
.Sh SEE ALSO
.Xr gcc 1 ,
+.Xr __alignof__ 3 ,
.Xr attribute 3 ,
.Xr offsetof 3
.Sh CAVEATS
Added files:
Index: src/share/man/man3/__alignof__.3
diff -u /dev/null src/share/man/man3/__alignof__.3:1.1
--- /dev/null Sun Dec 19 08:10:09 2010
+++ src/share/man/man3/__alignof__.3 Sun Dec 19 08:10:09 2010
@@ -0,0 +1,84 @@
+.\" $NetBSD: __alignof__.3,v 1.1 2010/12/19 08:10:09 jruoho Exp $
+.\"
+.\" Copyright (c) 2010 Jukka Ruohonen <[email protected]>
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\" notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\" notice, this list of conditions and the following disclaimer in the
+.\" documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+.\" POSSIBILITY OF SUCH DAMAGE.
+.\"
+.Dd December 19, 2010
+.Dt __alignof__ 3
+.Os
+.Sh NAME
+.Nm __alignof__
+.Nd GNU extension for alignment of an object
+.Sh SYNOPSIS
+.Ft int
+.Fn __alignof__ "void type"
+.Sh DESCRIPTION
+The
+.Fn __alignof__
+operator returns the alignment of its operand.
+The operand can be a type or an expression.
+If the operand is a
+.Sq lvalue ,
+the return value represents the required alignment of the underlying type,
+not the actual alignment of the specified
+.Sq lvalue .
+.Pp
+The returned value is specific to the architecture and the
+.Tn ABI .
+If the architecture does not impose strict alignment requirements,
+.Fn __alignof__
+returns the minimum required alignment.
+If
+.Xr __aligned 3
+is used to increase the alignment,
+.Fn __alignof__
+returns the specified alignment.
+.Sh EXAMPLES
+The syntax is comparable to the
+.Fn sizeof
+operator.
+If the architecture aligns integers along 32-bit address boundaries,
+the following should print the value 4.
+.Bd -literal -offset indent
+(void)printf(\*[q]%d\\n\*[q], __alignof__(int));
+.Ed
+.Pp
+On the other hand, the following example probably prints the value 1,
+even though this is unlikely to be the actual alignment of the
+structure member.
+.Bd -literal -offset indent
+struct align {
+ int x;
+ char y;
+} a;
+
+(void)printf(\*[q]%d\\n\*[q], __alignof__(a.y));
+.Ed
+.Sh SEE ALSO
+.Xr gcc 1 ,
+.Xr attribute 3 ,
+.Xr offsetof 3 ,
+.Xr typeof 3
+.Sh CAVEATS
+This is a non-standard, compiler-specific extension.
