select.mk: Tune ccache options
With these adjustments, cached object files can now be shared across
multiple Android trees on a single workstation:
* Compiler binary modification time no longer causes cache misses,
as a hash of the compiler binary is taken rather than looking
at the mtime and size
* Header file modification time no longer causes cache misses,
the headers are now always hashed
* Macros such as __DATE__ and __TIME__ no longer cause cache misses
* All paths in preprocessed source (due to use of -g) are now relative
These options require ccache 3.1 or later to be used; ccache 2.4 will
Signed-off-by: Andrew Boie <email@example.com>
diff --git a/core/combo/select.mk b/core/combo/select.mk
index 803cfc0..e485d00 100644
@@ -60,6 +60,23 @@
+ # The default check uses size and modification time, causing false misses
+ # since the mtime depends when the repo was checked out
+ export CCACHE_COMPILERCHECK := content
+ # See man page, optimizations to get more cache hits
+ # implies that __DATE__ and __TIME__ are not critical for functionality.
+ # Ignore include file modification time since it will depend on when
+ # the repo was checked out
+ export CCACHE_SLOPPINESS := time_macros,include_file_mtime,file_macro
+ # Turn all preprocessor absolute paths into relative paths.
+ # Fixes absolute paths in preprocessed source due to use of -g.
+ # We don't really use system headers much so the rootdir is
+ # fine; ensures these paths are relative for all Android trees
+ # on a workstation.
+ export CCACHE_BASEDIR := /
CCACHE_HOST_TAG := $(HOST_PREBUILT_TAG)
# If we are cross-compiling Windows binaries on Linux
# then use the linux ccache binary instead.