gcc/libstdc++-v3/doc/html/manual/ext_concurrency_impl.html

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Implementation</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.78.1" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, runtime, library" /><link rel="home" href="../index.html" title="The GNU C++ Library" /><link rel="up" href="ext_concurrency.html" title="Chapter 30. Concurrency" /><link rel="prev" href="ext_concurrency.html" title="Chapter 30. Concurrency" /><link rel="next" href="ext_concurrency_use.html" title="Use" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Implementation</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ext_concurrency.html">Prev</a> </td><th width="60%" align="center">Chapter 30. Concurrency</th><td width="20%" align="right"> <a accesskey="n" href="ext_concurrency_use.html">Next</a></td></tr></table><hr /></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="manual.ext.concurrency.impl"></a>Implementation</h2></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="manual.ext.concurrency.impl.atomic_fallbacks"></a>Using Built-in Atomic Functions</h3></div></div></div><p>The functions for atomic operations described above are either
implemented via compiler intrinsics (if the underlying host is
capable) or by library fallbacks.</p><p>Compiler intrinsics (builtins) are always preferred.  However, as
the compiler builtins for atomics are not universally implemented,
using them directly is problematic, and can result in undefined
function calls.
</p><p>Prior to GCC 4.7 the older <code class="code">__sync</code> intrinsics were used.
An example of an undefined symbol from the use
of <code class="code">__sync_fetch_and_add</code> on an unsupported host is a
missing reference to <code class="code">__sync_fetch_and_add_4</code>.
</p><p>Current releases use the newer <code class="code">__atomic</code> intrinsics,
which are implemented by library calls if the hardware doesn't support them.
Undefined references to functions like
<code class="code">__atomic_is_lock_free</code> should be resolved by linking to
<code class="filename">libatomic</code>, which is usually
installed alongside libstdc++.
</p><p>In addition, on some hosts the compiler intrinsics are enabled
conditionally, via the <code class="code">-march</code> command line flag. This makes
usage vary depending on the target hardware and the flags used during
compile.
</p><p>
<em><span class="remark">
Incomplete/inconsistent. This is only C++11.
</span></em>
</p><p>
If builtins are possible for bool-sized integral types,
<code class="code">ATOMIC_BOOL_LOCK_FREE</code> will be defined.
If builtins are possible for int-sized integral types,
<code class="code">ATOMIC_INT_LOCK_FREE</code> will be defined.
</p><p>For the following hosts, intrinsics are enabled by default.
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>alpha</p></li><li class="listitem"><p>ia64</p></li><li class="listitem"><p>powerpc</p></li><li class="listitem"><p>s390</p></li></ul></div><p>For others, some form of <code class="code">-march</code> may work. On
non-ancient x86 hardware, <code class="code">-march=native</code> usually does the
trick.</p><p> For hosts without compiler intrinsics, but with capable
hardware, hand-crafted assembly is selected. This is the case for the following hosts:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>cris</p></li><li class="listitem"><p>hppa</p></li><li class="listitem"><p>i386</p></li><li class="listitem"><p>i486</p></li><li class="listitem"><p>m48k</p></li><li class="listitem"><p>mips</p></li><li class="listitem"><p>sparc</p></li></ul></div><p>And for the rest, a simulated atomic lock via pthreads.
</p><p> Detailed information about compiler intrinsics for atomic operations can be found in the GCC <a class="link" href="http://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html" target="_top"> documentation</a>.
</p><p> More details on the library fallbacks from the porting <a class="link" href="internals.html#internals.thread_safety" title="Thread Safety">section</a>.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="manual.ext.concurrency.impl.thread"></a>Thread Abstraction</h3></div></div></div><p>A thin layer above IEEE 1003.1 (i.e. pthreads) is used to abstract
the thread interface for GCC. This layer is called "gthread," and is
comprised of one header file that wraps the host's default thread layer with
a POSIX-like interface.
</p><p> The file &lt;gthr-default.h&gt; points to the deduced wrapper for
the current host. In libstdc++ implementation files,
&lt;bits/gthr.h&gt; is used to select the proper gthreads file.
</p><p>Within libstdc++ sources, all calls to underlying thread functionality
use this layer. More detail as to the specific interface can be found in the source <a class="link" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a00883_source.html" target="_top">documentation</a>.
</p><p>By design, the gthread layer is interoperable with the types,
functions, and usage found in the usual &lt;pthread.h&gt; file,
including <code class="code">pthread_t</code>, <code class="code">pthread_once_t</code>, <code class="code">pthread_create</code>,
etc.
</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ext_concurrency.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ext_concurrency.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ext_concurrency_use.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 30. Concurrency </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Use</td></tr></table></div></body></html>
-												PR libstdc++/54102, part 2

2012-08-28  Benjamin Kosnik  <bkoz@redhat.com>

	PR libstdc++/54102, part 2
	* doc/Makefile.am (XSL_HTML_STYLE): use xhtml, not html.
	* doc/Makefile.in: Regenerate.
	* doc/html/*: Same.

From-SVN: r190771

											
										
										
											2012-08-29 06:44:10 +02:00
+								<?xml version="1.0" encoding="UTF-8" standalone="no"?>
-												concurrency_extensions.xml: Update documentation on atomics.

	* doc/xml/manual/concurrency_extensions.xml: Update documentation
	on atomics.
	* doc/xml/manual/using.xml: Likewise. Improve markup.
	* doc/html/*: Regenerate.

From-SVN: r222230

											
										
										
											2015-04-20 13:07:50 +02:00
+								<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Implementation</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.78.1" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, runtime, library" /><link rel="home" href="../index.html" title="The GNU C++ Library" /><link rel="up" href="ext_concurrency.html" title="Chapter 30. Concurrency" /><link rel="prev" href="ext_concurrency.html" title="Chapter 30. Concurrency" /><link rel="next" href="ext_concurrency_use.html" title="Use" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Implementation</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ext_concurrency.html">Prev</a> </td><th width="60%" align="center">Chapter 30. Concurrency</th><td width="20%" align="right"> <a accesskey="n" href="ext_concurrency_use.html">Next</a></td></tr></table><hr /></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="manual.ext.concurrency.impl"></a>Implementation</h2></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="manual.ext.concurrency.impl.atomic_fallbacks"></a>Using Built-in Atomic Functions</h3></div></div></div><p>The functions for atomic operations described above are either
-												*: Regenerate.

2011-09-27  Benjamin Kosnik  <bkoz@redhat.com>

	* doc/html/*: Regenerate.

	* doc/Makefile.am: Un-nest the ext output directory.
	* doc/Makefile.in: Regenerate.
	* spine.xml: Remove authors, add abstract for short
	contents. Rename to index.html for html output.
	* manual/spine.xml: Authors here, manual starts with index.html.
	* api.xml: Update.
	* faq.xml: Same.

Co-Authored-By: Jonathan Wakely <jwakely.gcc@gmail.com>

From-SVN: r179304

											
										
										
											2011-09-28 03:37:10 +02:00
+								implemented via compiler intrinsics (if the underlying host is
 								capable) or by library fallbacks.</p><p>Compiler intrinsics (builtins) are always preferred.  However, as
 								the compiler builtins for atomics are not universally implemented,
 								using them directly is problematic, and can result in undefined
-												concurrency_extensions.xml: Update documentation on atomics.

	* doc/xml/manual/concurrency_extensions.xml: Update documentation
	on atomics.
	* doc/xml/manual/using.xml: Likewise. Improve markup.
	* doc/html/*: Regenerate.

From-SVN: r222230

											
										
										
											2015-04-20 13:07:50 +02:00
+								function calls.
 								</p><p>Prior to GCC 4.7 the older <code class="code">__sync</code> intrinsics were used.
 								An example of an undefined symbol from the use
-												*: Regenerate.

2011-09-27  Benjamin Kosnik  <bkoz@redhat.com>

	* doc/html/*: Regenerate.

	* doc/Makefile.am: Un-nest the ext output directory.
	* doc/Makefile.in: Regenerate.
	* spine.xml: Remove authors, add abstract for short
	contents. Rename to index.html for html output.
	* manual/spine.xml: Authors here, manual starts with index.html.
	* api.xml: Update.
	* faq.xml: Same.

Co-Authored-By: Jonathan Wakely <jwakely.gcc@gmail.com>

From-SVN: r179304

											
										
										
											2011-09-28 03:37:10 +02:00
+								of <code class="code">__sync_fetch_and_add</code> on an unsupported host is a
-												concurrency_extensions.xml: Update documentation on atomics.

	* doc/xml/manual/concurrency_extensions.xml: Update documentation
	on atomics.
	* doc/xml/manual/using.xml: Likewise. Improve markup.
	* doc/html/*: Regenerate.

From-SVN: r222230

											
										
										
											2015-04-20 13:07:50 +02:00
+								missing reference to <code class="code">__sync_fetch_and_add_4</code>.
 								</p><p>Current releases use the newer <code class="code">__atomic</code> intrinsics,
 								which are implemented by library calls if the hardware doesn't support them.
 								Undefined references to functions like
 								<code class="code">__atomic_is_lock_free</code> should be resolved by linking to
 								<code class="filename">libatomic</code>, which is usually
 								installed alongside libstdc++.
-												*: Regenerate.

2011-09-27  Benjamin Kosnik  <bkoz@redhat.com>

	* doc/html/*: Regenerate.

	* doc/Makefile.am: Un-nest the ext output directory.
	* doc/Makefile.in: Regenerate.
	* spine.xml: Remove authors, add abstract for short
	contents. Rename to index.html for html output.
	* manual/spine.xml: Authors here, manual starts with index.html.
	* api.xml: Update.
	* faq.xml: Same.

Co-Authored-By: Jonathan Wakely <jwakely.gcc@gmail.com>

From-SVN: r179304

											
										
										
											2011-09-28 03:37:10 +02:00
+								</p><p>In addition, on some hosts the compiler intrinsics are enabled
 								conditionally, via the <code class="code">-march</code> command line flag. This makes
 								usage vary depending on the target hardware and the flags used during
 								compile.
 								</p><p>
-												abi.xml: Replace gcc-x.y.z with GCC x.y.z or x.y...

	* doc/xml/manual/abi.xml: Replace gcc-x.y.z with GCC x.y.z or x.y,
	remove excessive duplication of version information.
	* doc/html/*: Regenerate.

From-SVN: r182206

											
										
										
											2011-12-11 15:59:26 +01:00
+								<em><span class="remark">
 								Incomplete/inconsistent. This is only C++11.
 								</span></em>
 								</p><p>
-												*: Regenerate.

2011-09-27  Benjamin Kosnik  <bkoz@redhat.com>

	* doc/html/*: Regenerate.

	* doc/Makefile.am: Un-nest the ext output directory.
	* doc/Makefile.in: Regenerate.
	* spine.xml: Remove authors, add abstract for short
	contents. Rename to index.html for html output.
	* manual/spine.xml: Authors here, manual starts with index.html.
	* api.xml: Update.
	* faq.xml: Same.

Co-Authored-By: Jonathan Wakely <jwakely.gcc@gmail.com>

From-SVN: r179304

											
										
										
											2011-09-28 03:37:10 +02:00
+								If builtins are possible for bool-sized integral types,
-												abi.xml: Replace gcc-x.y.z with GCC x.y.z or x.y...

	* doc/xml/manual/abi.xml: Replace gcc-x.y.z with GCC x.y.z or x.y,
	remove excessive duplication of version information.
	* doc/html/*: Regenerate.

From-SVN: r182206

											
										
										
											2011-12-11 15:59:26 +01:00
+								<code class="code">ATOMIC_BOOL_LOCK_FREE</code> will be defined.
-												*: Regenerate.

2011-09-27  Benjamin Kosnik  <bkoz@redhat.com>

	* doc/html/*: Regenerate.

	* doc/Makefile.am: Un-nest the ext output directory.
	* doc/Makefile.in: Regenerate.
	* spine.xml: Remove authors, add abstract for short
	contents. Rename to index.html for html output.
	* manual/spine.xml: Authors here, manual starts with index.html.
	* api.xml: Update.
	* faq.xml: Same.

Co-Authored-By: Jonathan Wakely <jwakely.gcc@gmail.com>

From-SVN: r179304

											
										
										
											2011-09-28 03:37:10 +02:00
+								If builtins are possible for int-sized integral types,
-												abi.xml: Replace gcc-x.y.z with GCC x.y.z or x.y...

	* doc/xml/manual/abi.xml: Replace gcc-x.y.z with GCC x.y.z or x.y,
	remove excessive duplication of version information.
	* doc/html/*: Regenerate.

From-SVN: r182206

											
										
										
											2011-12-11 15:59:26 +01:00
+								<code class="code">ATOMIC_INT_LOCK_FREE</code> will be defined.
-												*: Regenerate.

2011-09-27  Benjamin Kosnik  <bkoz@redhat.com>

	* doc/html/*: Regenerate.

	* doc/Makefile.am: Un-nest the ext output directory.
	* doc/Makefile.in: Regenerate.
	* spine.xml: Remove authors, add abstract for short
	contents. Rename to index.html for html output.
	* manual/spine.xml: Authors here, manual starts with index.html.
	* api.xml: Update.
	* faq.xml: Same.

Co-Authored-By: Jonathan Wakely <jwakely.gcc@gmail.com>

From-SVN: r179304

											
										
										
											2011-09-28 03:37:10 +02:00
+								</p><p>For the following hosts, intrinsics are enabled by default.
-												*: Regenerate.

2013-02-11  Benjamin Kosnik  <bkoz@redhat.com>

	* doc/html/*: Regenerate.

From-SVN: r195959

											
										
										
											2013-02-12 00:24:26 +01:00
+								</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>alpha</p></li><li class="listitem"><p>ia64</p></li><li class="listitem"><p>powerpc</p></li><li class="listitem"><p>s390</p></li></ul></div><p>For others, some form of <code class="code">-march</code> may work. On
-												*: Regenerate.

2011-09-27  Benjamin Kosnik  <bkoz@redhat.com>

	* doc/html/*: Regenerate.

	* doc/Makefile.am: Un-nest the ext output directory.
	* doc/Makefile.in: Regenerate.
	* spine.xml: Remove authors, add abstract for short
	contents. Rename to index.html for html output.
	* manual/spine.xml: Authors here, manual starts with index.html.
	* api.xml: Update.
	* faq.xml: Same.

Co-Authored-By: Jonathan Wakely <jwakely.gcc@gmail.com>

From-SVN: r179304

											
										
										
											2011-09-28 03:37:10 +02:00
+								non-ancient x86 hardware, <code class="code">-march=native</code> usually does the
 								trick.</p><p> For hosts without compiler intrinsics, but with capable
 								hardware, hand-crafted assembly is selected. This is the case for the following hosts:
-												*: Regenerate.

2013-02-11  Benjamin Kosnik  <bkoz@redhat.com>

	* doc/html/*: Regenerate.

From-SVN: r195959

											
										
										
											2013-02-12 00:24:26 +01:00
+								</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>cris</p></li><li class="listitem"><p>hppa</p></li><li class="listitem"><p>i386</p></li><li class="listitem"><p>i486</p></li><li class="listitem"><p>m48k</p></li><li class="listitem"><p>mips</p></li><li class="listitem"><p>sparc</p></li></ul></div><p>And for the rest, a simulated atomic lock via pthreads.
-												backwards_compatibility.xml (backwards.third.headers): Update link.

	* doc/xml/manual/backwards_compatibility.xml (backwards.third.headers):
	Update link.
	* doc/xml/manual/policy_data_structures_biblio.xml (bibliography):
	Fix broken links.
	* doc/xml/manual/shared_ptr.xml (shared_ptr.impl): Likewise.
	* doc/xml/manual/using_exceptions.xml (bibliography): Likewise.
	* doc/xml/manual/concurrency_extensions.xml
	(manual.ext.concurrency.impl.atomic_fallbacks): Likewise.
	* doc/html/*: Regenerate.

From-SVN: r209002

											
										
										
											2014-04-01 23:31:02 +02:00
+								</p><p> Detailed information about compiler intrinsics for atomic operations can be found in the GCC <a class="link" href="http://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html" target="_top"> documentation</a>.
-												*: Regenerate.

2011-09-27  Benjamin Kosnik  <bkoz@redhat.com>

	* doc/html/*: Regenerate.

	* doc/Makefile.am: Un-nest the ext output directory.
	* doc/Makefile.in: Regenerate.
	* spine.xml: Remove authors, add abstract for short
	contents. Rename to index.html for html output.
	* manual/spine.xml: Authors here, manual starts with index.html.
	* api.xml: Update.
	* faq.xml: Same.

Co-Authored-By: Jonathan Wakely <jwakely.gcc@gmail.com>

From-SVN: r179304

											
										
										
											2011-09-28 03:37:10 +02:00
+								</p><p> More details on the library fallbacks from the porting <a class="link" href="internals.html#internals.thread_safety" title="Thread Safety">section</a>.
-												*: Regenerate.

2013-02-11  Benjamin Kosnik  <bkoz@redhat.com>

	* doc/html/*: Regenerate.

From-SVN: r195959

											
										
										
											2013-02-12 00:24:26 +01:00
+								</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="manual.ext.concurrency.impl.thread"></a>Thread Abstraction</h3></div></div></div><p>A thin layer above IEEE 1003.1 (i.e. pthreads) is used to abstract
-												*: Regenerate.

2011-09-27  Benjamin Kosnik  <bkoz@redhat.com>

	* doc/html/*: Regenerate.

	* doc/Makefile.am: Un-nest the ext output directory.
	* doc/Makefile.in: Regenerate.
	* spine.xml: Remove authors, add abstract for short
	contents. Rename to index.html for html output.
	* manual/spine.xml: Authors here, manual starts with index.html.
	* api.xml: Update.
	* faq.xml: Same.

Co-Authored-By: Jonathan Wakely <jwakely.gcc@gmail.com>

From-SVN: r179304

											
										
										
											2011-09-28 03:37:10 +02:00
+								the thread interface for GCC. This layer is called "gthread," and is
 								comprised of one header file that wraps the host's default thread layer with
 								a POSIX-like interface.
 								</p><p> The file &lt;gthr-default.h&gt; points to the deduced wrapper for
 								the current host. In libstdc++ implementation files,
 								&lt;bits/gthr.h&gt; is used to select the proper gthreads file.
 								</p><p>Within libstdc++ sources, all calls to underlying thread functionality
-												*: Regenerate.

2012-08-28  Benjamin Kosnik  <bkoz@redhat.com>

	* doc/html/*: Regenerate.

From-SVN: r190770

											
										
										
											2012-08-29 04:09:55 +02:00
+								use this layer. More detail as to the specific interface can be found in the source <a class="link" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a00883_source.html" target="_top">documentation</a>.
-												*: Regenerate.

2011-09-27  Benjamin Kosnik  <bkoz@redhat.com>

	* doc/html/*: Regenerate.

	* doc/Makefile.am: Un-nest the ext output directory.
	* doc/Makefile.in: Regenerate.
	* spine.xml: Remove authors, add abstract for short
	contents. Rename to index.html for html output.
	* manual/spine.xml: Authors here, manual starts with index.html.
	* api.xml: Update.
	* faq.xml: Same.

Co-Authored-By: Jonathan Wakely <jwakely.gcc@gmail.com>

From-SVN: r179304

											
										
										
											2011-09-28 03:37:10 +02:00
+								</p><p>By design, the gthread layer is interoperable with the types,
 								functions, and usage found in the usual &lt;pthread.h&gt; file,
 								including <code class="code">pthread_t</code>, <code class="code">pthread_once_t</code>, <code class="code">pthread_create</code>,
 								etc.
-												Makefile.am: Add missing file.

	* doc/Makefile.am: Add missing file. Use generate.consistent.ids
	parameter for DocBook HTML generation.
	* doc/Makefile.in: Regenerate.
	* doc/doxygen/user.cfg.in: Unset DOT_FONTNAME.
	* doc/xml/faq.xml: Update content and improve formatting.
	* doc/xml/manual/abi.xml: Add stable ID attribute and fix links.
	* doc/xml/manual/allocator.xml: Add stable ID attribute.
	* doc/xml/manual/bitmap_allocator.xml: Likewise.
	* doc/xml/manual/build_hacking.xml: Likewise.
	* doc/xml/manual/codecvt.xml: Change URL.
	* doc/xml/manual/ctype.xml: Add stable ID attribute.
	* doc/xml/manual/debug_mode.xml: Likewise.
	* doc/xml/manual/documentation_hacking.xml: Likewise.
	* doc/xml/manual/evolution.xml: Likewise.
	* doc/xml/manual/extensions.xml: Likewise.
	* doc/xml/manual/locale.xml: Likewise.
	* doc/xml/manual/messages.xml: Make section id consistent, improve
	markup, change URL.
	* doc/xml/manual/parallel_mode.xml: Add stable ID attributes.
	* doc/xml/manual/profile_mode.xml: Likewise.
	* doc/xml/manual/shared_ptr.xml: Likewise. Also remove old info.
	* doc/xml/manual/status_cxx1998.xml: Add stable ID attributes.
	* doc/xml/manual/status_cxx2011.xml: Likewise.
	* doc/xml/manual/status_cxx2014.xml: Likewise.
	* doc/xml/manual/status_cxxtr1.xml: Likewise.
	* doc/xml/manual/status_cxxtr24733.xml: Likewise.
	* doc/xml/manual/using.xml: Likewise.
	* doc/html/*: Regenerate.

From-SVN: r211376

											
										
										
											2014-06-09 16:47:17 +02:00
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