ccache/NEWS
2010-02-27 14:01:14 +01:00

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Changes since ccache 2.4
------------------------
New features and improvements:
- ccache now has a "direct mode" where it computes a hash of the source code
and compiler arguments without running the preprocessor. By not running the
preprocessor, CPU usage is reduced; the runtime is about 0.2-1.0 times that
of ccache running in traditional mode. The relative 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 CCACHE_NODIRECT.
- When hashing the output from the preprocessor, absolute paths are rewritten
to relative paths, but only for paths under the directory specified by
CCACHE_BASEDIR. Paths specified by -I and similar options get the same
treatment. This is done to get cache hits even when compiling with -g and
when using absolute include directory paths. Absolute paths in the standard
error text will also be more accurate. The default value of CCACHE_BASEDIR
is the current working directory. To disable the rewriting, set
CCACHE_BASEDIR to the empty string.
- Object files are now by default stored compressed in the cache. The runtime
cost is negligible, and more files will fit in the ccache directory and in
the disk cache. CCACHE_NOCOMPRESS can be set to disable object file
compression.
- Added CCACHE_COMPILERCHECK option that 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.
- Temporary files are now created in the directory they will end up in. This
makes ccache more friendly to Linux's directory layout.
- Added support for long command-line options.
- A CACHEDIR.TAG file is now created in the cache directory. See
<http://www.brynosaurus.com/cachedir/>.
- Improved logging.
- By default, ccache now puts temporary files in CCACHE_DIR/tmp to avoid
cluttering the top directory.
- 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.
- Standard error output from the compiler is now only stored in the cache if
it's non-empty.
- 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 CCACHE_PREFIX, etc.), ccache copes with it properly.
- Added installcheck and distcheck make targets.
- Clarified cache size limit options' semantics
- Improved display of cache max size values.
Bug fixes:
- Fixed build on FreeBSD.
- Improved detection of home directory.
- User-defined CPPFLAGS and LDFLAGS are now respected in the Makefile.
- Fixed NFS issues.
- Bail out on too hard compiler options --coverage, -fprofile-arcs,
-fprofile-generate, -fprofile-use, -ftest-coverage and -save-temps. Also
bail out on "@file" style options.
- -MD/-MMD options without -MT/-MF are now handled correctly.
- Added support for -Wp,-MD and -Wp,-MMD options.
- Corrected LRU cleanup handling of object files.
- utimes() is now used instead of utime() when available.
- Non-writable cache directories are now handled gracefully.
- Corrected documentation about sharing the cache directory.
- Fixed compilation warnings from GCC 4.3.
- The command specified by CCACHE_PREFIX is no longer part of the hash.
- Fixed bad memory access spotted by Valgrind.
- Fixed a bug in x_realloc.
- Removed deprecated constructions from ccache.yo.
- Freed memory is no longer referenced when compiling a .i/.ii file and
falling back to running the real compiler.
- The test suite is now immune to external values of the CCACHE_* environment
variables.
Upgrading notes:
- The way the hashes are calculated has changed, so you won't get cache hits
for compilation results stored by older ccache versions.
- The statistics counters "files in cache" and "cache size" now only count
object files. (Previously, files containing cached standard error output
were counted as well.) The existing values of the two counters will be
erroneous at first after the upgrade, but will correct themselves
eventually when enough cleanups have been made, or when you run "ccache
--cleanup".
- The "max file" and "max cache size" settings now specify thresholds for
object files count and size.
- Because of the changes mentioned above, you might as well clear the old
cache directory with "ccache -C" if you want, unless you plan to keep using
an older ccache version.