ci: shippable: remove CCACHE_UNIFY=true
The ccache unify mode does not increase cache hits in the Shippable
build, contrary to what is claimed in commit a2a52e198719 ("ci:
shippable: enable ccache's 'unify' option"). Disable this mode,
because it is slower than the default mode [1] and might cause
corrupted builds [2].
Unify mode was enabled in the above commit, but that commit also set
CFG_DEBUG_INFO=n. It was in fact this configuration flag that allowed
better caching, by preventing -g3 from being added to the C flags.
With -g3, the preprocessor output contains all the macro definitions
(such as the configuration variables from config.h). Without it (or
with -g), those defines are not visible after the preprocessing stage
and therefore adding defines that do not change the actual code has no
impact and cached objects can be re-used.
$ echo '#define FOO 1' | gcc -x c -E - | grep '#define FOO 1'
$ echo '#define FOO 1' | gcc -x c -g3 -E - | grep '#define FOO 1'
#define FOO 1
[1] ccache(1) man page
[2] .incbin directive bug: https://github.com/ccache/ccache/issues/497
Signed-off-by: Jerome Forissier <jerome@forissier.org>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/.shippable.yml b/.shippable.yml
index afe136c..c6284de 100644
--- a/.shippable.yml
+++ b/.shippable.yml
@@ -13,7 +13,7 @@
- export PATH=/usr/local/bin:$PATH # clang
- export CROSS_COMPILE32="ccache arm-linux-gnueabihf-"
- export CROSS_COMPILE64="ccache aarch64-linux-gnu-"
- - export CFG_DEBUG_INFO=n; export CCACHE_UNIFY=true
+ - export CFG_DEBUG_INFO=n
- export CFG_WERROR=y
- function _make() { make -j$(getconf _NPROCESSORS_ONLN) -s O=out $* && ccache -s && ccache -z; }
- ccache -z
