ccache/NEWS.txt
2010-04-24 10:36:57 +02:00

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ccache news
===========
ccache 3.0pre1 (unreleased)
---------------------------
Changes since version 2.4.
General
~~~~~~~
- ccache is now licensed under the GNU Public License (GPL) version 3 or
later.
Upgrade 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 --cleanup` if you want, unless you plan to
keep using an older ccache version.
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.
- A `CCACHE_COMPILERCHECK` 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.
- 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/>.
- Messages printed to the debug log (specified by `CCACHE_LOGFILE`) have
been improved.
- 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.
- For debugging purposes, the variable `CCACHE_VERBOSE` may now be set to
make ccache print executed commands to standard output.
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.
- The `-finput-charset` option is now handled correctly.
- Added support for `-Wp,-MD` and `-Wp,-MMD` options.
- Debug information containing line numbers of predefined and command-line
macros (enabled with the compiler option `-g3`) will now be correct.
- 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`.
- 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.