[src/trunk]: src Document the __builtin_return_address() GNU extension. Again...

[jruoho <jruoho%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/3674d05cc356
branches:  trunk
changeset: 759884:3674d05cc356
user:      jruoho <jruoho%NetBSD.org@localhost>
date:      Sun Dec 19 09:30:49 2010 +0000

description:
Document the __builtin_return_address() GNU extension. Again this is well
justified due to the wide use of these non-standard extensions in the tree.

diffstat:

 distrib/sets/lists/comp/mi                |   8 +++-
 share/man/man3/Makefile                   |   6 +-
 share/man/man3/__builtin_return_address.3 |  67 +++++++++++++++++++++++++++++++
 3 files changed, 78 insertions(+), 3 deletions(-)

diffs (133 lines):

diff -r 4c0807ed52e8 -r 3674d05cc356 distrib/sets/lists/comp/mi
--- a/distrib/sets/lists/comp/mi        Sun Dec 19 08:56:17 2010 +0000
+++ b/distrib/sets/lists/comp/mi        Sun Dec 19 09:30:49 2010 +0000
@@ -1,4 +1,4 @@
-#      $NetBSD: mi,v 1.1555 2010/12/19 08:10:07 jruoho Exp $
+#      $NetBSD: mi,v 1.1556 2010/12/19 09:30:49 jruoho Exp $
 #
 # Note: don't delete entries from here - mark them as "obsolete" instead.
 #
@@ -4908,7 +4908,9 @@
 ./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_frame_address.0 comp-c-catman           .cat
 ./usr/share/man/cat3/__builtin_object_size.0   comp-c-catman           .cat
+./usr/share/man/cat3/__builtin_return_address.0        comp-c-catman           .cat
 ./usr/share/man/cat3/__cacheline_aligned.0     comp-c-catman           .cat
 ./usr/share/man/cat3/__constfunc.0             comp-c-catman           .cat
 ./usr/share/man/cat3/__dead.0                  comp-c-catman           .cat
@@ -10997,7 +10999,9 @@
 ./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_frame_address.html     comp-c-htmlman          html
 ./usr/share/man/html3/__builtin_object_size.html       comp-c-htmlman          html
+./usr/share/man/html3/__builtin_return_address.html    comp-c-htmlman          html
 ./usr/share/man/html3/__cacheline_aligned.html comp-c-htmlman          html
 ./usr/share/man/html3/__constfunc.html         comp-c-htmlman          html
 ./usr/share/man/html3/__dead.html              comp-c-htmlman          html
@@ -16886,7 +16890,9 @@
 ./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_frame_address.3 comp-c-man              .man
 ./usr/share/man/man3/__builtin_object_size.3   comp-c-man              .man
+./usr/share/man/man3/__builtin_return_address.3        comp-c-man              .man
 ./usr/share/man/man3/__cacheline_aligned.3     comp-c-man              .man
 ./usr/share/man/man3/__constfunc.3             comp-c-man              .man
 ./usr/share/man/man3/__dead.3                  comp-c-man              .man
diff -r 4c0807ed52e8 -r 3674d05cc356 share/man/man3/Makefile
--- a/share/man/man3/Makefile   Sun Dec 19 08:56:17 2010 +0000
+++ b/share/man/man3/Makefile   Sun Dec 19 09:30:49 2010 +0000
@@ -1,8 +1,9 @@
-#      $NetBSD: Makefile,v 1.65 2010/12/19 08:10:08 jruoho Exp $
+#      $NetBSD: Makefile,v 1.66 2010/12/19 09:30:50 jruoho Exp $
 #      @(#)Makefile    8.2 (Berkeley) 12/13/93
 
 MAN=   _DIAGASSERT.3 __CONCAT.3 __UNCONST.3 CMSG_DATA.3 \
-       __alignof__.3 __arraycount.3 __insn_barrier.3 \
+       __alignof__.3 __arraycount.3 \
+       __builtin_return_address.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 \
@@ -15,6 +16,7 @@
 
 MLINKS+=__CONCAT.3 __STRING.3
 MLINKS+=__UNCONST.3 __UNVOLATILE.3
+MLINKS+=__builtin_return_address.3 __builtin_frame_address.3
 MLINKS+=attribute.3 __dead.3 \
        attribute.3 __pure.3 \
        attribute.3 __constfunc.3 \
diff -r 4c0807ed52e8 -r 3674d05cc356 share/man/man3/__builtin_return_address.3
--- /dev/null   Thu Jan 01 00:00:00 1970 +0000
+++ b/share/man/man3/__builtin_return_address.3 Sun Dec 19 09:30:49 2010 +0000
@@ -0,0 +1,67 @@
+.\" $NetBSD: __builtin_return_address.3,v 1.1 2010/12/19 09:30:50 jruoho Exp $
+.\"
+.\" Copyright (c) 2010 Jukka Ruohonen <jruohonen%iki.fi@localhost>
+.\" 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 __BUILTIN_RETURN_ADDRESS 3
+.Os
+.Sh NAME
+.Nm __builtin_return_address
+.Nd the return address of a function
+.Sh SYNOPSIS
+.Ft void *
+.Fn __builtin_return_address "unsigned int level"
+.Ft void *
+.Fn __builtin_frame_address "unsigned int level"
+.Sh DESCRIPTION
+The
+.Fn __builtin_return_address
+is a
+.Tn GNU
+extension for obtaining the return address of the current function
+or one of the callers of the current function.
+.Pp
+The parameter
+.Fa level
+specifies the number of frames that should be scanned up in the call stack.
+A value 0 returns the address of the current function,
+a value 1 requests the address of the caller of the current function,
+a value 2 asks for the address of the caller's caller, and so forth.
+If the top of the call stack has been reached, the function will return 0.
+Note also that on some architectures it is only possible
+to determine the address of the current function.
+In such cases a value 0 is returned.
+Thus, it is usually safe to only use the value 0 for
+.Fa level .
+.Pp
+The
+.Fn __builtin_frame_address
+behaves similarly, but returns the address of the function
+frame rather than the return address of the function.
+.Sh SEE ALSO
+.Xr gcc 1 ,
+.Xr __builtin_object_size 3
+.Sh CAVEATS
+These are non-standard, compiler-specific extensions.