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<body>
<div id="header">
<h1>ccache news</h1>
<span id="revnumber">version 3.1</span>
<div id="toc">
<div id="toctitle">Table of Contents</div>
<noscript><p><b>JavaScript must be enabled in your browser to display the table of contents.</b></p></noscript>
</div>
</div>
<div id="content">
<h2 id="_ccache_3_1">ccache 3.1</h2>
<div class="sectionbody">
<div class="paragraph"><p>Release date: 2010-09-16</p></div>
<h3 id="_new_features_and_improvements">New features and improvements</h3><div style="clear:left"></div>
<div class="ulist"><ul>
<li>
<p>
Added support for hashing the output of a custom command (e.g. <tt>$compiler
--version</tt>) to identify the compiler instead of stat-ing or hashing the
compiler binary. This can improve robustness when the compiler (as seen
by ccache) actually isn’t the real compiler but another compiler wrapper.
</p>
</li>
<li>
<p>
Added support for caching compilations that use precompiled headers. (See
the manual for important instructions regarding this.)
</p>
</li>
<li>
<p>
Locking of the files containing statistics counters is now done using
symlinks instead of POSIX locks. This should make ccache behave a lot
better on file systems where POSIX locks are slow or broken (e.g. NFS on
some systems).
</p>
</li>
<li>
<p>
Manifest files are now updated without the need of taking locks.
</p>
</li>
<li>
<p>
Updates of statistics counters are now always done in one of the
sub-level statistics files. This reduces lock contention, which
especially improves performance on slow NFS mounts.
</p>
</li>
<li>
<p>
Reading and writing of statistics counters has been made
forward-compatible (unknown counters are retained).
</p>
</li>
<li>
<p>
Files are now read without using mmap(). This has two benefits: it’s more
robust against file changes during reading and it improves performance on
poor systems where mmap() doesn’t use the disk cache.
</p>
</li>
<li>
<p>
Added <tt>.cp</tt> and <tt>.CP</tt> as known C++ suffixes.
</p>
</li>
<li>
<p>
Improved logging.
</p>
</li>
<li>
<p>
Added <tt>-install_name</tt> as an option known to take an argument. (This
improves statistics when using the Darwin linker.)
</p>
</li>
</ul></div>
<h3 id="_bug_fixes">Bug fixes</h3><div style="clear:left"></div>
<div class="ulist"><ul>
<li>
<p>
Non-fatal error messages are now never printed to stderr but logged
instead.
</p>
</li>
<li>
<p>
Fixed a bug affecting failing commands when <tt>--ccache-skip</tt> is used.
</p>
</li>
<li>
<p>
Made <tt>--ccache-skip</tt> work for all options.
</p>
</li>
<li>
<p>
EINTR is now handled correctly.
</p>
</li>
</ul></div>
<h3 id="_other">Other</h3><div style="clear:left"></div>
<div class="ulist"><ul>
<li>
<p>
Work on porting ccache to win32 (native), mostly done by Ramiro Polla.
The port is not yet finished, but will hopefully be complete in some
subsequent release.
</p>
</li>
<li>
<p>
Added a <tt>--nostats</tt> flag to the performance benchmark program.
</p>
</li>
<li>
<p>
Made the performance benchmark program more accurate when measuring cache
hits.
</p>
</li>
<li>
<p>
Added a new test framework for unit tests written in C.
</p>
</li>
<li>
<p>
Got rid of <tt>configure-dev</tt>; dev mode is now given by <tt>dev.mk.in</tt>
presence.
</p>
</li>
<li>
<p>
Improved documentation on how to combine ccache with other compiler
wrappers (like <tt>distcc</tt>).
</p>
</li>
<li>
<p>
New <tt>LICENSE.txt</tt> file with licensing and copyright details about bundled
source code.
</p>
</li>
<li>
<p>
New <tt>AUTHORS.txt</tt> file with a list of ccache contributors.
</p>
</li>
<li>
<p>
New <tt>HACKING.txt</tt> file with some notes about ccache code conventions.
</p>
</li>
</ul></div>
</div>
<h2 id="_ccache_3_0_1">ccache 3.0.1</h2>
<div class="sectionbody">
<div class="paragraph"><p>Release date: 2010-07-15</p></div>
<h3 id="_bug_fixes_2">Bug fixes</h3><div style="clear:left"></div>
<div class="ulist"><ul>
<li>
<p>
The statistics counter “called for link” is now correctly updated when
linking with a single object file.
</p>
</li>
<li>
<p>
Fixed a problem with out-of-source builds.
</p>
</li>
</ul></div>
</div>
<h2 id="_ccache_3_0">ccache 3.0</h2>
<div class="sectionbody">
<div class="paragraph"><p>Release date: 2010-06-20</p></div>
<h3 id="_general">General</h3><div style="clear:left"></div>
<div class="ulist"><ul>
<li>
<p>
ccache is now licensed under the GNU General Public License (GPL) version
3 or later.
</p>
</li>
</ul></div>
<h3 id="_upgrade_notes">Upgrade notes</h3><div style="clear:left"></div>
<div class="ulist"><ul>
<li>
<p>
The way the hashes are calculated has changed, so you won’t get cache
hits for compilation results stored by older ccache versions. Because of
this, you might as well clear the old cache directory with <tt>ccache
--clear</tt> if you want, unless you plan to keep using an older ccache
version.
</p>
</li>
</ul></div>
<h3 id="_new_features_and_improvements_2">New features and improvements</h3><div style="clear:left"></div>
<div class="ulist"><ul>
<li>
<p>
ccache now has a “direct mode” where it computes a hash of the source
code (including all included files) and compiler options without
running the preprocessor. By not running the preprocessor, CPU usage is
reduced; the speed is somewhere between 1 and 5 times that of ccache
running in traditional mode, depending on the circumstances. The speedup
will be higher when I/O is fast (e.g., when files are in the disk cache).
The direct mode can be disabled by setting <tt>CCACHE_NODIRECT</tt>.
</p>
</li>
<li>
<p>
Support has been added for rewriting absolute paths to relative paths
when hashing, in order to increase cache hit rate when building the same
source code in different directories even when compiling with <tt>-g</tt> and
when using absolute include directory paths. This is done by setting the
<tt>CCACHE_BASEDIR</tt> environment variable to an absolute path that specifies
which paths to rewrite.
</p>
</li>
<li>
<p>
Object files are now optionally stored compressed in the cache. The
runtime cost is negligible, and more files will fit in the ccache
directory and in the disk cache. Set <tt>CCACHE_COMPRESS</tt> to enable object
file compression. Note that you can’t use compression in combination with
the hard link feature.
</p>
</li>
<li>
<p>
A <tt>CCACHE_COMPILERCHECK</tt> option has been added. This option tells ccache
what compiler-identifying information to hash to ensure that results
retrieved from the cache are accurate. Possible values are: none (don’t
hash anything), mtime (hash the compiler’s mtime and size) and content
(hash the content of the compiler binary). The default is mtime.
</p>
</li>
<li>
<p>
It is now possible to specify extra files whose contents should be
included in the hash sum by setting the <tt>CCACHE_EXTRAFILES</tt> option.
</p>
</li>
<li>
<p>
Added support for Objective-C and Objective-C++. The statistics counter
“not a C/C++ file” has been renamed to “unsupported source language”.
</p>
</li>
<li>
<p>
Added support for the <tt>-x</tt> compiler option.
</p>
</li>
<li>
<p>
Added support for long command-line options.
</p>
</li>
<li>
<p>
A <tt>CACHEDIR.TAG</tt> file is now created in the cache directory. See
<a href="http://www.brynosaurus.com/cachedir/">http://www.brynosaurus.com/cachedir/</a>.
</p>
</li>
<li>
<p>
Messages printed to the debug log (specified by <tt>CCACHE_LOGFILE</tt>) have
been improved.
</p>
</li>
<li>
<p>
You can relax some checks that ccache does in direct mode by setting
<tt>CCACHE_SLOPPINESS</tt>. See the manual for more information.
</p>
</li>
<li>
<p>
<tt>CCACHE_TEMPDIR</tt> no longer needs to be on the same filesystem as
<tt>CCACHE_DIR</tt>.
</p>
</li>
<li>
<p>
The default value of <tt>CCACHE_TEMPDIR</tt> has been changed to
<tt>$CCACHE_DIR/tmp</tt> to avoid cluttering the top directory.
</p>
</li>
<li>
<p>
Temporary files that later will be moved into the cache are now created
in the cache directory they will end up in. This makes ccache more
friendly to Linux’s directory layout.
</p>
</li>
<li>
<p>
Improved the test suite and added tests for most of the new
functionality. It’s now also possible to specify a subset of tests to
run.
</p>
</li>
<li>
<p>
Standard error output from the compiler is now only stored in the cache
if it’s non-empty.
</p>
</li>
<li>
<p>
If the compiler produces no object file or an empty object file, but
gives a zero exit status (could be due to a file system problem, a buggy
program specified by <tt>CCACHE_PREFIX</tt>, etc.), ccache copes with it
properly.
</p>
</li>
<li>
<p>
Added <tt>installcheck</tt> and <tt>distcheck</tt> make targets.
</p>
</li>
<li>
<p>
Clarified cache size limit options' and cleanup semantics.
</p>
</li>
<li>
<p>
Improved display of cache max size values.
</p>
</li>
<li>
<p>
The following options are no longer hashed in the preprocessor mode:
<tt>-imacros</tt>, <tt>-imultilib</tt>, <tt>-iprefix</tt>, <tt>-iquote</tt>, <tt>-isysroot</tt>,
<tt>-iwithprefix</tt>, <tt>-iwithprefixbefore</tt>, <tt>-nostdinc</tt>, <tt>-nostdinc++</tt> and
<tt>-U</tt>.
</p>
</li>
</ul></div>
<h3 id="_bug_fixes_3">Bug fixes</h3><div style="clear:left"></div>
<div class="ulist"><ul>
<li>
<p>
Various portability improvements.
</p>
</li>
<li>
<p>
Improved detection of home directory.
</p>
</li>
<li>
<p>
User-defined <tt>CPPFLAGS</tt> and <tt>LDFLAGS</tt> are now respected in the Makefile.
</p>
</li>
<li>
<p>
Fixed NFS issues.
</p>
</li>
<li>
<p>
Computation of the hash sum has been improved to decrease the risk of
hash collisions. For instance, the compiler options <tt>-X -Y</tt> and <tt>-X-Y</tt>
previously contributed equally to the hash sum.
</p>
</li>
<li>
<p>
Bail out on too hard compiler options <tt>--coverage</tt>, <tt>-fprofile-arcs</tt>,
<tt>-fprofile-generate</tt>, <tt>-fprofile-use</tt>, <tt>-frepo</tt>, <tt>-ftest-coverage</tt> and
<tt>-save-temps</tt>. Also bail out on <tt>@file</tt> style options.
</p>
</li>
<li>
<p>
Errors when using multiple <tt>-arch</tt> compiler options are now noted as
“unsupported compiler option”.
</p>
</li>
<li>
<p>
<tt>-MD</tt>/<tt>-MMD</tt> options without <tt>-MT</tt>/<tt>-MF</tt> are now handled correctly.
</p>
</li>
<li>
<p>
The <tt>-finput-charset</tt> option is now handled correctly.
</p>
</li>
<li>
<p>
Added support for <tt>-Wp,-MD</tt> and <tt>-Wp,-MMD</tt> options.
</p>
</li>
<li>
<p>
The compiler options <tt>-Xassembler</tt>, <tt>-b</tt>, <tt>-G</tt> and <tt>-V</tt> are now correctly
recognized as taking an argument.
</p>
</li>
<li>
<p>
Debug information containing line numbers of predefined and command-line
macros (enabled with the compiler option <tt>-g3</tt>) will now be correct.
</p>
</li>
<li>
<p>
Corrected LRU cleanup handling of object files.
</p>
</li>
<li>
<p>
<tt>utimes()</tt> is now used instead of <tt>utime()</tt> when available.
</p>
</li>
<li>
<p>
Non-writable cache directories are now handled gracefully.
</p>
</li>
<li>
<p>
Corrected documentation about sharing the cache directory.
</p>
</li>
<li>
<p>
Fixed compilation warnings from GCC 4.3.
</p>
</li>
<li>
<p>
The command specified by <tt>CCACHE_PREFIX</tt> is no longer part of the hash.
</p>
</li>
<li>
<p>
Fixed bad memory access spotted by Valgrind.
</p>
</li>
<li>
<p>
Fixed a bug in <tt>x_realloc</tt>.
</p>
</li>
<li>
<p>
Freed memory is no longer referenced when compiling a <tt>.i</tt>/<tt>.ii</tt> file and
falling back to running the real compiler.
</p>
</li>
<li>
<p>
The test suite is now immune to external values of the <tt>CCACHE_*</tt>
environment variables.
</p>
</li>
<li>
<p>
Improved detection of recursive invocation.
</p>
</li>
<li>
<p>
The ccache binary is now not unconditionally stripped when installing.
</p>
</li>
<li>
<p>
Statistics counters are now correctly updated for -E option failures and
internal errors.
</p>
</li>
</ul></div>
</div>
</div>
<div id="footnotes"><hr /></div>
<div id="footer">
<div id="footer-text">
Version 3.1<br />
Last updated 2010-09-16 18:56:48 CEST
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</div>
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